Hydroxyethyl cellulose as a multifunctional agent for integrated brine desalination, CO₂ capture, and enhanced oil recovery

This study presents a novel approach for integrating hydroxyethyl cellulose (HEC) into a sustainable framework targeting three major challenges: brine treatment, carbon dioxide (CO₂) capture, and enhanced oil recovery (EOR). Utilizing a modified Solvay process within an inert particle-spouted bed reactor, the research investigates the physicochemical interactions of HEC with high-salinity brine and CO₂ gas under controlled experimental conditions. The incorporation of HEC significantly improved CO₂ capture efficiency, reaching a maximum of 99.2 %, by enhancing carbonate precipitation and facilitating mass transfer between gaseous and aqueous phases. Simultaneously, HEC contributed to brine desalination by promoting ionic complexation and selective precipitation, achieving up to 32.4 % reduction in total salinity. Experimental measurements showed a significant reduction in brine ion concentrations including magnesium (Mg²⁺), and calcium (Ca²⁺) further validating the ion-exchange and precipitation mechanisms facilitated by the process. In addition to water treatment and gas capture capabilities, HEC-treated brine exhibited favourable interfacial tension properties. Core flooding and interfacial tension measurements demonstrated that HEC could enhance oil recovery by up to 65 % due to its ability to alter wettability and stabilize displacement fronts in porous media. These combined results highlight the multifunctionality of HEC as a bio-derived, biodegradable additive that not only addresses environmental challenges associated with brine disposal and greenhouse gas emissions but also contributes to resource recovery in petroleum operations. The outcomes support the feasibility of integrating HEC into circular economy models that connect water treatment, climate mitigation, and energy recovery. This work lays the foundation for scaling up bio-polymer-enhanced desalination and carbon capture systems for real-world applications.