Removal of Total Hydrocarbon from Oilfield Produced Water using Activated Carbon prepared from Coconut Shells

Abstract

The adsorption capacity of coconut shell activated carbon as adsorbent for the removal of total hydrocarbon from produced water was investigated. The physico-chemical properties of the produced water were determined and the adsorbent was characterized in terms of pH and other surface characteristics. The effects of adsorption process variables on the adsorption capacity of the activated carbon for the the removal of total hydrocarbon was evaluated and optimized using the response surface methodology. The adsorption process variables considered and their range of values are adsorbent dosage of 0.4 to 1.0 g, contact time of 20 to 60 mins and temperature of 30 to 50. The physicochemical properties of the produced water before treatment revealed that produced water was contaminated with a high concentration of hydrocarbon and other contaminants. Elemental composition showed that the adsorbent contained predominantly CaO (73.22%) and P₂O₅ (20.59%). The BET surface area, pore volume and pore size of the adsorbent were found to be 689.406 m².g^-1, 0.266 cm³.g^-1 and 2.153 nm respectively. The maximum amount of THC adsorbed in the adsorption process was found to be 1,068,451.73 mg.g^-1. This maximum was achieved using an adsorbent dosage of  0.40 g, a contact time of 60 mins at a temperature of 30. The high and close R-squared values of the experimental and predicted values of the THC adsorption indicate reasonable agreement. The high amount of THC adsorbed showed that coconut shell activated carbon is efficient for the treatment of wastewater streams laden with hydrocarbon.