Ethomeen C/15 surfactant enhances CO₂ mineralization in oilfield produced water

Mitigating climate change requires novel approaches to decrease atmospheric CO₂ concentrations, which substantially reduces global warming. Although conventional CO₂ storage in geological formations is a valid strategy, it involves logistical and cost constraints. This study presents an innovative approach for converting CO₂ into valuable minerals by utilizing the nonionic Ethomeen C/15 surfactant to enhance CO₂ mineralization in oilfield produced water. The primary objective of this study is to investigate the efficiency of Ethomeen C/15-based carbonation and how varying concentrations of this surfactant can influence the composition and characteristics of minerals produced as byproducts of CO₂ utilization. Comprehensive characterization was carried out using WDXRF, XRD, FT-IR, SEM-EDS, particle size and zeta potential (ζ) measurements, and TGA. The results demonstrate that varying C/15 concentration (0.01, 0.1, and 1 wt%) markedly increased CO₂ uptake from 832 mg/L (with solid yield 9.4 g/L) at 0.01 wt% to 2967 mg/L (with solid yield 11 g/L) at 1 wt%, approximately a 3.5-fold gain. The characterization confirmed the formation of tunable mineral phases such as calcite, brucite, portlandite and halite; their concentrations modulated by the surfactant dose and the dominant phase in all solid yields is calcite peaked at 59.7 wt% at 0.1 wt% of C/15. Higher C/15 doses produced smaller, more uniform particles (troughed at 4.01 μm at 1 wt% C/15) with higher surface area (peaked at 6869 cm²/g at 1 wt% C/15) and altered surface charge (varying ζ-potential values). TGA confirmed corresponding changes in thermal stability of the carbonate and hydroxide phases, and the shape as well as wavenumber shifting in FT-IR ν ₃ absorption feature of CO₃²⁻ ion in calcite (from broad at ∼1430 cm⁻¹ at 0.01 % C/15 to sharp at ∼1405 cm⁻¹ for 1 % C/15) indicated varying spectral response. This work highlights the first use of Ethomeen C/15 with its varying concentrations for CO₂ sequestration and utilization, and the findings suggest that C/15 surfactant-based CO₂ mineralization offers a controllable and efficient pathway for CO₂ sequestration in oilfield produced water to recycle both effluents under mild conditions.