Electrocoagulation with polarity switch for fast oil removal from oil in water emulsions

• Published in: Journal of environmental management 2018-05, Vol.213, p.119-125
• Main Authors: Gobbi, Lorena C.A., Nascimento, Izabela L., Muniz, Eduardo P., Rocha, Sandra M.S., Porto, Paulo S.S.
• Format: Article
• Language: English
• Subjects: Al electrodes; Batch reactor; Oil removal; Oily water; Polarity reversal
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2018.01.069

An electrocoagulation technique using a 3.5 L reactor, with aluminum electrodes in a monopolar arrangement with polarity switch at each 10 s was used to separate oil from synthetic oily water similar in oil concentration to produced water from offshore platforms. Up to 98% of oil removal was achieved after 20 min of processing. Processing time dependence of the oil removal and pH was measured and successfully adjusted to exponential models, indicating a pseudo first order behavior. Statistical analysis was used to prove that electrical conductivity and total solids depend significantly on the concentration of electrolyte (NaCl) in the medium. Oil removal depends mostly on the distance between the electrodes but is proportional to electrolyte concentration when initial pH is 8. Electrocoagulation with polarity switch maximizes the lifetime of the electrodes. The process reduced oil concentration to a value below that stipulated by law, proving it can be an efficient technology to minimize the offshore drilling impact in the environment. [Display omitted] •An electrocoagulation system was built to separate crude emulsified oil from water.•It had 3.5 L, power switch at each 10 s and aluminum electrodes.•Oil removal of 97.77% was achieved.•Exponential models were proposed for the variation of pH and oil concentration with time.•The effects of distance between electrodes, pH, and electrolyte (NaCl) concentration were studied.