Trivalent chromium(Cr(Ⅲ))can form stable soluble complexes with organic components,altering its adsorption properties in the water-soil environment.This increases the risk of Cr(Ⅲ)migrating to deeper soils and trans...Trivalent chromium(Cr(Ⅲ))can form stable soluble complexes with organic components,altering its adsorption properties in the water-soil environment.This increases the risk of Cr(Ⅲ)migrating to deeper soils and transforming into toxic Cr(VI)due to the presence of manganese oxides in sediments.In this study,Citric Acid(CA)was selected as a representative organic ligand to prepare and characterize Cr(III)-CA complexes.The characteristics,mechanisms and environmental factors influencing the adsorption of Cr(Ⅲ)-CA on porous media(silts and fine sands)were investigated in the study.The results show that Cr(Ⅲ)coordinates with CA at a 1:1 molar ratio,forming stable and soluble Cr(Ⅲ)-CA complexes.Compared to Cr(III)ions,the equilibrium adsorption capacity of Cr(Ⅲ)-CA is an order of magnitude lower in silts and fine sands.The adsorption of Cr(Ⅲ)-CA in silts and fine sands is dominated by chemical adsorption of monolayers,following the pseudo-second-order kinetic equation and the Langmuir isotherm adsorption model.Varying contents of clay minerals and iron-aluminum oxides prove to be the main causes of differences in adsorption capacity of Cr(Ⅲ)-CA in silts and fine sands.Changes in solution pH affect the adsorption rate and capacity of Cr(Ⅲ)-CA by altering its ionic form.The adsorption process is irreversible and only minimally influenced by ionic strength,suggesting that inner-sphere complexation serves as the dominant Cr(Ⅲ)-CA adsorption mechanism.展开更多
This paper presents methods of modifying the active carbon with oxidizing agent and high temperature treatment.The ion exchange capacity of modified active carbon were detected.The active carbon has been amployed as a...This paper presents methods of modifying the active carbon with oxidizing agent and high temperature treatment.The ion exchange capacity of modified active carbon were detected.The active carbon has been amployed as an adsorbent for removing of Cr(Ⅲ) from equeous solution.The effect of removal of Cr(Ⅲ) of the pH of solution and time of adsorption were discussed.In addition,the mechanism of adsorption with modified the active carbon for Cr(Ⅲ) were discussed.展开更多
In this paper the crosslinking reaction between partially hydrolyzed Polyacrylamide (HPAM) with ultrahigh molecular weight and chromium (Ⅲ) was investigated by atomic absorption method. The results showed that when t...In this paper the crosslinking reaction between partially hydrolyzed Polyacrylamide (HPAM) with ultrahigh molecular weight and chromium (Ⅲ) was investigated by atomic absorption method. The results showed that when the concentration of HPAM was fixed , the crosslinking density decreased with the increase of n (COO -)/ n . When the amount of Cr(Ⅲ) was fixed, the crosslinking density increased with the increase of n (COO -)/ n . When the initial pH value of HPAM/Cr(Ⅲ) system was between 4 and 8, the crosslinking density increased with the increase of pH value. The crosslinking density also increased with the increase of temperature and the increase of salinity.展开更多
The transfer behavior of Cr（Ⅲ） through the emulsion liquid membrane system of TBP-Span80-atoleine -kerosene was studied.The effects of membrane phase component, pH value in external phase, concentration of H2SO4 in...The transfer behavior of Cr（Ⅲ） through the emulsion liquid membrane system of TBP-Span80-atoleine -kerosene was studied.The effects of membrane phase component, pH value in external phase, concentration of H2SO4 in internal phase,ratio of emulsion-water （R ew）and coexisting ions on the transport rate of Cr（Ⅲ） were investigated.The results showed that the transport rate of Cr（Ⅲ）could reach 99.5% under the optimun conditions of 7%TBP, 5%Span80, 4% atoleine, 84%kerosene, 1.0 mol·L -1 H2SO 4 in internal phase and pH 3.5 in external phase.This method was applied to the treatment of Cr（Ⅲ） waste-water, and the residual concentration of Cr（Ⅲ） could be reduced to 1.0 mg·L -1 ,which was below the national standard of waste-water discharge.展开更多
基金financially supported jointly by Natural Science Foundation of Fujian Province of China(NO.2023J01227)Natural Science Foundation of Hebei Province(NO.D2020504003)Key Laboratory of Groundwater Remediation of Hebei Province and China Geological Survey(NO.SK202303).
