Carbonated silicate melts transport oxidized carbon from the deep to shallow mantle,and thus play an important role in the deep carbon cycle.However,it is unclear how carbonated silicate melts are formed.Here,we repor...Carbonated silicate melts transport oxidized carbon from the deep to shallow mantle,and thus play an important role in the deep carbon cycle.However,it is unclear how carbonated silicate melts are formed.Here,we report whole-rock major and trace element,and Mg-Zn-Fe isotope,and in situ olivine and clinopyroxene Mg isotope data for peridotites and pyroxenites in Cenozoic alkaline basalts from Shulan and Yitong,Northeast China,to reveal the formation mechanisms of carbonated silicate melts.As residues of the primitive mantle,most of the Shulan and Yitong(spinel)harzburgite and lherzolite have relatively lower δ26Mg and higher δ66Zn than the mantle values,and show LREE-enriched patterns.These features indicate that these peridotites have been modified by carbonated silicate melt,transforming them into carbonated peridotites.The Shulan websterites exhibit metasomatic textures,and most of their whole-rock and in situ δ26Mg values are lower than the mantle values,which also supports the presence of a carbonated lithospheric mantle.The Yitong cumulate orthopyroxenites,representing silica-rich melts,have lower δ26Mg and higher δ66Zn values than mantle peridotites,implying that recycled carbonate has been involved in these silica-rich melts.The Yitong cumulate wehrlites and(olivine)websterites display major element compositions similar to those of carbonated peridotite melts,coupled with low whole-rock and clinopyroxene δ26Mg values,high δ66Zn and δ57Fe values,indicating the occurrence of carbonated silicate melts.The transition from orthopyroxenites to(olivine)websterites is marked by the decreasing of their whole-rock δ26Mg,δ57Fe values and Zn/Fe ratios and increasing of their δ66Zn values,along with decreasing of their crystallization temperatures,suggesting that silica-rich melts were gradually transformed into carbonated silicate melts via continuous interaction with carbonated peridotite.Our findings demonstrate that silica-rich melts from the stagnant slab can extract carbon from pre-existing carbonated mantle within the big mantle wedge.展开更多
Efficient lubrication of magnesium alloys is a highly challenging topic in the field of tribology.In this study,magnesium silicate hydroxide(MSH)nanotubes with serpentine structures were synthesized.The tribological b...Efficient lubrication of magnesium alloys is a highly challenging topic in the field of tribology.In this study,magnesium silicate hydroxide(MSH)nanotubes with serpentine structures were synthesized.The tribological behavior of AZ91D magnesium alloy rubbed against GCr15 steel was studied under lubricating oil with surface-modified MSH nanotubes as additives.The effects of the concentration,applied load,and reciprocating frequency on the friction and wear of the AZ91D alloy were studied using an SRV-4 sliding wear tester.Results show a decrease of 18.7–68.5%in friction coefficient,and a reduction of 19.4–54.3%in wear volume of magnesium alloy can be achieved by applying the synthetic serpentine additive under different conditions.A suspension containing 0.3 wt.%MSH was most efficient in reducing wear and friction.High frequency and medium load were more conducive to improving the tribological properties of magnesium alloys.A series of beneficial physical and chemical processes occurring at the AZ91D alloy/steel interface can be used to explain friction and wear reduction based on the characterization of the morphology,chemical composition,chemical state,microstructure,and nanomechanical properties of the worn surface.The synthetic MSH,with serpentine structure and nanotube morphology,possesses excellent adsorbability,high chemical activity,and good self-lubrication and catalytic activity.Therefore,physical polishing,tribochemical reactions,and physicalchemical depositions can occur easily on the sliding contacts.A dense tribolayer with a complex composition and composite structure was formed on the worn surface.Its high hardness,good toughness and plasticity,and prominent lubricity resulted in the improvement of friction and wear,making the synthetic MSH a promising efficient oil additive for magnesium alloys under boundary and mixed lubrication.展开更多
This study aims to develop a chloride diffusion simulation method that considers the hydration microstructure and pore solution properties during the hydration of tricalcium silicate(C3S).The method combines the hydra...This study aims to develop a chloride diffusion simulation method that considers the hydration microstructure and pore solution properties during the hydration of tricalcium silicate(C3S).The method combines the hydration simulation,thermodynamic calculation,and finite element analysis to examine the effects of pore solution,including effect of electrochemical potential,effect of chemical activity,and effect of mechanical interactions between ions,on the chloride effective diffusion coefficient of hydrated C3S paste.The results indicate that the effect of electrochemical potential on chloride diffusion becomes stronger with increasing hydration age due to the increase in the content of hydrated calcium silicate;as the hydration age increases,the effect of chemical activity on chloride diffusion weakens when the number of diffusible elements decreases;the effect of mechanical interactions between ions on chloride diffusion decreases with the increase of hydration age.展开更多
Sm^(3+)-doped materials exhibit red and orange emissions in the visible light region,showing broad applica⁃tion prospects in both laser and display material fields.However,the inherent small emission and absorption cr...Sm^(3+)-doped materials exhibit red and orange emissions in the visible light region,showing broad applica⁃tion prospects in both laser and display material fields.However,the inherent small emission and absorption cross-sections of Sm^(3+)result in low luminous efficiency,posing challenges for achieving high-quality solid-state lighting.Here,the excellent white emission of Sm^(3+)doped lithium aluminum silicate(LAS)glass was realized by introducing the Ag aggregates through Ag ion exchange.Under 395 nm excitation,the Ag-doped samples exhibit significant fluo⁃rescence enhancement with color coordinates close to the equal energy white point E(0.33,0.33)and a color ren⁃dering index(CRI)of 81.8.The study reveals that the surface plasmon resonance(SPR)effect of Ag nanoparticles enhances the luminescence of Sm^(3+),while the energy transfer mechanism between Ag^(+)and Sm^(3+)also promotes fluores⁃cence enhancement.By adjusting the concentration of AgNO_(3) and the exchange time,a series of high-quality full-spectrum white light emissions were obtained,indicating that the Ag ion-exchanged Sm^(3+)-doped LAS glass has good application potential in the development of solid-state lighting devices.Moreover,variations in the excitation wave⁃length can effectively tune the emission color,further demonstrating the tunability and practicality of this material in optoelectronic applications.展开更多
