Quartz is, in most cases, the major gangue mineral found in the manganese ore. Mn iron, dissolved from the surface of ore, will determine the interfacial properties of the particles and, thus, their flotation behavior...Quartz is, in most cases, the major gangue mineral found in the manganese ore. Mn iron, dissolved from the surface of ore, will determine the interfacial properties of the particles and, thus, their flotation behavior. In this work, the effect of Mn2+ on quartz flotation was investigated through flotation tests. It was found that quartz can be depressed with Mn2+ and floated with dodecylamine in the pH region 7-8. In order to prove the validity of the findings, UV spectrophotometry, FTIR and SEM-EDS were carried out. UV spectrophotometry tests results show that Mn2+ can competitive adsorb with RNH3+ in the surface of quartz at acidic and neutral pH values. The FTIR measurements and SEM-EDS analysis indicate that Mn2+ forms precipitation and adsorbs on the negatively charged quartz surface, it induces quartz recovery dropping in alkaline pH. Furthermore, in the case of sodium hexametaphosphate(SH), sodium silicate or citric acid, the effects of Mn2+ were also studied. This depression in the given Mn2+ did not disappear. Citric acid is an appropriate modifier to separate quartz depressed by Mn2+ from other ores at pH 7.展开更多
Antimony(Sb)is a toxic and carcinogenic element that often enters soil in the form of antimony trioxide(Sb_(2)O_(3))and coexists with manganese(Mn)in weakly alkaline conditions.Mn oxides such as birnessite have been f...Antimony(Sb)is a toxic and carcinogenic element that often enters soil in the form of antimony trioxide(Sb_(2)O_(3))and coexists with manganese(Mn)in weakly alkaline conditions.Mn oxides such as birnessite have been found to promote the oxidative dissolution of Sb_(2)O_(3),but few researches concerned the co-transformations of Sb_(2)O_(3) and Mn(II)in environment.This study investigated themutual effect of abiotic oxidation of Mn(II)and the coupled oxidative dissolution of Sb_(2)O_(3).The influencing factors,such as Mn(II)concentrations,pH and oxygen were also discussed.Furthermore,their co-transformed mechanism was also explored based on the analysis of Mn(II)oxidation products with or without Sb_(2)O_(3) using XRD,SEM and XPS.The results showed that the oxidative dissolution of Sb_(2)O_(3) was enhanced under higher pH and higher Mn(II)loadings.With a lower Mn(II)concentration such as 0.01 mmol/L Mn(II)at pH 9.0,the improved dissolution of Sb_(2)O_(3) was attributed to the generation of dissolved intermediate Mn(III)species with strong oxidation capacity.However,under higher Mn(II)concentrations,both amorphous Mn(III)oxides and intermediate Mn(III)species were responsible for promoting the oxidative dissolution of Sb_(2)O_(3).Most released Sb(∼72%)was immobilized by Mn oxides and Sb(V)was dominant in the adsorbed and dissolved total Sb.Meanwhile,the presence of Sb_(2)O_(3) not only inhibited the removal of Mn(II)by reducing Mn(III)to Mn(II)but also affected the final products of Mn oxides.For example,amorphous Mn oxides were formed instead of crystalline Mn(III)oxides,such as MnOOH.Furthermore,rhodochrosite(MnCO_(3))was formed with the high Mn(II)/Sb_(2)O_(3) ratio,but without being observed in the low Mn(II)/Sb_(2)O_(3) ratio.The results of study could help provide more understanding about the fate of Sb in the environment and the redox transformation of Mn.展开更多
The authors have prepared supramolecular systems as artificial metalloproteins composed of several chiral salen-type Mn（II） and Co（II） complexes in a HSA （human serum albumin） matrix. The docking was discussed b...The authors have prepared supramolecular systems as artificial metalloproteins composed of several chiral salen-type Mn（II） and Co（II） complexes in a HSA （human serum albumin） matrix. The docking was discussed by UV-vis spectral changes and a ligand-protein docking simulation program. After linearly polarized UV light irradiation, that anisotropy of molecular orientation of the complexes increased was confirmed by polarized IR spectra. The authors have observed that the electrochemical behavior of the aligned complexes incorporating diphenyl groups in HSA can be tuned without UV radiation damage of HSA higher structures.展开更多
Studies widely acknowledge the enhancement of permanganate(Mn(Ⅶ))oxidation of organic contaminants by coexisting matrices in water.This study investigated the positive influence of Mn(Ⅱ),a common soluble metal ion,o...Studies widely acknowledge the enhancement of permanganate(Mn(Ⅶ))oxidation of organic contaminants by coexisting matrices in water.This study investigated the positive influence of Mn(Ⅱ),a common soluble metal ion,on the removal of trace organic pollutants by Mn(Ⅶ).Results showed that introducing 20μmol/L Mn(Ⅱ)at pH 5.0 accelerated trace organic pollutant removal by promoting colloidal MnO_(2)formation.UV-vis spectrum,quenching,and probe experiments confirmed role of MnO_(2)in sulfamethoxazole(SMX)oxidation,with Mn(Ⅲ)playing a predominant role.Meanwhile,in situ-generated MnO_(2)facilitated Mn(Ⅶ)*formation,enhancing oxidation performance,as indicated by Raman spectroscopy and electrochemical analysis.Eleven transformation products(TPs)of SMX in the Mn(Ⅶ)/Mn(Ⅱ)process were detected by UPLC-QTOF-MS/MS.Subsequently,the reaction pathways of SMX were elucidated through Fukui index analysis and the identification of TPs.Additionally,toxicity simulations with Toxicity Estimation Software Tool(T.E.S.T.)software revealed significantly lower cytotoxicity of TPs of SMX compared to the parent compound.This study unveils an effective strategy to enhance Mn(Ⅶ)-mediated degradation of organic pollutants in water,elucidating Mn(Ⅱ)-induced Mn(Ⅶ)activation mechanisms.展开更多
