Volatile organic compounds(VOCs)exhausted from industrial processes are the major atmospheric pollutants,which could destroy the ecological environment and make hazards to human health seriously.Catalytic oxidation is...Volatile organic compounds(VOCs)exhausted from industrial processes are the major atmospheric pollutants,which could destroy the ecological environment and make hazards to human health seriously.Catalytic oxidation is regarded as the most competitive strategy for the efficient elimination of low-concentration VOCs.Supported noble metal catalysts are preferred catalysts due to their excellent low-temperature catalytic activity.To further lower the cost of catalysts,single atom catalysts(SAC)have been fabricated and extensively studied for application in VOCs oxidation due to their 100%atom-utilization efficiency and unique catalytic performance.In this review,we comprehensively summarize the recent advances in supported noble metal(e.g.,Pt,Pd,Au,and Ag)catalysts and SAC for VOCs oxidation since 2015.Firstly,this paper focuses on some important influencing factors that affect the activity of supported noble metal catalysts,including particle size,valence state and dispersion of noble metals,properties of the support,metal oxide/ion modification,preparation method,and pretreatment conditions of catalysts.Secondly,we briefly summarize the catalytic performance of SAC for typical VOCs.Finally,we conclude the key influencing factors and provide the prospects and challenges of VOCs oxidation.展开更多
The South African government has proven its commitment to the reduction of anthropogenic carbon emissions by unveiling the carbon capture,utilization,and storage(CCUS)pilot demonstration research site on August 30,202...The South African government has proven its commitment to the reduction of anthropogenic carbon emissions by unveiling the carbon capture,utilization,and storage(CCUS)pilot demonstration research site on August 30,2024.The CCUS approach is to form part of the Integrated Resource Plan as one of the critical aspects of the country’s energy mix.This puts CCUS at the forefront of the adoption of clean energy initiatives.This paper reviews the progress on CCUS initiatives in South Africa since the publication of the 2010 technical report on the geological storage of carbon dioxide(CO_(2))with a focus on onshore sequestration.The focus is on the current status,future opportunities,and the possibility of developing numerical models and simulations of various South African coal ranks to simulate CO_(2)sequestration potential with reference to the related literature.The paper also delves into the ongoing Leandra pilot CCS demonstration project in Mpumalanga Province,the status of the identified unmineable coalfields available for CCS in South Africa,collaborations,and future prospects for CCS in the country.The purpose is to contribute to advancing the local CCS technology and mitigating anthropogenic CO_(2)emissions.Through this review paper,it is established that promoting the advancement and implementation of CCS in South Africa requires continuous advanced research activities from scholars and private and government institutions because of the critical need to understand the fluid induced response of geological formations,especially coal formations,for the secure and effective application of this sequestration method.展开更多
It is well known that transition metal sulfides(TMS)(i.e.,NiS_(2))undergo electrochemical reconstructions to generate highly active Ni_(3)S_(2) during the process of hydrogen evolution reaction(HER)under overpotential...It is well known that transition metal sulfides(TMS)(i.e.,NiS_(2))undergo electrochemical reconstructions to generate highly active Ni_(3)S_(2) during the process of hydrogen evolution reaction(HER)under overpotentials of<500 mV.However,at higher overpotentials,Ni_(3)S_(2) can theoretically be further restructured into Ni and thus form Ni/Ni_(3)S_(2) heterogeneous interface structures,which may provide opportunities to further enhance HER activity of NiS_(2).Here,we selected NiS_(2) as a model electrocatalyst and investigated the influence of the reconstruction results induced from regular to ultrahigh overpotentials on its electrocatalytic hydrogen precipitation performance.The experimental results showed that the most significant enhancement of hydrogen precipitation performance was obtained for the NiS_(2)@CC-900(900 means 900 mV overpotential)sample after the ultra-high overpotential induced reconstruction.Compared with the initial overpotential of 161 mV(10 mA cm^(-2)),the overpotential of the reconstructed sample reduced by 67 mV(42%).The characterization results showed that an ultra-high overpotential of 900 mV induced deep reconstruction of NiS_(2),formed highly reactive Ni/Ni_(3)S_(2) heterogeneous interfaces,which is more conducive to improved HER performance and match well with theoretical calculations results.We demonstrated ultrahigh overpotential was an effective strategy to induce NiS_(2) deeply reconstruction and significantly improve its HER performance,and this strategy was also applicable to CoS_(2) and FeS_(2).This study provides an extremely simple and universal pathway for the reasonable construction of efficient electrocatalysts by induced TMS deeply reconstruction.展开更多
The aim of this paper was preliminary design of the process for low-temperature coal tar hydrocrackmg m supercritical gasoline based on Aspen Plus with the concept of energy self-sustainability. In order to ensure the...The aim of this paper was preliminary design of the process for low-temperature coal tar hydrocrackmg m supercritical gasoline based on Aspen Plus with the concept of energy self-sustainability. In order to ensure the correct- ness and accuracy of the simulation, we did the following tasks： selecting reasonable model compounds for low-tem- perature coal tar; describing the nature of products gasoline and diesel accurately; and confirming the proper property study method for each block by means of experience and trial. The purpose of energy self-sustainability could be pos- sibly achieved, on one hand, by using hot stream to preheat cold stream and achieving temperature control of streams, and on the other hand, by utilizing gas （byproduct of the coal tar hydrocracking） combustion reaction to provide energy. Results showed that the whole process could provide a positive net power of about 609 kW-h for processing the low- temperature coal tar with a flowrate of 2 268 kg/h. The total heat recovery amounted to 2 229 kW-h, among which 845 kW＇h was obtained from the gas combustion reaction, and 1 116 kW＇h was provided by the reactor＇s outlet stream, with the rest furnished by hot streams of the products gasoline, diesel and residue. In addition, the process flow sheet could achieve products separation well, and specifically the purity of product gasoline and diesel reached 97.2% and 100%, respectively.展开更多