A novel method for scandium recovery is proposed through high-surface area silanol-rich silica sorbents which were prepared with calcium silicate hydrate(C-S-H) as raw material.Two types of silanol-rich silica particl...A novel method for scandium recovery is proposed through high-surface area silanol-rich silica sorbents which were prepared with calcium silicate hydrate(C-S-H) as raw material.Two types of silanol-rich silica particles,i.e.,LAC-S(silica derived from acid leaching of amorphous C-S-H) and LLC-S(silica derived from acid leaching of low-crystallinity C-S-H) are obtained after calcium ions are removed from both amorphous and low-crystallinity forms of C-S-H through a facile acid leaching process(3 mol/L,25℃,24 h).(29)^Si NMR spectroscopy reveals that the proportion of silicon atoms carrying silanol groups increases from less than 43% to over 80% when silica particles are transferred from a dry state to an aqueous solution.Batch adsorption experiments were conducted to evaluate the sorption performance and selectivity of these silica sorbents toward Sc(Ⅲ).The scandium sorption capacities of LAC-S and LLC-S at an equilibrium pH of 4.2 are 174.45 and 129.57 mg/g,respectively.The separation factors(SFSc/Ln) of both silica particles exceed 1000 in the initial pH range of 3.5-5.The loaded scandium ions are recovered with 3 mol/L hydrochloric acid and the sorbents exhibit good reusability.This strategy provides an efficient and green method for recovering scandium from aqueous solutions.展开更多
The oxygen evolution reaction(OER)is regarded as the bottleneck of electrolytic water splitting.Thus,developing robust earth-abundant electrocatalysts for efficient OER has received a great deal of attention and it is...The oxygen evolution reaction(OER)is regarded as the bottleneck of electrolytic water splitting.Thus,developing robust earth-abundant electrocatalysts for efficient OER has received a great deal of attention and it is an ongoing scientific challenge.Herein,hierarchical hollow nanorods assembled with ultrathin mesoporous cobalt silicate hydroxide nanosheets(denoted as CoSi)were successfully fabricated,using the silica nanotube derived from halloysite as a sacrificial template,via a simple hydrothermal method.The resulting cobalt silicate hydroxide nanosheets stack with thicknesses∼10 nm,as confirmed by transmis-sion electron microscopy.The elaborated nanoarchitecture possesses a high specific surface area(SSA)al-lowing good exposure to the cobalt active centers exhibiting superior catalytic activity vs analogs synthe-sized using sodium silicate.Among all as-prepared CoSi samples,those synthesized at 150℃(CoSi-150)exhibited the minimum overpotential of∼347 mV at a current density of 10 mA cm^(-2).In addition,CoSi-150 also exhibited superior performance against typical cobalt-based catalysts,and its surface hydroxyl groups were beneficial for the enhancement of OER performance.Furthermore,the CoSi-150 showed ex-cellent durability and stability after the 105 s chronopotentiometry test in 1 M KOH.This design concept provides a new strategy for the low-cost preparation of high-quality cobalt water splitting electrocata-lysts.展开更多
An in-depth understanding of the hydration mechanism of tricalcium silicate is an important basis for optimizing cement strength development.In this study,the adsorption of water molecules onto the M3-C3S(001)surface ...An in-depth understanding of the hydration mechanism of tricalcium silicate is an important basis for optimizing cement strength development.In this study,the adsorption of water molecules onto the M3-C3S(001)surface at different water coverage levels(θ=1/5,2/5,3/5,4/5,and 1)was investigated using first-principles calculations.The results demonstrate that the conclusions obtained for single water molecule adsorption cannot be fully applied to multiple water molecule adsorption.The total adsorption energies become more negative with increasing water coverage,while the average adsorption energy of each water molecule becomes more positive with increasing water coverage.The water–water interactions reduce the water–surface interactions and are responsible for the anticooperative adsorption of multiple water molecules onto M3-C_(3)S(001).The formation of Ca–OH(–Ca)bonds favors the detachment of Ca from co-valent oxygen,which reveals the significant role of dissociative adsorption.This work aims to extend the water adsorption study on M3-C3S(001)from single water molecule adsorption to multiple water molecule adsorption,providing more detailed insights into the initial water reaction on the C3S surface.展开更多
Aqueous zinc-based energy storage systems offer high theoretical specific capacity,low cost,intrinsic safety,and environmental compatibility,positioning them as promising candidates for next-generation energy storage ...Aqueous zinc-based energy storage systems offer high theoretical specific capacity,low cost,intrinsic safety,and environmental compatibility,positioning them as promising candidates for next-generation energy storage and conversion technologies.However,issues such as zinc dendrite growth,hydrogen evolution reaction(HER),and surface passivation hinder their practical deployment.To address these challenges,a hollow nanotubular magnesium silicate(denoted MgSi)interfacial layer was constructed on the zinc metal anode(Zn@MgSi).The unique layer structure and negatively charged surface of MgSi facilitate the desolvation of[Zn(H_(2)O)_(6)]^(2+)by stripping water molecules,while temporarily immobilizing Zn^(2+)to suppress random diffusion.The combined effects of the electric field-guided Zn^(2+)distribution and rapid ion transport through the layer structure co-regulate Zn^(2+)flux,leading to uniform,dendrite-free zinc deposition.Consequently,the Zn@MgSi symmetric cell demonstrates a high Zn^(2+)transference number(0.64),extended cycling life exceeding 1600 h at 1 mA cm^(−2),and stable operation for 200 h at 5 mA cm^(−2).Furthermore,zinc-ion hybrid capacitors employing Zn@MgSi electrodes exhibit excellent cycling stability over 5000 cycles.This work highlights the efficacy of artificial interfacial layers in stabilizing zinc metal anodes and provides valuable insights into the development of advanced aqueous zinc-ion energy storage systems.展开更多
Heavy metal-contaminated sites are primarily treated via solidification and adsorption.Calcium silicate hydrate(C-S-H)is generated during the soil stabilization process and contributes significantly to the strength an...Heavy metal-contaminated sites are primarily treated via solidification and adsorption.Calcium silicate hydrate(C-S-H)is generated during the soil stabilization process and contributes significantly to the strength and durability of the stabilized soil.To understand how the soil moisture content and heavy metal concentration affect the transport of heavy metals and the tensile strength of C-S-H,this study performed molecular dynamics(MD)simulations under different moisture and concentration levels.The results showed that Pb2+presented the highest adsorption to the surface of C-S-H due to its strong electrostatic interaction energy.The adsorption density peaks of Pb2+were 1.5–5 times greater than those of Cd2+and Zn2+.Zn2+and Cd2+ions were more likely to be adsorbed onto water molecules and form a larger hydrated radius than Pb2+.The adsorption of heavy metals onto C-S-H initially increased as the metal concentration increased and then decreased because of the limited sorption sites on C-S-H.The diffusion coefficients of the multicomponent metals in C-S-H showed no consistent trends.The maximum tensile strength of C-S-H decreased with increasing soil moisture and heavy metal concentrations.The tensile stress increased approximately linearly with strain until it reached a peak,after which it gradually declined but remained above zero,indicating good ductility and toughness under unsaturated conditions.These findings offer valuable molecular insights into the interactions between C-S-H and heavy metals and soil moisture,thereby advancing our understanding of their combined effects on soil stabilization.展开更多
