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Study On Adsorption Properties Of Cd2+and Pb2+ In Wastewater By Diatomite

Posted on:2014-08-31Degree:MasterType:Thesis
Country:ChinaCandidate:J LingFull Text:PDF
GTID:2251330401970657Subject:Municipal engineering
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Diatomite is a siliceous,sedimentary rock consisting principally of the opal. Theadsorption performance of Cd2+and Pb2+on natural diatomite and Sodium DodecylSulfonate were studied by research.The adsorption results of the adsorption by naturalor organic diatomite were compared, and the affecting factors such as dosing quantity,initial pH, temperature, initial concentration of Cd2+and Pb2+and absorption time onthe adsorption.In addition, the kinetics,isotherms and thermodynamics of Cd2+andPb2+on two absorbents were analysed.Diatomite had good adsorption ability for Pb2+and Cd2+in wastewater. Theadsorption ability of diatomite is greatly enhanced after organic madified of rawdiatomite by Sodium Dodecyl Sulfonate. The adsorption results of Pb2+on natural ororganic diatomite were better. The adsorption of Pb2+and Cd2+on two diatomiteswere strongly dependent on dosing quantity, initial pH, temperature and initialconcentration of Cd2+and Pb2+. The removal rate and absorption capacity of diatomiteincreased with increasing dosing quantity, increasing pH, increasing temperature. Andthe removal rate was decreased with increasing initial concentration of Cd2+and Pb2+,but the absorption capacity was opposed to the removal rate.The adsorption rates of nature diatomite and modified diatomite were rapid andthe adsorption rates of the first5min had reached more than90%of the90min. Theadsorption kinetics all fitted well to the Lagergren psedo-second order equation andthe adsorption isotherms of Cd2+and Pb2+on two diatomites were fitted well to theFreundlich and Langmuir equation. The thermodynamic analysis of adsorption ofCd2+and Pb2+on two diatomites demonstrated that G<0, the adsorption process isspontaneous; H>0, demonstrated adsorption is a endothermic reaction and hightemperature can enhance the adsorption reaction; S>0, demonstrated entropy ofadsorption reaction increased.
Keywords/Search Tags:diatomite, adsorption, Cd2+and Pb2+, organic madification
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