Batch and soil column experiments were conducted to evaluate the influence of KH2PO4, （NH4）H2PO4and Ca（H2PO4）2on the adsorption and leaching characteristics of Cu and Zn in red soil. The results show that all the ...Batch and soil column experiments were conducted to evaluate the influence of KH2PO4, （NH4）H2PO4and Ca（H2PO4）2on the adsorption and leaching characteristics of Cu and Zn in red soil. The results show that all the three phosphates can greatly improve the adsorption capacity of red soil for Cu and Zn, and the effect of different phosphates on Cu and Zn adsorption follows the order of Ca（H2PO4）2〉KH2PO4〉（NH4）H2PO4. The addition of phosphate has little effect on the mobility of Cu. Ca（H2PO4）2and （NH4）H2PO4 show a strong ability in immobilizing Zn while the immobilization ability of KH2PO4 is much weaker. All the three phosphates are helpful for modifying the partitioning of Cu and Zn from the non-residual phase to the residual phase; however, they could also enhance the contents of Cu and Zn associated with exchangeable and carbonates fractions.展开更多
A comparison between the effects of ordinary walnut shell and phosphoric acid modified walnut shell on adsorption of Cr（Ⅵ） was carried out. The experimental results showed that owing to larger surface void of modif...A comparison between the effects of ordinary walnut shell and phosphoric acid modified walnut shell on adsorption of Cr（Ⅵ） was carried out. The experimental results showed that owing to larger surface void of modified walnut shell its adsorption of Cr（Ⅵ） was better. When the temperature was 35 ℃, adsorbent particle size was 1.0-1.6 mm, shaker shock rate was 200 r/min, and dosage of walnut shell was 0.80 g, the Cr（Ⅵ） removal rate reached 99.4%. The fitting of adsorption isotherm and kinetics model showed that, Langmuir isotherm model could reflect the adsorption process of modified walnut shell; and both the adsorption processes of ordinary and modified walnut shells accorded with the pseudo-second-order kinetic equations.展开更多
Effects of citrate and tartrate on phosphate adsorption and desorption from kaolinite, goethite, amorphous Al-oxide and Ultisol were studied. P adsorption was significantly decreased as the concentration of the organi...Effects of citrate and tartrate on phosphate adsorption and desorption from kaolinite, goethite, amorphous Al-oxide and Ultisol were studied. P adsorption was significantly decreased as the concentration of the organic anions increased from 10-5 to 10-1 M. At 0.1 M and pH 7.0, tartrate decreased P adsorption by 27.6% - 50.6% and citrate by 37.9 - 80.4%, depending on the kinds of adsorbent. Little Al and/ or Fe were detected in the equilibrium solutions, even at the highest concentration of the organic anions. Effects of the organic anions on phosphate adsorption follow essentially the competitive adsorption mechanism.The selectivity coefficients for competitive adsorption can be used to compare the effectiveness of different organic anions in reducing P adsorption under given conditions.Phosphate desorption was increased by 3 to 100 times in the presence of 0.001 M citrate or tartrate compared to that in 0.02 M KC1 solution alone. However, for all the soil and clay minerals studied the amount of P desorbed by citrate or tartrate was generally lower than or close to that of isotopically exchangeable P. The effect of organic anions on phosphate desorption arises primarily from ligand exchange.展开更多
The advantage of using an available and abundant residual biomass, such as lignin, as a raw material for activated carbons is that it provides additional economical interest to the technical studies. In the current in...The advantage of using an available and abundant residual biomass, such as lignin, as a raw material for activated carbons is that it provides additional economical interest to the technical studies. In the current investigation, a more complete understanding of adsorption of Cr（VI） from aqueous systems onto HaPO4-acid activated lignin has been achieved via microcolumns, which were operated under various process conditions. The practice of using microcolumn is appropriate for defining the adsorption parameters and for screening a large number of poten- tial adsorbents. The effects of solution pH （2-8）, initial metal ion concentration （0.483-1.981 mmol.L-1）, flow rate （1.0-3.1 cm3-min-1）, ionic strength （0.01-0.30 mmol-L-1） and adsorbent mass （0.11 0.465 g） on Cr（VI） adsorption were studied by assessing the microcolmnn breakthrough curve. The microcolumn data were fitted by the Thomas model, the modified Dose model and the BDST model. As expected, the adsorption capacity increased with initial Cr（VI） concentration. High linear flow rates, pH values and ionic strength led to early breakthrough of Cr（VI）. The model constants obtained in this study can be used for the design of pilot scale adsorption process.展开更多
基金Project(41271294)supported by the National Natural Science Foundation of ChinaProject(NCET-09-330)supported by Program for New Century Excellent Talents in University,China
文摘Batch and soil column experiments were conducted to evaluate the influence of KH2PO4, （NH4）H2PO4and Ca（H2PO4）2on the adsorption and leaching characteristics of Cu and Zn in red soil. The results show that all the three phosphates can greatly improve the adsorption capacity of red soil for Cu and Zn, and the effect of different phosphates on Cu and Zn adsorption follows the order of Ca（H2PO4）2〉KH2PO4〉（NH4）H2PO4. The addition of phosphate has little effect on the mobility of Cu. Ca（H2PO4）2and （NH4）H2PO4 show a strong ability in immobilizing Zn while the immobilization ability of KH2PO4 is much weaker. All the three phosphates are helpful for modifying the partitioning of Cu and Zn from the non-residual phase to the residual phase; however, they could also enhance the contents of Cu and Zn associated with exchangeable and carbonates fractions.
