Adsorption mechanism of Pb2+ and Cd2+ on diatomite in liquid/solid systems
液/固体系中硅藻土对Pb2+和Cd2+的吸附机制

In order to promote application levels of diatomite in treatment of wastewater containing heavy metals, adsorption influencing factors, isotherms, kinetics of Pb2+ and Cd2+ on diatomite were studied by static adsorption experiment in liquid/solid systems. The results showed that adsorption quantity of Pb2+ and Cd2+ on diatomite will enlarge as decrease of diatomite dose and increase of ion initial concentration, pH, adsorption time. Adsorption isotherms of Pb2+ and Cd2+ on diatomite were both consistent with Langmuir model. The maximum adsorption quantities of Pb2+ and Cd2+ were 10.428 mg/g and 7.916 mg/g, respectively. The adsorption property of Pb2+ on diatomite was better. Hydration energy of Pb2+ was lower, so Pb2+ can take off water film smoothly, and get into diatomite channels to react with active groups easily. Two-constant equation can indicate adsorption kinetics of Pb2+ and Cd2+ on diatomite well, adsorption rate of Cd2+ on diatomite is higher.