Demulsifier systems applied to breakdown petroleum sludge

Three sets of demulsifier systems based on nonyl phenol ethoxylates (n =9, 11, 13) were prepared. These demulsifiers have been employed to breakdown petroleum sludge obtained from the main drainage basin of Al-Hamra Oil Company. These systems were composed of 4% inorganic acid solution, 10% of aqueous phase solution composed of NP-9, NP-11 and NP-13 as surfactants and isopropyl or butyl alcohol as co-surfactants and the balance of the system is an oil phase (benzene/toluene, 1:1mixture). The breakdown of petroleum sludges was evaluated by TPH analysis, determination of the amount of aqueous phase and sediments separated from the sludge. Furthermore, the oil phase recovered from the sludge was mixed with fresh crude oil obtained from Al-Hamra Oil Company in 1:1 ratio and the API of the mixture was calculated. Effect of demulsifier system composition and its concentration in parts per million were also studied. It was found that the best demulsifier composition for complete breakdown of the sludge was the one based on NP-13. (C) 2011 Elsevier B.V. All rights reserved.