Removal of azo-dye acid red B (ARB) by adsorption and catalytic combustion using magnetic CuFe_2O_4 powder

摘要

The effectiveness of magnetic CuFe_2O_4 powder as adsorbent/catalyst for the removal of azo-dye acid Red B (ARB) from water by adsorption and subsequent catalytic combustion was studied.Magnetic CuFe_2O_4 powder showed excellent adsorption properties towards ARB at pH <5.5,and it could be conveniently recovered by magnetic separation technology after adsorption.The combustion decomposition of ARB in the presence or absence of CuFe_2O_4 was studied by a system for thermal degradation studies (STDS) and in situ FTIR.The results indicated that different reactive pathways existed for the combustion under different conditions.In the presence of CuFe_2O_4,the temperature needed for oxidation reaction and for combustion was 150 and 300degC,respectively.The reaction products were observed to be SO_2,CO_2,H_2O,and nitrate.There was neither volatile organic compound (VOCs) emitted to atmosphere during reaction nor organic matter deposited on the surface of CuFe_2O_4 after the combustion.Comparatively,in the absence of CuFe_2O_4,the oxidation and combustion of ARB required a higher temperature (300 and 500degC,respectively) and produced a lot of toxic organic compounds emitted to atmosphere besides SO_3,CO_2 and H_2O during the reaction.In addition,sulfate was generated instead of nitrate.The experiments of adsorption-combustion cycles demonstrated that there was no evident change in adsorption properties and catalytic activity of magnetic CuFe_2O_4 powder after seven cycles.