基金Supported by National Natural Science Foundation of China(51168013)National Key Technology Support Program(2014BAC04B03)~~
文摘A comparison between the effects of ordinary walnut shell and phosphoric acid modified walnut shell on adsorption of Cr（Ⅵ） was carried out. The experimental results showed that owing to larger surface void of modified walnut shell its adsorption of Cr（Ⅵ） was better. When the temperature was 35 ℃, adsorbent particle size was 1.0-1.6 mm, shaker shock rate was 200 r/min, and dosage of walnut shell was 0.80 g, the Cr（Ⅵ） removal rate reached 99.4%. The fitting of adsorption isotherm and kinetics model showed that, Langmuir isotherm model could reflect the adsorption process of modified walnut shell; and both the adsorption processes of ordinary and modified walnut shells accorded with the pseudo-second-order kinetic equations.
文摘Effects of citrate and tartrate on phosphate adsorption and desorption from kaolinite, goethite, amorphous Al-oxide and Ultisol were studied. P adsorption was significantly decreased as the concentration of the organic anions increased from 10-5 to 10-1 M. At 0.1 M and pH 7.0, tartrate decreased P adsorption by 27.6% - 50.6% and citrate by 37.9 - 80.4%, depending on the kinds of adsorbent. Little Al and/ or Fe were detected in the equilibrium solutions, even at the highest concentration of the organic anions. Effects of the organic anions on phosphate adsorption follow essentially the competitive adsorption mechanism.The selectivity coefficients for competitive adsorption can be used to compare the effectiveness of different organic anions in reducing P adsorption under given conditions.Phosphate desorption was increased by 3 to 100 times in the presence of 0.001 M citrate or tartrate compared to that in 0.02 M KC1 solution alone. However, for all the soil and clay minerals studied the amount of P desorbed by citrate or tartrate was generally lower than or close to that of isotopically exchangeable P. The effect of organic anions on phosphate desorption arises primarily from ligand exchange.
文摘The advantage of using an available and abundant residual biomass, such as lignin, as a raw material for activated carbons is that it provides additional economical interest to the technical studies. In the current investigation, a more complete understanding of adsorption of Cr（VI） from aqueous systems onto HaPO4-acid activated lignin has been achieved via microcolumns, which were operated under various process conditions. The practice of using microcolumn is appropriate for defining the adsorption parameters and for screening a large number of poten- tial adsorbents. The effects of solution pH （2-8）, initial metal ion concentration （0.483-1.981 mmol.L-1）, flow rate （1.0-3.1 cm3-min-1）, ionic strength （0.01-0.30 mmol-L-1） and adsorbent mass （0.11 0.465 g） on Cr（VI） adsorption were studied by assessing the microcolmnn breakthrough curve. The microcolumn data were fitted by the Thomas model, the modified Dose model and the BDST model. As expected, the adsorption capacity increased with initial Cr（VI） concentration. High linear flow rates, pH values and ionic strength led to early breakthrough of Cr（VI）. The model constants obtained in this study can be used for the design of pilot scale adsorption process.
