Treatment Of Polyaniline And Aniline Wastewater Based On Advanced Fenton Oxidation Processes

Polyaniline,a polymer,has great promise applications in metallic protection,supercapacitors and other fields based on its high conductivity and good redox reversibility.Accompany with the production of polyaniline,huge amount of wastewater containing a large number of aniline and aniline derivatives is produced.The pollution of wastewater to the environment is the main factor restricting the industrial production of polyaniline.Fenton reaction based advanced oxidation processes is an effective method for the treatment of organic wastewater.Hence,it is of great theoretical and practical significance to study the advanced oxidation processes based on Fenton reaction for the treatment of polyaniline and aniline wastewater.First,the main physicochemical properties and organic pollutants of polyaniline wastewater were determined.Polyaniline wastewater was treated by the coupling of anodic oxidation process and cathodic electro-Fenton process.The effects of Fe²⁺concentration and current density on the removal of chemical oxygen demand(COD)from polyaniline wastewater were investigated.The·OH and SO₄^·-generated during the treatment were determined by electron spin resonance(ESR).Under the condition of constant current density 14 m A cm^-2,p H 3.0,Fe²⁺concentration 0.2 m M and 160 m L min^-1 oxygen flow rate,89%COD was removed after 360 min treatment.The morphology and high specific capacitance of polyaniline synthesized from the treated polyaniline wastewater are similar to those of polyaniline synthesized from fresh solution.Second,the polyaniline wastewater was treated by photoelectro-Fenton/black TiO₂,in which the black TiO₂ nanotubes synthesized by electrochemical method was used as heterogeneous photocatalyst,the Ir O₂/Ti and graphite felt(GF)were used as anode and cathode,respectively.The effects of p H,Fe²⁺concentration and current density on COD removal of polyaniline wastewater were studied.Under the conditions of constant current density 16 m A/cm²,p H 3.0,Fe²⁺concentration 0.2 m M and 200 m L min^-1 oxygen flow rate,300 W Xe,89%COD was removed after 360 min treatment.Third,the chemical modified graphite felt(M-GF)was prepared by oxidation of potassium permanganate,concentrated sulfuric acid and heating in ammonia atmosphere.The structure and properties of M-GF were characterized.The surface of M-GF has a large number of functional groups containing oxygen,sulfur and nitrogen.The M-GF has good hydrophilicity and electrocatalytic performance.The concentration of H₂O₂ generated by M-GF electrode is higher than that of GF electrode.The degradation of aniline by electro-Fenton using M-GF electrode was studied,and the degradation efficiency of aniline by electro Fenton using M-GF electrode is higher than that by electro-Fenton using GF electrode.Forth,Co₃Fe₃O₈/g-C₃N₄ was synthesized by hydrothermal method.The structure and properties of Co₃Fe₃O₈/g-C₃N₄ were characterized.The characterization results show that Co₃Fe₃O₈ interacts with g-C₃N₄ nanosheets through intermolecular force and chemical bond.The heterostructure between Co₃Fe₃O₈ and g-C₃N₄ can enhance the lifetime of photogenerated electrons and holes.The effects of various factors on the degradation of aniline by photo-Fenton-like process were studied.The ESR measurement shows that the photo-Fenton-like degradation of aniline by the Co₃Fe₃O₈/g-C₃N₄ is a multi-process and various reactive oxygen species are involved,such as O₂^·-,h⁺,·OH,etc.