Applying bio-oxidation waste solution(BOS)to chemical-biological two-stage oxidation process can significantly improve the bio-oxidation efficiency of arsenopyrite.This study aims to clarify the enhanced oxidation mec...Applying bio-oxidation waste solution(BOS)to chemical-biological two-stage oxidation process can significantly improve the bio-oxidation efficiency of arsenopyrite.This study aims to clarify the enhanced oxidation mechanism of arsenopyrite by evaluating the effects of physical and chemical changes of arsenopyrite in BOS chemical oxidation stage on mineral dissolution kinetics,as well as microbial growth activity and community structure composition in bio-oxidation stage.The results showed that the chemical oxidation contributed to destroying the physical and chemical structure of arsenopyrite surface and reducing the particle size,and led to the formation of nitrogenous substances on mineral surface.These chemical oxidation behaviors effectively promoted Fe^(3+)cycling in the bio-oxidation system and weakened the inhibitory effect of the sulfur film on ionic diffusion,thereby enhancing the dissolution kinetics of the arsenopyrite.Therefore,the bio-oxidation efficiency of arsenopyrite was significantly increased in the two-stage oxidation process.After 18 d,the two-stage oxidation process achieved total extraction rates of(88.8±2.0)%,(86.7±1.3)%,and(74.7±3.0)%for As,Fe,and S elements,respectively.These values represented a significant increase of(50.8±3.4)%,(47.1±2.7)%,and(46.0±0.7)%,respectively,compared to the one-stage bio-oxidation process.展开更多
Silver ion can be useful in improving chalcopyrite bioleaching efficiency.In this work,leaching kinetics of this process was investigated using silver-bearing solid waste under different chalcopyrite/solid waste ratio...Silver ion can be useful in improving chalcopyrite bioleaching efficiency.In this work,leaching kinetics of this process was investigated using silver-bearing solid waste under different chalcopyrite/solid waste ratios.Bioleaching behavior indicates that silver-bearing solid waste can enhance the bioleaching process,and the redox potential is much higher than the proposed appropriate range(380−480 mV vs Ag/AgCl)with the solid waste added.There is a positive correlation between temperature and copper extraction rate.The kinetics data fit well with the shrinking-core model.Under these leaching conditions,the bioleaching of chalcopyrite is controlled by internal diffusion with calculated apparent activation energy(Ea)of 28.24 kJ/mol.This work is possible benificial to promote the industrial application of silver catalyst in leaching of chalcopyrite.展开更多
In this work,the bioleaching process of pyrite,chalcocite and covellite which were the main phase compositions for Zijin copper mineral was comprehensively studied.The influence parameters,such as leaching temperature...In this work,the bioleaching process of pyrite,chalcocite and covellite which were the main phase compositions for Zijin copper mineral was comprehensively studied.The influence parameters,such as leaching temperature,Fe^(3+)concentration,pH of solution and bacteria concentration were investigated.The leaching kinetics of the pyrite,chalcocite and covellite under the studied conditions was successfully modeled by an empirical diffusion-like equation,respectively.The apparent activity energy of pyrite leaching,chalcocite leaching(stage Ⅱ)and covellite leaching was calculated to be 69.29,65.02 and 84.97 kJ/mol,respectively.展开更多
The crystal structure,formation kinetics and micro-morphology of CaO·SiO2 during high-temperature sintering process were studied in low-calcium system by XRD,FT-IR,Raman and SEM-EDS methods.When the molar ratio o...The crystal structure,formation kinetics and micro-morphology of CaO·SiO2 during high-temperature sintering process were studied in low-calcium system by XRD,FT-IR,Raman and SEM-EDS methods.When the molar ratio of CaCO3 to SiO2 is 1.0,β-2CaO·SiO2 forms firstly during the heating process,and then CaO·SiO2 is generated by the transformation reaction of pre-formed 2CaO·SiO2 with SiO2.3CaO·SiO2 and 3CaO·2SiO2 do not form either in the heating or sintering process.Rising the sintering temperature and prolonging the holding time promote the phase transition of 2CaO·SiO2 to CaO·SiO2,resulting in the sintered products a small blue shift and broadening in Raman spectra.The content of CS can reach 97.4%when sintered at 1400℃ for 1 h.The formation kinetics of CaO·SiO2 follows the second-order chemical reaction model,and the corresponding apparent activation energy and pre-exponential factor are 505.82 kJ/mol and 2.16×10^14 s^−1 respectively.展开更多