The latest works have been devoted to the stabilization mensuration for heavy metals and indicate that clay minerals can promote Cd(Ⅱ) precipitation by favoring the retention of Mn(Ⅱ). The assessment however has bee...The latest works have been devoted to the stabilization mensuration for heavy metals and indicate that clay minerals can promote Cd(Ⅱ) precipitation by favoring the retention of Mn(Ⅱ). The assessment however has been tempered due to lacking the information about the molecular-level surface complexation structure and Cd nucleation process on clay surfaces. In this study, microscopic mechanisms for adsorption and stabilization of Cd at montmorillonite interfaces with or without Mn loading were leveraged by combining surface complexation model(SCM) evaluations and density functional theory(DFT) calculations.Mn(Ⅱ) substitution resulted in increases in surface acidity equilibrium constant(pKa) by about 1 unit and complexation constant(lg K(SOCd+)) of Cd(Ⅱ) by about 0.15 units at clay surface, and Mn(Ⅱ) adion can provide extra active sites(i.e., OH-groups) for complexing Cd(Ⅱ) via hydrolysis. DFT calculations revealed Mn(Ⅱ) and Cd(Ⅱ) adions bind on base surfaces by isomorphic substitutions through weak long-range interactions, whereas on edge surfaces by surface complexation with strong but short-range connections. Adsorption energy calculations and electrostatic distribution showed heterogenous nucleation with subsequent cations on clay surfaces was thermodynamically favored, the stabilization process underwent the steps of the adsorption-hydrolysis-precipitation. The derived results provide a quantitative basis for understanding the precipitation and heterogenous nucleation of cations on clay surfaces in surficial environments.展开更多
基金Projects(21176026,21176242)supported by the National Natural Science Foundation of China
文摘Quartz is, in most cases, the major gangue mineral found in the manganese ore. Mn iron, dissolved from the surface of ore, will determine the interfacial properties of the particles and, thus, their flotation behavior. In this work, the effect of Mn2+ on quartz flotation was investigated through flotation tests. It was found that quartz can be depressed with Mn2+ and floated with dodecylamine in the pH region 7-8. In order to prove the validity of the findings, UV spectrophotometry, FTIR and SEM-EDS were carried out. UV spectrophotometry tests results show that Mn2+ can competitive adsorb with RNH3+ in the surface of quartz at acidic and neutral pH values. The FTIR measurements and SEM-EDS analysis indicate that Mn2+ forms precipitation and adsorbs on the negatively charged quartz surface, it induces quartz recovery dropping in alkaline pH. Furthermore, in the case of sodium hexametaphosphate(SH), sodium silicate or citric acid, the effects of Mn2+ were also studied. This depression in the given Mn2+ did not disappear. Citric acid is an appropriate modifier to separate quartz depressed by Mn2+ from other ores at pH 7.
基金This work was supported by the National Natural Science Foundation of China(Nos.42077184,41772251 and 41521001)the National Key Research and Development Program(No.2018YFC1801700).
文摘Antimony(Sb)is a toxic and carcinogenic element that often enters soil in the form of antimony trioxide(Sb_(2)O_(3))and coexists with manganese(Mn)in weakly alkaline conditions.Mn oxides such as birnessite have been found to promote the oxidative dissolution of Sb_(2)O_(3),but few researches concerned the co-transformations of Sb_(2)O_(3) and Mn(II)in environment.This study investigated themutual effect of abiotic oxidation of Mn(II)and the coupled oxidative dissolution of Sb_(2)O_(3).The influencing factors,such as Mn(II)concentrations,pH and oxygen were also discussed.Furthermore,their co-transformed mechanism was also explored based on the analysis of Mn(II)oxidation products with or without Sb_(2)O_(3) using XRD,SEM and XPS.The results showed that the oxidative dissolution of Sb_(2)O_(3) was enhanced under higher pH and higher Mn(II)loadings.With a lower Mn(II)concentration such as 0.01 mmol/L Mn(II)at pH 9.0,the improved dissolution of Sb_(2)O_(3) was attributed to the generation of dissolved intermediate Mn(III)species with strong oxidation capacity.However,under higher Mn(II)concentrations,both amorphous Mn(III)oxides and intermediate Mn(III)species were responsible for promoting the oxidative dissolution of Sb_(2)O_(3).Most released Sb(∼72%)was immobilized by Mn oxides and Sb(V)was dominant in the adsorbed and dissolved total Sb.Meanwhile,the presence of Sb_(2)O_(3) not only inhibited the removal of Mn(II)by reducing Mn(III)to Mn(II)but also affected the final products of Mn oxides.For example,amorphous Mn oxides were formed instead of crystalline Mn(III)oxides,such as MnOOH.Furthermore,rhodochrosite(MnCO_(3))was formed with the high Mn(II)/Sb_(2)O_(3) ratio,but without being observed in the low Mn(II)/Sb_(2)O_(3) ratio.The results of study could help provide more understanding about the fate of Sb in the environment and the redox transformation of Mn.
