REMOVAL OF HEAVY METALS FROM CRUDE OIL REFINERY EFFLUENT USING COCONUT SHELL-BASED ACTIVATED CARBON
Onwudinjo C.F1, Olayebi O.O2
ABSTRACT
Industrial effluents are treated before their disposal in the environment using solid adsorbents such as molecular sieves, silica gel, zeolite amongst others. This study was conducted to evaluate the removal of heavy metals from petroleum refinery effluent using activated carbons made from coconut shells. A critical aspect of this method was that the removal was performed on several metals at a PH range in which a given metal undergoes an adsorption process, making the method useful for wastewater treatment. To prepare the adsorbent, Pyrolysis was done at 400oC while chemical activation using ZnCl2 at 500oC. The effects of contact time, adsorbent dosage, stirring speed, and pH on the rate of removal of heavy metals were thoroughly investigated to ascertain the effectiveness of the locally made absorbent at a room temperature of 25oC with intervals of 10 minutes from 30 to 60 minutes. Adsorption of metal ions increased with contact time. Cr3+, Cu 2+, Pb2+, and Zn 2+ were removed using the produced adsorbent. The percentage metal ions removal reached equilibrium within 60 minutes for Cr, 30 minutes for both Cu, Pb, and Zn; with Cr(III) recording 14.61% removal, Cu(II) 100%, Pb 60.85%, and Zn(II) 50.67% removal. Consequently, there is a trend of Cu 2+>Pb 2+>Zn 2+,>Cr3+ after which increase in time did not yield further removal of metal ions, but resulted in desorption of some of the metal ions (lead and zinc) from the adsorbent surface. For Cr, the maximum removal was attained at 2g with 17.96% removal.
Keywords: Heavy Metals, Industrial Effluents, Adsorbent, Adsorption, Pyrolysis, Environmental Pollution