In the current era of renewable energy prominence,the wide operational capacity of coal-fired boilers has emerged as crucial for ensuring the sustainability of power plants.However,attaining ultra-low nitrogen oxides(...In the current era of renewable energy prominence,the wide operational capacity of coal-fired boilers has emerged as crucial for ensuring the sustainability of power plants.However,attaining ultra-low nitrogen oxides(NO_x)emissions during periods of low-load operations presents a significant and persistent challenge for coal power enterprises.While techniques such as biomass re-burning and advanced re-burning have shown promise in enhancing NO reduction effciency above 800℃,their elevated levels of chlorine(Cl)and alkali metals pose potential risks to boiler equipment integrity.Therefore,this study proposes the utilization of biomass char derived from pyrolysis as a dual-purpose solution to enhance NO reduction efficiency while safeguarding boiler integrity during low-load operations.Findings indicate that pyrolysis treatment effectively reduces the Cl and alkali metal content of biomass.Specifically,it was determined that biomass char produced through deeply pyrolysis at 300℃achieves the highest NO reduction efficiency while minimizing the presence of harmful components.At a reduction temperature of 700℃,both re-burning and advanced re-burning techniques exhibit NO reduction efficiencies of 55.90%and 62.22%,which is already an ideal deficiency at low temperatures.The addition of water vapor at 700-800℃obviously avoids the oxidation of ammonia to NO in advanced reburning.Upon further analysis,denitrification efficiency in biomass char re-burning and advanced reburning is influenced not only by volatile content but also by physicochemical properties such as porosity and surface functional group distribution under certain reaction conditions.This study provides a theoretical framework for the industrial implementation of biomass char for NO control in coal-fired power plants,offering insights into optimizing NO reduction efficiency while mitigating potential risks to boiler equipment.展开更多
The persistence of chlorinated alkanes in aquatic environments poses significant health risks due to its biotoxicity and high volatility,which contributes to both water and air pollution.This study investigates the ef...The persistence of chlorinated alkanes in aquatic environments poses significant health risks due to its biotoxicity and high volatility,which contributes to both water and air pollution.This study investigates the efficacy of carbon dioxide radical anion(CO_(2)·^(-))mediated advanced reduction processes(ARPs)for the reductive dechlorination of chlorinated alkanes using small molecular monocarboxylic acids(SMAs)under UV irradiation.The study focused on formic acid(HCOOH),acetic acid(CH_3COOH),and propionic acid(CH_3CH_(2)COOH)to generate CO_(2)·^(-),revealing that UV/HCOOH system exhibits a notably high chloroform(CF)degradation efficiency of 97.8%in 90 min.Kinetic studies indicated a linear relationship between the HCOOH concentrations and the observed reaction rate constants(k_(obs)),demonstrating that CO_(2)·^(-)production is crucial for CF degradation.Electron paramagnetic resonance spectroscopy identified CO_(2)·^(-)and hydroxyl radicals(HO·)as the active species,with the former playing a predominant role in CF degradation.The study also explored the influence of carbon chain length in SMAs on CF degradation,finding that longer chains decrease the degradation efficiency,potentially due to reduced UV activation.A higher reaction rate constant(k_(obs))under acidic conditions,with a marked decrease in efficiency as the pH exceeds 3.7,where HCOO^(-)becomes predominant.This study enhances our understanding of CO_(2)·^(-)mediated ARPs and explores potential applications in environmental remediation,providing insights into the pathways and mechanisms of CF degradation.The UV/SMAs systems offer advantages for practical applications,such as milder reaction conditions and higher efficiency compared to traditional methods.展开更多
The dehalogenation of organohalides has been a research hotspot in bioremediation field;however,the influence of tourmaline,a natural ore that can generate spontaneous electric field,on organohalide-respiring bacteria...The dehalogenation of organohalides has been a research hotspot in bioremediation field;however,the influence of tourmaline,a natural ore that can generate spontaneous electric field,on organohalide-respiring bacteria(OHRB)and their dechlorination process is not well known.In this study,the effect and mechanism of tourmaline on the reductive dechlorination of 2,3-dichlorophenol(2,3-DCP)by Desulfitobacterium hafniense DCB-2Twere explored.The characterization results confirmed that tourmaline had good stability and the optimal dosage of tourmaline was 2.5 g/L,which shortened the total time required for dechlorination reaction to 72 hr.Besides,tourmaline amendment also increased the proportion of 2-chlorophenol(2-CP)from 18%to 30%of end products,while that of 3-CP decreased correspondingly.The theoretical calculations showed that the bond charge of the orthosubstituted chlorine declined from-0.179 to-0.067,and that of meta-substituted chlorine increased from-0.111 to-0.129,which indicated that the spontaneous electric field of tourmaline affected the charge distribution of 2,3-DCP and was more conducive to the generation of 2-CP.Overall,tourmaline with the spontaneous electric field affected the reductive dechlorination pathway of Desulfitobacterium,and the tourmaline-OHRB combining system might serve as a novel strategy for the bioremediation of environments polluted with chlorinated phenols.展开更多
Herein,the degradation of florfenicol(FLO)over zero-valent iron(ZVI)enhanced by SiC was systematically investigated.It was found that 5 g/L of ZVI/SiC(1:3)at pH 3.0 could completely degrade 20 mg/L of FLO within 1 h,w...Herein,the degradation of florfenicol(FLO)over zero-valent iron(ZVI)enhanced by SiC was systematically investigated.It was found that 5 g/L of ZVI/SiC(1:3)at pH 3.0 could completely degrade 20 mg/L of FLO within 1 h,with a Kobsvalue of 0.0873 min^(-1),12.5 times greater than that of pure ZVI(0.0069 min^(-1)).Vibrating sample magnetometer(VSM)characterizations revealed that the use of SiC supporter reduces the magnetic intensity of ZVI,which mitigates iron particle agglomeration,increases Brunauer-Emmett-Teller(BET)surface area,and enhances FLO degradation efficiency.Furthermore,ZVI/SiC exhibits a much lower hydrogen evolution potential(HEP)and significantly higher corrosion currents compared to pure ZVI.FLO was proposed to undergo degradation via reductive dechlorination,involving a hydrogenolysis mechanism that entails the cleavage of theσbond.This study provides new insights into the reduction hydrogenation mechanism of ZVI.展开更多
