title: Influence of ultrasonic waves on the removal of different oil components from oily sludge.
abstract: Ultrasonic technology is a promising tool for washing oily sludge to recover oil. In this study, the influence of ultrasonic conditions on the removal of different oil components from oily sludge was investigated to optimize ultrasonic washing technology. Among the three frequencies (25, 50 and 100 kHz) applied, ultrasonic washing at 25 kHz exhibited the best performance in terms of oil extraction rate and efficiency. An ultrasonic intensity of 0.33 W/cm2 was necessary to overcome the energy threshold for oil washing. Application of a standing wave or dual frequencies did not improve the oil removal performance perceptibly. The optimum conditions for the removal of oil from oily sludge were an ultrasonic frequency of 25 kHz, intensity of 0.33 W/cm2 and sludge/water ratio of 1/2 (in volume). Thin-layer chromatographic flame ionization detection showed that ultrasonication could overcome high energy thresholds, resulting in an increase in the removal of asphaltenes and resins, with the removal of asphaltenes particularly affected by frequency. This study could provide valuable information for the application of ultrasonic technology in oily sludge treatment.
authors.affiliation: a State Key Laboratory of Environmental Aquatic Chemistry , Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , POB 2871, Beijing 100085 , People's Republic of China.
authors.forename: Yinxin
authors.initials: Y
authors.lastname: Gao
authors.forename: Ran
authors.initials: R
authors.lastname: Ding
authors.forename: Song
authors.initials: S
authors.lastname: Wu
authors.forename: Yunqiang
authors.initials: Y
authors.lastname: Wu
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.forename: Min
authors.initials: M
authors.lastname: Yang
mesh_terms: D019220:High-Energy Shock Waves; D009821:Oils / Q000737:chemistry / Q000302:isolation & purification* / Q000528:radiation effects*; D011829:Radiation Dosage; D012037:Refuse Disposal / Q000379:methods*; D012722:Sewage / Q000032:analysis* / Q000737:chemistry*; D013010:Sonication / Q000379:methods*
chemical_list: D009821:Oils; D012722:Sewage
keywords: oil family compositions; oil removal; oily sludge; ultrasonic washing; ultrasound