Adsorption of Lead from aqueous solutions using natural diatomite

In this work, natural diatomite clay of Iran has been used as an adsorbent for removing of lead from aqueous solution in a batch mode. The effect of several variables like pH, contact time, initial concentration and temperature on lead sorption onto the diatomite is investigated. Kinetic data were analyzed using pseudofirst- order, pseudo-second-order and double-exponential models. The equilibrium experimental data were tested with Freundlich, Langmuir and Dubbin-Radushkevich. The maximum adsorption capacity of lead ion for natural diatomite was found to be 25.01 mg/g at T=45 ºC. Thermodynamic parameters showed that the lead sorption onto the diatomite is endothermic and spontaneous for adsorption of lead. Because of low-cost and local availability of natural diatomite; this clay has suitable potential for removal of lead ions in practical process.