A numerical procedure to determine the equivalent hydrodynamic dispersion coefficients and Péclet number（Pe） of a fractured rock is presented using random walk particle tracking method.The geometrical effects o...A numerical procedure to determine the equivalent hydrodynamic dispersion coefficients and Péclet number（Pe） of a fractured rock is presented using random walk particle tracking method.The geometrical effects of fracture system on hydrodynamic dispersion are studied.The results obtained from the proposed method agree well with those of empirical models,which are the scale-dependent hydrodynamic dispersion coefficients in an asymptotic or exponential form.A variance case is added to investigate the influence of longitudinal hydrodynamic dispersion in individual fractures on the macro-hydrodynamic dispersion at the fracture network scale,and its influence is demonstrated with a verification example.In addition,we investigate the influences of directional flow and stress conditions on the behavior of hydrodynamic dispersion in fracture networks.The results show that the magnitudes of the hydrodynamic dispersion coefficients are relatively smaller when the flow direction is parallel to the dip directions of fracture sets.Compressive stresses significantly reduce hydrodynamic dispersion.However,the remaining questions are：（1） whether the deformed fracture network under high stress conditions may make the scale-dependent hydrodynamic dispersion coefficients have asymptotic or exponential forms,and（2） what the conditions for existence of a well-defined equivalent hydrodynamic dispersion tensor are.They need to be further investigated.展开更多
The current study is directed to the rapidly developing field of inorganic material 3D object production at nano-/micro scale.The fabrication method includes laser lithography of hybrid organic-inorganic materials wit...The current study is directed to the rapidly developing field of inorganic material 3D object production at nano-/micro scale.The fabrication method includes laser lithography of hybrid organic-inorganic materials with subsequent heat treatment leading to a variety of crystalline phases in 3D structures.In this work,it was examined a series of organometallic polymer precursors with different silicon(Si)and zirconium(Zr)molar ratios,ranging from 9:1 to 5:5,prepared via sol-gel method.All mixtures were examined for perspective to be used in 3D laser manufacturing by fabricating nano-and micro-feature sized structures.Their spatial downscaling and surface morphology were evaluated depending on chemical composition and crystallographic phase.The appearance of a crystalline phase was proven using single-crystal X-ray diffraction analysis,which revealed a lower crystallization temperature for microstructures compared to bulk materials.Fabricated 3D objects retained a complex geometry without any distortion after heat treatment up to 1400℃.Under the proper conditions,a wide variety of crystalline phases as well as zircon(ZrSiO_(4)-a highly stable material)can be observed.In addition,the highest new record of achieved resolution below 60 nm has been reached.The proposed preparation protocol can be used to manufacture micro/nano-devices with high precision and resistance to high temperature and aggressive environment.展开更多
It is globally accepted that soil carbon （C） dynamics are at the core of interlinked environmental problems, deteriorating soil quality and changing climate. Its management remains a complex enigma for the scientifi...It is globally accepted that soil carbon （C） dynamics are at the core of interlinked environmental problems, deteriorating soil quality and changing climate. Its management remains a complex enigma for the scientific community due to its intricate relationship with soil nitrogen （N） availability and moisture-temperature interactions. This article reviews the management aspects of soil C dynamics in light of recent advances, particularly in relation to the availability of inorganic N pools and associated microbial processes under changing climate. Globally, drastic alterations in soil C dynamics under changing land use and management practices have been primarily attributed to the variation in soil N availability, resulting in a higher decomposition rate and a considerable decline in soil organic C （SOC） levels due to increased soil CO2 emissions, degraded soil quality, and increased atmospheric CO2 concentrations, leading to climate warming. Predicted climate warming is proposed to enhance SOC decomposition, which may further increase soil N availability, leading to higher soil CO2 effiux. However, a literature survey revealed that soil may also act as a potential C sink, if we could manage soil inorganic N pools and link microbial processes properly. Studies also indicated that the relative, rather than the absolute, availability of inorganic N pools might be of key importance under changing climate, as these N pools are variably affected by moisture-temperature interactions, and they have variable impacts on SOC turnover. Therefore, multi-factorial studies are required to understand how the relative availability of inorganic N pools and associated microbial processes may determine SOC dynamics for improved soil C management.展开更多
Cu(II) and Mn(II) metals embedded on mesoporous SBA-15 were synthesized by co-precipitation technique.The support and catalysts were characterized by SEM–EDX,TEM,BET,XRD and ICP-AES methods.The catalytic activity of ...Cu(II) and Mn(II) metals embedded on mesoporous SBA-15 were synthesized by co-precipitation technique.The support and catalysts were characterized by SEM–EDX,TEM,BET,XRD and ICP-AES methods.The catalytic activity of these catalysts was evaluated for styrene oxidation at various reaction conditions such as styrene to TBHP mole ratio,temperature,catalyst amount by using TBHP as an oxidizing agent.Major reaction products were styrene oxide and benzaldehyde and highest styrene conversion(97.3%) was observed at styrene to TBHP mole ratio of 1:4,temperature at 80 °C and 20 mg of catalyst.Further,the recyclability of the catalysts was observed and found that they can be recycled three times without major loss in their activity and selectivity.展开更多
The separation of ethylene glycol(EG)and 1,2-butanediol(1,2-BDO)azeotrope in the synthesis process of EG via coal and biomass is becoming of increasing commercial and environmental importance.Selective adsorption is d...The separation of ethylene glycol(EG)and 1,2-butanediol(1,2-BDO)azeotrope in the synthesis process of EG via coal and biomass is becoming of increasing commercial and environmental importance.Selective adsorption is deemed as the most promising methods because of energy saving and environment favorable.In this paper,NaY zeolite was used to separate 1,2-BDO from EG,and its adsorption properties was then investigated.The isotherms of EG and 1,2-BDO in vapor and liquid phases from 298 to 328 K indicated that they fitted Langmuir model quite well,and the NaY zeolite absorbent favored EG more than 1,2-BDO.The Grand Canonical Monte Carlo(GCMC)and molecular dynamics(MD)simulation techniques were conducted to investigate the competition adsorption and diffusion characteristics in different adsorption regions.It was observed that EG and 1,2-BDO molecules all have the most probable locations of the center of the 12-membered ring near the Na cations.The diffusivities of EG are lower than those of 1,2-BDO at the same adsorption concentration.At last,the breakthrough curves of the binary mixture regressed from the empirical Dose–Response model in fixed-bed column showed that the adsorption selectivity of EG could reach to as high as 2.43,verified that the NaY zeolite could effectively separate EG from 1,2-BDO.This work is also helpful for further separation of other dihydric alcohol mixtures from coal and biomass fermentation.展开更多
