The uptake capacities, and the adsorption kinetics, of copper, Cu（Ⅱ）, nickel, Ni（Ⅱ）, and cadmium, Cd（Ⅱ）, on peat have been studied under static conditions. The results show that the adsorption rates are rapid...The uptake capacities, and the adsorption kinetics, of copper, Cu（Ⅱ）, nickel, Ni（Ⅱ）, and cadmium, Cd（Ⅱ）, on peat have been studied under static conditions. The results show that the adsorption rates are rapid： equilibrium is reached in twenty minutes. The adsorption of copper, nickel and cadmium is pH dependent over the pH range from 2 to 6. The adsorption kinetics can be excellently described by the Elovich kinetic equation. The adsorption isotherm fits a Langmuir model very well. The adsorption capacities follow the order Cu^2＋ 〉 Ni^2＋〉 Cd^2＋ in single-component systems and the competitive adsorption capacities fall in the decreasing order Cu^2＋ 〉 Ni^2＋〉 Cd^2＋ in multi-component systems. The adsorption capacities of these three heavy metal ions on peat are consistent with their observed competitive adsorption capacities.展开更多
The effect of solution conditions on the depression of chlorite using CMC (carboxymethyl cellulose) as depressant was studied through flotation tests and adsorption measurements. Flotation and adsorption tests were fi...The effect of solution conditions on the depression of chlorite using CMC (carboxymethyl cellulose) as depressant was studied through flotation tests and adsorption measurements. Flotation and adsorption tests were first studied as a function of initial solution conditions. The results show that electrostatic repulsion between CMC molecules and chlorite surface hinders the approach of the CMC molecules to the chlorite surface and CMC adsorbs to a great extent at high ionic concentration (10-4 mol/L ions as opposed to 0 mol/L ions) or low pH (3 as opposed to 9). The enhanced adsorption density is attributed to the decreased electrostatic repulsion between CMC and mineral surface. The solution condition that yielded the lowest initial adsorbed amount (0 mol/L ions, pH 9) was used as a reference to investigate the response of the adsorbed CMC layer to a switch in solution conditions after adsorption. The two kinds of solution switches (reducing the solution pH or increasing ionic concentration) result in an increased depression effect of CMC on chlorite flotation, as a result of conformational change of CMC pre-adsorbed layer. The change in the flotation recovery of the CMC-coated chlorite following the solution switches is reversible.展开更多
基金Project[2006]331 supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,Ministry of Education of China0504 by the Doctoral Initial Foundation of East China University of Technology070712 by the Initial Foundation by Key Laboratory of Nuclear Resources and Environment,Ministry of Education of China
文摘The uptake capacities, and the adsorption kinetics, of copper, Cu（Ⅱ）, nickel, Ni（Ⅱ）, and cadmium, Cd（Ⅱ）, on peat have been studied under static conditions. The results show that the adsorption rates are rapid： equilibrium is reached in twenty minutes. The adsorption of copper, nickel and cadmium is pH dependent over the pH range from 2 to 6. The adsorption kinetics can be excellently described by the Elovich kinetic equation. The adsorption isotherm fits a Langmuir model very well. The adsorption capacities follow the order Cu^2＋ 〉 Ni^2＋〉 Cd^2＋ in single-component systems and the competitive adsorption capacities fall in the decreasing order Cu^2＋ 〉 Ni^2＋〉 Cd^2＋ in multi-component systems. The adsorption capacities of these three heavy metal ions on peat are consistent with their observed competitive adsorption capacities.
基金Project(51174229) supported by the National Natural Science Foundation of China
文摘The effect of solution conditions on the depression of chlorite using CMC (carboxymethyl cellulose) as depressant was studied through flotation tests and adsorption measurements. Flotation and adsorption tests were first studied as a function of initial solution conditions. The results show that electrostatic repulsion between CMC molecules and chlorite surface hinders the approach of the CMC molecules to the chlorite surface and CMC adsorbs to a great extent at high ionic concentration (10-4 mol/L ions as opposed to 0 mol/L ions) or low pH (3 as opposed to 9). The enhanced adsorption density is attributed to the decreased electrostatic repulsion between CMC and mineral surface. The solution condition that yielded the lowest initial adsorbed amount (0 mol/L ions, pH 9) was used as a reference to investigate the response of the adsorbed CMC layer to a switch in solution conditions after adsorption. The two kinds of solution switches (reducing the solution pH or increasing ionic concentration) result in an increased depression effect of CMC on chlorite flotation, as a result of conformational change of CMC pre-adsorbed layer. The change in the flotation recovery of the CMC-coated chlorite following the solution switches is reversible.