The features of organic pollutants degradation mainly characterized by bio-flocculation for step-A of adsorption-biodegredation（AB） process were studied. By investigating the relationship of extracellular polymeric ...The features of organic pollutants degradation mainly characterized by bio-flocculation for step-A of adsorption-biodegredation（AB） process were studied. By investigating the relationship of extracellular polymeric substances（EPS） with bioflocculation and introducing kinetic model of organic pollutant degradation into EPS, the kinetic model of organic pollutant degradation for step-A hioflocculation was deducted. And through the experiments, the kinetic constants were calculated as follows： k1 =0. 005 3; kc1 =1 710.7 and vmax1=10 min^-1.展开更多
In this study, a lab-scale upflow anaerobic sludge blanket(UASB) reactor was applied to studying the high-rate nitrogen removal of granule-based anammox process. The nitrogen removal rate(NRR) finally improved to 15.7...In this study, a lab-scale upflow anaerobic sludge blanket(UASB) reactor was applied to studying the high-rate nitrogen removal of granule-based anammox process. The nitrogen removal rate(NRR) finally improved to 15.77 kg/m3/d by shortening hydraulic retention time(HRT) to 1.06 h. Well-shaped red anammox granules were extensively enriched inside the reactor. The results of nitrogen removal kinetics indicated that the present bioreactor has great nitrogen removal potential, because the maximum rate of substrate utilization(Umax) predicted by Stover-Kincannon model is suggested as 55.68 kg/(m3·d). Analysis of the microbial community showed that the anammox genus Candidatus Kuenenia dominated the bacterial communities. The relative abundance of Candidatus Kuenenia rose from 12.29% to 36.95% after progressively shorter HRT and higher influent substrate concentrations, illustrating the stability of nitrogen removal performance and biomass enrichment offered by the UASB in carrying out high-rate anammox process.展开更多
The gene sod in Acidithiobacillusferrooxidans may play a crucial role in its tolerance to the extremely acidic, toxic and oxidative environment of bioleaching. For insight into the anti-toxic mechanism of the bacteria...The gene sod in Acidithiobacillusferrooxidans may play a crucial role in its tolerance to the extremely acidic, toxic and oxidative environment of bioleaching. For insight into the anti-toxic mechanism of the bacteria, a three-dimensional （3D） molecular structure of the protein encoded by this gene was built by homology modeling techniques, refined by molecular dynamics simulations, assessed by PROFILE-3D and PROSTAT programs and its key residues were further detected by evolutionary trace analysis. Through these procedures, some trace residues were identified and spatially clustered. Among them, the residues of Asn38, Glyl03 and Glul61 are randomly scattered throughout the mapped structure; interestingly, the other residues are all distinctly clustered in a subgroup near Fe atom. From these results, this gene can be confirmed at 3D level to encode the Fe-depending superoxide dismutase and subsequently play an anti-toxic role. Furthermore, the detected key residues around Fe binding site can be conjectured to be directly responsible for Fe binding and catalytic function.展开更多
The biosorption mechanism of Cr （Ⅳ） ions on Synechococcus sp. biosorbent was studied by analyzing the biosorption kinetics as well as speciation change and bond formation during the biosorption process. The kinetic...The biosorption mechanism of Cr （Ⅳ） ions on Synechococcus sp. biosorbent was studied by analyzing the biosorption kinetics as well as speciation change and bond formation during the biosorption process. The kinetics study shows that the adsorption process of Cr （Ⅳ） consists of a very fast stage in the first several minutes, in which more than half of the saturation adsorption is attained, and a slower stage that approximately follows the first order kinetic model, basically Freundlich isotherm models were observed. Comparative studies of FT-LR spectra of K2Cr2O7, free cells of Synechococcus sp., and Cr-bound cells of Synechococcus sp show that the speciation of chromium that binds to the cells ofSynechococcus sp. is Cr （Ⅲ）, instead of Cr （Ⅳ）, and the carboxylic, alcoholic, amido and amino groups may be involved in the binding of Cr （Ⅲ）. Integrative analyses of the surface electric potential, the effect of pH value on adsorption behavior of Cr （Ⅵ）, and the results of FT-IR show that the biosorption of Cr （Ⅵ） follows two subsequent steps, biosorption of Cr2O7 ^2- by electrostatical force at the protonated active sites and reduction of Cr2O7^2- to Cr^3＋ by the reductive groups on the surface of the biosorbents.展开更多