The emission wavelength of current near-infrared phosphors activated by Cr^(3+)is generally smaller than 900 nm in near-infrared(NIR)Ⅰ region,and it is extremely challenging and is of great practical significance to ...The emission wavelength of current near-infrared phosphors activated by Cr^(3+)is generally smaller than 900 nm in near-infrared(NIR)Ⅰ region,and it is extremely challenging and is of great practical significance to realize emission towards NIR-Ⅱ region.In this study,a novel Cr^(3+)excited KSrScSi_(2)O_(7)silicate broad-band phosphor was prepared using the traditional solid-state method.Cr^(3+)resides in a weak crystal field in the KSrScSi_(2)O_(7)lattice and exhibits broad-band near-infrared emission at 984 nm,longer than those of most Cr^(3+)activated phosphors,under 493 nm blue light excitation.This is due to the stro ng charge polarization caused by the unique local coordination environment of the silicate matrix,which leads to a reduction in the crystal field splitting energy of the[ScO_(6)]octahedron where Cr^(3+)is located and the downward shift of the^(4)T_(2)energy level.The optimal doping concentration of Cr^(3+)is found to be 2 mol%,and the quenching mechanism is dipole-dipole interaction.Compared to the phosphors with similar emission wavelengths(λ_(em)>900 nm),KSrScSi_(2)O_(7):Cr^(3+)demonstrates outstanding advantages in various aspects of luminescent performance.The fabricated phosphor-converted light-emitting diode(pc-LED)is shown to have the potential for night vision and non-invasive imaging.Novel application of KSrScSi_(2)O_(7):xCr^(3+)as stable green ceramic pigments is also explored.The KSrScSi_(2)O_(7):xCr^(3+)powders show a bright yellowish green appearance,and the KSrScSi_(2)O_(7):0.02Cr^(3+)typical composition has chromaticity values of L^(*)=82.73,a^(*)=-8.53,b^(*)=7.97.Remarkably,the glazing samples using KSrScSi_(2)O_(7):xCr^(3+)as pigments well retain the bright color after 1200℃sintering in different atmospheres.Therefore,multifunctional applications of KSrScSi_(2)O_(7):xCr^(3+)for near-infrared spectroscopy and as ceramic pigments are achieved in this work.展开更多
The leaching kinetics of zinc silicate in ammonium chloride solution was investigated. The effects of stirring speed （150？400 r/min）, leaching temperature （95-108 ℃, particle size of zinc silicate （61-150 μm...The leaching kinetics of zinc silicate in ammonium chloride solution was investigated. The effects of stirring speed （150？400 r/min）, leaching temperature （95-108 ℃, particle size of zinc silicate （61-150 μm） and the concentration of ammonium chloride （3.5-5.5 mol/L） on leaching rate of zinc were studied. The results show that decreasing the particle size of zinc silicate and increasing the leaching temperature and concentration of ammonium chloride can obviously enhance the leaching rate of zinc. Among the kinetic models of the porous solids tested, the grain model with porous diffusion control can well describe the zinc leaching kinetics. The apparent activation energy of the leaching reaction is 161.26 kJ/mol and the reaction order with respect to ammonium chloride is 3.5.展开更多
The adsorption isotherm of sodium polyacrylate on dicalcium silicate（2CaO-SiO2） in sodium aluminate solution at 80 ℃ was studied.The type of surface adsorption of sodium polyacrylate is saturated adsorption,and the...The adsorption isotherm of sodium polyacrylate on dicalcium silicate（2CaO-SiO2） in sodium aluminate solution at 80 ℃ was studied.The type of surface adsorption of sodium polyacrylate is saturated adsorption,and the adsorption behavior belongs to L-type,according with the monolayer adsorption model of Langmuir equation.The surface coverage of sodium polyacrylate is 1.06 mol/μm2.The relation curve between the surface pressure and the molecular area of adsorption film was obtained by Gibbs formula.The variation of interfacial energy caused by adsorption as well as the relationship between the relation curve and the type of adsorption was discussed.展开更多
Silicate sol post-treatment was applied to form a complete composite coating on the phosphated zinc layer. The chemical compositions of the coatings were investigated using XPS. The coated samples were firstly scratch...Silicate sol post-treatment was applied to form a complete composite coating on the phosphated zinc layer. The chemical compositions of the coatings were investigated using XPS. The coated samples were firstly scratched and then exposed to the neutral salt spray(NSS) chamber for different time. The microstructure and chemical compositions of the scratches were studied using SEM and EDS. And the non-scratched coated samples were compared. The self-healing mechanism of the composite coatings was discussed. The results show that during corrosion, the self-healing ions in composite coatings dissolve, diffuse and transfer to the scratches or the defects, and then recombine with Zn2+ to form insoluble compound, which deposits and covers the exposed zinc. The corrosion products on the scratches contain silicon, phosphorous, oxygen, chloride and zinc, and they are compact, fine, needle and flake, effectively inhibiting the corrosion formation and expansion of the exposed zinc layer. The composite coatings have good self-healing ability.展开更多
The influences of sodium silicate on manganese electrodeposition in sulfate solution were investigated. Manganese electrodeposition experiments indicate that a certain amount of sodium silicate can improve cathode cur...The influences of sodium silicate on manganese electrodeposition in sulfate solution were investigated. Manganese electrodeposition experiments indicate that a certain amount of sodium silicate can improve cathode current efficiency and initial pH 7.0?8.0 is the optimized pH for high cathode current efficiency. The analyses of scanning electron microscopy (SEM) and X-ray diffraction (XRD) indicate the compact morphology and nanocrystalline structure of electrodeposits. X-ray photoelectron spectrometry (XPS) analysis shows that the elements of Mn, Si and O exist in the deposit. The solution chemistry calculations of sulfate electrolyte and sodium silicate solution indicate that species of Mn2+, MnSO4, Mn(SO4)2?2 , Mn2+, MnSiO3, Mn(NH3)2+, SiO32?and HSiO3? are the main active species during the process of manganese electrodeposition. The reaction trend between Mn2+ and Si-containing ions is confirmed by the thermodynamic analysis. In addition, polarization curve tests confirm that sodium silicate can increase the overpotential of hydrogen evolution reaction, and then indirectly improve the cathode current efficiency.展开更多
The distributions of local structural units of calcium silicate melts were quantified by means of classical molecular dynamics simulation and a newly constructed structural thermodynamic model. The distribution of fiv...The distributions of local structural units of calcium silicate melts were quantified by means of classical molecular dynamics simulation and a newly constructed structural thermodynamic model. The distribution of five kinds of Si-O tetrahedra Qi from these two methods was compared with each other and also with the experimental Raman spectra, an excellent agreement was achieved. These not only displayed the panorama distribution of microstructural units in the whole composition range, but also proved that the thermodynamic model is suitable for the utilization as the subsequent application model of spectral experiments for the thermodynamic calculation. Meanwhile, the five refined regions mastered by different disproportionating reactions were obtained. Finally, the distributions of two kinds of connections between Qi were obtained, denoted as Qi-Ca-Qj and Qi-[Ob]-Qj, from the thermodynamic model, and a theoretical verification was given that the dominant connections for any composition are equivalent connections.展开更多