A magnetic-separated catalyst of chitosan-palladium complex （Fe3O-CS-Pd） based on chitosan coated Fe3O4 microspheres was prepared by the ＂bottom-up＂ approach. The catalytic behavior of the catalyst in the cross co...A magnetic-separated catalyst of chitosan-palladium complex （Fe3O-CS-Pd） based on chitosan coated Fe3O4 microspheres was prepared by the ＂bottom-up＂ approach. The catalytic behavior of the catalyst in the cross coupling reaction of acrylic acid （AA） with iodobenzene （ArI） was investigated. Compared with the traditional homogeneous palladium catalysts, the catalyst was easily separated and reused.展开更多
Increased environmental pollution due to the organic wastes over the world is one of the most burning issues.These organic wastes lie under the category of biodegradable waste and can be effectively degraded from thei...Increased environmental pollution due to the organic wastes over the world is one of the most burning issues.These organic wastes lie under the category of biodegradable waste and can be effectively degraded from their complex compound into simple one by the action of microbes or other living organisms.Moreover,lignocellulosic biomass is a major part of the biodegradable waste and belongs to the group of renewable energy source,which can be very effective for bioenergy production.Biomasses are made up of different compounds such as cellulose,hemicelluloses,lignin and protein.Apart from these components,based on the structural analysis biomass also consist of bioactive substances such as carotenoids,flavonoids,lignin and antioxidants.This review explores a complete overview of the classification,component and the structure of the biomass.Moreover,it discusses how biomasses can play the key role of substrate in many sectors such as industrial bioenergy production including gaseous and liquid biofuels.展开更多
The plant Aloe vera is used in Ayurvedic, Homoeopathic and Allopathic streams of medicine, and not only tribal community but also most of the people for food and medicine. The plant leaves contains numerous vitamins, ...The plant Aloe vera is used in Ayurvedic, Homoeopathic and Allopathic streams of medicine, and not only tribal community but also most of the people for food and medicine. The plant leaves contains numerous vitamins, minerals, enzymes, amino acids, natural sugars and other bioactive compounds with emollient, purgative, anti-microbial, anti inflammatory, antioxidant, aphrodisiac, anti-helmenthic, antifungal, antiseptic and cosmetic values for health care. This plant has potential to cure sunburns, burns and minor cuts, and even skin cancer. The external use in cosmetic primarily acts as skin healer and prevents injury of epithelial tissues, cures acne and gives a youthful glow to skin, also acts as extremely powerful laxative.展开更多
The bio-molecules from various plant components and microbial species have been used as potential agents for the synthesis of silver nanoparticles (AgNPs). In spite of a wide range of bio-molecules assisting in the pr...The bio-molecules from various plant components and microbial species have been used as potential agents for the synthesis of silver nanoparticles (AgNPs). In spite of a wide range of bio-molecules assisting in the process, synthesizing stable and widely applicable AgNPs by many researchers still poses a considerable challenge to the researchers. The biological agents for synthesizing AgNPs cover compounds produced naturally in microbes and plants. More than 100 different biological sources for synthesizing AgNPs are reported in the past decade by various authors. Reaction parameters under which the AgNPs were being synthesized hold prominent impact on their size, shape and application. Available published information on AgNPs synthesis, effects of various parameters, characterization techniques, properties and their application are summarised and critically discussed in this review.展开更多
Through washability study, a couple of parameters were investigated for a low volatile Pakistani Coal (coking). The aim was to find out the effect of the action of reducing material release characteristics for low vol...Through washability study, a couple of parameters were investigated for a low volatile Pakistani Coal (coking). The aim was to find out the effect of the action of reducing material release characteristics for low volatile Pakistani coal. The “Index of washability” (IW) and “Near gravity material Index” (NGMI) were used as parameters to express the ease of washability. Run of Mine coal is crushed to four different sizes as mentioned 80 mm, 30 mm, 18 mm and 11 mm in a pestle and mortar. Calculations of IW show that it is inversely proportional to top size of feed, indicating that washability increases with the decrease of size. From NGMI calculations it was concluded that gravity method is not recommended for separation at this specific gravity range. So study divulges that the critical specific gravity for crushing to 30 mm is 1.67 and for 11 mm is 1.56.展开更多
Lagerstroemia speciosa bark（LB） embedded magnetic nanoparticles were prepared by co-precipitation of Fe2＋ and Fe3＋ salt solution with ammonia and LB for Cr（Ⅵ） removal from aqueous solution.The native LB,magneti...Lagerstroemia speciosa bark（LB） embedded magnetic nanoparticles were prepared by co-precipitation of Fe2＋ and Fe3＋ salt solution with ammonia and LB for Cr（Ⅵ） removal from aqueous solution.The native LB,magnetic nanoparticle（MNP）,L.spedosa embedded magnetic nanoparticle（MNPLB） and Cr（Ⅵ） adsorbed MNPLB particles were characterized by SEM-EDX,TEM,BET-surface area,FT-IR,XRD and TGA methods.TEM analysis confirmed nearly spherical shape of MNP with an average diameter of 8.76 nm and the surface modification did not result in the phase change of MNP as established by XRD analysis,while led to the formation of secondary particles of MNPLB with diameter of 18.54 nm.Characterization results revealed covalent binding between the hydroxyl group of MNP and carboxyl group of LB particles and further confirmed its physico-chemical nature favorable for Cr（Ⅵ） adsorption.The Cr（Ⅵ） adsorption on to MNPLB particle as an adsorbent was tested under different contact time,initial Cr（Ⅵ） concentration,adsorbent dose,initial pH,temperature and agitation speed.The results of the equilibrium and kinetics of adsorption were well described by Langmuir isotherm and pseudo-second-order model,respectively.The thermodynamic parameters suggest spontaneous and endothermic nature of Cr（Ⅵ）adsorption onto MNPLB.The maximum adsorption capacity for MNPLB was calculated to be 434.78 mg/g and these particles even after Cr（Ⅵ） adsorption were collected effortlessly from the aqueous solution by a magnet.The desorption of Cr（Ⅵ）-adsorbed MNPLB was found to be more than 93.72%with spent MNPLB depicting eleven successive adsorption-desorption cycles.展开更多
