The boiler ash from palm oil mills is produced from the combustion of shells and fibers used as boiler fuel. Boiler ash is generally not widely utilized and is only stored around the plant, even though it has a relatively high silica content, making it a potential low-cost adsorbent to improve the quality of crude palm oil (CPO), including free fatty acid (FFA) content, moisture content, and impurity content. This study aimed to evaluate the effect of activator type (NaOH, H3PO4 , and NaCl) and concentration (10%, 20%, and 30%) on the effectiveness of palm oil mill boiler ash as an adsorbent for reducing FFA, water content, and impurity content in CPO, and to characterize the surface morphology of the boiler ash before and after activation. The research used a factorial Completely Randomized Design (CRD) with three replications, analyzed by ANOVA followed by Duncan's test. Boiler ash was sieved (250 mesh), activated for 24 hours, neutralized, and oven-dried before being contacted with CPO for 45 minutes. Surface morphology was observed using Scanning Electron Microscopy (SEM). The results showed that all three activators significantly reduced FFA and water content with increasing concentration. The 30% H3PO4 activator produced the best performance, decreasing FFA from 7.98% to 3.47% and water content from 0.61% to 0.33%, followed closely by 30% NaCl and 30% NaOH. However, impurity content increased slightly in all treatments, from an average of 0.66% to a range of 0.71-0.80%. SEM images revealed that boiler ash activated with 30% H3PO4 exhibited a more uniform and porous surface compared to the non-activated ash. These findings indicate that palm oil mill boiler ash activated with H3PO4 is a promising low-cost adsorbent for improving CPO quality, although additional filtration steps are recommended to control the resulting increase in impurity content during industrial-scale application.
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