On-surface Ullmann-type reaction,or the dehalogenated coupling,is arguably the most pivotal reaction in on-surface synthesis for the fabrications of carbon nanostructures.Hitherto,the vast majority of works rely on ac...On-surface Ullmann-type reaction,or the dehalogenated coupling,is arguably the most pivotal reaction in on-surface synthesis for the fabrications of carbon nanostructures.Hitherto,the vast majority of works rely on activating the C-Br bond of aryl bromide which has a moderate bond dissociation energy.The C-Cl bond of aryl chloride has a higher dissociation energy and requires much higher thermal energy to break the bond.In this study,we have explored the on-surface photo-induced dechlorination and achieved the activation of three distinct aryl chlorines on the Au(111)surface with mild temperatures.This work enriches our understanding of on-surface photo-induced reactions and highlights the potential of photochemistry in realizing unconventional reactions.展开更多
A three-dimensional numerical model verified by previous experimental data is developed to simulate the fluidized bed gasification of refuse derived fuel （RDF）. The CaO dechlorination model obtained by the thermal g...A three-dimensional numerical model verified by previous experimental data is developed to simulate the fluidized bed gasification of refuse derived fuel （RDF）. The CaO dechlorination model obtained by the thermal gravity analysis （TGA） is coupled to investigate the process of CaO dechlorination. An Eulerian-Eulerian method is adopted to simulate the gas-solid flow and self-developed chemical reaction modules are used to simulate chemical reactions. Flow patterns, gasification results and dechlorination efficiency are obtained by numerical simulation. Meanwhile, simulations are performed to evaluate the effects of Ca/Cl molar ratio and temperature on dechlorination efficiency. The simulation results show that the presence of bubbles in the gasifier lowers the CaO dechlorination efficiency. Increasing the Ca/Cl molar ratio can enhance the dechlorination efficiency. However, with the temperature increasing, the dechlorination efficiency increases initially and then decreases. The optimal Ca/Cl molar ratio is in the range of 3. 0 to 3. 5 and the optimal temperature is 923K.展开更多
Catalytic nickel was successfully incorporated into nanoscale iron to enhance its dechlorination efficiency for trichloroethylene （TCE）, one of the most commonly detected chlorinated organic compounds in groundwater...Catalytic nickel was successfully incorporated into nanoscale iron to enhance its dechlorination efficiency for trichloroethylene （TCE）, one of the most commonly detected chlorinated organic compounds in groundwater. Ethane was the predominant product. The greatest dechlorination efficiency was achieved at 22 molar percent of nickel. This nanoscale Ni-Fe is poorly ordered and inhomogeneous; iron dissolution occurred whereas nickel was relatively stable during the 24-hr reaction. The morphological characterization provided significant new insights on the mechanism of catalytic hydrodcchlorination by bimetallic nanoparticles. TCE degradation and ethane production rates were greatly affected by environmental parameters such as solution pH, temperature and common groundwater ions. Both rate constants decreased and then increased over the pH range of 6.5 to 8.0, with the minimum value occurring at pH 7.5. TCE degradation rate constant showed an increasing trend over the temperature range of 10 to 25℃. However, ethane production rate constant increased and then decreased over the range, with the maximum value occurring at 20℃, Most salts in the solution appeared to enhance the reaction in the first half hour but overall they displayed an inhibitory effect. Combined ions showed a similar effect as individual salts.展开更多
Pd modified electrodes possess problems such as easy agglomeration and low electrolytic ability,and the use of manganese dioxide(MnO_(2)) to facilitate Pd reduction of organic pollutants is just started.However,there ...Pd modified electrodes possess problems such as easy agglomeration and low electrolytic ability,and the use of manganese dioxide(MnO_(2)) to facilitate Pd reduction of organic pollutants is just started.However,there is still a limited understanding of how to match the Pd load and MnO_(2) to realize optimal dechlorination efficiency at minimum cost.Here,a Pd/MnO_(2)/Ni foam cathode was successfully fabricated and applied for the efficient electrochemical dechlorination of 2,4,6-trichlorophenol(2,4,6-TCP).The optimal electrocatalytic hydrodechlorination(ECH)performance with 2,4,6-TCP dechlorination efficiency(92.58%in 180 min)was obtained when the concentration of PdCl_(2) precipitation was 1 mmol/L,the deposition time of MnO_(2) was 300 s and cathode potential was-0.8 V.Performance influenced by the exogenous factors(e.g.,initial pH and coexisted ions)were further investigated.It was found that the neutral pH was the most favorable for ECH and a reduction in dechlorination efficiency(6%~47.6%)was observed in presence of 5 mmol/L of NO_(2)^(-),NO_(3)^(-),S^(2-)or SO_(3)^(2-).Cyclic voltammetry(CV)and quenching experiments verified the existence of three hydrogen species on Pd surface,including adsorbed atomic hydrogen(H^(*)_(ads)),absorbed atomic hydrogen(H^(*)_(abs)),and molecular hydrogen(H_(2)).And the introduction of MnO_(2)promoted the generation of atomic H^(*).Only adsorbed atomic hydrogen(H^(*)_(ads)) was confirmed that it truly facilitated the ECH process.Besides H^(*)_(ads) induced reduction,the direct reduction by cathode electrons also participated in the 2,4,6-TCP dechlorination process.Pd/MnO_(2)/Ni foam cathode shows excellent dechlorination performance,fine stability and recyclable potential,which provides strategies for the effective degradation of persistent halogenated organic pollutants in groundwater.展开更多
