Recovery of reactive potassium compounds as chemical agents in wastewaters from KOH-activated carbon production

Abstract Chemical activation consumes copious quantities of chemicals is therefore hampered by its low economic feasibility. However, this issue can be overcome through the recovery and reuse of alkali compounds leached into wastewater. Because the leached potassium compounds exist as the relatively less reactive K₂CO₃, we explored three different approaches to remove carbonate ions (CO₃ ²⁻) from the wastewater: (i) CO₂ stripping after acidification, (ii) exchanging CO₃²⁻ for OH⁻ using strong basic anion exchange resins, and (iii) inducing a phase transition via a reaction with Ca(OH)₂ to precipitate CaCO₃. Both ion exchange and phase transition convert K₂CO₃ into highly reactive potassium compounds such as KOH. The phase transition effectively enhanced the specific surface area of the activated carbon and thus had implications for pore development in carbon precursors, while offering a viable recovery strategy for alkali compounds that reduces costs by approximately 20% compared to traditional methods. These findings suggest that the in-situ recycling of wastewater for the production of activated carbon can improve the economic viability of manufacturing processes.