Carbon(C)sequestered in the mantle andcrust over geological timescales accounts for more than 99% of allcarbon in the bulk silicate Earth and plays a fundamental role in driving surface biogeochemical cycles,which inv...Carbon(C)sequestered in the mantle andcrust over geological timescales accounts for more than 99% of allcarbon in the bulk silicate Earth and plays a fundamental role in driving surface biogeochemical cycles,which involve only a tiny fraction of Earth's total carbon inventory[1].In addition to CO_(2) released through near surface weathering of sedimentary rocks[2],a substantial,butstill poorly quantified,amount of carbon in the deeper crust and mantle(hereafter referred to as deeply-sourced carbon)could be mobilized by magmatism and metamorphism and then outgassed in volcanic and non-volcanic settings.展开更多
The aim of the present work was to produce a polyaluminium ferric silicate chloride （PAFSiC） coagulant from acidic and alkaline wastewater of purifying graphite by roasting, and subsequently to evaluate coagulation ...The aim of the present work was to produce a polyaluminium ferric silicate chloride （PAFSiC） coagulant from acidic and alkaline wastewater of purifying graphite by roasting, and subsequently to evaluate coagulation efficiency of the reagent by treating surface water from the Yellow River as well as municipal wastewater in comparison with the conventional coagulant polyaluminium chloride （PAC）. The PAFSiC coagulant was prepared by co-polymerization. The effects of （Al＋Fe）/Si molar ratio, OH/（Al＋Fe） molar ratio （i.e., γ value）, coagulant dosage and pH value of test suspension on the coagulation behavior of FAFSiC and the stability of the PAFSiC were also examined. Results showed that PAFSiC performed more efficiently than PAC in removing turbidity, chemical oxygen demand （COD）, and total phosphate （TP）. The PAFSiC with a γ value of 2.0 and （Al＋Fe）/Si ratio of 5 （PAFSiC 2.0/5） showed excellent coagulation effect for both turbidity and COD, while PAFSiC 1.0/5 was the best for TP. The optimum coagulation pH range of PAFSiC 2.0/5 was 5.0–9.0, slightly wider than that of PAC （6.0–8.0）. The process can be easily incorporated into high-purity graphite production plants, thereby reducing wastewater pollution and producing a valuable coagulant.展开更多
Analysis and comparison of Jiaozhou Bay data collected from May 1991 to February 1994(12 seasonal investigations) provided by the Ecological Station of Jiaozhou Bay revealed the characteristic spatiotemporal variation...Analysis and comparison of Jiaozhou Bay data collected from May 1991 to February 1994(12 seasonal investigations) provided by the Ecological Station of Jiaozhou Bay revealed the characteristic spatiotemporal variation of the ambient concentration Si:DIN and Si:16P ratios and the seasonal variation of Jiaozhou Bay Si:DIN and Si:16P ratios showing that the Si:DIN ratios were < 1 throughout the year in Jiaozhou Bay; and that the Si:16P ratios were < 1 throughout Jiaozhou Bay in spring, autumn and winter. The results proved that silicate limited phytoplankton growth in spring, autumn and winter in Jiaozhou Bay. Analysis of the Si:DIN and Si:P ratios showed that the nutrient Si has been limiting the growth of phytoplankton throughout the year in some Jiaozhou Bay waters; and that the silicate deficiency changed the phytoplankton assemblage structure. Analysis of discontinuous 1962 to 1998 nutrient data showed that there was no N or P limitation of phytoplankton growth in that period. The authors consider that the annual cyclic change of silicate limits phytoplankton growth in spring, autumn and winter every year in Jiaozhou Bay; and that in many Jiaozhou Bay waters where the phytoplankton as the predominant species need a great amount of silicate, analysis of the nutrients N or P limitation of phytoplankton growth relying only on the N and P nutrients and DIN:P ratio could yield inaccurate conclusions. The results obtained by applying the rules of absolute and relative limitation fully support this view. The authors consider that the main function of nutrient silicon is to regulate and control the mechanism of the phytoplankton growth process in the ecological system in estuaries, bays and the sea. The authors consider that according to the evolution theory of Darwin, continuous environmental pressure gradually changes the phytoplankton assemblage's structure and the physiology of diatoms. Diatoms requiring a great deal of silicon either constantly decrease or reduce their requirement for silicon. This will cause a series of huge changes in the ecosystem so that the whole ecosystem requires continuous renewal, change and balancing. Human beings have to reduce marine pollution and enhance the capacity of continental sources to transport silicon to sustain the continuity and stability in the marine ecosystem.nt展开更多
The electrochemical mechanism involved in the selective separation of chalcopyrite from galena was investigated by flotation and electrochemical methods in the presence of sodium sulfite and sodium silicate,respective...The electrochemical mechanism involved in the selective separation of chalcopyrite from galena was investigated by flotation and electrochemical methods in the presence of sodium sulfite and sodium silicate,respectively,as a single depressant and their mixture as a combined depressant.Flotation tests revealed that the floatability of chalcopyrite was unaffected by depressants and its recovery remained constant(>80%)within the studied dosage range.Galena flotation was severely depressed with descending depressing order as follows:combined depressant﹥sodium silicate﹥sodium sulfite.Electrochemical analysis confirmed the high affinity of depressants on the galena surface,resulting in the formation of hydrophilic species,such as lead sulfite,lead sulfate,and lead orthosilicate.The oxidation of chalcopyrite surface and depressants did not exhibit any signals;conversely,the self-oxidation of chalcopyrite was depressed.The results of cyclic voltammograms well agreed with flotation results,demonstrating that chalcopyrite primarily reacted with the collector O-isopropyl-N-ethyl thionocarbamate and that galena mostly reacted with depressants.展开更多
Batch adsorption from aqueous solutions in a slightly basic medium of Methylene Blue, up to 2500 mg/L, onto synthetic magnesium silicate （Florisil） of three particle size ranges （mean diameters of 112, 200 and 425 ...Batch adsorption from aqueous solutions in a slightly basic medium of Methylene Blue, up to 2500 mg/L, onto synthetic magnesium silicate （Florisil） of three particle size ranges （mean diameters of 112, 200 and 425 μm） was compared to the corresponding adsorption onto activated carbon and Amberlite XAD-2. The best fit of the kinetic results was achieved by a pseudo second-order equation. The equilibrium data were found to be well represented by the Langmuir isotherm equation. Amberlite XAD-2, an unspecific adsorbent capable of adsorbing exclusively through a surface effect, exhibited a poor dye uptake, confirming that the adsorption mechanism on Florisil was due to electrostatic attraction and ion exchange. Moreover, the comparison between Florisil and the other adsorbents was performed on the basis of the evaluation of the surface area and pore volume occupied by the adsorbed dye.展开更多
基金financially supported by the National Natural Science Foundation of China(Grants Nos.42572064 and 42422203)the Program for Jilin University Science and Technology Innovative Research Team(Grant No.2021-TD-05)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.45124031D045)the Graduate Innovation Fund of Jilin University.