Photocatalysis of water with and without ultrasound was studied using rGO supported CdS catalyst utilizing visible light. A higher hydrogen production was observed when ultrasound was used. This is attributed to a fas...Photocatalysis of water with and without ultrasound was studied using rGO supported CdS catalyst utilizing visible light. A higher hydrogen production was observed when ultrasound was used. This is attributed to a faster removal of bubbles of hydrogen from the surface of photocatalyst due to the mechanical energy associated with ultrasound overcoming surface tension. It has been further reported that the rate of hydrogen production decreased with time due to reversible deactivation of catalyst. This has been attributed to decrease in rate of hydrogen desorption with time.展开更多
Pipeline is a conventional, efficient and economic way for oil transportations. The use of a good system for detecting and locating leaks in pipeline contribute significantly to operational safety and cost saving in p...Pipeline is a conventional, efficient and economic way for oil transportations. The use of a good system for detecting and locating leaks in pipeline contribute significantly to operational safety and cost saving in petroleum industry. This paper aims to study the heavy oil-water flow in vertical ducts including leakage. A transient numerical analysis, using the ANSYS-CFX? 11.0 commercial software is performed. The mathematical modeling considers the effect of drag and gravitational forces between the phases and turbulent flow. Mass flow rate of the phases in the leaking orifice, the pressure drop as a function of the time and the velocity distributions are presented and discussed. We can conclude that volumetric fraction of phases and fluid mixture velocity affect pressure drop and mass flow rate at the leak hole.展开更多
Poly （N-isopropylacrylamide） （PNIPAAm）/carboxymethylated chitosan （CMCH） hydrogels were prepared by irradiating the aqueous solution mixture of NIPAAm and CMCH by 60 Co γ-ray.The effects of feed ratio of NIPAAm...Poly （N-isopropylacrylamide） （PNIPAAm）/carboxymethylated chitosan （CMCH） hydrogels were prepared by irradiating the aqueous solution mixture of NIPAAm and CMCH by 60 Co γ-ray.The effects of feed ratio of NIPAAm and CMCH,temperature,pH and ionic strength on the swelling ratio of PNIPAAm/CMCH hydrogels were studied.The results show that the addition of CMCH shifts the lower critical solution temperature （LCST） of the PNIPAAm hydrogel to higher temperature.The PNIPAAm/CMCH hydrogel displays not only pH-and thermo-sensitivity,but also ion-sensitivity.Differential scanning calorimetry （DSC） was applied for the determination of the LCST of the hydrogel.展开更多
Poly（ether ether ketone） （PEEK） is a high-performance semi-crystalline thermoplastic polymer. Exposure of the polymeric surface to solvents can have a strong effect like softening/swelling of polymeric network or ...Poly（ether ether ketone） （PEEK） is a high-performance semi-crystalline thermoplastic polymer. Exposure of the polymeric surface to solvents can have a strong effect like softening/swelling of polymeric network or dissolution. In this study, nano-indentation analysis was performed to study the effect of acetone on the surface mechanical properties of PEEK using different exposure time. The experiments were performed with a constant loading rate （10 nrn/s） to a maximum indentation displacernent （1000 nrn）. A 30-second hold segrnent was included at the maximum load to account for any creep eft）ors followed by an unloading segrnent to 80% unloading. The indentation hardness and the elastic modulus were corn- puted as a continuous function of the penetration displacernent in the continuous stiffness mode （CSM） indentation. The experirnental data showed that the peak load decreased from -5.2 mN to -1.7 mN as exposure tirne in solvent environrnent increased from 0 to 18 days. The elastic modulus and the hardness of PEEK samples also displayed a decreasing trend as a function of exposure tirne in the solvent environrnent. Two empirical models were used to fit the experirnental data of hardness as a function of exposure tirne which showed a good agreernent with the experirnental values.展开更多
Aluminous refractory materials with high alumina contents are widely used in the steel industry,and the higher the alumina content,the higher the working temperature.Properties such as high refractoriness and thermal ...Aluminous refractory materials with high alumina contents are widely used in the steel industry,and the higher the alumina content,the higher the working temperature.Properties such as high refractoriness and thermal shock resistance lead these refractory materials to be used as channel linings of blast furnaces,where they are exposed to the attack by slag,molten steel,working cycles and sudden temperature changes between 25℃(room temperature)and 1520℃(the temperature of molten pig iron).In this work,microstructural changes in post-mortem aluminous refractory bricks were investigated by apparent porosity,X-ray diffraction analysis(XRD),Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy,and X-ray dispersion energy spectrometry(SEM/EDS).The results showed an increase in the apparent porosity and the bulk density and the presence of the phases mullite,sillimanite,alumina,and quartz in the post-mortem brick.Calcium and magnesium were not detected in the microstructure of the post-mortem brick,indicating that slags did not corrode these refractory materials.Therefore,the microstructural changes that occurred in the post-mortem bricks must be due to thermal cycling.In the X-ray diffraction(XRD)test,mullite,sillimanite,quartz,andα-alumina phases were identified.These results indicate that the aluminous refractory was obtained from sillimanite.In infrared spectroscopy(FTIR)it was possible to identify the vibration bands referring to the Si-O and Al-O bonds.The increase in the porosity is a result of cracks caused by work cycles at high temperatures and the temperature gradient to which the refractory was subjected during use.Through the micrograph it was possible to identify the presence of acicular mullite.The absence of magnesium and calcium in the microanalysis results by energy dispersed X-ray spectrometry(EDS)indicates that there was no infiltration by slag or liquid iron.These results indicate that the microstructural changes that occurred in the post-mortem aluminous refractory were of a thermal nature.展开更多
基金supported by Beijing Natural Science Foundation(No.8244060)China Postdoctoral Science Foundation(No.2023M730143)+3 种基金the National Natural Science Foundation of China(No.22425601)the National Key R&D Program of China(No.2023YFB3810801)Beijing Nova Program(No.20240484659)the R&D Program of Beijing Municipal Education Commission(No.KZ202210005011).