o-Dichlorobenzene (o-DCB) was dechlorinated by Pd/Fe powder in water throughcatalytic reduction. The dechlorination reaction is believed to take place on the surface site ofthe catalyst via a pseuclo-first-order react...o-Dichlorobenzene (o-DCB) was dechlorinated by Pd/Fe powder in water throughcatalytic reduction. The dechlorination reaction is believed to take place on the surface site ofthe catalyst via a pseuclo-first-order reaction. The final reduction product of o-DCB is benzene.The dechlorination rate increases with the increase of bulk loading of palladium due to the increaseof both the surface loading of palladium and the total surface area. Dechlorination efficiencyaccounts for 90% at Pd/Fe mass ratio 0.02% and metal to solution ratio about 53.3g · L^(-1) in 120minutes. Dechlorination is affected by the reaction temperature, pH, Pd/Fe ratio and the addition ofPd/Fe. E_a is found to be 102.5 kJ · mol^(-1) in the temperature range of 287—313 K.展开更多
Nanoscale bimetallic Ni/Fe particles were synthesized from the reaction of sodium borohydride （NaBH4） with reduction of Ni^2＋ and Fe^2＋ in aqueous solution. The obtained Ni/Fe particles were characterized by TEM ...Nanoscale bimetallic Ni/Fe particles were synthesized from the reaction of sodium borohydride （NaBH4） with reduction of Ni^2＋ and Fe^2＋ in aqueous solution. The obtained Ni/Fe particles were characterized by TEM （transmission electron microscope）, XRD （X-ray diffractometer）, and N2-BET. The dechlorination activity of the Ni/Fe was investigated using p-chlorophenol （p-CP） as a probe agent. Results demonstrated that the nanoscale Ni/Fe could effectively dechlorinate p-CP at relatively low metal to solution ratio of 0.4 g/L （Ni 5 wt%）. The target with initial concentration ofp-CP 0.625 mmol/L was dechlorinted completely in 60 rain under ambient temperature and pressure. Factors affecting dechlorination efficiency, including reaction temperature, pH, Ni loading percentage over Fe, and metal to solution ratio, were investigated. The possible mechanism of dechlorination ofp-CP was proposed and discussed. The pseudo-first- order reaction took place on the surface of the Ni/Fe bimetallic particles, and the activation energy of the dechlorination reaction was determined to be 21.2 kJ/mol at the temperature rang of 287-313 K.展开更多
Laboratory studies were conducted to find out the efficacy of uniquely prepared zero valent iron impregnated silica in transforming xenobiotic chlorophenols namely 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlor...Laboratory studies were conducted to find out the efficacy of uniquely prepared zero valent iron impregnated silica in transforming xenobiotic chlorophenols namely 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol. Continuous mode column experiments were performed to investigate the transformation of chlorophenols by varying pH, column height, flow rate and initial chlorophenol concentration. Reusability study of the zero valent iron impregnated silica was studied as well as the morphological changes and the chemical composition of the catalyst medium were also investigated. Dechlorination kinetic studies were conducted and the order of dechlorination of chlorophenols was found to be 2,4,6-trichlorophenol 〉 2,4-dichlorophenol 〉 4-chlorophenol. The optimum pH, column height and flow rate were found to be 7, 20 cm and 0.75 L/hr respectively for all chlorophenols in the reaction duration of 4 hr. Intermediates formed during dechlorination study were identified by gas chromatography-mass spectroscopy analysis. This method was applied to real pulp and paper wastewater and was found satisfactory.展开更多
Nanoscale Pd/Fe bimetallic particles were synthesized with an efficient method to dechlorinate o-chlorophenol. The nanoscale Pd/Fe particles were determined by transmission electron microscopy and BET specific surface...Nanoscale Pd/Fe bimetallic particles were synthesized with an efficient method to dechlorinate o-chlorophenol. The nanoscale Pd/Fe particles were determined by transmission electron microscopy and BET specific surface area analysis. Most of the particles are in the size range of 20—100 nm. The BET specific surface area of synthesized nanoscale Pd/Fe particles is 12.4 m 2/g. In contrast, a commercially available fine iron powder(<100 mesh) has a specific surface area of 0.49 m 2/g. Batch studies demonstrated that the nanoscale particles can effectively dechlorinate o-chlorophenol. The dechlorination reaction takes place on the surface of synthesized nanoscale Pd/Fe bimetallic particles in a pseudo-first order reaction. The surface-area-normalized rate coefficients(k_ SA) are comparable to those reported in the literature for chlorinated ethenes. The observed reaction rate constants(k_ obs) are dominated by the mass fraction of Pd and the mass concentration of the nanoscale Pd/Fe particles.展开更多
Transformation of polychlorinated biphenyls （PCBs） by zero-valent iron represents one of the latest innovative technologies for environmental remediation. The dechlorination of 4-chlorobiphenyl （4-C1BP） by nanosca...Transformation of polychlorinated biphenyls （PCBs） by zero-valent iron represents one of the latest innovative technologies for environmental remediation. The dechlorination of 4-chlorobiphenyl （4-C1BP） by nanoscale zero-valent iron （NZVI） in the presence of humic acid or metal ions was investigated. The results showed that the dechlorination of 4-C1BP by NZVI increased with decreased solution pH. When the initial pH value was 4.0, 5.5, 6.8, and 9.0, the de.chlorination efficiencies of 4-CIBP after 48 hr were 53.8%, 47.8%, 35.7%, and 35.6%, respectively. The presence of humic acid inhibited the reduction of 4-CIBP in the first 4 hi＇, and then significantly accelerated the dechlorination by reaching 86.3% in 48 hr. Divalent metal ions, Co2＋, Cu2＋, and Ni2＋, were reduced and formed bimetals with NZVI, thereby enhanced the dechlorination of 4-CIBP. The dechlorination percentages of 4-CIBP in the presence of 0.1 mmol/L Co2~, Cuz~ and Niz~ were 66.1%, 66.0% and 64.6% in 48 hr, and then increased to 67.9%, 71.3% and 73.5%, after 96 hr respectively. The dechlorination kinetics of 4-C1BP by the NZVI in all cases followed pseudo-first order model. The results provide a basis for better understanding of the dechlorination mechanisms of PCBs in real environment.展开更多
