Degradation of 4-chloroguaiacol by dark Fenton and solar photo-Fenton advanced oxidation processes.

This paper evaluates the dark Fenton and the solar photo-Fenton advanced oxidation processes for the treatment of solutions containing 4-chloroguaiacol (4-CG). The 4-CG was chosen as a model compound found in pulp and paper wastewater formed in the bleaching process in the pulp industry. The effects of operating parameters, including reaction time, hydrogen peroxide-to-ferrous iron molar ratio (H2O2/Fe2+), initial chemical oxygen demand (COD), pH value, and temperature, on 4-CG degradation efficiency using the solar photo-Fenton process were investigated. It was demonstrated that both processes could effectively degrade 4-CG in water and followed first-order kinetics. The degradation rate in solar photo-Fenton oxidation was much faster than that of the dark reaction. The 4-CG degradation depends on its concentration in the solution. The degradation efficiency decreases when the concentration of the 4-CG increases. Under the conditions of pH 3, H2O2/Fe2+ molar ratio 2, H2O2 16 mmol x L(-1), Fe2+ 8 mmol x L(-1), initial COD 640 mg x L(-1), reaction time approximately 24 minutes, and temperature 25 degrees C, the 4-CG and COD percent removal were greater than 80 and 89%, respectively.