基金Project(52274348)supported by the National Natural Science Foundation of ChinaProject(2022JH1/10400024)supported by the Major Projects for the“Revealed Top”Science and Technology of Liaoning Province,China。
文摘Applying bio-oxidation waste solution(BOS)to chemical-biological two-stage oxidation process can significantly improve the bio-oxidation efficiency of arsenopyrite.This study aims to clarify the enhanced oxidation mechanism of arsenopyrite by evaluating the effects of physical and chemical changes of arsenopyrite in BOS chemical oxidation stage on mineral dissolution kinetics,as well as microbial growth activity and community structure composition in bio-oxidation stage.The results showed that the chemical oxidation contributed to destroying the physical and chemical structure of arsenopyrite surface and reducing the particle size,and led to the formation of nitrogenous substances on mineral surface.These chemical oxidation behaviors effectively promoted Fe^(3+)cycling in the bio-oxidation system and weakened the inhibitory effect of the sulfur film on ionic diffusion,thereby enhancing the dissolution kinetics of the arsenopyrite.Therefore,the bio-oxidation efficiency of arsenopyrite was significantly increased in the two-stage oxidation process.After 18 d,the two-stage oxidation process achieved total extraction rates of(88.8±2.0)%,(86.7±1.3)%,and(74.7±3.0)%for As,Fe,and S elements,respectively.These values represented a significant increase of(50.8±3.4)%,(47.1±2.7)%,and(46.0±0.7)%,respectively,compared to the one-stage bio-oxidation process.
基金Project(2018JJ1041)supported by the Natural Science Foundation of Hunan,ChinaProjects(51774332,U1932129,51804350 and 51934009)supported by the National Natural Science Foundation of China。
文摘Silver ion can be useful in improving chalcopyrite bioleaching efficiency.In this work,leaching kinetics of this process was investigated using silver-bearing solid waste under different chalcopyrite/solid waste ratios.Bioleaching behavior indicates that silver-bearing solid waste can enhance the bioleaching process,and the redox potential is much higher than the proposed appropriate range(380−480 mV vs Ag/AgCl)with the solid waste added.There is a positive correlation between temperature and copper extraction rate.The kinetics data fit well with the shrinking-core model.Under these leaching conditions,the bioleaching of chalcopyrite is controlled by internal diffusion with calculated apparent activation energy(Ea)of 28.24 kJ/mol.This work is possible benificial to promote the industrial application of silver catalyst in leaching of chalcopyrite.
基金Project(51574036)supported by the National Natural Science Foundation of China。
文摘In this work,the bioleaching process of pyrite,chalcocite and covellite which were the main phase compositions for Zijin copper mineral was comprehensively studied.The influence parameters,such as leaching temperature,Fe^(3+)concentration,pH of solution and bacteria concentration were investigated.The leaching kinetics of the pyrite,chalcocite and covellite under the studied conditions was successfully modeled by an empirical diffusion-like equation,respectively.The apparent activity energy of pyrite leaching,chalcocite leaching(stage Ⅱ)and covellite leaching was calculated to be 69.29,65.02 and 84.97 kJ/mol,respectively.
基金Projects(51674075,51774079)supported by the National Natural Science Foundation of ChinaProject(2018YFC1901903)supported by the National Key R&D Program of ChinaProject(N182508026)supported by the Fundamental Research Funds for the Central Universities of China。
文摘The crystal structure,formation kinetics and micro-morphology of CaO·SiO2 during high-temperature sintering process were studied in low-calcium system by XRD,FT-IR,Raman and SEM-EDS methods.When the molar ratio of CaCO3 to SiO2 is 1.0,β-2CaO·SiO2 forms firstly during the heating process,and then CaO·SiO2 is generated by the transformation reaction of pre-formed 2CaO·SiO2 with SiO2.3CaO·SiO2 and 3CaO·2SiO2 do not form either in the heating or sintering process.Rising the sintering temperature and prolonging the holding time promote the phase transition of 2CaO·SiO2 to CaO·SiO2,resulting in the sintered products a small blue shift and broadening in Raman spectra.The content of CS can reach 97.4%when sintered at 1400℃ for 1 h.The formation kinetics of CaO·SiO2 follows the second-order chemical reaction model,and the corresponding apparent activation energy and pre-exponential factor are 505.82 kJ/mol and 2.16×10^14 s^−1 respectively.
