Synthesis and performances for treating oily wastewater of polyether copolymers based on polyethyleneimine

The demulsification of the oily wastewater generated in the oil recovery process is very important in the crude oil exploitation. In present work, 10 block copolymers based on polyethyleneimine were synthesized, and their performances for treating oily wastewater were studied. The evaluation of demulsification efficiency, the effects of temperature, and the dosage on the treatment of oily wastewater by prepared copolymers were also investigated. To explore the causes of the differences, the interface activity of prepared copolymer molecules at water-oil interface was investigated by the interfacial tension, and a mechanism diagram of demulsification of wastewater by the prepared copolymers was proposed. The demulsification of wastewater could be divided into 3 processes that were (1) adsorption, (2) congestion, and (3) coalescence. The prepared copolymer molecule acted as a hand in the oily wastewater to achieve the demulsification.