Modification Of Poly(O-phenylenediamine) And Its Application In The Removal Of Heavy Metal Ions From Water

As one of the typical water pollutants,heavy metal ions can not be degraded.Therefore,it is of great significance to study how to control the stability of heavy metals in the environment or to remove them.Studies on conductive polymer adsorbent show that intra-particle diffusion has limitations and high cost.Considering that the functional modification of polymer is beneficial to adjust the molecular structure and properties of polymer,and is a promising method to improve the adsorption performance of materials,the functional modification of polyphenylenediamine（PoPD）was proposed to improve its removal performance of heavy metal ions.Specific research contents are as follows:（1）PoPD and CDs/PoPD composites were prepared.The results show that the doping of Cd S significantly improves the removal rate of heavy metal ions by PoPD.The maximum adsorption capacities of CDs/PoPD composites for Cu²⁺,Pb²⁺and Cd²⁺were 48.88 mg·g^-1,53.44 mg·g^-1 and 36.20 mg·g^-1,respectively.The adsorption process is characterized by physical adsorption and chemical adsorption and follows the quasi-second-order kinetic model and Langmuir adsorption isotherm model.The regeneration efficiency of CDs/PoPD composite was 85.95%after 4 times of use,and the reusability was slightly higher than that of PoPD.（2）The electroreduction of Cu²⁺was carried out in a single cell three-electrode system by potentiostatic method using a graphite electrode coated with PoPD and CDs/PoPD,respectively.The results show that the optimum electrode potential of PoPD and CDs/PoPD electroreduction of Cu²⁺are-0.2 V,the optimum initial concentration is 25 mg·L^-1,and the optimum pH is 2 and 3,respectively.Under the optimal conditions,the maximum removal rates of Cu²⁺by PoPD and CDs/PoPD electroreduction are 64.69%and 73.34%,respectively,and follow the quasi-first-order kinetics.After three times of repeated use,it still maintains good stability.（3）The results showed that the optimal electrode potential,initial concentration and pH of Cu²⁺were-0.4 V,15 mg·L^-1 and 4,respectively.The maximum removal rate of Cu²⁺was 83.28%under the optimal conditions,and the quasi-first order kinetics was observed.The removal rate of Cu²⁺by PoPD electroreduction is the highest among the three materials.After repeated use for 5 times,it still maintains high stability.