Surfactants based on recycled poly(ethylene terephthalate) for breaking water-in-oil emulsions

Poly(ethylene terephthalate), waste was depolymerized with propylene glycol to an oligoester. The glycolyzed product was reacted with polyethylene glycol of different molecular weights, namely 600, 1000 and 4000, to form surfactants having different hydrophile-lipophile balances and hence different surface activities. The interfacial tension at the aqueous-benzene interface was determined. It was found that the demulsifier concentration that causes a minimum interfacial tension is always less than that inducing maximum efficiency. The data revealed that the efficiency increases on increasing the concentration of demulsifier, contact time and hydrophilicity.