基金project (2004B4604A01-01) supported by the Mega-projects of Science Research for the 10th Five-Year Plan
文摘The features of organic pollutants degradation mainly characterized by bio-flocculation for step-A of adsorption-biodegredation（AB） process were studied. By investigating the relationship of extracellular polymeric substances（EPS） with bioflocculation and introducing kinetic model of organic pollutant degradation into EPS, the kinetic model of organic pollutant degradation for step-A hioflocculation was deducted. And through the experiments, the kinetic constants were calculated as follows： k1 =0. 005 3; kc1 =1 710.7 and vmax1=10 min^-1.
基金Project(51878662)supported by the National Natural Science Foundation of ChinaProject(2017SK2420)supported by the Science and Technology of Hunan Province,ChinaProject(2019JJ20033)supported by the Distinguished Youth Natural Science Foundation of Hunan Province,China。
文摘In this study, a lab-scale upflow anaerobic sludge blanket(UASB) reactor was applied to studying the high-rate nitrogen removal of granule-based anammox process. The nitrogen removal rate(NRR) finally improved to 15.77 kg/m3/d by shortening hydraulic retention time(HRT) to 1.06 h. Well-shaped red anammox granules were extensively enriched inside the reactor. The results of nitrogen removal kinetics indicated that the present bioreactor has great nitrogen removal potential, because the maximum rate of substrate utilization(Umax) predicted by Stover-Kincannon model is suggested as 55.68 kg/(m3·d). Analysis of the microbial community showed that the anammox genus Candidatus Kuenenia dominated the bacterial communities. The relative abundance of Candidatus Kuenenia rose from 12.29% to 36.95% after progressively shorter HRT and higher influent substrate concentrations, illustrating the stability of nitrogen removal performance and biomass enrichment offered by the UASB in carrying out high-rate anammox process.
基金Project(2004CB619201) supported by the National Basic Research Program of ChinaProject (50321402) supported by the National Natural Science Foundation of China
文摘The gene sod in Acidithiobacillusferrooxidans may play a crucial role in its tolerance to the extremely acidic, toxic and oxidative environment of bioleaching. For insight into the anti-toxic mechanism of the bacteria, a three-dimensional （3D） molecular structure of the protein encoded by this gene was built by homology modeling techniques, refined by molecular dynamics simulations, assessed by PROFILE-3D and PROSTAT programs and its key residues were further detected by evolutionary trace analysis. Through these procedures, some trace residues were identified and spatially clustered. Among them, the residues of Asn38, Glyl03 and Glul61 are randomly scattered throughout the mapped structure; interestingly, the other residues are all distinctly clustered in a subgroup near Fe atom. From these results, this gene can be confirmed at 3D level to encode the Fe-depending superoxide dismutase and subsequently play an anti-toxic role. Furthermore, the detected key residues around Fe binding site can be conjectured to be directly responsible for Fe binding and catalytic function.
基金Project(50321402) supported by the National Natural Science Foundation of China
文摘The biosorption mechanism of Cr （Ⅳ） ions on Synechococcus sp. biosorbent was studied by analyzing the biosorption kinetics as well as speciation change and bond formation during the biosorption process. The kinetics study shows that the adsorption process of Cr （Ⅳ） consists of a very fast stage in the first several minutes, in which more than half of the saturation adsorption is attained, and a slower stage that approximately follows the first order kinetic model, basically Freundlich isotherm models were observed. Comparative studies of FT-LR spectra of K2Cr2O7, free cells of Synechococcus sp., and Cr-bound cells of Synechococcus sp show that the speciation of chromium that binds to the cells ofSynechococcus sp. is Cr （Ⅲ）, instead of Cr （Ⅳ）, and the carboxylic, alcoholic, amido and amino groups may be involved in the binding of Cr （Ⅲ）. Integrative analyses of the surface electric potential, the effect of pH value on adsorption behavior of Cr （Ⅵ）, and the results of FT-IR show that the biosorption of Cr （Ⅵ） follows two subsequent steps, biosorption of Cr2O7 ^2- by electrostatical force at the protonated active sites and reduction of Cr2O7^2- to Cr^3＋ by the reductive groups on the surface of the biosorbents.
