Process-intensified single-step pretreatment of spent coffee grounds-derived biocrude oil: Removal of inorganics and emulsified water for sustainable biofuel applications

Abstract

The limitations of upgrading fast pyrolysis biocrude oil to transportation fuels, such as its high inorganic content and emulsified water, contribute to catalyst poisoning and reduced distillation efficiency. This study proposes a process-based innovation containing an integrated single-stage pretreatment designed to effectively remove inorganics, emulsified water, and water-soluble organics from spent coffee grounds biocrude oil. The optimized experimental method incorporates acid washing, ultrasonication, chemical demulsification, and phase separation, eliminating the need for a multistage process. Under optimized conditions, inorganic removal resulted in 87% overall efficiency with substantial reductions of Al3+, Fe3+, Mg2+, Ca2+, and K+, and a 96% reduction in emulsified water from biocrude oil. The fuel quality was improved, including a total acid number reduction by 41%, asphaltene content by 80%, and nitrogen content by 21%. The developed pretreatment technology reduces chemical consumption, energy input, and processing time, thus supporting its compatibility with downstream refinery operations.