Sustainable conversion of polystyrene waste into polymeric surfactants to be evaluated as pour point deperssants for waxy crude oil

Abstract

Disposing of polystyrene trash is an environmental concern, and converting it into value-added products is appealing . This research study focuses on implementing a sustainable method to convert polystyrene waste into polymeric nonionic surfactants. The polymeric nonionic surfactant additives were prepared by grafting polystyrene waste (WPS) with a methacrylic monomer (MMA), followed by an esterification reaction with polyethylene glycol of different molecular weights (400 and 1000). The chemical composition of the synthesized compounds was justified by spectroscopic analysis. Interfacial tension (IFT) was investigated to gain insights into the behavior of the polymeric nonionic surfactants produced at the interface. The modified waste polymers were evaluated as pour depressants and paraffin inhibitors. Additionally, the rheological properties of the modified waste polymers were examined. The findings revealed that, the IFT between oil and water decreased from 21 to 7 mN/m for WSPA400 and even further to 4 mN/m for WSPA1000. At a concentration of 500 ppm, WPSA1000 exhibited the maximum depression effect than WPSA400, reducing the pour point temperature from 27 °C to 12 °C and 3 °C, respectively. Also, At 500 ppm, the amount of wax deposition declined from 8.5 g to 1.90 g and 0.95 g after treating the crude oil with WPSA 400 and WPSA 1000. The rheological measurements further revealed that the WPSA1000 additive outperformed the WPSA400 additive in terms of enhancing the fluidity of oil. In order to acquire a more comprehensive understanding of the mechanisms involved in pour point depression, the utilization of polarizing optical microscopy was used to explore the effect of WPSA1000 as a pour point depressant.