Hydrogen Peroxide/iron Load Bentonite In Collaborative Processing Waste Water Of Uranium (Ⅵ) Experimental Study

Uranium mining and milling production in China generated a lot of waste rock,mine tailings and tailings water, causing long-lasting radioactive contamination.Bentonite, which has large specific surface area, low cost and easy affinity for organicand inorganic ions, is considered as the main candidate in the treatment of U（Ⅵ）. Thispaper prepared Fe-immobilized bentonite by bentonite and ferric chloride, discussedthe uranium （VI） adsorption performance and impact factors by Fe-immobilizedbentonite. Adding hydrogen peroxide to development the composite system containsH₂O₂and Fe-immobilized bentonite, studied the synergistic adsorption of U （VI）. Last,this paper investigated the co-processing mechanism and the influencing factors bymodern analytical techniques. The main results of this work are as follow:（1） The Fe-immobilized bentonite was prepared by purification, sodium and loadof iron compounds. Its basal spacing and the specific surface area of the bentonite wasincreased, while the content of SiO2substantially reduced. Also, two new phases likeNa_0.3（Al,Mg）₂Si₄O₁₀（OH）₂and Fe₂O₃were produced. These results indicate that thestructure of the bentonite was greatly changed.（2） The possible use of Fe-immobilized bentonite as the adsorbent of U（Ⅵ） fromaqueous solution and the effect of several operating parameters like pH, ionic strength,adsorbent dose, adsorption time, coexisting ions and temperature were investigatedusing batch techniques. The results indicated that adsorption of on U（Ⅵ）Fe-immobilized bentonite is strongly dependent on pH and ionic strength. When thepH was6,ionic strength was0.01mol·L^-1,the adsorption rate reached to91.8%. Theremoval of U（Ⅵ） was rather quick and the kinetic adsorption data was simulated wellby a pseudo-second-order rate equation. The equilibrium adsorption results were fittedbetter with Langmuir isotherm, the theory saturated adsorption was0.71mol·g^-1. AtpH<6.5, the adsorption of U（Ⅵ） decreased significantly as the competition ofCa²⁺,Mg²⁺, CO32-and HCO3-.（3） The effect of H₂O₂on the adsorption onto Fe-immobilized bentonite wasinvestigated at various conditions of initial solution pH, H₂O₂concentration, U（Ⅵ）concentration and coexisting ions by batch techniques. The results indicated that theadsorption enhanced by precipitation reaction between H₂O₂and UO2²⁺as well as theFenton reaction between H₂O₂and Fe-immobilized bentonite. The adsorption is strongly dependent on pH, H₂O₂enhanced the U（Ⅵ） adsorption to greater than98%at pH3⁶. The facilitation of adsorption by H₂O₂increased as uranium concentrationincreases, when the initial U（Ⅵ） concentration was0.64mmol L^-1,the saturationamount for U（Ⅵ） adsorbed by Fe-immobilized bentonite was3.13mmol·g^-1. Theadsorption of U（Ⅵ） increased as the competition of Ca²⁺,Mg²⁺.