文摘Volatile organic compounds(VOCs)exhausted from industrial processes are the major atmospheric pollutants,which could destroy the ecological environment and make hazards to human health seriously.Catalytic oxidation is regarded as the most competitive strategy for the efficient elimination of low-concentration VOCs.Supported noble metal catalysts are preferred catalysts due to their excellent low-temperature catalytic activity.To further lower the cost of catalysts,single atom catalysts(SAC)have been fabricated and extensively studied for application in VOCs oxidation due to their 100%atom-utilization efficiency and unique catalytic performance.In this review,we comprehensively summarize the recent advances in supported noble metal(e.g.,Pt,Pd,Au,and Ag)catalysts and SAC for VOCs oxidation since 2015.Firstly,this paper focuses on some important influencing factors that affect the activity of supported noble metal catalysts,including particle size,valence state and dispersion of noble metals,properties of the support,metal oxide/ion modification,preparation method,and pretreatment conditions of catalysts.Secondly,we briefly summarize the catalytic performance of SAC for typical VOCs.Finally,we conclude the key influencing factors and provide the prospects and challenges of VOCs oxidation.
基金supported by the National Research Foundation (NRF) - South Africa [Grant No. TTK2204224344].
文摘The South African government has proven its commitment to the reduction of anthropogenic carbon emissions by unveiling the carbon capture,utilization,and storage(CCUS)pilot demonstration research site on August 30,2024.The CCUS approach is to form part of the Integrated Resource Plan as one of the critical aspects of the country’s energy mix.This puts CCUS at the forefront of the adoption of clean energy initiatives.This paper reviews the progress on CCUS initiatives in South Africa since the publication of the 2010 technical report on the geological storage of carbon dioxide(CO_(2))with a focus on onshore sequestration.The focus is on the current status,future opportunities,and the possibility of developing numerical models and simulations of various South African coal ranks to simulate CO_(2)sequestration potential with reference to the related literature.The paper also delves into the ongoing Leandra pilot CCS demonstration project in Mpumalanga Province,the status of the identified unmineable coalfields available for CCS in South Africa,collaborations,and future prospects for CCS in the country.The purpose is to contribute to advancing the local CCS technology and mitigating anthropogenic CO_(2)emissions.Through this review paper,it is established that promoting the advancement and implementation of CCS in South Africa requires continuous advanced research activities from scholars and private and government institutions because of the critical need to understand the fluid induced response of geological formations,especially coal formations,for the secure and effective application of this sequestration method.
文摘It is well known that transition metal sulfides(TMS)(i.e.,NiS_(2))undergo electrochemical reconstructions to generate highly active Ni_(3)S_(2) during the process of hydrogen evolution reaction(HER)under overpotentials of<500 mV.However,at higher overpotentials,Ni_(3)S_(2) can theoretically be further restructured into Ni and thus form Ni/Ni_(3)S_(2) heterogeneous interface structures,which may provide opportunities to further enhance HER activity of NiS_(2).Here,we selected NiS_(2) as a model electrocatalyst and investigated the influence of the reconstruction results induced from regular to ultrahigh overpotentials on its electrocatalytic hydrogen precipitation performance.The experimental results showed that the most significant enhancement of hydrogen precipitation performance was obtained for the NiS_(2)@CC-900(900 means 900 mV overpotential)sample after the ultra-high overpotential induced reconstruction.Compared with the initial overpotential of 161 mV(10 mA cm^(-2)),the overpotential of the reconstructed sample reduced by 67 mV(42%).The characterization results showed that an ultra-high overpotential of 900 mV induced deep reconstruction of NiS_(2),formed highly reactive Ni/Ni_(3)S_(2) heterogeneous interfaces,which is more conducive to improved HER performance and match well with theoretical calculations results.We demonstrated ultrahigh overpotential was an effective strategy to induce NiS_(2) deeply reconstruction and significantly improve its HER performance,and this strategy was also applicable to CoS_(2) and FeS_(2).This study provides an extremely simple and universal pathway for the reasonable construction of efficient electrocatalysts by induced TMS deeply reconstruction.
