Multiobjective Optimization and Sustainability Assessment of an Improved Wet Sulfuric Acid-Based Ionic Liquid Process for the Utilization of Hydrogen Sulfide Using a Symmetry Approach

Abstract

Ionic liquids (ILs) are efficient media for the liquid-phase sulfuric acid reaction. Under mild situations, the reaction of H 2 S with CH 4 in ILs happens extremely quick and virtually complete, resulting in liquid sulfuric acid (H 2 SO 4(l) ). 1-hexyl-3methylimidazolium chloride ([hmim][Cl]) ILs were formerly the most effective at capturing and converting H 2 S. It can convert H 2 S to H 2 SO 4(l) with a proportion of up to 96%. This study aimed to develop cutting-edge techniques and assess their applicability for different acidic gas capacities and H 2 S amounts by considering three sustainability metrics which are people (safety), planet (ecological), and profit. Then, to maximize profit while lowering the global warming potential (GWP), fire explosion damage index (FEDI), and toxicity damage index (TDI), a multiobjective optimization (MOO) case was performed. The trade-off between economic, environmental, and safety performance was expressed through Pareto-optimal solutions. The improved wet sulfuric acid (WSA)-based IL method was safer (lower fire and explosion damage index), ecologically friendly (lower GWP), and portable. The findings indicate that the improved WSA-based on IL gives the optimum results compared to conventional WSA processes, such as the profit of 5688$/h increased from 1896$/h, the GWP of 0.0138-ton CO 2 -eq decreased from 0.0275-ton CO 2 -eq, the TDI of 6.72 decreased from 13.44, and the FEDI of 6.18 decreased from 20.6, respectively. This discovery opens the door to a viable strategy for capturing and converting H 2 S from an acid gas stream.