(533a) Selective Capture and Mineralization of CO2/SOx Gas Using Industrial Wastewater.

Moving forward from the Paris Agreement, the UN climate change conference in Glasgow (COP26) has brought the world leaders together to produce new "building blocks” to advance in previous enactments and to accelerate the action in lowering carbon dioxide emissions. With the awareness of importance on carbon capture technology, the Glasgow pact calls for a finance support in adapting to build resilience against the climate change. While, CCS technology is acceptable for large-scale process and commercial applications, it possesses drawbacks in cost of implementation and geological restraints. The intense energy requirement for regeneration of sorbents and potential catastrophic leakage is a challenge that CCS technology has faced. To ease the burden on, CCU process is applied for permanent sequestration of greenhouse gas with producing value-added product from the waste pollutant.

Herein, a novel CCUS process is designed by introducing seawater as a stable feedstock to capture greenhouse gases from flue gas. The alkali absorbent, sodium hydroxide obtained from the seawater is used to selectively capture CO₂ and SO₂ from the flue gas. The difference in kinetic allows the absorbent to preferentially capture the SO₂ even the partial pressure of SO₂ is low as in ppm level. The suggested process concept only requires a single absorbent to capture CO₂ and SO₂ without the need of an additional flue-gas desulfurization process by applying the two-batch type reactors. Each reactor selectively captures CO₂ and SO₂ gases until it is saturated and fed with calcium and magnesium ions to produce metal carbonates. The final products CaSO₄, MgCO₃ were analyzed with X-ray diffraction (XRD), Scanning electron microscopy (SEM) to verify the crystal shape of the final products. The present study investigated the absorption rate of CO₂/SO₂ gas within different molar ratios of absorbents at different partial pressures based on their kinetic reaction rate.

This research summarizes our research team’s previous works based on the carbonation process using metal ions present in industrial wastewater. Abundance of metal ions present in industrial wastewater gives advantages in reliable feedstocks and allows sustainable carbon emission cycles. While, the suggested process only compromised with a single absorbent to capture both CO₂ and SO₂, it provides alternative routes to capture flue gas through an economically viable process. It also provides the meaning of sustainable development in which all the materials used in the process are acquired from the seawater.