低品位硅藻土吸附重金属的研究

硅藻土是一种生物硅质沉积岩,具有较大的比表面积,在工业上常用作吸附材料。但低品位硅藻土不利于直接加工利用,在矿产开发中常被忽视或丢弃。为更好地开发和利用低品位硅藻土,采用静态吸附实验研究了低品位硅藻土吸附四种重金属离子（Pb2＋、Zn2＋、Cu2＋、Cd2＋）的动力学规律,用伪一阶、伪二阶模型及粒内扩散模型（Weber和Morris模型）对其吸附过程进行拟合,结果表明,硅藻土对四种重金属离子的吸附均符合伪二阶动力学模型。同时,实验也研究了硅藻土吸附Pb2＋、Zn2＋、Cu2＋、Cd2＋的热力学,并分别用Langmuir、Freundlich和Dubinin-Radushkevich（D-R）方程进行拟合。结果表明,Freundlich和D-R方程都能很好地描述硅藻土对Pb2＋、Zn2＋、Cu2＋、Cd2＋的吸附热力学。并且硅藻土对这四种重金属离子的吸附均为吸热反应。

Study on the adsorption of heavy metals with raw linjiang diatomite

Diatomite is a siliceous sedimentary rock,which is generally used as adsorbent materials in industrial fields due to big specific surface area.Low-grade diatomite is usually ignored or disposed during the process of mining and cannot be used directly.This experiment will provide a theoretical basis for development and utilization of low-grade diatomite.The experiment of static adsorption studied kinetic study about adsorption of leads,zinc,copper and cadmium using raw diatomite.The test data were further analyzed with three kinetic models（i.e.,pseudo-first order kinetics,pseudo-second order kinetics and intraparticle diffusion model）.The pseudo-second order kinetic equation was found to best-fit the test data as judged by the correlation coefficients.Moreover,the experiment studied adsorption isotherms and thermodynamics for the four heavy metals.Three isothermal equations（Langmuir,Freundlich and D-R isotherm） were applied to evaluate the test results.The Freundlich and D-R model was found to be the best in fitting the isotherms.The positive enthalpy（ΔH） indicates adsorption of leads,zinc,copper and cadmium is endothermic process.