Synthesis of CuxCo3−xO4 nanocatalyst for degradation of nitrogenous organic wastewater in Fenton-like membrane reactor

Abstract

Membrane Fenton-like process with cobalt–copper spinel catalyst is proposed to degrade nitrogenous organic hazardous in wastewater. Cu-auxiliary cobalt oxide (CuxCo3–xO4) was synthesized with the dispersion co-precipitation method. As-prepared CuCo2O4 performed as the best catalyst for Fenton degradation on nitrogen-containing organic compound as methylene blue (C16H18N3ClS) in water and N,N-dimethylacetamide [CH3CON(CH3)2] in industrial wastewater. Lattice substation of Cu2+ to Co2+ ion increased the oxygen vacancies and catalytic activity. The catalyst stability was improved owing to hybrid polarization confinement (total metal elution less than 0.8 mg/L). Methylene blue in water (C0 = 100 mg/L) was completely decolorized in 50 min using 0.6 g/L CuCo2O4 and 0.09 M H2O2 at intrinsic pH 6.7. Degradation reaction rate constant was increased by two folds as k = 0.076 min−1 catalyzed by CuCo2O4 over k = 0.039 min−1 by Co3O4. DMAc-contaminant wastewater of high CODs 19,080 mg/L was treated using 2.4 g/L CuCo2O4 and 2.4 M H2O2 at intrinsic pH = 7.6. Removal rate of DMAc was enhanced from 81 to 99% in the ceramic membrane reactor when H2O2 was activated, and self-sweeping effect was suppressed. As a result, Total Organic Nitrogen (2900 mg/L) in the wastewater was mineralized by 99.9% with a fast transformation to inorganic NO3− ion. Biodegradability of the resistant organic wastewater was remarkably improved, and BOD/COD was increased by 18 folds.