Advanced oxidative degradation of benzoic acid and 4-nitro benzoic acid–A comparative study

Abstract

Risks to ecosystem vary significantly depending upon the nature and extend of exposure to hazardous chemicals. Stringent rules laid by various Environment protection agencies distinguish risks on the basis the utility and runaway hazards. Benzoic acid and 4-Nitro benzoic acid are widely used in food preservatives, cosmetic, and pharmaceutical industries. Anthropogenic releases of such chemicals into the environment are predominantly into water and soil. In the present study, advance oxidative processes namely UV/H2O2 and dark and UV Fenton, solar Fenton were investigated for the degradation of benzoic acid and 4-Nitrobenzoic acid (4-NBA) in lab-scale photoreactor. The process being highly dependent on experimental parameters, degradation studies were carried out at different [H2O2]/[BA], [H2O2]/[4-NBA] molar ratios and pH values in order to establish optimum experimental conditions for the processes studied. The obtained results show that Fenton process works effectively at acidic conditions and has much higher oxidation rate as compared with the UV/H2O2 process in case of BA, whereas for 4NBA Fenton like process works more effective. Oxidative degradation of contaminants by solar Fenton process was having highest degradation rate for Fenton process than for Fenton like process in both BA and 4-NBA. The optimum degradation conditions for 4-NBA by the photo Fenton like process are at pH 3.5, [Fe3+] at 4 ppm with molar ratio of 1.5 for [H2O2]/[4-NBA].The optimum degradation conditions for BA by the photo Fenton process are at pH 3.5, [Fe2+] at 7 ppm with molar ratio of 5.0 for [H2O2]/[4-BA].