Preparation Of Graded Pore NiAl Alloy Membrane And Its Catalytic Performance For Separation Of Dye Wastewater

NiAl intermetallic compound,as a new high-temperature porous alloy material,has the advantages of high melting point,low density,high thermal conductivity,good oxidation resistance and corrosion resistance,but it is difficult to form during the sintering process of preparing NiAl alloy membrane features.In this paper,powder metallurgy combined with dealloying method is used to prepare NiAl membranes with different proportions of graded pores,and the forming mechanism of graded pores is studied.The prepared hierarchical pore NiAl(hp-NiAl)membrane was used as the anode assembly electrocatalytic membrane reactor(ECMR),the effect of ECMR on Congo red dye treatment was studied,and the preparation process parameters of the hp-NiAl membrane and ECMR operating parameters were optimized.Through XRD characterization of NiAl membrane,the best temperature for preparing different nickel aluminum alloy phases is determined:the best temperature for NiAl₃ phase is 750?,the best temperature for NiAl₃ and Ni₂Al₃ mixed phase is850?,and the best temperature for Ni₂Al₃ phase is 1300?.The phase transformation path during the metal membrane preparation process is analyzed,and the role of Al metal in the dealloying is also explained.The microstructure and pore size distribution of graded porous NiAl membrane were analyzed by SEM and BET.XRD,SEM and bet characterization,electrochemical performance test(CV)and electrocatalytic performance test were used to determine the optimal preparation parameters of NiAl membrane with hierarchical pores.When the mass ratio of Ni:Al was 59:41 and the sintering temperature was 1300°C,the comprehensive properties of the NiAl membrane with graded pores were the best,the porosity was 37%,and the pure water permeation flux was 509 L·(h·m²·bar)^-1.The hp-NiAl membrane was used as anode and Na₂SO₄ was used as electrolyte(solution concentration 15 g·L^-1)to assemble ECMR.Taking the decolorization rate,COD removal rate and TOC removal rate of Congo red dye as indexes,the operation parameters of ECMR treatment of Congo red dye were optimized.The optimal parameters were:voltage 1.2 V,residence time 10 min,initial concentration 150 mg·L^-1.Under these parameters,the decolorization rate of Congo red was 99.7%,COD removal rate was 73%,and TOC removal rate was 58.6%.