Kinetics and Thermodynamics Study on the Adsorption of Husk to Cadmium Ions in Water
CHEN Yun-nen et al(College of Resource and Environmental Engineering,Jiangxi University of Science and Technology,Ganzhou,Jiangxi 341000)
[Objective] The purpose was to study the adsorption process of husk to cadmium ions in water and its influencing factors.[Method] The influences of physical and chemical parameters such as pH value,reaction time and temperature and the initial concn.of cadmium ions on the adsorption process were investigated by batch adsorption.And then the adsorption process was studied in kinetics and thermodynamics.[Result] The adsorption process accorded with Langmuir adsorption isothermal model.The dynamic adsorption model of husk to cadmium ions accorded with quasi-second dynamic equation better.When the reaction temperature was 298 K,pH value was 6,husk addition was 4 g/L,shaking velocity was 150 rpm and reaction time was 30 min,the adsorption effect of husk on cadmium ions was best.As the reaction temperature increased,the adsorption of husk to cadmium ions was accelerated.The enthalpy change of the adsorption was positive and its free energy change was negative.[Conclusion] Husk was a low-cost and effective adsorbent to dispose the wastewater containing cadmium and its adsorption process was spontaneous endothermic reaction.