Study On Adsorption Performance And Mechanism Of Sodium Alginate Composites To Hexavalent Uranium

Mining and Metallurgy of uranium has produced a large amount of radioactivewaste water, which constituted potential hazards to the ecological envirment.Compared with the existing adsorption of uranium materials, high polymer materialhas the advantages such as easy operation,environmentally friendly and energy saving.And because of these reasons, they get a lot of attention. Alginate is one of the mostcommom soluble water alginate, contains a large number of hydrophilic groups, suchas COONa、 OH. The related studies showed that sodium alginate had greatpotential in heavy metal wastewater and radioactive waste water treatment.Hydroxyethyl cellulose soluble in cold water and hot water, no gel properties, goodthermal stability, no precipitation in the acid solution, can be used as thickening agent,adhesive, coating agent,etc.As is known to as, humic acid widely exists in the nature,is not a single compound, and is composed by several multisubstituted hydroxylaromatic carboxylic acid similar species composition, species of thesemolecular’size has big difference, the structure is not consistent, belongs to themacromolecular polyethylene electric material, found from its structure observation,humic acid contains rich groups such as COOH, OH. Electrostatic interactions,ion exchange and complexation are used to enhance material for the metal cationadsorption.The two kinds of hybrid materials was employed to absorb uranium forcomparisons in order to provide some basic data for the uranium adsorption by thenew material.Two kinds of polymer composite porous(GA/SA-HEC、GA/SA-HA) film weremade of glutaraldehyde crosslinked by mixing sodium alginate with hydroxyethylcellulose or humic. Two films was employed to remove U(VI) ions from aqueoussolution, and its adsorption properties were discussed. By changing the pH, initialU(VI) ions concentration, temperature of environment, and contact time, the optimumconditions of adsorption were determined.The process of adsorption were investigatedby kinetic and thermodynamic analysis, The physico-chemical properties of the filmbefore and after adsorption were investigated by FR-IR, SEM and EDS. The experimental result shows that the optimal pH of is GA/SA-HEC5,and the other’s is6; there are a positive correlation between the temperature of environment and theuranium adsorption quantity, and the adsorption time is90minutes,too. The data areall fitted to pseudo-second-order kinetic well, mainly show particle internal diffusion,the experimental data fit well with the Langmuir model, when the temperature is45℃，the maximum adsorption capacity of GA/SA-HEC for U(VI) ions is found as357.1mg/g,and another one is476.2mg/g. The result of FT-IR, SEM and EDSindicate that the main adsorption mechanism exists ion exchange, both of the film’sinteraction groups with the U(VI) is carboxyl.