method.The particles were(SEM),transmission electon characterired by X-ray difnction(XRD),X-ray fluorescence(XRF).sanning cletron microscope hose methods indicated that Emmett Tllrentrogen(BET-N)method.Data obrained f...method.The particles were(SEM),transmission electon characterired by X-ray difnction(XRD),X-ray fluorescence(XRF).sanning cletron microscope hose methods indicated that Emmett Tllrentrogen(BET-N)method.Data obrained fom was close to theoretical value.microscope(TEM),and Brunaue-Ea are Dee Pa 10 Fe rmi by weig PUEee;chains composed nosca cale Pd/Fe nanoscale Pd/Fe bimtali paricles Spherial ganules with diameler of f 4711.5 nm connected with one anober to form chains and bitalli prticles.Specic surface are a of particles was 51 m^(2)/g.The factors,such as secies of reductants,Pd/Fe ratio,dose of were studied.Dechlorination nanoscale PdFe bitall part rticles 0.182%Pd/Fe efet of monochoroacetic Bacid by iffret reductants>nanoscale Fe>reductive Fe.When the Pd/Fe ratio was lower than 0.083%,incresing Pd/Fe ratio would icreue dchlorinatio eficiency DE)of MCAA.When the Pd/Fe ratio,was higher than 0.083%,icreasing Pd/Fe ratio!Caused a derese in DE Adding more nanoscale Pd/Fe bimetallici I particles to solution would enhance;DE.The DE of MCAA decresed as ial pH of soluia i icreased.展开更多
Chlorobenzene was dechlorinated by Pd/Fe bimetallic system in water through catalytic reduction. The dechlorination rate increases with increase of bulk loading of Pd due to the increase of both the surface loading o...Chlorobenzene was dechlorinated by Pd/Fe bimetallic system in water through catalytic reduction. The dechlorination rate increases with increase of bulk loading of Pd due to the increase of both the surface loading of the Pd and the total surface area. For conditions with 0.005% Pd/Fe, 45% dechlorination efficiency was achieved within 5 h. The dechlorinated reaction is believed to take place on the bimetal surface in a pseudo-first-order reaction, with the rate constant being 0.0043 min-1.展开更多
The application of electron donor and electron shuttle substances has a vital influence on electron transfer,thus may affect the reductive dechlorination of 1,1,1-trichoro-2,2-bis（p-chlorophenyl）ethane（DDT） in ana...The application of electron donor and electron shuttle substances has a vital influence on electron transfer,thus may affect the reductive dechlorination of 1,1,1-trichoro-2,2-bis（p-chlorophenyl）ethane（DDT） in anaerobic reaction systems.To evaluate the roles of citric acid and anthraquinone-2,6-disulfonate（AQDS） in accelerating the reductive dechlorination of DDT in Hydragric Acrisols that contain abundant iron oxide,a batch anaerobic incubation experiment was conducted in a slurry system with four treatments of（1） control,（2） citric acid,（3） AQDS,and（4） citric acid ＋ AQDS.Results showed that DDT residues decreased by 78.93%-92.11% of the initial quantities after 20 days of incubation,and 1,1-dichloro-2,2-bis（4-chlorophenyl）-ethane（DDD） was the dominant metabolite.The application of citric acid accelerated DDT dechlorination slightly in the first 8 days,while the methanogenesis rate increased quickly,and then the acceleration effect improved after the 8th day while the methanogenesis rate decreased.The amendment by AQDS decreased the Eh value of the reaction system and accelerated microbial reduction of Fe（III） oxides to generate Fe（II）,which was an efficient electron donor,thus enhancing the reductive dechlorination rate of DDT.The addition of citric acid ＋ AQDS was most efficient in stimulating DDT dechlorination,but no significant interaction between citric acid and AQDS on DDT dechlorination was observed.The results will be of great significance for developing an efficient in situ remediation strategy for DDT-contaminated sites.展开更多
Catalytic reductive dechlorination of monochlorobenzene(MCB) was carried out in the palladium/iron system. With low Pd loading(0 005%), 45% dechlorination efficiency was achieved within 5 h. Pd as catalyst accelerated...Catalytic reductive dechlorination of monochlorobenzene(MCB) was carried out in the palladium/iron system. With low Pd loading(0 005%), 45% dechlorination efficiency was achieved within 5 h. Pd as catalyst accelerated the reductive dechlorination reaction. Dechlorination mechanism and kinetics were discussed. The reaction took place on the bimetal surface in a pseudo first order reaction, with the rate constant being 0 0071 min -1 ( K SA =8 0×10 -3 L/(m 2·h). The reduction product for MCB was benzene.展开更多
Electrochemical dechlorination of chloroform in neutral aqueous solution was investigated using palladium-loaded electrodes at ambient temperature. Palladium/foam-nickel （Pd/foam-Ni） and palladium/polymeric pyrrole ...Electrochemical dechlorination of chloroform in neutral aqueous solution was investigated using palladium-loaded electrodes at ambient temperature. Palladium/foam-nickel （Pd/foam-Ni） and palladium/polymeric pyrrole film/foam-nickel （Pd/PPy/foam-Ni） composite electrodes which provided catalytic surface for reductive dechlorination of chloroform in aqueous solution were prepared using an electrodepositing method. Scanning electron microscope （SEM） micrographs showed that polymeric pyrrole film modified the electrode-surface characteristics and resulted in the uniform dispersion of needle-shaped palladium particles on foam-Ni supporting electrode. The experimental results of dechlorination indicated that the removal efficiency of chloroform and current efficiency in neutral aqueous solution on Pd/PPy/foam-Ni electrode could be up to 36.8% and 33.0% at dechlorination current of 0.1 mA and dechlorination time of 180 min, which is much higher than that of Pd/foam-Ni electrode.展开更多
Detoxification of chlorinated organic compounds via reaction with nickel/iron powder was implemented in aqueous solution. Compared to iron, nickel/iron bimetallic powder had higher hydrodechlorination activities for b...Detoxification of chlorinated organic compounds via reaction with nickel/iron powder was implemented in aqueous solution. Compared to iron, nickel/iron bimetallic powder had higher hydrodechlorination activities for both atrazine (ATR) and p-chlorophenol (pCP); nickel/iron (2.96%, w/w) was shown to have the largest specific surface area and the optimum proportion for the dechlorination of both ATR and pCP. Electrochemical measurements showed that the adsorbed hydrogen atom on the nickel must have been the dominant reductive agent for the dechlorination of both ATR andpCP in this system.展开更多
Using fixed-bed reaction method and changing the gas composition and dust content,the influence of blast furnace top gas composition and dust on HCl removal with low temperature Ca-based antichlor was studied.It was f...Using fixed-bed reaction method and changing the gas composition and dust content,the influence of blast furnace top gas composition and dust on HCl removal with low temperature Ca-based antichlor was studied.It was found that,when the content of CO2 in blast furnace top gas increased,the dechlorination efficiency was getting worse obviously;when the contents of CO and N2 increased,the dechlorination efficiency was getting better to a certain extent;when the content of H2 changed,the dechlorination efficiency got no significant change;as the content of dust increased,the dechlorination efficiency got better obviously when the content was less than 15 g/m3,but it would be got worse quickly when the content was more than 20 g/m3,and the best content was 15–20 g/m3;the suitable site of the process of dechlorination was after gravity dust collector and before bag dust collector.展开更多