文摘Carbonated silicate melts transport oxidized carbon from the deep to shallow mantle,and thus play an important role in the deep carbon cycle.However,it is unclear how carbonated silicate melts are formed.Here,we report whole-rock major and trace element,and Mg-Zn-Fe isotope,and in situ olivine and clinopyroxene Mg isotope data for peridotites and pyroxenites in Cenozoic alkaline basalts from Shulan and Yitong,Northeast China,to reveal the formation mechanisms of carbonated silicate melts.As residues of the primitive mantle,most of the Shulan and Yitong(spinel)harzburgite and lherzolite have relatively lower δ26Mg and higher δ66Zn than the mantle values,and show LREE-enriched patterns.These features indicate that these peridotites have been modified by carbonated silicate melt,transforming them into carbonated peridotites.The Shulan websterites exhibit metasomatic textures,and most of their whole-rock and in situ δ26Mg values are lower than the mantle values,which also supports the presence of a carbonated lithospheric mantle.The Yitong cumulate orthopyroxenites,representing silica-rich melts,have lower δ26Mg and higher δ66Zn values than mantle peridotites,implying that recycled carbonate has been involved in these silica-rich melts.The Yitong cumulate wehrlites and(olivine)websterites display major element compositions similar to those of carbonated peridotite melts,coupled with low whole-rock and clinopyroxene δ26Mg values,high δ66Zn and δ57Fe values,indicating the occurrence of carbonated silicate melts.The transition from orthopyroxenites to(olivine)websterites is marked by the decreasing of their whole-rock δ26Mg,δ57Fe values and Zn/Fe ratios and increasing of their δ66Zn values,along with decreasing of their crystallization temperatures,suggesting that silica-rich melts were gradually transformed into carbonated silicate melts via continuous interaction with carbonated peridotite.Our findings demonstrate that silica-rich melts from the stagnant slab can extract carbon from pre-existing carbonated mantle within the big mantle wedge.
基金support from the National Natural Science Foundation of China(grant number 52075544)Innovation Funds of Jihua Laboratory(X220971UZ230)+1 种基金Basic and Applied Basic Research Foundation of Guangdong Province(2022A1515110649)Funds from Research Platforms of Guangdong Higher Education Institutes(2022ZDJS038).
文摘Efficient lubrication of magnesium alloys is a highly challenging topic in the field of tribology.In this study,magnesium silicate hydroxide(MSH)nanotubes with serpentine structures were synthesized.The tribological behavior of AZ91D magnesium alloy rubbed against GCr15 steel was studied under lubricating oil with surface-modified MSH nanotubes as additives.The effects of the concentration,applied load,and reciprocating frequency on the friction and wear of the AZ91D alloy were studied using an SRV-4 sliding wear tester.Results show a decrease of 18.7–68.5%in friction coefficient,and a reduction of 19.4–54.3%in wear volume of magnesium alloy can be achieved by applying the synthetic serpentine additive under different conditions.A suspension containing 0.3 wt.%MSH was most efficient in reducing wear and friction.High frequency and medium load were more conducive to improving the tribological properties of magnesium alloys.A series of beneficial physical and chemical processes occurring at the AZ91D alloy/steel interface can be used to explain friction and wear reduction based on the characterization of the morphology,chemical composition,chemical state,microstructure,and nanomechanical properties of the worn surface.The synthetic MSH,with serpentine structure and nanotube morphology,possesses excellent adsorbability,high chemical activity,and good self-lubrication and catalytic activity.Therefore,physical polishing,tribochemical reactions,and physicalchemical depositions can occur easily on the sliding contacts.A dense tribolayer with a complex composition and composite structure was formed on the worn surface.Its high hardness,good toughness and plasticity,and prominent lubricity resulted in the improvement of friction and wear,making the synthetic MSH a promising efficient oil additive for magnesium alloys under boundary and mixed lubrication.
基金Funded by the Natural Science Foundation of Jiangsu Province(No.BK20241529)China Postdoctoral Science Foundation(No.2024M750736)。
文摘This study aims to develop a chloride diffusion simulation method that considers the hydration microstructure and pore solution properties during the hydration of tricalcium silicate(C3S).The method combines the hydration simulation,thermodynamic calculation,and finite element analysis to examine the effects of pore solution,including effect of electrochemical potential,effect of chemical activity,and effect of mechanical interactions between ions,on the chloride effective diffusion coefficient of hydrated C3S paste.The results indicate that the effect of electrochemical potential on chloride diffusion becomes stronger with increasing hydration age due to the increase in the content of hydrated calcium silicate;as the hydration age increases,the effect of chemical activity on chloride diffusion weakens when the number of diffusible elements decreases;the effect of mechanical interactions between ions on chloride diffusion decreases with the increase of hydration age.
文摘Sm^(3+)-doped materials exhibit red and orange emissions in the visible light region,showing broad applica⁃tion prospects in both laser and display material fields.However,the inherent small emission and absorption cross-sections of Sm^(3+)result in low luminous efficiency,posing challenges for achieving high-quality solid-state lighting.Here,the excellent white emission of Sm^(3+)doped lithium aluminum silicate(LAS)glass was realized by introducing the Ag aggregates through Ag ion exchange.Under 395 nm excitation,the Ag-doped samples exhibit significant fluo⁃rescence enhancement with color coordinates close to the equal energy white point E(0.33,0.33)and a color ren⁃dering index(CRI)of 81.8.The study reveals that the surface plasmon resonance(SPR)effect of Ag nanoparticles enhances the luminescence of Sm^(3+),while the energy transfer mechanism between Ag^(+)and Sm^(3+)also promotes fluores⁃cence enhancement.By adjusting the concentration of AgNO_(3) and the exchange time,a series of high-quality full-spectrum white light emissions were obtained,indicating that the Ag ion-exchanged Sm^(3+)-doped LAS glass has good application potential in the development of solid-state lighting devices.Moreover,variations in the excitation wave⁃length can effectively tune the emission color,further demonstrating the tunability and practicality of this material in optoelectronic applications.
基金Project supported by the National Natural Science Foundation of China (52064002)Guangxi Science and Technology Major Project(AA23073018)。
文摘A novel method for scandium recovery is proposed through high-surface area silanol-rich silica sorbents which were prepared with calcium silicate hydrate(C-S-H) as raw material.Two types of silanol-rich silica particles,i.e.,LAC-S(silica derived from acid leaching of amorphous C-S-H) and LLC-S(silica derived from acid leaching of low-crystallinity C-S-H) are obtained after calcium ions are removed from both amorphous and low-crystallinity forms of C-S-H through a facile acid leaching process(3 mol/L,25℃,24 h).(29)^Si NMR spectroscopy reveals that the proportion of silicon atoms carrying silanol groups increases from less than 43% to over 80% when silica particles are transferred from a dry state to an aqueous solution.Batch adsorption experiments were conducted to evaluate the sorption performance and selectivity of these silica sorbents toward Sc(Ⅲ).The scandium sorption capacities of LAC-S and LLC-S at an equilibrium pH of 4.2 are 174.45 and 129.57 mg/g,respectively.The separation factors(SFSc/Ln) of both silica particles exceed 1000 in the initial pH range of 3.5-5.The loaded scandium ions are recovered with 3 mol/L hydrochloric acid and the sorbents exhibit good reusability.This strategy provides an efficient and green method for recovering scandium from aqueous solutions.
