Remediation of phenol and phenolic derivatives by catalytic wet peroxide oxidation over Co-Ni layered double nano hydroxides

Abstract

Abstract The catalytic wet peroxide oxidation (CWPO) of phenol and phenolic derivatives from wastewater was investigated over Co-Ni layered double nano hydroxides under different conditions. Co-Ni LDHs was synthesized by the co-precipitation method and characterized by XRD, FTIR and SEM. The experiments were designed by Box–Behnken type of response surface methodology (RSM) through considering four process variables: C H 2 O 2 (M), (Co-Ni LDHs) dosage, CPhenol (ppm) and reaction time (min). The optimum condition was predicted to be 4.03 g/L, 77.8 min, 0.5 mL H2O2 and 100 ppm (phenol) of catalyst amount, reaction time, H2O2 volume and phenol concentration, respectively. The predicted percent of phenol degradation under optimum conditions was 92.9%, whereas the experimental testing of optimum condition led to 94% degradation for phenol. Pareto analysis predicted that the order of relative importance of the four independent factors is as follows: phenol concentration (x4, 11.43%) > catalyst dosage (x1, 3.26%) > reaction time (x2, 0.81%) > peroxide volume (x3, 0.6). The evaluation of the activity of the Co-Ni (1:1) LDH in a real phenolic wastewater containing phenol (50 ppm), 3-amino phenol (5 ppm) and p-nitro phenol (5 ppm) resulted in 53.18, 36.84 and 26.13 removal percentage, respectively.