The Experiment Study On Adsorption,Immobilization And Regeneration To Heavy Metal Ions By Bentonite Composite Adsorbent Particles

The acid mine drainage?AMD? contains large amount of Fe²⁺?Mn²⁺?Cu²⁺?Zn²⁺ and acidity. In order to solve these problems, the static and dynamic tests were studied on the adsorption, immobilization and regeneration of Fe²⁺? Mn²⁺?Cu²⁺?Zn²⁺ by a new economical and environmentally friendly adsorbent.Based on the previous research, the bentonite was the main material and then added different auxiliary materials ?bitter spar, fly ash or steel slag? with different proportion of adhesion agents ?sodium carbonate or sodium silicate?. By high-temperature roasting the different bentonite composite particles were created. Using the different particles, the effect of adsorption to Fe²⁺?Mn²⁺?Cu²⁺?Zn²⁺, dissipation rates, the total alkalinity released and the cost were studied. Then came to the conclusion:5%Na2CO3 bentonite-slag is the best environmental mineral adsorbent.Through the static and dynamic tests, the adsorption and its mechanism of the best adsorbent were conducted. The results show that the saturated adsorption capacity of the composite adsorbent to Fe²⁺?Mn²⁺?Cu²⁺?Zn²⁺ are 69.70mg/g?68.42mg/g?68.90mg/g and 64.50mg/g. Fe²⁺?Mn²⁺?Cu²⁺ are in coincidence with BET adsorption, Zn²⁺ is in coincidence with Freundlich. And the sorption kinetics of Fe²⁺?Mn²⁺?Cu²⁺?Zn²⁺ are in coincidence with the pseudo-second-order kinetic model. Adsorption, chemical precipitation and coagulation are the combined action of the adsorption.In order to realize particles to be recycled and further stabilize heavy metal ions, the SRB deoxidizes SO42- and releases S2-, the regeneration of composite particles were experienced.The results show that as the adsorption process of Fe²⁺ changed the structure of the adsorbent,adding Fe²⁺ caused Na+ and Fe²⁺ exchange to make the support of the montmorillonite crystal layer in the bentonite collapse and the particles become powder. The results of regeneration to Mn²⁺ Cu²⁺?Zn²⁺ show that immobilization and regeneration effects are remarkable. The bentonite composite particles can be recycled many times. It is revealed that S2- and Fe²⁺ Mn²⁺?Cu²⁺?Zn²⁺ can generate sulfide precipitation which can realize real immobilization,at the same time,can make the particles point regeneration.Based on the static and dynamic tests, the best particles combined with microorganism to deal with AMD were performed. The results show that the column which the bentonite-steel composite particles and biological carrier were stratified is best for the removal of acidity?Fe²⁺? Mn²⁺?Cu²⁺?Zn²⁺. At the same time, microbial reduction generated S2- can saturate adsorbent regeneration, achieving the goal of adsorbent used many times. So this process has the synergy, which is an innovative and efficient water treatment method. It is worthy of popularization and application.