Lubricating oil additives and the environment — an overview

AbstractIn this paper are reported some practical considerations relating to lubricant additive manufacture, and to additivated lubricants' impact on the environment. Widely used engine oil additives are mainly dithiophosphates, overbased calcium sulphonates, succinimidic dispersants, and polymer VI improvers. Production of these additives creates a potential environmental problems due to the hazardous emissions such as H2S and HCl and sludge obtained during purification. New processes are described which lead to the reduction of toxic and other harmful pollutants.Gear oil additives, although these may be used in lower amounts, also make for ecological problems. A high quantity of sulphur‐containing waste water is produced during manufacture of sulphurised EP additives. Some possibilities for recovering sulphur from this waste water are presented. The reduction of the chlorine content in EP additives is another important task, and new processes to produce EP additives with low residual chlorine content are discussed. Metal working fluid additives comprise emulsifiers, corrosion inhibitors, antiwear and EP additives. Their fabrication usually produces toxic and harmful residual products. Additivated lubricants may promote ecological injury. Oil leakage from engines working in harbours, parks, and entertainment areas are dangerous and difficult to avoid. To counter this, biodegradable base stocks were developed, but there are few data concerning the biode‐gradability of the additives used. Used oils are generally collected and recovered, but a significant quantity of used oil is directly burned. Burning of additivated used oils in incorrect equipment leads to dangerous emissions, such as sulphur oxides. Because sulphur‐containing additives cannot be replaced in engine oils or gear oils, the main ecological measure is the reduction of the quantity of used oils burned.