Experimental Study On Uranium (Ⅵ) In Treated Wastewater By Modified

Goethite is a kind of inorganic colloid widely exists in the soil, with low pricesand stronger adsorption ability. Humic acid is also widespread in soil organic colloid,with a variety of reactive functional groups, which has high complexing ability andadsorption of uranium. Therefore, the research adopted synthetic methods to modifiedgoethite with humic acid, and then discusses goethite and humic acid modifiedgoethite influencing efficacy and mechanism of removal of wastewater containinguranium.Using a series of characterization methods obtained goethite particle size, surfacearea, changes of morphological in the electron microscope and functional groups,further analysis the adsorption mechanism. Studies have shown that: Goethiteadsorption U(VI) belongs to spontaneous endothermic process, the adsorption processfits to the Freundlich isotherm equation and the pseudo-second adsorption kineticsmodel. D-R isothermal adsorption model parameters showed that the physicaladsorption plays an important role in the adsorption process. Characterization resultsshowed that the adsorption mechanism mainly involves ion exchange andcomplexation.The goethite modified with humic acid (HA-α-FeOOH) was prepared bysynthetic method. Investigate the effects of dosage, the adsorption time,HA-α-FeOOH dosage, initial concentration of U(VI) ions and pH on the adsorption U(VI) process. Also use a series of characterization methods to obtain the changes ofmodified goethite indicators for the further analysis. It is shown that the removal rateof5mg·L-1U(Ⅵ) wastewater by HA-α-FeOOH almost reaches at100%under thecondition of pH4,25℃, and contact time for4hours. The experimental data fittedwell with Freundlich isotherm model and matched well with pseudo-second-orderkinetic model, the main mode is multilayer adsorption. FTIR and SEM-EDS resultsshowed that the adsorption mainly involves internal complexation and ion exchange,and the main binding sites with U(VI) are hydroxy、phenolic hydroxyl and carboxyl.