Development of a Cleaning Treatment for Polyethylene Terephthalate Bottles Using a Moderately Concentrated Alkaline Solution

Abstract

We investigated the effects of hydroxide ion (OH^-), sodium hypochlorite (NaOCl), and food emulsifier on cleaning of polyethylene terephthalate (PET) particles fouled with catechin or bovine serum albumin (BSA) under moderate alkaline conditions. The efficiency of the removal of catechin or BSA increased depending on the OCl^- concentration, and the synergistic action of OH^- and OCl^- was observed in the pH range of 10 to 12. The addition of food emulsifier to NaOH solutions could improve the efficiency of PET particle cleaning by lowering the surface tension of the NaOH solution. In addition, high-efficiency cleaning could be achieved by the combined use of food emulsifiers and NaOCl, even when NaOH solutions of moderate pHs of 11 to 12 were used. It was demonstrated that PET bottles stained by tea beverages could be more successfully cleaned using the detergent formulations suggested in this model experiment than a common detergent for glass bottles. It was demonstrated that the combined use of moderate concentrations of OH^-, OCl^-, and food emulsifiers can provide an adequate cleaning treatment for PET bottles.