Environmental implications of crude glycerin used in special products for the metalworking industry and in biodegradable mulching films

Abstract

Crude glycerin from biodiesel supply chain can replace synthetic glycerol or other chemicals in industrial applications. To improve sustainability according to the biorefinery perspective, a purification phase will be carried out only if it is really necessary to reach standards for industrial processes or final products. In metal working, the use of crude glycerin-based hydraulic fluids, replacing mineral oil-based and glycol-based ones, has fulfilled industrial requirements and made it possible to increase (i) worker safety because of its non-flammability; (ii) biodegradability and (iii) time-life of the product due to anti-wear properties; in addition, post-use waste management will be simplified, due to the possibility to declassify fluids as special waste. In biodegradable mulching films, the replacement of synthetic glycerol was successful because it made it possible both to maintain the same compounding conditions and to obtain the same yields and film biodegradation in an agronomic trial on muskmelon. The benefits compared with conventional polyethylene films are the same as conventional readily biodegradable films. The key parameters in the analytical composition of glycerin concerning specific industrial applications are discussed; the environmental benefits in metal working fluid formulation and in mulching film compounding are then assessed.