Performance of fatty acid-modified spent coffee grounds as a potential adsorbent for oil adsorption

Abstract

Problems caused by fats, oils, and grease (FOG) in sewer systems have escalated over the years. FOG produced from households, restaurants, stalls, and food processing facilities have contaminated water resources through the sewer system. Thus, trace removal of oil from wastewater is a necessary measure to ensure minimal discharge of FOG into the environment. In the present study, due to the high volumes of coffee waste with no commercial value being generated daily, spent coffee grounds (SCG) were exploited as an oil adsorbent. However, due to their low hydrophobicity, SCG tend to have limited oil adsorption capacity. In this work, SCG underwent pre-treatment using alkali and were further modified with waste cooking oil (WCO) that contained free fatty acids (FFAs) at different ratios (1:10, 1:20, and 1:30) in order to enhance their oil adsorption performance. The performance of the synthesised adsorbents was tested in a batch adsorption process at different contact times. From the batch adsorption test, the highest oil adsorption capacity (2.807 ± 0.086?g/g) was observed using the 1:10 ratio of SCG to FFAs-WCO within 180?min of contact time.