基金supported by the Central Government Guiding Local Science and Technology Development Fund Projects(No.236Z4108G)China Scholarship Council,the National Natu-ral Science Foundation of China(No.51874115)+2 种基金the Open Project of State Key Laboratory of Environment-friendly Energy Materials(No.22kfhg09)the Open Project of Key Laboratory of Solid Waste Treatment and Resource Recycle of Ministry of Education(No.22kfgk01)the Youth Talent Support Program of Hebei Province,the Giant Plan Innovation Team Project of Hebei Province,and the Excellent Young Scientist Foundation of Hebei province,China(No.E2018202241).
文摘The oxygen evolution reaction(OER)is regarded as the bottleneck of electrolytic water splitting.Thus,developing robust earth-abundant electrocatalysts for efficient OER has received a great deal of attention and it is an ongoing scientific challenge.Herein,hierarchical hollow nanorods assembled with ultrathin mesoporous cobalt silicate hydroxide nanosheets(denoted as CoSi)were successfully fabricated,using the silica nanotube derived from halloysite as a sacrificial template,via a simple hydrothermal method.The resulting cobalt silicate hydroxide nanosheets stack with thicknesses∼10 nm,as confirmed by transmis-sion electron microscopy.The elaborated nanoarchitecture possesses a high specific surface area(SSA)al-lowing good exposure to the cobalt active centers exhibiting superior catalytic activity vs analogs synthe-sized using sodium silicate.Among all as-prepared CoSi samples,those synthesized at 150℃(CoSi-150)exhibited the minimum overpotential of∼347 mV at a current density of 10 mA cm^(-2).In addition,CoSi-150 also exhibited superior performance against typical cobalt-based catalysts,and its surface hydroxyl groups were beneficial for the enhancement of OER performance.Furthermore,the CoSi-150 showed ex-cellent durability and stability after the 105 s chronopotentiometry test in 1 M KOH.This design concept provides a new strategy for the low-cost preparation of high-quality cobalt water splitting electrocata-lysts.
基金supported by the Young Elite Scientists Sponsorship Program by CAST(No.2023QNRC001)Natural Science Foundation of Hunan Province,China(No.2024JJ2074)supported in part by the High Performance Computing Center of Central South University,China and the Pawsey Supercomputing Centre with funding from the Australian Government and the Government of Western Australia.
文摘An in-depth understanding of the hydration mechanism of tricalcium silicate is an important basis for optimizing cement strength development.In this study,the adsorption of water molecules onto the M3-C3S(001)surface at different water coverage levels(θ=1/5,2/5,3/5,4/5,and 1)was investigated using first-principles calculations.The results demonstrate that the conclusions obtained for single water molecule adsorption cannot be fully applied to multiple water molecule adsorption.The total adsorption energies become more negative with increasing water coverage,while the average adsorption energy of each water molecule becomes more positive with increasing water coverage.The water–water interactions reduce the water–surface interactions and are responsible for the anticooperative adsorption of multiple water molecules onto M3-C_(3)S(001).The formation of Ca–OH(–Ca)bonds favors the detachment of Ca from co-valent oxygen,which reveals the significant role of dissociative adsorption.This work aims to extend the water adsorption study on M3-C3S(001)from single water molecule adsorption to multiple water molecule adsorption,providing more detailed insights into the initial water reaction on the C3S surface.
基金the Doctoral Research Startup Fund of Hubei University of Science and Technology(Grant No.BK202504)the Natural Science Foundation of Liaoning Province(Grant No.2023-MS-115).
文摘Aqueous zinc-based energy storage systems offer high theoretical specific capacity,low cost,intrinsic safety,and environmental compatibility,positioning them as promising candidates for next-generation energy storage and conversion technologies.However,issues such as zinc dendrite growth,hydrogen evolution reaction(HER),and surface passivation hinder their practical deployment.To address these challenges,a hollow nanotubular magnesium silicate(denoted MgSi)interfacial layer was constructed on the zinc metal anode(Zn@MgSi).The unique layer structure and negatively charged surface of MgSi facilitate the desolvation of[Zn(H_(2)O)_(6)]^(2+)by stripping water molecules,while temporarily immobilizing Zn^(2+)to suppress random diffusion.The combined effects of the electric field-guided Zn^(2+)distribution and rapid ion transport through the layer structure co-regulate Zn^(2+)flux,leading to uniform,dendrite-free zinc deposition.Consequently,the Zn@MgSi symmetric cell demonstrates a high Zn^(2+)transference number(0.64),extended cycling life exceeding 1600 h at 1 mA cm^(−2),and stable operation for 200 h at 5 mA cm^(−2).Furthermore,zinc-ion hybrid capacitors employing Zn@MgSi electrodes exhibit excellent cycling stability over 5000 cycles.This work highlights the efficacy of artificial interfacial layers in stabilizing zinc metal anodes and provides valuable insights into the development of advanced aqueous zinc-ion energy storage systems.
基金supported by the National Natural Science Foundation of China(Grant Nos.42030710 and 52308345)the National Key Research and Development Program of China(Grant No.2023YFC3707903).
文摘Heavy metal-contaminated sites are primarily treated via solidification and adsorption.Calcium silicate hydrate(C-S-H)is generated during the soil stabilization process and contributes significantly to the strength and durability of the stabilized soil.To understand how the soil moisture content and heavy metal concentration affect the transport of heavy metals and the tensile strength of C-S-H,this study performed molecular dynamics(MD)simulations under different moisture and concentration levels.The results showed that Pb2+presented the highest adsorption to the surface of C-S-H due to its strong electrostatic interaction energy.The adsorption density peaks of Pb2+were 1.5–5 times greater than those of Cd2+and Zn2+.Zn2+and Cd2+ions were more likely to be adsorbed onto water molecules and form a larger hydrated radius than Pb2+.The adsorption of heavy metals onto C-S-H initially increased as the metal concentration increased and then decreased because of the limited sorption sites on C-S-H.The diffusion coefficients of the multicomponent metals in C-S-H showed no consistent trends.The maximum tensile strength of C-S-H decreased with increasing soil moisture and heavy metal concentrations.The tensile stress increased approximately linearly with strain until it reached a peak,after which it gradually declined but remained above zero,indicating good ductility and toughness under unsaturated conditions.These findings offer valuable molecular insights into the interactions between C-S-H and heavy metals and soil moisture,thereby advancing our understanding of their combined effects on soil stabilization.