文摘Trivalent chromium(Cr(Ⅲ))can form stable soluble complexes with organic components,altering its adsorption properties in the water-soil environment.This increases the risk of Cr(Ⅲ)migrating to deeper soils and transforming into toxic Cr(VI)due to the presence of manganese oxides in sediments.In this study,Citric Acid(CA)was selected as a representative organic ligand to prepare and characterize Cr(III)-CA complexes.The characteristics,mechanisms and environmental factors influencing the adsorption of Cr(Ⅲ)-CA on porous media(silts and fine sands)were investigated in the study.The results show that Cr(Ⅲ)coordinates with CA at a 1:1 molar ratio,forming stable and soluble Cr(Ⅲ)-CA complexes.Compared to Cr(III)ions,the equilibrium adsorption capacity of Cr(Ⅲ)-CA is an order of magnitude lower in silts and fine sands.The adsorption of Cr(Ⅲ)-CA in silts and fine sands is dominated by chemical adsorption of monolayers,following the pseudo-second-order kinetic equation and the Langmuir isotherm adsorption model.Varying contents of clay minerals and iron-aluminum oxides prove to be the main causes of differences in adsorption capacity of Cr(Ⅲ)-CA in silts and fine sands.Changes in solution pH affect the adsorption rate and capacity of Cr(Ⅲ)-CA by altering its ionic form.The adsorption process is irreversible and only minimally influenced by ionic strength,suggesting that inner-sphere complexation serves as the dominant Cr(Ⅲ)-CA adsorption mechanism.
文摘This paper presents methods of modifying the active carbon with oxidizing agent and high temperature treatment.The ion exchange capacity of modified active carbon were detected.The active carbon has been amployed as an adsorbent for removing of Cr(Ⅲ) from equeous solution.The effect of removal of Cr(Ⅲ) of the pH of solution and time of adsorption were discussed.In addition,the mechanism of adsorption with modified the active carbon for Cr(Ⅲ) were discussed.
文摘In this paper the crosslinking reaction between partially hydrolyzed Polyacrylamide (HPAM) with ultrahigh molecular weight and chromium (Ⅲ) was investigated by atomic absorption method. The results showed that when the concentration of HPAM was fixed , the crosslinking density decreased with the increase of n (COO -)/ n . When the amount of Cr(Ⅲ) was fixed, the crosslinking density increased with the increase of n (COO -)/ n . When the initial pH value of HPAM/Cr(Ⅲ) system was between 4 and 8, the crosslinking density increased with the increase of pH value. The crosslinking density also increased with the increase of temperature and the increase of salinity.
文摘The transfer behavior of Cr（Ⅲ） through the emulsion liquid membrane system of TBP-Span80-atoleine -kerosene was studied.The effects of membrane phase component, pH value in external phase, concentration of H2SO4 in internal phase,ratio of emulsion-water （R ew）and coexisting ions on the transport rate of Cr（Ⅲ） were investigated.The results showed that the transport rate of Cr（Ⅲ）could reach 99.5% under the optimun conditions of 7%TBP, 5%Span80, 4% atoleine, 84%kerosene, 1.0 mol·L -1 H2SO 4 in internal phase and pH 3.5 in external phase.This method was applied to the treatment of Cr（Ⅲ） waste-water, and the residual concentration of Cr（Ⅲ） could be reduced to 1.0 mg·L -1 ,which was below the national standard of waste-water discharge.
