Study On Wastewater Treatment By Zn-air Battery Based On Synthesis Of H₂O₂

With the development of society,people’s daily activities and factory operations will inevitably discharge organic waste water,causing the deterioration of the water pollution ecosystem.Therefore,green and efficient treatment of organic waste water is urgent.We develop and demonstrate a clean,robust and self-powered technology for efficient wastewater treatment via an ultraviolet zinc-air battery（UV-ZAB）system with partially oxidized carbon nanotubes directly assembled on nickel foam（OCNTs@NF）as the cathode.The ZAB allows for efficient on-site production of H₂O₂ by electrochemical oxygen reduction,that enables rapid degradation of model organic pollutants and actual pollutants from industrial wastewaters,where the UV light can be self-powered by the ZAB system with lowering energy consumption.This article has carried out the following work:1.Use nitric acid vapor to oxidize multi-walled carbon nanotubes and configure them into a dispersion with a suitable concentration.There is a difference in oxygen reduction potential between the oxygen-containing carbon nanotubes and the metal,so when the NF is immersed in a uniform dispersion at medium time,the carbon nanotubes will self-assemble and arrange compactly on the surface of the NF,and then undergo high-temperature reduction to obtain OCNTs@NF.OCNTs@NF shows a uniform three-dimensional porous structure,which is helpful for O₂ adsorption and H₂O₂ transfer,and can be prepared in a large area;nitric acid oxidation introduces hydroxyl,carboxyl and other oxygen-containing groups,and high temperature reduction introduces H₂O₂ active sites,The test results show that as the reduction temperature increases,the H₂O₂ selectivity increases.ORR test shows that OCNTs@NF is a promising cathode for producing H₂O₂ in acid electrolyte,and the selectivity of H₂O₂ is 82%.2.This paper constructs a UV/ZAB wastewater treatment system:OCNTs@NF,Zn and Na₂SO₄ solutions are used as cathode,anode and electrolyte,respectively.The decomposition of Rhodamine B（RhB）and the degradation of RhB,and the influencing factors of the degradation effect of the system were studied.The results show that the annealing temperature,hydrophobic treatment,oxygen mass transfer,electrolyte pH and current density of OCNTs@NF all affect the synthesis of H₂O₂ in ZAB.The experiment found that 2%PTFE treated OCNTs@NF-600T,pH=2 Na₂SO₄solution,at a current density of 10mA/cm²,synthesis of 215.1μmol of H₂O₂within 3h;combined with UV 30min degradation of 99%of 20 mg/L RhB,and it still maintains high degradation efficiency after 10 cycles.The system can also decolor and degrade methylene blue,methyl orange and phenol red,which proves the universal applicability of UV/ZAB;the printing and dyeing wastewater can be treated within 4 hours to reach the discharge standard,which demonstrates the feasibility of the system practical application.Multiple ZAB packs are connected in series to construct a self-powered system to supply power to UV and treat wastewater,which has the prospect of commercial application.