REMOVAL OF PHENOL BY ELECTRO,COAGULATION AND ADSORPTION

Abstract

The present study focuses on the possibility of using electrocoagulation (EC) to remove phenol from the wastewater using a cell with vertically oriented aluminium electrodes which are used as sacrificial anode and as cathode. The removal of phenol was investigated in terms of various parameters such as: Initial pH, Sodium chloride dosage, Inter electrode distance, Current density, Operating time and Initial phenol concentration. And the present study also includes the effect of addition of Granular activated carbon (GAC), in EC cell, on phenol removal efficiency. Removal of phenol during EC is due to combined effect of sweep coagulation and adsorption. It is generally accepted that coagulation is brought about primarily by reduction in net surface charge to a point where colloidal particles, previously stabilized by electrostatic repulsion, can approach closely enough for Van der Waals forces to hold them together and allow aggregation. In the EC process, coagulant is generated in situ by electrolytic oxidation of an aluminum anode material. Results obtained with synthetic wastewater revealed the most effective removal capacities of phenol could be achieved when the initial pH was 7. The results showed that, at high current density of 25 mA/cm2 and at solution pH 7, remarkable removal of 90% of phenol was achieved in 2'/2 h. The rate of Electrocoagulation was observed to increase as phenol concentration decreases; the maximum removal rate was attained at 50 mg/L phenol concentration. The addition of GAC as adsorbent resulted in remarkable increase in the removal rate of phenol at lower current densities and operating time, than the conventional electrocoagulation process. By the addition of GAC in the dosages of 50, 100, 150, 200 and 250 mg/1 increases the efficiency by the amount of 13.95, 19.95, 22.7, 26.2 and 28.8 percentage resp., after 30 min of process with comparative to electrocoagulation without GAC. Similarly, after 120 min of process the increase in efficiencies were found to be 3.8, 4.6, 6.7, 9.1 and 14.4 percentage resp. The experimental results with addition of GAC shows that the highest percentage removal 97 was achieved for 120 min operating time and current density of 25 mA/cm2 which was approximately 15% more, by Conventional EC process. It is also observed that a percentage removal of 70.1% is achieved at an adsorbent dosage of 250 mg/I whereas at an adsorbent dosage of 50 mg/I, 55.25% observed. Therefore, it iii has been concluded that addition of adsorbent enhances the process of electrocoagulation, reduces the operating time and energy consumption which is economical. The present study shows that, EC of phenol using aluminum electrodes with Addition of GAC is a promising process