基金Project supported by the Natural Science Foundation of The Educational Department of Liaoning Province(JYTMS20231627)。
文摘The emission wavelength of current near-infrared phosphors activated by Cr^(3+)is generally smaller than 900 nm in near-infrared(NIR)Ⅰ region,and it is extremely challenging and is of great practical significance to realize emission towards NIR-Ⅱ region.In this study,a novel Cr^(3+)excited KSrScSi_(2)O_(7)silicate broad-band phosphor was prepared using the traditional solid-state method.Cr^(3+)resides in a weak crystal field in the KSrScSi_(2)O_(7)lattice and exhibits broad-band near-infrared emission at 984 nm,longer than those of most Cr^(3+)activated phosphors,under 493 nm blue light excitation.This is due to the stro ng charge polarization caused by the unique local coordination environment of the silicate matrix,which leads to a reduction in the crystal field splitting energy of the[ScO_(6)]octahedron where Cr^(3+)is located and the downward shift of the^(4)T_(2)energy level.The optimal doping concentration of Cr^(3+)is found to be 2 mol%,and the quenching mechanism is dipole-dipole interaction.Compared to the phosphors with similar emission wavelengths(λ_(em)>900 nm),KSrScSi_(2)O_(7):Cr^(3+)demonstrates outstanding advantages in various aspects of luminescent performance.The fabricated phosphor-converted light-emitting diode(pc-LED)is shown to have the potential for night vision and non-invasive imaging.Novel application of KSrScSi_(2)O_(7):xCr^(3+)as stable green ceramic pigments is also explored.The KSrScSi_(2)O_(7):xCr^(3+)powders show a bright yellowish green appearance,and the KSrScSi_(2)O_(7):0.02Cr^(3+)typical composition has chromaticity values of L^(*)=82.73,a^(*)=-8.53,b^(*)=7.97.Remarkably,the glazing samples using KSrScSi_(2)O_(7):xCr^(3+)as pigments well retain the bright color after 1200℃sintering in different atmospheres.Therefore,multifunctional applications of KSrScSi_(2)O_(7):xCr^(3+)for near-infrared spectroscopy and as ceramic pigments are achieved in this work.
基金Project(2014CB643404)supported by the National Basic Research Program of ChinaProject(51374254)supported by the National Natural Science Foundation of China
文摘The leaching kinetics of zinc silicate in ammonium chloride solution was investigated. The effects of stirring speed （150？400 r/min）, leaching temperature （95-108 ℃, particle size of zinc silicate （61-150 μm） and the concentration of ammonium chloride （3.5-5.5 mol/L） on leaching rate of zinc were studied. The results show that decreasing the particle size of zinc silicate and increasing the leaching temperature and concentration of ammonium chloride can obviously enhance the leaching rate of zinc. Among the kinetic models of the porous solids tested, the grain model with porous diffusion control can well describe the zinc leaching kinetics. The apparent activation energy of the leaching reaction is 161.26 kJ/mol and the reaction order with respect to ammonium chloride is 3.5.
基金Project(50974036)supported by the National Natural Science Foundation of China
文摘The adsorption isotherm of sodium polyacrylate on dicalcium silicate（2CaO-SiO2） in sodium aluminate solution at 80 ℃ was studied.The type of surface adsorption of sodium polyacrylate is saturated adsorption,and the adsorption behavior belongs to L-type,according with the monolayer adsorption model of Langmuir equation.The surface coverage of sodium polyacrylate is 1.06 mol/μm2.The relation curve between the surface pressure and the molecular area of adsorption film was obtained by Gibbs formula.The variation of interfacial energy caused by adsorption as well as the relationship between the relation curve and the type of adsorption was discussed.
基金Project(2012J05099)supported by the Natural Science Foundation of Fujian Province,ChinaProject(YKJ10021R)supported by the Scientific Research Project of Xiamen University of Technology
文摘Silicate sol post-treatment was applied to form a complete composite coating on the phosphated zinc layer. The chemical compositions of the coatings were investigated using XPS. The coated samples were firstly scratched and then exposed to the neutral salt spray(NSS) chamber for different time. The microstructure and chemical compositions of the scratches were studied using SEM and EDS. And the non-scratched coated samples were compared. The self-healing mechanism of the composite coatings was discussed. The results show that during corrosion, the self-healing ions in composite coatings dissolve, diffuse and transfer to the scratches or the defects, and then recombine with Zn2+ to form insoluble compound, which deposits and covers the exposed zinc. The corrosion products on the scratches contain silicon, phosphorous, oxygen, chloride and zinc, and they are compact, fine, needle and flake, effectively inhibiting the corrosion formation and expansion of the exposed zinc layer. The composite coatings have good self-healing ability.
基金Project(2015BAB17B01)supported by the National Science and Technology Support Program of ChinaProject(21376273)supported by the National Natural Science Foundation of China
文摘The influences of sodium silicate on manganese electrodeposition in sulfate solution were investigated. Manganese electrodeposition experiments indicate that a certain amount of sodium silicate can improve cathode current efficiency and initial pH 7.0?8.0 is the optimized pH for high cathode current efficiency. The analyses of scanning electron microscopy (SEM) and X-ray diffraction (XRD) indicate the compact morphology and nanocrystalline structure of electrodeposits. X-ray photoelectron spectrometry (XPS) analysis shows that the elements of Mn, Si and O exist in the deposit. The solution chemistry calculations of sulfate electrolyte and sodium silicate solution indicate that species of Mn2+, MnSO4, Mn(SO4)2?2 , Mn2+, MnSiO3, Mn(NH3)2+, SiO32?and HSiO3? are the main active species during the process of manganese electrodeposition. The reaction trend between Mn2+ and Si-containing ions is confirmed by the thermodynamic analysis. In addition, polarization curve tests confirm that sodium silicate can increase the overpotential of hydrogen evolution reaction, and then indirectly improve the cathode current efficiency.
基金Project(2012CB722805)supported by the National Basic Research Program of ChinaProjects(50504010,50974083,51174131,51374141)supported by the National Natural Science Foundation of China+1 种基金Project(50774112)supported by the Joint Fund of NSFC and Baosteel,ChinaProject(07QA4021)supported by the Shanghai"Phosphor"Science Foundation,China
文摘The distributions of local structural units of calcium silicate melts were quantified by means of classical molecular dynamics simulation and a newly constructed structural thermodynamic model. The distribution of five kinds of Si-O tetrahedra Qi from these two methods was compared with each other and also with the experimental Raman spectra, an excellent agreement was achieved. These not only displayed the panorama distribution of microstructural units in the whole composition range, but also proved that the thermodynamic model is suitable for the utilization as the subsequent application model of spectral experiments for the thermodynamic calculation. Meanwhile, the five refined regions mastered by different disproportionating reactions were obtained. Finally, the distributions of two kinds of connections between Qi were obtained, denoted as Qi-Ca-Qj and Qi-[Ob]-Qj, from the thermodynamic model, and a theoretical verification was given that the dominant connections for any composition are equivalent connections.