文摘The authors have prepared supramolecular systems as artificial metalloproteins composed of several chiral salen-type Mn（II） and Co（II） complexes in a HSA （human serum albumin） matrix. The docking was discussed by UV-vis spectral changes and a ligand-protein docking simulation program. After linearly polarized UV light irradiation, that anisotropy of molecular orientation of the complexes increased was confirmed by polarized IR spectra. The authors have observed that the electrochemical behavior of the aligned complexes incorporating diphenyl groups in HSA can be tuned without UV radiation damage of HSA higher structures.
基金support from the National Natural Science Foundation of China(Nos.52300102,523B2094)the Key Laboratory of Jiangxi Province for Persistent Pollutants Prevention Control and Resource Reuse(No.2023SSY02061)+1 种基金the Natural Science Foundation of Sichuan Province(No.2024NSFSC0130)Miaozi Project in Science and Technology Innovation Program of Sichuan Province(No.MZGC20230098)。
文摘Studies widely acknowledge the enhancement of permanganate(Mn(Ⅶ))oxidation of organic contaminants by coexisting matrices in water.This study investigated the positive influence of Mn(Ⅱ),a common soluble metal ion,on the removal of trace organic pollutants by Mn(Ⅶ).Results showed that introducing 20μmol/L Mn(Ⅱ)at pH 5.0 accelerated trace organic pollutant removal by promoting colloidal MnO_(2)formation.UV-vis spectrum,quenching,and probe experiments confirmed role of MnO_(2)in sulfamethoxazole(SMX)oxidation,with Mn(Ⅲ)playing a predominant role.Meanwhile,in situ-generated MnO_(2)facilitated Mn(Ⅶ)*formation,enhancing oxidation performance,as indicated by Raman spectroscopy and electrochemical analysis.Eleven transformation products(TPs)of SMX in the Mn(Ⅶ)/Mn(Ⅱ)process were detected by UPLC-QTOF-MS/MS.Subsequently,the reaction pathways of SMX were elucidated through Fukui index analysis and the identification of TPs.Additionally,toxicity simulations with Toxicity Estimation Software Tool(T.E.S.T.)software revealed significantly lower cytotoxicity of TPs of SMX compared to the parent compound.This study unveils an effective strategy to enhance Mn(Ⅶ)-mediated degradation of organic pollutants in water,elucidating Mn(Ⅱ)-induced Mn(Ⅶ)activation mechanisms.
基金supported by the National Natural Science Foundation of China(No.42177010)the Youth innovation of Chinese Academy of Agricultural Sciences(No.Y2023QC17)the Agricultural Science and Technology Innovation Program(Nos.CAAS-ZDRW202308 and CAAS-ZDRW202408-01).
文摘The latest works have been devoted to the stabilization mensuration for heavy metals and indicate that clay minerals can promote Cd(Ⅱ) precipitation by favoring the retention of Mn(Ⅱ). The assessment however has been tempered due to lacking the information about the molecular-level surface complexation structure and Cd nucleation process on clay surfaces. In this study, microscopic mechanisms for adsorption and stabilization of Cd at montmorillonite interfaces with or without Mn loading were leveraged by combining surface complexation model(SCM) evaluations and density functional theory(DFT) calculations.Mn(Ⅱ) substitution resulted in increases in surface acidity equilibrium constant(pKa) by about 1 unit and complexation constant(lg K(SOCd+)) of Cd(Ⅱ) by about 0.15 units at clay surface, and Mn(Ⅱ) adion can provide extra active sites(i.e., OH-groups) for complexing Cd(Ⅱ) via hydrolysis. DFT calculations revealed Mn(Ⅱ) and Cd(Ⅱ) adions bind on base surfaces by isomorphic substitutions through weak long-range interactions, whereas on edge surfaces by surface complexation with strong but short-range connections. Adsorption energy calculations and electrostatic distribution showed heterogenous nucleation with subsequent cations on clay surfaces was thermodynamically favored, the stabilization process underwent the steps of the adsorption-hydrolysis-precipitation. The derived results provide a quantitative basis for understanding the precipitation and heterogenous nucleation of cations on clay surfaces in surficial environments.
