title: Remediation of oil-contaminated sand with self-collapsing air microbubbles.
abstract: In this study, a novel chemical-free approach for cleaning oil-contaminated sand with self-collapsing air microbubbles (MBs) with diameter less than 50 μm was developed without the use of chemicals, such as surfactants and alkalis. Diesel and rotary-vane pump oil-contaminated fine and medium sands were treated with MBs to study the effect of oil viscosity and sand grain size on oil removal with MBs. About 95 % of diesel removal was achieved for 24 h old 10 % (w/w) diesel-contaminated medium sand in contrast to only 70 % removal from fine sand after 40-min treatment with MBs. While rotary-vane pump oil removal exceeds that of diesel after 40-min treatment with MBs, combination of mechanical stirring with MBs significantly enhanced the oil removal rate, whereby 95 % diesel removal was achieved from fine sand in 30 min in contrast to only 52 % diesel removal with MBs alone. A possible MBs cleaning mechanism for oil-contaminated sand was also proposed. This study provides experimental evidence for the applicability of self-collapsing MBs as a novel chemical-free approach for cleaning oil-contaminated sand.
authors.affiliation: Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, Singapore, 637141, Singapore. ashu0002@e.ntu.edu.sg.
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Agarwal
authors.affiliation: School of Mechanical & Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore.
authors.forename: Yufeng
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, Singapore, 637141, Singapore. cyliu@ntu.edu.sg.|School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore. cyliu@ntu.edu.sg.
authors.forename: Yu
authors.initials: Y
authors.lastname: Liu
mesh_terms: D052918:Environmental Restoration and Remediation / Q000379:methods; D005742:Gasoline / Q000032:analysis; D045423:Microbubbles; D059392:Petroleum Pollution / Q000032:analysis*; D012822:Silicon Dioxide / Q000737:chemistry; D012989:Soil Pollutants / Q000302:isolation & purification*; D014835:Volatilization
chemical_list: D005742:Gasoline; D012989:Soil Pollutants; D012822:Silicon Dioxide
keywords: Diesel; Microbubbles; Remediation; Rotary-vane pump oil; Sand