基金supported by the National Key Research and Development Program of China(2020YFA0607700)the National Natural Science Foundation of China(41930642 and 42522211).
文摘Carbon(C)sequestered in the mantle andcrust over geological timescales accounts for more than 99% of allcarbon in the bulk silicate Earth and plays a fundamental role in driving surface biogeochemical cycles,which involve only a tiny fraction of Earth's total carbon inventory[1].In addition to CO_(2) released through near surface weathering of sedimentary rocks[2],a substantial,butstill poorly quantified,amount of carbon in the deeper crust and mantle(hereafter referred to as deeply-sourced carbon)could be mobilized by magmatism and metamorphism and then outgassed in volcanic and non-volcanic settings.
基金supported by the National Natural Science Foundation of China (No. 20971112)the Major Public Service Project of Henan Province (No. 101100910300)+1 种基金the Natural Science Research Pro- gram of Education Department in Henan Province (No. 2011A610012)the Science and Technology Program of Zhengzhou City (No. 10PTGG339-4)
文摘The aim of the present work was to produce a polyaluminium ferric silicate chloride （PAFSiC） coagulant from acidic and alkaline wastewater of purifying graphite by roasting, and subsequently to evaluate coagulation efficiency of the reagent by treating surface water from the Yellow River as well as municipal wastewater in comparison with the conventional coagulant polyaluminium chloride （PAC）. The PAFSiC coagulant was prepared by co-polymerization. The effects of （Al＋Fe）/Si molar ratio, OH/（Al＋Fe） molar ratio （i.e., γ value）, coagulant dosage and pH value of test suspension on the coagulation behavior of FAFSiC and the stability of the PAFSiC were also examined. Results showed that PAFSiC performed more efficiently than PAC in removing turbidity, chemical oxygen demand （COD）, and total phosphate （TP）. The PAFSiC with a γ value of 2.0 and （Al＋Fe）/Si ratio of 5 （PAFSiC 2.0/5） showed excellent coagulation effect for both turbidity and COD, while PAFSiC 1.0/5 was the best for TP. The optimum coagulation pH range of PAFSiC 2.0/5 was 5.0–9.0, slightly wider than that of PAC （6.0–8.0）. The process can be easily incorporated into high-purity graphite production plants, thereby reducing wastewater pollution and producing a valuable coagulant.
基金funded by the NSFC(No.40036010)subsidized by Special Funds from the National Key BaBic Research Program of P.R.China(G19990437)+2 种基金the Postdoctoral Foundation of Ocean University of Qingdaothe Director’s Foundation of the Beihai Monitoring Center of the State Oceanic Administrationthe Foundation of Shanghai Fisheries University
文摘Analysis and comparison of Jiaozhou Bay data collected from May 1991 to February 1994(12 seasonal investigations) provided by the Ecological Station of Jiaozhou Bay revealed the characteristic spatiotemporal variation of the ambient concentration Si:DIN and Si:16P ratios and the seasonal variation of Jiaozhou Bay Si:DIN and Si:16P ratios showing that the Si:DIN ratios were < 1 throughout the year in Jiaozhou Bay; and that the Si:16P ratios were < 1 throughout Jiaozhou Bay in spring, autumn and winter. The results proved that silicate limited phytoplankton growth in spring, autumn and winter in Jiaozhou Bay. Analysis of the Si:DIN and Si:P ratios showed that the nutrient Si has been limiting the growth of phytoplankton throughout the year in some Jiaozhou Bay waters; and that the silicate deficiency changed the phytoplankton assemblage structure. Analysis of discontinuous 1962 to 1998 nutrient data showed that there was no N or P limitation of phytoplankton growth in that period. The authors consider that the annual cyclic change of silicate limits phytoplankton growth in spring, autumn and winter every year in Jiaozhou Bay; and that in many Jiaozhou Bay waters where the phytoplankton as the predominant species need a great amount of silicate, analysis of the nutrients N or P limitation of phytoplankton growth relying only on the N and P nutrients and DIN:P ratio could yield inaccurate conclusions. The results obtained by applying the rules of absolute and relative limitation fully support this view. The authors consider that the main function of nutrient silicon is to regulate and control the mechanism of the phytoplankton growth process in the ecological system in estuaries, bays and the sea. The authors consider that according to the evolution theory of Darwin, continuous environmental pressure gradually changes the phytoplankton assemblage's structure and the physiology of diatoms. Diatoms requiring a great deal of silicon either constantly decrease or reduce their requirement for silicon. This will cause a series of huge changes in the ecosystem so that the whole ecosystem requires continuous renewal, change and balancing. Human beings have to reduce marine pollution and enhance the capacity of continental sources to transport silicon to sustain the continuity and stability in the marine ecosystem.nt
基金Project(51374247)supported by the National Natural Science Foundation of ChinaProject(2015CX005)supported by Innovation Driven Plan of Central South University,China+1 种基金Project(B14034)supported by the National“111”Project,ChinaProject supported by the Open Sharing Fund for Large-scale Instruments and Equipment of Central South University and Collaborative Innovation Center for Clean and Efficient Utilization of Strategic Metal Mineral Resources,China。
文摘The electrochemical mechanism involved in the selective separation of chalcopyrite from galena was investigated by flotation and electrochemical methods in the presence of sodium sulfite and sodium silicate,respectively,as a single depressant and their mixture as a combined depressant.Flotation tests revealed that the floatability of chalcopyrite was unaffected by depressants and its recovery remained constant(>80%)within the studied dosage range.Galena flotation was severely depressed with descending depressing order as follows:combined depressant﹥sodium silicate﹥sodium sulfite.Electrochemical analysis confirmed the high affinity of depressants on the galena surface,resulting in the formation of hydrophilic species,such as lead sulfite,lead sulfate,and lead orthosilicate.The oxidation of chalcopyrite surface and depressants did not exhibit any signals;conversely,the self-oxidation of chalcopyrite was depressed.The results of cyclic voltammograms well agreed with flotation results,demonstrating that chalcopyrite primarily reacted with the collector O-isopropyl-N-ethyl thionocarbamate and that galena mostly reacted with depressants.
文摘Batch adsorption from aqueous solutions in a slightly basic medium of Methylene Blue, up to 2500 mg/L, onto synthetic magnesium silicate （Florisil） of three particle size ranges （mean diameters of 112, 200 and 425 μm） was compared to the corresponding adsorption onto activated carbon and Amberlite XAD-2. The best fit of the kinetic results was achieved by a pseudo second-order equation. The equilibrium data were found to be well represented by the Langmuir isotherm equation. Amberlite XAD-2, an unspecific adsorbent capable of adsorbing exclusively through a surface effect, exhibited a poor dye uptake, confirming that the adsorption mechanism on Florisil was due to electrostatic attraction and ion exchange. Moreover, the comparison between Florisil and the other adsorbents was performed on the basis of the evaluation of the surface area and pore volume occupied by the adsorbed dye.
