Treatment Of Acid Mine Drainage Containing Cu²⁺ And Zn²⁺ By Magnetically Modified Bentonite-Steel Slag Composite

In this paper,the removal effect of heavy metal ions and the solid-liquid separation effect of powdered adsorption materials are considered.The magnetic modified bentonite steel slag composite（MB-G）is used to treat Cu²⁺and Zn²⁺in acid mine drainage.Adsorption synergistic co-precipitation to achieve the dual effect of improving the removal effect and achieving solid-liquid separation.Comparing the removal effect and sedimentation performance of different materials on Cu²⁺and Zn²⁺,MB-G with better removal effect and sedimentation performance was selected as the adsorption material for subsequent experiments,and the ratio experiment was carried out to comprehensively remove the effect and sedimentation performance.Bentonite:Steel slag is 2:8 as the ratio of MB-G in subsequent experiments.The effects of reaction conditions on the removal of Cu²⁺and Zn²⁺by MB-G were investigated,and the optimal reaction conditions were determined by orthogonal experiments.The isothermal and kinetic models were established.The results showed that the solution concentration,initial pH,dosage and reaction time had significant effects on the removal efficiency and sedimentation performance of MB-G.The application of external magnetic force had no significant effect on MB-G removal effect,and the sedimentation velocity and effect were both Influential;the optimal reaction conditions for MB-G treatment of Cu²⁺are:reaction time 120 min,dosage 1g/L,Cu²⁺concentration 100mg/L,pH About 6,the corresponding removal rate is about99.17%;the optimal reaction conditions for treating Zn²⁺are:reaction time 240 min,dosage 2.5g/L,Zn²⁺concentration 100mg/L,pH about 6,the corresponding removal rate is about 99.74%,both of them have good sedimentation performance under the action of magnetic field;The adsorption process of MB-Gfor Cu²⁺and Zn²⁺is suitable for Freundlich isotherm model and quasi-secondary kinetic model.Combined with SEM,XRD and EDS microscopic analysis,it is revealed that the removal of Cu²⁺and Zn²⁺by MB-G includes synergistic effects of adsorption and coprecipitation such as electrostatic adsorption,chemical precipitation,ion exchange,surface complexation and encapsulation;especially MB-G The process of Zn²⁺treatment has obvious adsorption bridging effect,and long chain macromolecular bridged polymer is formed in the mineral phase of Zn²⁺coagulation.The sedimentation performance of MB-G after treatment of Zn²⁺is better than that of treated Cu²⁺.The results of the removal and competition of various ions in the multi-system show that the order of competitive removal of the four ions is:Fe²⁺>Cu²⁺>Zn²⁺>Mn²⁺.Magnetically modified bentonite steel slag composite（MB-G）is an excellent mineral environmentally friendly material for treating wastewater containing Cu²⁺and Zn²⁺acid mines.The paper has 62 figures,21 tables and 63 references.