Chemical Destabilization of Fresh and Spent Cutting Oil Emulsions: Differences between an Ecofriendly and Two Commercial Synthetic Lubricants

Danilo Spasiano, Andrea Petrella and Vito Lacedra
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Danilo Spasiano: Department of Civil, Environmental, Land, Building Engineering and Chemistry, Polytechnic University of Bari, Via E. Orabona, 4, 70125 Bari, Italy
Andrea Petrella: Department of Civil, Environmental, Land, Building Engineering and Chemistry, Polytechnic University of Bari, Via E. Orabona, 4, 70125 Bari, Italy
Vito Lacedra: Dana Incorporated, Strada Provinciale Modugno-Bari, 4, 70132 Bari, Italy

Sustainability, 2020, vol. 12, issue 14, 1-10

Abstract: The aim of this study was to evaluate if eco-friendly lubricants had an additional advantage over conventional synthetic lubricants in terms of emulsion treatment of metalworking wastewater. To these purpose, two fresh commercial synthetic cutting oil emulsions were compared with an emulsion obtained from a new cutting oil produced from the reuse of slaughtering waste (CADT-605 from Kimya Srl, Bari, Italy). The breaking of the fresh emulsions was carried out with the addition of small amounts of sulfuric acid (2–20 mL/L) followed by pH neutralization by means of calcium hydroxide. During the two-step treatments, COD, BOD 5 and non-ionic surfactant (NIS) concentrations were monitored in the aqueous phase. The results demonstrated that the best results were obtained with the emulsion produced with the bio-based lubricant. In addition, this cutting oil was tested in a metalworking plant within 30 days and the resulting spent emulsion was treated with the proposed process. In all the cases, the treatment led to a drastic decrease of the COD, BOD 5 and NIS contents that allow the discharge of resulting aqueous phase in sewers or in surface water bodies, together with the other wastewater produced by the plant, in agreement with the Italian regulation.

Keywords: emulsion breaking; surfactants; COD; BOD 5; spent emulsions; metalworking wastewater (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2020
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