基金the financial support from the National Natural Science Foundation of China(No.2117619)the Shaanxi Province Major Project of Innovation of Science and Technology(No.2008zkc03205,No.2011KTZB03-03-01)
文摘The aim of this paper was preliminary design of the process for low-temperature coal tar hydrocrackmg m supercritical gasoline based on Aspen Plus with the concept of energy self-sustainability. In order to ensure the correct- ness and accuracy of the simulation, we did the following tasks： selecting reasonable model compounds for low-tem- perature coal tar; describing the nature of products gasoline and diesel accurately; and confirming the proper property study method for each block by means of experience and trial. The purpose of energy self-sustainability could be pos- sibly achieved, on one hand, by using hot stream to preheat cold stream and achieving temperature control of streams, and on the other hand, by utilizing gas （byproduct of the coal tar hydrocracking） combustion reaction to provide energy. Results showed that the whole process could provide a positive net power of about 609 kW-h for processing the low- temperature coal tar with a flowrate of 2 268 kg/h. The total heat recovery amounted to 2 229 kW-h, among which 845 kW＇h was obtained from the gas combustion reaction, and 1 116 kW＇h was provided by the reactor＇s outlet stream, with the rest furnished by hot streams of the products gasoline, diesel and residue. In addition, the process flow sheet could achieve products separation well, and specifically the purity of product gasoline and diesel reached 97.2% and 100%, respectively.
基金the financial supports from Swedish Nuclear Fuel and Waste Management Co.(SKB) through the DECOVALEX-2011 project
文摘A numerical procedure to determine the equivalent hydrodynamic dispersion coefficients and Péclet number（Pe） of a fractured rock is presented using random walk particle tracking method.The geometrical effects of fracture system on hydrodynamic dispersion are studied.The results obtained from the proposed method agree well with those of empirical models,which are the scale-dependent hydrodynamic dispersion coefficients in an asymptotic or exponential form.A variance case is added to investigate the influence of longitudinal hydrodynamic dispersion in individual fractures on the macro-hydrodynamic dispersion at the fracture network scale,and its influence is demonstrated with a verification example.In addition,we investigate the influences of directional flow and stress conditions on the behavior of hydrodynamic dispersion in fracture networks.The results show that the magnitudes of the hydrodynamic dispersion coefficients are relatively smaller when the flow direction is parallel to the dip directions of fracture sets.Compressive stresses significantly reduce hydrodynamic dispersion.However,the remaining questions are：（1） whether the deformed fracture network under high stress conditions may make the scale-dependent hydrodynamic dispersion coefficients have asymptotic or exponential forms,and（2） what the conditions for existence of a well-defined equivalent hydrodynamic dispersion tensor are.They need to be further investigated.
基金The US AMRDEC grant No.W911NF-16-2-0069“Enhanced Absorption in Stopped-Light Photonic Nanostructures:Applications to Efficient Sensing”EU LASERLAB-EUROPE(grant agreement No.871124Horizon 2020 research and innovation programme)projects are acknowleged for the financial support.D.G.acknowledges the financial support from the European Social Fund(project No 09.3.3-LMT-K712-17-0016)under grant agreement with the Research Council of Lithuania(LMTLT).
文摘The current study is directed to the rapidly developing field of inorganic material 3D object production at nano-/micro scale.The fabrication method includes laser lithography of hybrid organic-inorganic materials with subsequent heat treatment leading to a variety of crystalline phases in 3D structures.In this work,it was examined a series of organometallic polymer precursors with different silicon(Si)and zirconium(Zr)molar ratios,ranging from 9:1 to 5:5,prepared via sol-gel method.All mixtures were examined for perspective to be used in 3D laser manufacturing by fabricating nano-and micro-feature sized structures.Their spatial downscaling and surface morphology were evaluated depending on chemical composition and crystallographic phase.The appearance of a crystalline phase was proven using single-crystal X-ray diffraction analysis,which revealed a lower crystallization temperature for microstructures compared to bulk materials.Fabricated 3D objects retained a complex geometry without any distortion after heat treatment up to 1400℃.Under the proper conditions,a wide variety of crystalline phases as well as zircon(ZrSiO_(4)-a highly stable material)can be observed.In addition,the highest new record of achieved resolution below 60 nm has been reached.The proposed preparation protocol can be used to manufacture micro/nano-devices with high precision and resistance to high temperature and aggressive environment.
文摘It is globally accepted that soil carbon （C） dynamics are at the core of interlinked environmental problems, deteriorating soil quality and changing climate. Its management remains a complex enigma for the scientific community due to its intricate relationship with soil nitrogen （N） availability and moisture-temperature interactions. This article reviews the management aspects of soil C dynamics in light of recent advances, particularly in relation to the availability of inorganic N pools and associated microbial processes under changing climate. Globally, drastic alterations in soil C dynamics under changing land use and management practices have been primarily attributed to the variation in soil N availability, resulting in a higher decomposition rate and a considerable decline in soil organic C （SOC） levels due to increased soil CO2 emissions, degraded soil quality, and increased atmospheric CO2 concentrations, leading to climate warming. Predicted climate warming is proposed to enhance SOC decomposition, which may further increase soil N availability, leading to higher soil CO2 effiux. However, a literature survey revealed that soil may also act as a potential C sink, if we could manage soil inorganic N pools and link microbial processes properly. Studies also indicated that the relative, rather than the absolute, availability of inorganic N pools might be of key importance under changing climate, as these N pools are variably affected by moisture-temperature interactions, and they have variable impacts on SOC turnover. Therefore, multi-factorial studies are required to understand how the relative availability of inorganic N pools and associated microbial processes may determine SOC dynamics for improved soil C management.
文摘Cu(II) and Mn(II) metals embedded on mesoporous SBA-15 were synthesized by co-precipitation technique.The support and catalysts were characterized by SEM–EDX,TEM,BET,XRD and ICP-AES methods.The catalytic activity of these catalysts was evaluated for styrene oxidation at various reaction conditions such as styrene to TBHP mole ratio,temperature,catalyst amount by using TBHP as an oxidizing agent.Major reaction products were styrene oxide and benzaldehyde and highest styrene conversion(97.3%) was observed at styrene to TBHP mole ratio of 1:4,temperature at 80 °C and 20 mg of catalyst.Further,the recyclability of the catalysts was observed and found that they can be recycled three times without major loss in their activity and selectivity.