基金supported by the Open Topics of State Key Laboratory of Clean and Efficient Coal-Fired Power Generation and Pollution Control(D2022FK103)National Natural Science Foundation of China(22278250)+1 种基金the Shanxi Province Science and Technology Cooperation and Exchange Special Program(202104041101014)the Shanxi Province Scholarship Council。
文摘In the current era of renewable energy prominence,the wide operational capacity of coal-fired boilers has emerged as crucial for ensuring the sustainability of power plants.However,attaining ultra-low nitrogen oxides(NO_x)emissions during periods of low-load operations presents a significant and persistent challenge for coal power enterprises.While techniques such as biomass re-burning and advanced re-burning have shown promise in enhancing NO reduction effciency above 800℃,their elevated levels of chlorine(Cl)and alkali metals pose potential risks to boiler equipment integrity.Therefore,this study proposes the utilization of biomass char derived from pyrolysis as a dual-purpose solution to enhance NO reduction efficiency while safeguarding boiler integrity during low-load operations.Findings indicate that pyrolysis treatment effectively reduces the Cl and alkali metal content of biomass.Specifically,it was determined that biomass char produced through deeply pyrolysis at 300℃achieves the highest NO reduction efficiency while minimizing the presence of harmful components.At a reduction temperature of 700℃,both re-burning and advanced re-burning techniques exhibit NO reduction efficiencies of 55.90%and 62.22%,which is already an ideal deficiency at low temperatures.The addition of water vapor at 700-800℃obviously avoids the oxidation of ammonia to NO in advanced reburning.Upon further analysis,denitrification efficiency in biomass char re-burning and advanced reburning is influenced not only by volatile content but also by physicochemical properties such as porosity and surface functional group distribution under certain reaction conditions.This study provides a theoretical framework for the industrial implementation of biomass char for NO control in coal-fired power plants,offering insights into optimizing NO reduction efficiency while mitigating potential risks to boiler equipment.
基金supported by the National Natural Science Foundation of China(Nos.52270165 and 51978537)the Key Laboratory of Safety for Geotechnical and Structural Engineering of Hubei Province。
文摘The persistence of chlorinated alkanes in aquatic environments poses significant health risks due to its biotoxicity and high volatility,which contributes to both water and air pollution.This study investigates the efficacy of carbon dioxide radical anion(CO_(2)·^(-))mediated advanced reduction processes(ARPs)for the reductive dechlorination of chlorinated alkanes using small molecular monocarboxylic acids(SMAs)under UV irradiation.The study focused on formic acid(HCOOH),acetic acid(CH_3COOH),and propionic acid(CH_3CH_(2)COOH)to generate CO_(2)·^(-),revealing that UV/HCOOH system exhibits a notably high chloroform(CF)degradation efficiency of 97.8%in 90 min.Kinetic studies indicated a linear relationship between the HCOOH concentrations and the observed reaction rate constants(k_(obs)),demonstrating that CO_(2)·^(-)production is crucial for CF degradation.Electron paramagnetic resonance spectroscopy identified CO_(2)·^(-)and hydroxyl radicals(HO·)as the active species,with the former playing a predominant role in CF degradation.The study also explored the influence of carbon chain length in SMAs on CF degradation,finding that longer chains decrease the degradation efficiency,potentially due to reduced UV activation.A higher reaction rate constant(k_(obs))under acidic conditions,with a marked decrease in efficiency as the pH exceeds 3.7,where HCOO^(-)becomes predominant.This study enhances our understanding of CO_(2)·^(-)mediated ARPs and explores potential applications in environmental remediation,providing insights into the pathways and mechanisms of CF degradation.The UV/SMAs systems offer advantages for practical applications,such as milder reaction conditions and higher efficiency compared to traditional methods.
基金supported by the Natural Science Foundation of Hunan Province of China (No.2020JJ4194)the Shenzhen Science and Technology Program (No.JCYJ20220530160412027)+4 种基金the Changsha Science and Technology Program (No.kq2004022)the Science and Technology Innovation Program of Hunan Province (No.2022RC1026)the Project of the National Key Research and Development Program of China (No.2021YFC1910400)the Technical Innovation Leading Plan Project for Hunan High-tech Industry (Nos.2020SK2042 and2022GK4062)the Key R&D Project of Hunan Province of China (No.2022SK2067)。
文摘The dehalogenation of organohalides has been a research hotspot in bioremediation field;however,the influence of tourmaline,a natural ore that can generate spontaneous electric field,on organohalide-respiring bacteria(OHRB)and their dechlorination process is not well known.In this study,the effect and mechanism of tourmaline on the reductive dechlorination of 2,3-dichlorophenol(2,3-DCP)by Desulfitobacterium hafniense DCB-2Twere explored.The characterization results confirmed that tourmaline had good stability and the optimal dosage of tourmaline was 2.5 g/L,which shortened the total time required for dechlorination reaction to 72 hr.Besides,tourmaline amendment also increased the proportion of 2-chlorophenol(2-CP)from 18%to 30%of end products,while that of 3-CP decreased correspondingly.The theoretical calculations showed that the bond charge of the orthosubstituted chlorine declined from-0.179 to-0.067,and that of meta-substituted chlorine increased from-0.111 to-0.129,which indicated that the spontaneous electric field of tourmaline affected the charge distribution of 2,3-DCP and was more conducive to the generation of 2-CP.Overall,tourmaline with the spontaneous electric field affected the reductive dechlorination pathway of Desulfitobacterium,and the tourmaline-OHRB combining system might serve as a novel strategy for the bioremediation of environments polluted with chlorinated phenols.
