Production of powdered activated carbon from oil palm empty fruit bunch for removal of phenol and treatment of palm oil mill final effluent

Abstract

Empty fruit bunch (EFB) is one of the most abundant residues of the palm oil mill industry. Most of it left unused and being disposed to the landfill. Discharging the huge volume of empty fruit bunch (EFB) in a sanitary landfill will not only occupy a great deal of land, but also conveys an inherent potential for pollution of indigenous water resources. Moreover, palm oil processing requires large quantities of water results in palm oil mill effluent, which contains high concentration of phenolic compounds. Thus, it must be managed with extreme care to avoid adverse environmental or human health impacts. The aim of this study was to investigate the feasibility and the potential of converting palm oil industrial residue namely empty fruit bunch (EFB) into activated carbon. Powdered activated carbon samples were produced from oil palm empty fruit bunches (EFB) by varying the operating parameters of temperatures, CO2 gas flow rates and activation times using 2-level full factorial experimental design. The prepared EFB samples were carbonized for 30 minutes using nitrogen gas, followed by activation with CO2 gas. The optimum preparation conditions for PAC samples produced were investigated through adsorption tests on aqueous solution of phenol. Characterizations of the best quality AC sample prepared and the optimum conditions for adsorption of phenol were determined. Freundlich and Langmuir adsorption isotherms as well as pseudo first order and second order adsorption kinetics models on prepared AC were studied. Finally evaluation of the adsorption efficiency of the EFB based-AC was investigated in palm oil mill final effluent (POMFE) using a bench scale model. The experimental results had shown that the activated carbon prepared at activation temperature of 800ºC with CO2 gas flow rate of 0.1 L/min and activation time of 15 minutes represent the best absorbent of phenol. Characterization of the EFB based-AC showed good quality adsorbent with highly active sites and well-developed pores with BET surface area of 375m2 /g. However, the optimum conditions for adsorption of phenol were found to be PAC dose of 75 g/L, agitation speed of 150 rpm, contact time of 15 min and pH equal to 4. Freundlich and Langmuir as well as pseudo-second order kinetic models fitted the adsorption process of phenol by prepared AC. The maximum adsorption capacity of phenol (qm) was 17.36 mg/g. EFB based-AC in the bench scale model operation had shown good removals of 40% colour, 68% phenol, 61% COD, 42% BOD and 42% ammonical nitrogen at initial five minutes contact time. EFB based-AC was found comparable to the commercial grade powdered activated carbon; it is efficient adsorbent for the removal of contaminants from palm oil mill final effluent (POMFE). Thus, EFB based-AC would be promising in two ways: the industrial oil palm solid residue would be utilized for the production of activated carbon for the treatment of wastewaters including palm oil mill final effluent.