基金the National Natural Science Foundation of China(21576272)“Transformational Technologies for Clean Energy and Demonstration”Strategic Priority Research Program of Chinese Academy of Sciences,Grant No.XDA 21030600,Science and Technology Service Network Initiative,Chinese Academy of Sciences(KFJ-STS-QYZD-138).
文摘The separation of ethylene glycol(EG)and 1,2-butanediol(1,2-BDO)azeotrope in the synthesis process of EG via coal and biomass is becoming of increasing commercial and environmental importance.Selective adsorption is deemed as the most promising methods because of energy saving and environment favorable.In this paper,NaY zeolite was used to separate 1,2-BDO from EG,and its adsorption properties was then investigated.The isotherms of EG and 1,2-BDO in vapor and liquid phases from 298 to 328 K indicated that they fitted Langmuir model quite well,and the NaY zeolite absorbent favored EG more than 1,2-BDO.The Grand Canonical Monte Carlo(GCMC)and molecular dynamics(MD)simulation techniques were conducted to investigate the competition adsorption and diffusion characteristics in different adsorption regions.It was observed that EG and 1,2-BDO molecules all have the most probable locations of the center of the 12-membered ring near the Na cations.The diffusivities of EG are lower than those of 1,2-BDO at the same adsorption concentration.At last,the breakthrough curves of the binary mixture regressed from the empirical Dose–Response model in fixed-bed column showed that the adsorption selectivity of EG could reach to as high as 2.43,verified that the NaY zeolite could effectively separate EG from 1,2-BDO.This work is also helpful for further separation of other dihydric alcohol mixtures from coal and biomass fermentation.
基金the Shanghai Leading Academic Discipline Program (Grant No.T105)
文摘A magnetic-separated catalyst of chitosan-palladium complex （Fe3O-CS-Pd） based on chitosan coated Fe3O4 microspheres was prepared by the ＂bottom-up＂ approach. The catalytic behavior of the catalyst in the cross coupling reaction of acrylic acid （AA） with iodobenzene （ArI） was investigated. Compared with the traditional homogeneous palladium catalysts, the catalyst was easily separated and reused.
文摘Increased environmental pollution due to the organic wastes over the world is one of the most burning issues.These organic wastes lie under the category of biodegradable waste and can be effectively degraded from their complex compound into simple one by the action of microbes or other living organisms.Moreover,lignocellulosic biomass is a major part of the biodegradable waste and belongs to the group of renewable energy source,which can be very effective for bioenergy production.Biomasses are made up of different compounds such as cellulose,hemicelluloses,lignin and protein.Apart from these components,based on the structural analysis biomass also consist of bioactive substances such as carotenoids,flavonoids,lignin and antioxidants.This review explores a complete overview of the classification,component and the structure of the biomass.Moreover,it discusses how biomasses can play the key role of substrate in many sectors such as industrial bioenergy production including gaseous and liquid biofuels.
文摘The plant Aloe vera is used in Ayurvedic, Homoeopathic and Allopathic streams of medicine, and not only tribal community but also most of the people for food and medicine. The plant leaves contains numerous vitamins, minerals, enzymes, amino acids, natural sugars and other bioactive compounds with emollient, purgative, anti-microbial, anti inflammatory, antioxidant, aphrodisiac, anti-helmenthic, antifungal, antiseptic and cosmetic values for health care. This plant has potential to cure sunburns, burns and minor cuts, and even skin cancer. The external use in cosmetic primarily acts as skin healer and prevents injury of epithelial tissues, cures acne and gives a youthful glow to skin, also acts as extremely powerful laxative.
文摘The bio-molecules from various plant components and microbial species have been used as potential agents for the synthesis of silver nanoparticles (AgNPs). In spite of a wide range of bio-molecules assisting in the process, synthesizing stable and widely applicable AgNPs by many researchers still poses a considerable challenge to the researchers. The biological agents for synthesizing AgNPs cover compounds produced naturally in microbes and plants. More than 100 different biological sources for synthesizing AgNPs are reported in the past decade by various authors. Reaction parameters under which the AgNPs were being synthesized hold prominent impact on their size, shape and application. Available published information on AgNPs synthesis, effects of various parameters, characterization techniques, properties and their application are summarised and critically discussed in this review.
文摘Through washability study, a couple of parameters were investigated for a low volatile Pakistani Coal (coking). The aim was to find out the effect of the action of reducing material release characteristics for low volatile Pakistani coal. The “Index of washability” (IW) and “Near gravity material Index” (NGMI) were used as parameters to express the ease of washability. Run of Mine coal is crushed to four different sizes as mentioned 80 mm, 30 mm, 18 mm and 11 mm in a pestle and mortar. Calculations of IW show that it is inversely proportional to top size of feed, indicating that washability increases with the decrease of size. From NGMI calculations it was concluded that gravity method is not recommended for separation at this specific gravity range. So study divulges that the critical specific gravity for crushing to 30 mm is 1.67 and for 11 mm is 1.56.
基金financial support to the senior author(S.Srivastava)
文摘Lagerstroemia speciosa bark（LB） embedded magnetic nanoparticles were prepared by co-precipitation of Fe2＋ and Fe3＋ salt solution with ammonia and LB for Cr（Ⅵ） removal from aqueous solution.The native LB,magnetic nanoparticle（MNP）,L.spedosa embedded magnetic nanoparticle（MNPLB） and Cr（Ⅵ） adsorbed MNPLB particles were characterized by SEM-EDX,TEM,BET-surface area,FT-IR,XRD and TGA methods.TEM analysis confirmed nearly spherical shape of MNP with an average diameter of 8.76 nm and the surface modification did not result in the phase change of MNP as established by XRD analysis,while led to the formation of secondary particles of MNPLB with diameter of 18.54 nm.Characterization results revealed covalent binding between the hydroxyl group of MNP and carboxyl group of LB particles and further confirmed its physico-chemical nature favorable for Cr（Ⅵ） adsorption.The Cr（Ⅵ） adsorption on to MNPLB particle as an adsorbent was tested under different contact time,initial Cr（Ⅵ） concentration,adsorbent dose,initial pH,temperature and agitation speed.The results of the equilibrium and kinetics of adsorption were well described by Langmuir isotherm and pseudo-second-order model,respectively.The thermodynamic parameters suggest spontaneous and endothermic nature of Cr（Ⅵ）adsorption onto MNPLB.The maximum adsorption capacity for MNPLB was calculated to be 434.78 mg/g and these particles even after Cr（Ⅵ） adsorption were collected effortlessly from the aqueous solution by a magnet.The desorption of Cr（Ⅵ）-adsorbed MNPLB was found to be more than 93.72%with spent MNPLB depicting eleven successive adsorption-desorption cycles.
