OXIDATIVE AND ADSORPTIVE STUDIES ON REMOVAL OF HYDROQUINONE FROM AQUEOUS SOLUTION

Abstract

Phenol and its derivatives are present in wastewater from the manufacture of petroleum refineries, phenolic resins, formaldehyde resins, caprolactarn textile, and some pharmaceutical processes, paper and pulp, steel, petrochemical, petroleum, rubber, dyes, plastics, pharmaceutical, cosmetics industries, agrocheniicals etc. and in synthetic coal fuel conversion process wastewater. Due to its toxicity and difficulty to degrade, the presence of phenol becomes a considerable problem to environment and human health. Present study aims to impregnate iron (Fe) onto granular activated carbon (GAC) and characterize the iron loaded activated carbon (Fe-GAC) for its physico-chemical and analytical properties. Effect of various process parameters like Initial concentration (Co: 20-100 mg/L), pH (4-8), oxidant dose (CH2o2: 0.4-1.6 mLIL) and Catalyst dose (m: 0.5-1.5 g/L), was found on the oxidation of hydroquinone (HQ). Fe-GAC was also used as adsorbent in the batch adsorption study of adsorptive removal of HQ and effect of process parameter like initial concentration (CO: 25-1000 mg/L), pH (2-10), contact time (t: 0-24 h), temperature (T: 15-45 °C) and adsorbent dose (w: 5-50 g/L) was found on the adsorption of HQ along with the kinetics and isotherm study for the adsorption of HQ. Catalytic oxidation studies according to Taguchi's experimental design and ANOVA analysis shows that the optimum level of process parameter are C6=100 mg/L, p114, CH2O2_0.4 mLJL and m=1 g/L with pH as the most significant factor with 63.47% contribution. The predicted removal efficiency at optimum levels according to Taguchi's experimental design is 85.62% which is close enough to confirmation experiment which gives the 83.56% removal of HQ. The batch adsorption studies for adsorptive removal of HQ using Fe-GAC as adsorbent shows that the optimum values of process parameters are: pH=4, w=40 g/L and t=14 h. C° was taken as 100 mg/L as optimum. The adsorptive removal of HQ by Fe-GAC followed the pseudo-second order kinetics and Langmuir isotherm represented the best fit for the experimental data.