CO₂ capture and ions removal through reaction with potassium hydroxide in desalination reject brine: Statistical optimization

<p dir="ltr">Previous studies have investigated the overall performance of the modified Solvay process based on a new alkaline compound, namely, KOH. Preliminary results have confirmed its high reactivity and effectiveness in capturing CO₂ and managing reject brine. In this study, parametric sensitivity analysis has been carried out to optimize the operating conditions and thereby maximize CO₂ capture and ions removal from high-salinity brines. Response surface methodology (RSM) analysis using the central composite design (CCD) approach was implemented to statistically determine the impact of important operating conditions, including KOH concentration (30–110 g/l), CO₂ gas flow rate (400–1600 ml/min), gauge pressure (1–3 barg), and temperature (10–50 ^◦C) on key response process output variables, such as CO₂ uptake and ions reduction. The importance of these parameters and their interactions were confirmed by employing analysis of variance (ANOVA) approach at a confidence level of 95% (p < 0.05). These analyses demonstrated that under the optimized conditions of a temperature of 10 ^◦C, gauge pressure of 2.1 barg, CO₂ gas flow rate of 848.5 ml/min, KOH concentration of 110 g/l, and an inert mixing particle volume fraction of 15%, a maximum CO₂ uptake value of 0.58 g/g KOH, maximum sodium (Na⁺) removal of 44.1%, chloride (Cl⁻ ) removal of 40.1%, calcium (Ca²⁺) removal of 100%, and magnesium (Mg²⁺) removal of 99.8% were achieved. The characterization of the collected solid products at optimum conditions revealed the production of valuable and useful products, particularly sodium and potassium bicarbonates, in addition to KCl.</p><h2>Other Information</h2><p dir="ltr">Published in: Chemical Engineering and Processing - Process Intensification<br>License: <a href="http://creativecommons.org/licenses/by/4.0/" target="_blank">http://creativecommons.org/licenses/by/4.0/</a><br>See article on publisher's website: <a href="https://dx.doi.org/10.1016/j.cep.2021.108722" target="_blank">https://dx.doi.org/10.1016/j.cep.2021.108722</a></p>