Study On Removal Performance Of Heavy Metal/Organic Compound Pollution By Polypyrrole Supported On Rectorite

With the increasingly serious environmental pollution,more and more heavy metals and organic pollutants discharge into the environment.Rectorite was widely used in environmental remediation because of its stable physical and chemical properties,low cost and no secondary pollution.Functional materials were loaded on the surface of rectorite to achieve the goal of bidirectional removal of heavy metal/organic compound pollution.In this study,the conductive polymer polypyrrole(PPy)was loaded on rectorite(REC)to achieve the goal of bidirectional removal of heavy metal/organic compound pollution in water.The main results are as follows:Polypyrrole/calcium rectorite clay composites(PPy/Ca-REC composites)were prepared as a potential adsorbent,via in situ polymerization of pyrrole monomer for adsorption of Cr(Ⅵ)from aqueous solution.The adsorption of Cr(Ⅵ)onto the PPy/Ca-REC adsorbent was highly pH-dependent,and the removal efficiency by PPy/Ca-REC composites was much higher than the PPy homopolymer.Adsorption kinetics followed a pseudo-secondorder kinetic model with an equilibrium reached within 30-180 min.The adsorption isotherm data were fitted well by the Langmuir isotherm model with the maximum adsorption capacity of 714.29-833.33 mg/g at 25-45 ℃.The PPy/Ca-REC composites could be regenerated and reused for three consecutive adsorption-desorption cycles without loss of the original removal efficiency for Cr(Ⅵ)removal.Furthermore,the selective adsorption of Cr(Ⅵ)was demonstrated in binary adsorption systems with coexisting ions.The mechanisms of Cr(Ⅵ)removal containing electrostatic interactions,ionic interaction as well as reduction of Cr(Ⅵ)to Cr(III),which could be observed by the XPS results.A versatile composite adsorbent combination of polypyrrole and calcium rectorite(PPy/Ca-REC composites)that showed pH-tunable surface charge had been prepared by insitu polymerization method.The adsorption properties of PPy/Ca-REC composites were investigated using Cr(Ⅵ)and Rh B as the probe contaminants.The results showed that the PPy/Ca-REC composites exhibited excellent adsorption abilities toward anion contaminant and cation contaminant simultaneously,and the maximum adsorption capacities for Cr(Ⅵ)and Rh B adsorption were 232.56-256.41 mg/g and 38.17-42.92 mg/g at 25-45 ℃,respectively.The adsorption behaviors of these two contaminants were well described by the pseudo second-order adsorption model.The equilibrium data were well defined by Langmuir isotherm model for Cr(Ⅵ)and Freundlich isotherm model for Rh B,respectively.An alternative regeneration method in Cr(Ⅵ)/Rh B binary systems was proposed,which showed better regeneration performance compared with the single contaminant system.The mechanisms of Cr(Ⅵ)and Rh B removal containing electrostatic interactions,ion exchange,ionic interaction as well as the chemical reduction.By comparing the effects of powder materials and formed pellet materials,a cyclic adsorption device based on powder materials for non-activation treatment of compound pollution in water was designed.PPy/Ca-REC composite powder materials were applied in this adsorption device to realize the adsorption treatment of cationic pollutants(methylene blue,neutral red and malachite green)and anionic pollutants(methyl orange and reactive red X-3B).In order to demonstrate the cost and application value of rectorite used in this experiment,clay/PPy composites were synthesized by using common clays such as montmorillonite,sodium montmorillonite,bentonite and kaolin as templates.Compared with PPy/Ca-REC composites,the cost and effectiveness of these materials were analyzed,and the superiority of PPy/Ca-REC composites in practical application was confirmed.Through the research results of this paper,the removal mechanisms of all kinds of anion and cationic pollutants by PPy/Ca-REC composites were clarified,which provided a theoretical basis for this kind of materials to remove all kinds of pollutants in water environment,and a circulating adsorption device based on powder material for nonactivation treatment of compound pollution in water was designed,and PPy/Ca-REC composite material was applied to this dynamic small-scale test device,which provided a reference for the application of PPy/Ca-REC composite material in practical wastewater treatment.