基金financially supported by the Guangdong Basic and Applied Basic Research Foundation(No.2021A1515110954)National Key Research and Development Projects of China(No.2022YEC3203302)+1 种基金Guangdong Province Enterprise Science and Technology Commissioner Project(No.GDKTP2021048000)National Natural Science Foundation of China(No.41907292)。
文摘Herein,the degradation of florfenicol(FLO)over zero-valent iron(ZVI)enhanced by SiC was systematically investigated.It was found that 5 g/L of ZVI/SiC(1:3)at pH 3.0 could completely degrade 20 mg/L of FLO within 1 h,with a Kobsvalue of 0.0873 min^(-1),12.5 times greater than that of pure ZVI(0.0069 min^(-1)).Vibrating sample magnetometer(VSM)characterizations revealed that the use of SiC supporter reduces the magnetic intensity of ZVI,which mitigates iron particle agglomeration,increases Brunauer-Emmett-Teller(BET)surface area,and enhances FLO degradation efficiency.Furthermore,ZVI/SiC exhibits a much lower hydrogen evolution potential(HEP)and significantly higher corrosion currents compared to pure ZVI.FLO was proposed to undergo degradation via reductive dechlorination,involving a hydrogenolysis mechanism that entails the cleavage of theσbond.This study provides new insights into the reduction hydrogenation mechanism of ZVI.
基金supported by National Natural Science Foundation of China(Nos.22072086,22302120)。
文摘On-surface Ullmann-type reaction,or the dehalogenated coupling,is arguably the most pivotal reaction in on-surface synthesis for the fabrications of carbon nanostructures.Hitherto,the vast majority of works rely on activating the C-Br bond of aryl bromide which has a moderate bond dissociation energy.The C-Cl bond of aryl chloride has a higher dissociation energy and requires much higher thermal energy to break the bond.In this study,we have explored the on-surface photo-induced dechlorination and achieved the activation of three distinct aryl chlorines on the Au(111)surface with mild temperatures.This work enriches our understanding of on-surface photo-induced reactions and highlights the potential of photochemistry in realizing unconventional reactions.
基金The National Natural Science Foundation of China(No.51476032)
文摘A three-dimensional numerical model verified by previous experimental data is developed to simulate the fluidized bed gasification of refuse derived fuel （RDF）. The CaO dechlorination model obtained by the thermal gravity analysis （TGA） is coupled to investigate the process of CaO dechlorination. An Eulerian-Eulerian method is adopted to simulate the gas-solid flow and self-developed chemical reaction modules are used to simulate chemical reactions. Flow patterns, gasification results and dechlorination efficiency are obtained by numerical simulation. Meanwhile, simulations are performed to evaluate the effects of Ca/Cl molar ratio and temperature on dechlorination efficiency. The simulation results show that the presence of bubbles in the gasifier lowers the CaO dechlorination efficiency. Increasing the Ca/Cl molar ratio can enhance the dechlorination efficiency. However, with the temperature increasing, the dechlorination efficiency increases initially and then decreases. The optimal Ca/Cl molar ratio is in the range of 3. 0 to 3. 5 and the optimal temperature is 923K.
基金supported by the National Natural Science Foundation of China(No.20807004)the General Research an Development Founding for Universities directly under the Ministry of Education of China(BUCTZZ1202)
文摘Catalytic nickel was successfully incorporated into nanoscale iron to enhance its dechlorination efficiency for trichloroethylene （TCE）, one of the most commonly detected chlorinated organic compounds in groundwater. Ethane was the predominant product. The greatest dechlorination efficiency was achieved at 22 molar percent of nickel. This nanoscale Ni-Fe is poorly ordered and inhomogeneous; iron dissolution occurred whereas nickel was relatively stable during the 24-hr reaction. The morphological characterization provided significant new insights on the mechanism of catalytic hydrodcchlorination by bimetallic nanoparticles. TCE degradation and ethane production rates were greatly affected by environmental parameters such as solution pH, temperature and common groundwater ions. Both rate constants decreased and then increased over the pH range of 6.5 to 8.0, with the minimum value occurring at pH 7.5. TCE degradation rate constant showed an increasing trend over the temperature range of 10 to 25℃. However, ethane production rate constant increased and then decreased over the range, with the maximum value occurring at 20℃, Most salts in the solution appeared to enhance the reaction in the first half hour but overall they displayed an inhibitory effect. Combined ions showed a similar effect as individual salts.
基金supported by the NSFC-JSPS joint research program(No.51961145202)the Natural Science Foundation of Heilongjiang Province,China(No.C2018035)。
文摘Pd modified electrodes possess problems such as easy agglomeration and low electrolytic ability,and the use of manganese dioxide(MnO_(2)) to facilitate Pd reduction of organic pollutants is just started.However,there is still a limited understanding of how to match the Pd load and MnO_(2) to realize optimal dechlorination efficiency at minimum cost.Here,a Pd/MnO_(2)/Ni foam cathode was successfully fabricated and applied for the efficient electrochemical dechlorination of 2,4,6-trichlorophenol(2,4,6-TCP).The optimal electrocatalytic hydrodechlorination(ECH)performance with 2,4,6-TCP dechlorination efficiency(92.58%in 180 min)was obtained when the concentration of PdCl_(2) precipitation was 1 mmol/L,the deposition time of MnO_(2) was 300 s and cathode potential was-0.8 V.Performance influenced by the exogenous factors(e.g.,initial pH and coexisted ions)were further investigated.It was found that the neutral pH was the most favorable for ECH and a reduction in dechlorination efficiency(6%~47.6%)was observed in presence of 5 mmol/L of NO_(2)^(-),NO_(3)^(-),S^(2-)or SO_(3)^(2-).Cyclic voltammetry(CV)and quenching experiments verified the existence of three hydrogen species on Pd surface,including adsorbed atomic hydrogen(H^(*)_(ads)),absorbed atomic hydrogen(H^(*)_(abs)),and molecular hydrogen(H_(2)).And the introduction of MnO_(2)promoted the generation of atomic H^(*).Only adsorbed atomic hydrogen(H^(*)_(ads)) was confirmed that it truly facilitated the ECH process.Besides H^(*)_(ads) induced reduction,the direct reduction by cathode electrons also participated in the 2,4,6-TCP dechlorination process.Pd/MnO_(2)/Ni foam cathode shows excellent dechlorination performance,fine stability and recyclable potential,which provides strategies for the effective degradation of persistent halogenated organic pollutants in groundwater.
