The by-product of wet flue gas desulfurization,desulfurized steel slag(DS),had chemical characteristics like natural gypsum that can be used to improve saline-sodic soil.However,contamination risk of heavy metals for ...The by-product of wet flue gas desulfurization,desulfurized steel slag(DS),had chemical characteristics like natural gypsum that can be used to improve saline-sodic soil.However,contamination risk of heavy metals for cycling utilization of DS in agriculturewas concerned mostly.Both pot and field experiments were conducted for evaluating the potential pollution risk of DS as the amendment of saline-sodic soil.Results showed that application of DS decreased the contents of Cd,Cu,Zn,and Pb,while significantly increasing chromium(Cr)content in DS-amended soils.The field experiment demonstrated that the migration of heavy metals(Cd,Zn,Cu,and Pb)in the soil profile was negligible.The application of DS at the dosage of 22.5–225 tons/ha significantly increased the Cr content in alfalfa(Medicago sativa L.)but lower than the national standard for feed in China(GB 13078-2017).DS altered the chemical fraction of heavy metals(Zn,Cu,and Pb),transferred exchangeable,reducible into oxidizable and residual forms in DS-amended soil.Application of DS combined with fulvic acid(FA)could effectively reduce the movement of heavy metals in soil and the accumulation of Cr in alfalfa.Based on our results,DS was a safe and feasible material for agricultural use and presented relatively little pollution risk of heavy metals.However,the results also showed that DS to a certain extent had a potential environmental risk of Cr if larger dosages of DS were used.展开更多
This paper reported the preparation and application of novel chitosan-cellulose composite absorbents for the adsorption of Pb(II)and Cr(VI)ions in water.First,oxycellulose or dialdehyde cellulose(DAC)was prepared by s...This paper reported the preparation and application of novel chitosan-cellulose composite absorbents for the adsorption of Pb(II)and Cr(VI)ions in water.First,oxycellulose or dialdehyde cellulose(DAC)was prepared by sodium periodate oxidation of microcrystalline cellulose(MCC).Second,based on the mechanism of the Mannich reaction,a chitosan/cellulose-based adsorbent(TSFCD)was produced through a cross-linking reaction of thiosemicarbazide(TS)with DAC and chitosan(CS),which was designed specifically for the adsorption of Cr^(6+)ions from water.Similarly,another chitosan/cellulose-based adsorbent(DBFCM)was also prepared with 2,5-dithiobiurea(DB)as the cross-linking agent for the adsorption of Pb^(2+)ions in water.The adsorption performance of TSFCD and DBFCM for Cr^(6+)and Pb^(2+)ions,respectively,was investigated under various process conditions.Variables included adsorption temperature,time,initial metal ion concentration,pH,and adsorbent dosage.The adsorption kinetics of TSFCD and DBFCM were studied,and isothermal models were developed.Results showed that the adsorption amount increased with the increase of the reaction time,and reached a maximum at about 300 min for the TSFCD/Cr^(6+)system,and at about 240 min for DBFCM/Pb^(2+)system.The adsorption performance of TSFCD for Cr^(6+)and DBFCM for Pb^(2+)improved at higher temperature,and leveled off at 40℃ and 50℃,respectively.In addition,the removal rate of Cr^(6+)increased from 49.96%to 70.22%when the TSFCD dosage increased from 0.5 g/L to 3.5 g/L.Similarly,the removal rate of Pb^(2+)increased from 22.23%to 99.45%with the increase of DBFCM dosage from 0.5g/L to 5.0g/L.The adsorption processes of Pb^(2+)and Cr^(6+)were in line with the pseudo-second-order kinetic and the Langmuir isothermal model.展开更多
基金supported by the Science and Technology Innovation 2025 Major Project of Ningbo City,China(No.2018B10091)Ningbo Taiji Environmental Protection Equipment Co.,Ltd.(NTEPEC)provided experimental materials(desulfurized steel slag)。
文摘The by-product of wet flue gas desulfurization,desulfurized steel slag(DS),had chemical characteristics like natural gypsum that can be used to improve saline-sodic soil.However,contamination risk of heavy metals for cycling utilization of DS in agriculturewas concerned mostly.Both pot and field experiments were conducted for evaluating the potential pollution risk of DS as the amendment of saline-sodic soil.Results showed that application of DS decreased the contents of Cd,Cu,Zn,and Pb,while significantly increasing chromium(Cr)content in DS-amended soils.The field experiment demonstrated that the migration of heavy metals(Cd,Zn,Cu,and Pb)in the soil profile was negligible.The application of DS at the dosage of 22.5–225 tons/ha significantly increased the Cr content in alfalfa(Medicago sativa L.)but lower than the national standard for feed in China(GB 13078-2017).DS altered the chemical fraction of heavy metals(Zn,Cu,and Pb),transferred exchangeable,reducible into oxidizable and residual forms in DS-amended soil.Application of DS combined with fulvic acid(FA)could effectively reduce the movement of heavy metals in soil and the accumulation of Cr in alfalfa.Based on our results,DS was a safe and feasible material for agricultural use and presented relatively little pollution risk of heavy metals.However,the results also showed that DS to a certain extent had a potential environmental risk of Cr if larger dosages of DS were used.
基金Innovation research team of Guangxi Natural Science Foundation (No.2013GXNSFFA019005)the National High Technology Research and Development Program (No.2009AA06A416)Guangxi scientific and technological project (No.14251009)for their financial support.
文摘This paper reported the preparation and application of novel chitosan-cellulose composite absorbents for the adsorption of Pb(II)and Cr(VI)ions in water.First,oxycellulose or dialdehyde cellulose(DAC)was prepared by sodium periodate oxidation of microcrystalline cellulose(MCC).Second,based on the mechanism of the Mannich reaction,a chitosan/cellulose-based adsorbent(TSFCD)was produced through a cross-linking reaction of thiosemicarbazide(TS)with DAC and chitosan(CS),which was designed specifically for the adsorption of Cr^(6+)ions from water.Similarly,another chitosan/cellulose-based adsorbent(DBFCM)was also prepared with 2,5-dithiobiurea(DB)as the cross-linking agent for the adsorption of Pb^(2+)ions in water.The adsorption performance of TSFCD and DBFCM for Cr^(6+)and Pb^(2+)ions,respectively,was investigated under various process conditions.Variables included adsorption temperature,time,initial metal ion concentration,pH,and adsorbent dosage.The adsorption kinetics of TSFCD and DBFCM were studied,and isothermal models were developed.Results showed that the adsorption amount increased with the increase of the reaction time,and reached a maximum at about 300 min for the TSFCD/Cr^(6+)system,and at about 240 min for DBFCM/Pb^(2+)system.The adsorption performance of TSFCD for Cr^(6+)and DBFCM for Pb^(2+)improved at higher temperature,and leveled off at 40℃ and 50℃,respectively.In addition,the removal rate of Cr^(6+)increased from 49.96%to 70.22%when the TSFCD dosage increased from 0.5 g/L to 3.5 g/L.Similarly,the removal rate of Pb^(2+)increased from 22.23%to 99.45%with the increase of DBFCM dosage from 0.5g/L to 5.0g/L.The adsorption processes of Pb^(2+)and Cr^(6+)were in line with the pseudo-second-order kinetic and the Langmuir isothermal model.
