Investigating the Applicability of Kolbe Electrolysis for Sustainable Soapstock Recycling

 Soapstock, a byproduct during the deacidification step in vegetable oil refining, has been disposed of because there are no effective utilization methods. Various approaches for recycling soapstock, such as acidulation and physical extraction, have been proposed. However, these methods often suffer from inefficiencies and have limited practical impact. Recently, we have proposed a novel electrochemical recycling technique using Kolbe electrolysis to convert soapstock into caustic soda and biofuel for boiler use¹⁾. This approach provides a closed-loop pathway that achieves both waste reduction and resource generation.

 In this study, process simulation was conducted using Aspen to evaluate the energy balance and impacts. As a result, it is suggested that the energy obtained exceeds the energy input, leading to a positive net energy balance. Additionally, integrating this electrochemical process with existing vegetable oil refining processes was proposed, and a life cycle for soapstock treatment was assessed. The proposed process suggests a smaller environmental footprint compared to existing methods, offering a promising solution for sustainable soapstock management.

1) K. Hiromori et al., J. Chem. Eng. Jpn. 57(2024) 2332621.