基金the Returnee Foundation of Ministry of Education of China (No. 2002-247)Science and Technology Project of Zhejiang Province (No. 2004C34006).
文摘o-Dichlorobenzene (o-DCB) was dechlorinated by Pd/Fe powder in water throughcatalytic reduction. The dechlorination reaction is believed to take place on the surface site ofthe catalyst via a pseuclo-first-order reaction. The final reduction product of o-DCB is benzene.The dechlorination rate increases with the increase of bulk loading of palladium due to the increaseof both the surface loading of palladium and the total surface area. Dechlorination efficiencyaccounts for 90% at Pd/Fe mass ratio 0.02% and metal to solution ratio about 53.3g · L^(-1) in 120minutes. Dechlorination is affected by the reaction temperature, pH, Pd/Fe ratio and the addition ofPd/Fe. E_a is found to be 102.5 kJ · mol^(-1) in the temperature range of 287—313 K.
基金Project supported by the National Basic Research Program (973) of China(No. 2003CB415006)the National Natural Science Foundation of China (No. 20337020)
文摘Nanoscale bimetallic Ni/Fe particles were synthesized from the reaction of sodium borohydride （NaBH4） with reduction of Ni^2＋ and Fe^2＋ in aqueous solution. The obtained Ni/Fe particles were characterized by TEM （transmission electron microscope）, XRD （X-ray diffractometer）, and N2-BET. The dechlorination activity of the Ni/Fe was investigated using p-chlorophenol （p-CP） as a probe agent. Results demonstrated that the nanoscale Ni/Fe could effectively dechlorinate p-CP at relatively low metal to solution ratio of 0.4 g/L （Ni 5 wt%）. The target with initial concentration ofp-CP 0.625 mmol/L was dechlorinted completely in 60 rain under ambient temperature and pressure. Factors affecting dechlorination efficiency, including reaction temperature, pH, Ni loading percentage over Fe, and metal to solution ratio, were investigated. The possible mechanism of dechlorination ofp-CP was proposed and discussed. The pseudo-first- order reaction took place on the surface of the Ni/Fe bimetallic particles, and the activation energy of the dechlorination reaction was determined to be 21.2 kJ/mol at the temperature rang of 287-313 K.
文摘Laboratory studies were conducted to find out the efficacy of uniquely prepared zero valent iron impregnated silica in transforming xenobiotic chlorophenols namely 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol. Continuous mode column experiments were performed to investigate the transformation of chlorophenols by varying pH, column height, flow rate and initial chlorophenol concentration. Reusability study of the zero valent iron impregnated silica was studied as well as the morphological changes and the chemical composition of the catalyst medium were also investigated. Dechlorination kinetic studies were conducted and the order of dechlorination of chlorophenols was found to be 2,4,6-trichlorophenol 〉 2,4-dichlorophenol 〉 4-chlorophenol. The optimum pH, column height and flow rate were found to be 7, 20 cm and 0.75 L/hr respectively for all chlorophenols in the reaction duration of 4 hr. Intermediates formed during dechlorination study were identified by gas chromatography-mass spectroscopy analysis. This method was applied to real pulp and paper wastewater and was found satisfactory.
文摘Nanoscale Pd/Fe bimetallic particles were synthesized with an efficient method to dechlorinate o-chlorophenol. The nanoscale Pd/Fe particles were determined by transmission electron microscopy and BET specific surface area analysis. Most of the particles are in the size range of 20—100 nm. The BET specific surface area of synthesized nanoscale Pd/Fe particles is 12.4 m 2/g. In contrast, a commercially available fine iron powder(<100 mesh) has a specific surface area of 0.49 m 2/g. Batch studies demonstrated that the nanoscale particles can effectively dechlorinate o-chlorophenol. The dechlorination reaction takes place on the surface of synthesized nanoscale Pd/Fe bimetallic particles in a pseudo-first order reaction. The surface-area-normalized rate coefficients(k_ SA) are comparable to those reported in the literature for chlorinated ethenes. The observed reaction rate constants(k_ obs) are dominated by the mass fraction of Pd and the mass concentration of the nanoscale Pd/Fe particles.
基金supported by the National Basic Research and Development Program (973) of China (No. 2007CB936604)
文摘Transformation of polychlorinated biphenyls （PCBs） by zero-valent iron represents one of the latest innovative technologies for environmental remediation. The dechlorination of 4-chlorobiphenyl （4-C1BP） by nanoscale zero-valent iron （NZVI） in the presence of humic acid or metal ions was investigated. The results showed that the dechlorination of 4-C1BP by NZVI increased with decreased solution pH. When the initial pH value was 4.0, 5.5, 6.8, and 9.0, the de.chlorination efficiencies of 4-CIBP after 48 hr were 53.8%, 47.8%, 35.7%, and 35.6%, respectively. The presence of humic acid inhibited the reduction of 4-CIBP in the first 4 hi＇, and then significantly accelerated the dechlorination by reaching 86.3% in 48 hr. Divalent metal ions, Co2＋, Cu2＋, and Ni2＋, were reduced and formed bimetals with NZVI, thereby enhanced the dechlorination of 4-CIBP. The dechlorination percentages of 4-CIBP in the presence of 0.1 mmol/L Co2~, Cuz~ and Niz~ were 66.1%, 66.0% and 64.6% in 48 hr, and then increased to 67.9%, 71.3% and 73.5%, after 96 hr respectively. The dechlorination kinetics of 4-C1BP by the NZVI in all cases followed pseudo-first order model. The results provide a basis for better understanding of the dechlorination mechanisms of PCBs in real environment.
