The Study Of Removal Character And Mechanism Of Pb²⁺ By732Cation Ion Exchange Resin In Sodium Type

Lead is a common heavy metal used in industry. It threatens natural environment andhuman health due to its non-biodegradable and accumulating along the food chain. In thisstudy, ion exchange resin was employed to treat simulated watwater and acid batterywasterwater, which aim at studying removal efficiency of resin on lead ions, influencingfactors, reaction mechanism and the performance in column experiments, so that toprovide reliable experimental basises for the farther practice.The exchange capacity of732ion exchange resin on lead ions was used as index inthis study to research the effects of solid-to-liquid ratio, initial Pb2+concentration, contacttime, temperature, ion strength and pH in the batch experiments. The experimental resultsshow that732resin has a high efficiency for lead removal. Under optimum condition, themaximum exchange capacity for Pb2+could reach396.8mg/g resin. The solid-to-liquidratio, temperature, pH and ion strength had strong effects on the exchange capacity.Results indicate that the optimum solid-to-liquid ratio was0.5g/L; In the temperatureexperiments, exchange capacity increased when the temperature rose; The optimum pHwas4.0irrespective of the influence of precipitation; The results of ion strengthexperiments indicated that exchange capacity decreased as the increase of ion strength.Meanwhile, the results of contact time experiments demonstrate that4h was equilibriumtime. Pseudo first order model, pseudo second order model and Weber-Morris model werequoted to evaluate the reaction kinetics between732resin and Pb2+in the analyticalprocedure of kinetic data. The consequence shows that the ion exchange process followedthe pseudo first order model, which means the surface reaction is dominant. Langmuirisotherm equation and Freundlich isotherm equation were used in the analysis of isothermdata. The analytical results demonstrated that Langmuir isotherm equation gave a better fitwith experimental data, which indicates the reaction is a monolayer adsorption, and thisinference is in good agreement with kinetic data analysis.Furthermore, column experiments were designed to verify the performance of732resin in this study. In the dynamic conditions (resin dosage2.0g, flow rate10mL/min),the simulated wastewater (Pb2+concentration50mg/L) and real wastewater (Pb2+concentration44.14mg/L) were treated by732resin. Experimental results showed thathigh removal efficiency was observed in all experiments. The breakthrough time was37hand20h for simulated wastewater and real wastewater, respectively. After that,1mol/L NaOH was used to regenerate the saturated resin under a dynamic condition (flow rate10mL/min, time1h). The regenerated resin was used in the breakthrough experiments again,which the results indicated that NaOH has good effect on the regeneration of pollutedresin. Additionally, FTIR-ATR was used to determine the change of functional groups onraw resin, Pb loaded resin and regenerated resin. The results showed that sulfonic groupswere the dominant groups in the reaction.