The Design of Green Molecules for Demulsification

Abstract

Abstract New chemistries are needed to address the negative environmental impact of currently used demulsifier (DMO) formulations especially when used offshore to separate water from crude oil emulsions. The goal of the study was to synthesize new eco-friendly molecules with targeted environmental profile, which behave as DMOs and develop a better understanding of chemical structure – biodegradation and toxicity relationships. Different synthetic pathways were employed to assess the possibility of synthesizing molecules with specific biodegradation kinetics, acceptable toxicity as well as high demulsification performance. In the design of new DMO, we used highly biodegradable molecules as one of the building blocks of the final polymer. New DMO polymer biodegradability in seawater was evaluated by following the OECD guideline 306, and toxicity was tested against saltwater algae by measuring EC50 in 72 hours. The performance of the green DMO intermediates was tested in several crude oils in upstream and downstream applications using bottle test procedure and electrical desalting dehydration apparatus respectively. New molecules demonstrated > 60% biodegradability in 60 days and >10 mg/L toxicity to seawater algae. Synthesized DMO intermediates showed higher biodegradation profiles compared to currently used DMOs, which are based on alkoxylated alcohols, phenolic resins and diepoxides that are not biodegradable due to high molecular weight and strong C-C and C-O-C bonds in their chemical structure. The connections of the newly synthesized highly biodegradable molecules were achieved with the bonds, which are prone to hydrolysis. In addition, the created polymer was functionalized with hydrophobic building blocks to tune the final DMO performance. The results showed that these new molecules were able to separate water from crude oil emulsions and showed optimal and similar performance to some of the currently used non-biodegradable DMO intermediates. The performance of new DMOs was strongly dependent on their chemical structure and composition. Clear correlations of relative solubility number to chemical structure and performance were observed. Synthesized polymers exhibited a better biodegradation profile and better competitive performance to conventional non-biodegradable DMO products especially in terms of water drop during the bottle test evaluation. Due to systematic design of the synthesized polymers, this research led to a better understanding of chemical structure – biodegradation and toxicity relationships as well as performance of new DMO molecules.