Efficiency of maize cobs in the removal of oil and grease from synthetic wastewater.

Abstract

There are several pollutants that can harm our environment. Oil and grease (O&G) are one of the examples of such pollutants that cause severe environmental problems. The potential of using maize cobs a typical agro-based waste as an adsorbent for removal of O&G from synthetic wastewater was investigated in this work. The maize cobs were collected from the road side vendors of roasted maize in Kasubi market area. The cobs were washed with distilled water then dried under the sun to completely get rid of the water. The removal of O&G from water using maize cobs was investigated by preparation of synthetic water sample containing 50.0g/L old car engine oil into a glass vessel and allowed to a contact time of 4 hours. Oil and Grease recovery was achieved by using standard 5520B, Liquid-liquid, partition-gravimetric method. The adsorption experiments were performed at varying sorbent doses (100, 200, 300, 400, 500) g respectively. The maximum adsorption capacities increased significantly with a corresponding increase in the sorbent doses (20.72, 39.42, 57.83, 76.59 and 92.62) g respectively and correlation coefficient was obtained as 0.9992 from the graph showing mass of oil adsorbed against the mass of the mass cobs used. From the plot of mass of oil and grease adsorbed against concentration of oil retained in water, the correlation coefficient was obtained as 0.9254. The Freundlich adsorption isotherm model was plotted and the various values were obtained. From the graph, the correlation coefficient was obtained as 0.8016, the adsorption capacity was calculated as 132.8 and the adsorption intensity was obtained from the graph as 0.0395 which was indicative of the relative distribution of energy and heterogeneity of the maize cobs adsorbate sites. This work demonstrated that with adequate modifications to improve its hydrophobicity, maize cobs can potentially provide a low cost environmentally friendly adsorbent for oil spill clean-up. The results demonstrated that a crude oil adsorption with this readily available and biodegradable waste material is feasible. Due to its high affinity for oil and low water pick up, maize cobs adsorbent is convincingly hydrophobic and oleophilic.