Adsorption and Aggregation Mechanism of Cu2+and Zn2+by Bentonite Composite Particles
In order to solve the limitations of a single material to treat wastewater containing heavy metal ions,the bentonite and steel slag were used to prepare alkaline particles.The adsorption and aggregation mechanism of bentonite alkaline composite particles adsorbent on Cu,Zn was explored by combining macroscopic and microscopic means.The results show that the adsorption of composite particles on Cu2+,Zn2+is in accordance with the BET multimolecular layer adsorption,and the kinetic equation is in accordance with the proposed second-degree kinetic equation,which indicates that the adsorption process is accompanied by both physical adsorption and chemical adsorption.The morphology,structure and mineral phases of the adsorbed alkali particles were analyzed by XRD and SEM characterization.The results show that the layer spacings of the composite particles increase from 1.549 nm to 1.593 nm and 1.643 nm after the adsorption of Cu2+and Zn2+,indicating that Cu2+and Zn2+enter into the interlayer of the composite particles,which make the layer spacing larger,and the ion exchange occurres.At the same time,new mineral phases such as Na2CuSi3O8,Ca2CuO3,Cu5(SiO3)4(OH)2,Zn4Si2O7(OH)2,Ca2ZnSi2O7 are added into the composite particles,indicating that there is the existence of surface complexation reaction,and the alkaline mineral phases can have the precipitation reaction with Cu2+and Zn2+to achieve adsorption-polymerisation of heavy metal ions,which is an excellent adsorbent.
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