文摘method.The particles were(SEM),transmission electon characterired by X-ray difnction(XRD),X-ray fluorescence(XRF).sanning cletron microscope hose methods indicated that Emmett Tllrentrogen(BET-N)method.Data obrained fom was close to theoretical value.microscope(TEM),and Brunaue-Ea are Dee Pa 10 Fe rmi by weig PUEee;chains composed nosca cale Pd/Fe nanoscale Pd/Fe bimtali paricles Spherial ganules with diameler of f 4711.5 nm connected with one anober to form chains and bitalli prticles.Specic surface are a of particles was 51 m^(2)/g.The factors,such as secies of reductants,Pd/Fe ratio,dose of were studied.Dechlorination nanoscale PdFe bitall part rticles 0.182%Pd/Fe efet of monochoroacetic Bacid by iffret reductants>nanoscale Fe>reductive Fe.When the Pd/Fe ratio was lower than 0.083%,incresing Pd/Fe ratio would icreue dchlorinatio eficiency DE)of MCAA.When the Pd/Fe ratio,was higher than 0.083%,icreasing Pd/Fe ratio!Caused a derese in DE Adding more nanoscale Pd/Fe bimetallici I particles to solution would enhance;DE.The DE of MCAA decresed as ial pH of soluia i icreased.
文摘Chlorobenzene was dechlorinated by Pd/Fe bimetallic system in water through catalytic reduction. The dechlorination rate increases with increase of bulk loading of Pd due to the increase of both the surface loading of the Pd and the total surface area. For conditions with 0.005% Pd/Fe, 45% dechlorination efficiency was achieved within 5 h. The dechlorinated reaction is believed to take place on the bimetal surface in a pseudo-first-order reaction, with the rate constant being 0.0043 min-1.
基金supported by the National Natural Science Foundation of China (No.41201314)the Open Fund Project of State Key Laboratory of Soil and Sustainable Agriculture (No.0812201227)
文摘The application of electron donor and electron shuttle substances has a vital influence on electron transfer,thus may affect the reductive dechlorination of 1,1,1-trichoro-2,2-bis（p-chlorophenyl）ethane（DDT） in anaerobic reaction systems.To evaluate the roles of citric acid and anthraquinone-2,6-disulfonate（AQDS） in accelerating the reductive dechlorination of DDT in Hydragric Acrisols that contain abundant iron oxide,a batch anaerobic incubation experiment was conducted in a slurry system with four treatments of（1） control,（2） citric acid,（3） AQDS,and（4） citric acid ＋ AQDS.Results showed that DDT residues decreased by 78.93%-92.11% of the initial quantities after 20 days of incubation,and 1,1-dichloro-2,2-bis（4-chlorophenyl）-ethane（DDD） was the dominant metabolite.The application of citric acid accelerated DDT dechlorination slightly in the first 8 days,while the methanogenesis rate increased quickly,and then the acceleration effect improved after the 8th day while the methanogenesis rate decreased.The amendment by AQDS decreased the Eh value of the reaction system and accelerated microbial reduction of Fe（III） oxides to generate Fe（II）,which was an efficient electron donor,thus enhancing the reductive dechlorination rate of DDT.The addition of citric acid ＋ AQDS was most efficient in stimulating DDT dechlorination,but no significant interaction between citric acid and AQDS on DDT dechlorination was observed.The results will be of great significance for developing an efficient in situ remediation strategy for DDT-contaminated sites.
文摘Catalytic reductive dechlorination of monochlorobenzene(MCB) was carried out in the palladium/iron system. With low Pd loading(0 005%), 45% dechlorination efficiency was achieved within 5 h. Pd as catalyst accelerated the reductive dechlorination reaction. Dechlorination mechanism and kinetics were discussed. The reaction took place on the bimetal surface in a pseudo first order reaction, with the rate constant being 0 0071 min -1 ( K SA =8 0×10 -3 L/(m 2·h). The reduction product for MCB was benzene.
文摘Electrochemical dechlorination of chloroform in neutral aqueous solution was investigated using palladium-loaded electrodes at ambient temperature. Palladium/foam-nickel （Pd/foam-Ni） and palladium/polymeric pyrrole film/foam-nickel （Pd/PPy/foam-Ni） composite electrodes which provided catalytic surface for reductive dechlorination of chloroform in aqueous solution were prepared using an electrodepositing method. Scanning electron microscope （SEM） micrographs showed that polymeric pyrrole film modified the electrode-surface characteristics and resulted in the uniform dispersion of needle-shaped palladium particles on foam-Ni supporting electrode. The experimental results of dechlorination indicated that the removal efficiency of chloroform and current efficiency in neutral aqueous solution on Pd/PPy/foam-Ni electrode could be up to 36.8% and 33.0% at dechlorination current of 0.1 mA and dechlorination time of 180 min, which is much higher than that of Pd/foam-Ni electrode.
基金Project (No. 30270767) supported by the National Natural Science Foundation of China
文摘Detoxification of chlorinated organic compounds via reaction with nickel/iron powder was implemented in aqueous solution. Compared to iron, nickel/iron bimetallic powder had higher hydrodechlorination activities for both atrazine (ATR) and p-chlorophenol (pCP); nickel/iron (2.96%, w/w) was shown to have the largest specific surface area and the optimum proportion for the dechlorination of both ATR and pCP. Electrochemical measurements showed that the adsorbed hydrogen atom on the nickel must have been the dominant reductive agent for the dechlorination of both ATR andpCP in this system.
基金Project(51274080)supported by the National Natural Science Foundation of ChinaProject(E2013209051)supported by the Hebei Science Foundation and the Steel and Iron Joint Research Foundation Project,China+1 种基金Project(U1502273)supported by the Joint Funds of the Natural Science Foundation of China and Yunnan Provincial GovernmentProjects(N150202001,N150203003)supported by the Fundamental Research Funds for the Central Universities,China
文摘Using fixed-bed reaction method and changing the gas composition and dust content,the influence of blast furnace top gas composition and dust on HCl removal with low temperature Ca-based antichlor was studied.It was found that,when the content of CO2 in blast furnace top gas increased,the dechlorination efficiency was getting worse obviously;when the contents of CO and N2 increased,the dechlorination efficiency was getting better to a certain extent;when the content of H2 changed,the dechlorination efficiency got no significant change;as the content of dust increased,the dechlorination efficiency got better obviously when the content was less than 15 g/m3,but it would be got worse quickly when the content was more than 20 g/m3,and the best content was 15–20 g/m3;the suitable site of the process of dechlorination was after gravity dust collector and before bag dust collector.