基金the IIT(BHU)for providing financial support in the form of teaching assistantship
文摘Photocatalysis of water with and without ultrasound was studied using rGO supported CdS catalyst utilizing visible light. A higher hydrogen production was observed when ultrasound was used. This is attributed to a faster removal of bubbles of hydrogen from the surface of photocatalyst due to the mechanical energy associated with ultrasound overcoming surface tension. It has been further reported that the rate of hydrogen production decreased with time due to reversible deactivation of catalyst. This has been attributed to decrease in rate of hydrogen desorption with time.
文摘Pipeline is a conventional, efficient and economic way for oil transportations. The use of a good system for detecting and locating leaks in pipeline contribute significantly to operational safety and cost saving in petroleum industry. This paper aims to study the heavy oil-water flow in vertical ducts including leakage. A transient numerical analysis, using the ANSYS-CFX? 11.0 commercial software is performed. The mathematical modeling considers the effect of drag and gravitational forces between the phases and turbulent flow. Mass flow rate of the phases in the leaking orifice, the pressure drop as a function of the time and the velocity distributions are presented and discussed. We can conclude that volumetric fraction of phases and fluid mixture velocity affect pressure drop and mass flow rate at the leak hole.
基金supported by the Shanghai Nano-material Project Foundation (Grant No.0452NM024)the Shanghai Leading Academic Discipline Project (Grant No.T0105)
文摘Poly （N-isopropylacrylamide） （PNIPAAm）/carboxymethylated chitosan （CMCH） hydrogels were prepared by irradiating the aqueous solution mixture of NIPAAm and CMCH by 60 Co γ-ray.The effects of feed ratio of NIPAAm and CMCH,temperature,pH and ionic strength on the swelling ratio of PNIPAAm/CMCH hydrogels were studied.The results show that the addition of CMCH shifts the lower critical solution temperature （LCST） of the PNIPAAm hydrogel to higher temperature.The PNIPAAm/CMCH hydrogel displays not only pH-and thermo-sensitivity,but also ion-sensitivity.Differential scanning calorimetry （DSC） was applied for the determination of the LCST of the hydrogel.
文摘Poly（ether ether ketone） （PEEK） is a high-performance semi-crystalline thermoplastic polymer. Exposure of the polymeric surface to solvents can have a strong effect like softening/swelling of polymeric network or dissolution. In this study, nano-indentation analysis was performed to study the effect of acetone on the surface mechanical properties of PEEK using different exposure time. The experiments were performed with a constant loading rate （10 nrn/s） to a maximum indentation displacernent （1000 nrn）. A 30-second hold segrnent was included at the maximum load to account for any creep eft）ors followed by an unloading segrnent to 80% unloading. The indentation hardness and the elastic modulus were corn- puted as a continuous function of the penetration displacernent in the continuous stiffness mode （CSM） indentation. The experirnental data showed that the peak load decreased from -5.2 mN to -1.7 mN as exposure tirne in solvent environrnent increased from 0 to 18 days. The elastic modulus and the hardness of PEEK samples also displayed a decreasing trend as a function of exposure tirne in the solvent environrnent. Two empirical models were used to fit the experirnental data of hardness as a function of exposure tirne which showed a good agreernent with the experirnental values.
基金acknowledged DEQ/IT/UFRRJ,FEG/UNESP-Guaratinguetáand EEL/USP-Lorena for their support in carrying out the analyses.
文摘Aluminous refractory materials with high alumina contents are widely used in the steel industry,and the higher the alumina content,the higher the working temperature.Properties such as high refractoriness and thermal shock resistance lead these refractory materials to be used as channel linings of blast furnaces,where they are exposed to the attack by slag,molten steel,working cycles and sudden temperature changes between 25℃(room temperature)and 1520℃(the temperature of molten pig iron).In this work,microstructural changes in post-mortem aluminous refractory bricks were investigated by apparent porosity,X-ray diffraction analysis(XRD),Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy,and X-ray dispersion energy spectrometry(SEM/EDS).The results showed an increase in the apparent porosity and the bulk density and the presence of the phases mullite,sillimanite,alumina,and quartz in the post-mortem brick.Calcium and magnesium were not detected in the microstructure of the post-mortem brick,indicating that slags did not corrode these refractory materials.Therefore,the microstructural changes that occurred in the post-mortem bricks must be due to thermal cycling.In the X-ray diffraction(XRD)test,mullite,sillimanite,quartz,andα-alumina phases were identified.These results indicate that the aluminous refractory was obtained from sillimanite.In infrared spectroscopy(FTIR)it was possible to identify the vibration bands referring to the Si-O and Al-O bonds.The increase in the porosity is a result of cracks caused by work cycles at high temperatures and the temperature gradient to which the refractory was subjected during use.Through the micrograph it was possible to identify the presence of acicular mullite.The absence of magnesium and calcium in the microanalysis results by energy dispersed X-ray spectrometry(EDS)indicates that there was no infiltration by slag or liquid iron.These results indicate that the microstructural changes that occurred in the post-mortem aluminous refractory were of a thermal nature.
