The Adsorption Properties For Cu²⁺ And Zn²⁺ In Acid Mine Drainage Of Bentonite-Paper White Mud Composite Particles

In order to simultaneous removal of heavy metal ions and acidity in acid mine drainage at low cost and high efficiency,in this study,bentonite-paper white mud composite particles are used as adsorbents.The preparation conditions、adsorption and removal properties of Cu²⁺、Zn²⁺and their influencing factors were studied,at the same time the adsorption isothermal and kinetic equations were established.Based on static test,dynamic test was carried out,and characterized by SEM.The research results are as follows:（1）The optimal conditions for the preparation of the bentonite-paper white mud composite particles were determined as:papermaking white mud and bentonite are compounded in a ratio of 5:5,5%anhydrous Na₂CO₃ was added,and calcined at 500°C for 1 h.Microscopic characterization of the particles prepared under different conditions by SEM shows that the layered structure of the composite particles modified by calcination is obvious,the specific surface area is huge,the surface is porous and expands,so it has strong adsorption capacity for heavy metal ions..（2）Comparison of two kinds of bentonite composite particles,bentonite-paper white mud composite particles are superior to bentonite-steel slag composite particles in both the release of alkalinity and the removal of Cu²⁺and Zn²⁺.The results showed that bentonite-paper white mud composite particles can be used as a new type of water treatment adsorption material,so that the papermaking white mud can be utilized for resource utilization,and the problem of papermaking white mud outlet is solved economically and effectively.（3）The main influencing factors and influence laws of composite particles in treating Cu²⁺and Zn²⁺acid mine wastewater were determined by static experiments.The larger amount of the adsorbent,the higher pH value of the solution,and the faster oscillation rate,the better removal effect of the composite particles on Cu²⁺and Zn²⁺.As the concentration increases,the adsorption amount of Cu²⁺and Zn²⁺increases,but the removal rate decreases.By de-alkaliating the composite particles and adding the alkali test alone,the adsorption-concentration synergy of Cu²⁺and Zn²⁺by composite particles were preliminarily revealed.When Cu²⁺and Zn²⁺coexist,there is competitive adsorption,and Cu²⁺is preferentially removed.The adsorption of Cu²⁺and Zn²⁺by composite particles is consistent with BET multi-layer adsorption,and the quasi-second-order kinetic equation is more suitable for describing the adsorption process.（4）The results of the dynamic test study indicate that using bentonite-paper white mud composite particles as adsorbent dynamic treatment of Cu²⁺and Zn²⁺AMD with a concentration of 100mg/L,under the conditions of 0.576mL/min flow rate,HRT 2h,surface hydraulic load2.64m³/（m²?d）,the beds were depleted at 62d and 45d respectively,and the corresponding adsorption amounts were 57.32mg/g and 45.89mg/g.Bentonite-paper white mud composite particles can efficiently remove heavy metal ions and acidity in AMD,which is worthy of popularization and application.