Novellia Ardiansyah, Anggia Afza Utami, Amelia Amir, Maria Ulfah

Performance Evaluation and Adsorption Isotherm of Activated Bottom Ash for Free Fatty Acid Removal

Introduction

Performance evaluation and adsorption isotherm of activated bottom ash for free fatty acid removal. Evaluate activated bottom ash performance for free fatty acid (FFA) removal from crude palm oil (CPO). Research covers phosphoric acid treatment, contact time & adsorption isotherms.

Abstract

Boiler bottom ash is one of the by-products produced from the combustion of palm shells and fiber in the boiler furnace at high temperature. These were usually disposed of on the land around the palm mill, causing environmental problems. In this research, non-activated and activated bottom ash treated with phosphoric acid were used as an adsorbent for removing free fatty acids (FFA) from crude palm oil (CPO) recovery. This study had two parameters. The first parameter is an adsorbent activator concentration with the variation level of 0, 5, 10, and 15 %. The second parameter is contact time with four levels involved in this research. They were 1, 2, 3, and 4 hours. The bottom ash adsorbent with a 10% concentration of phosphoric acid and a 3-hour contact time had the highest efficiency and capacity in removing FFAs from CPO recovery. The lowering of water and impurity content in CPO recovery after the adsorption process was in the range of 0.05% to 0.22% and 0.01% to 0.04%, respectively. The isotherm model was evaluated using the Langmuir and the Freundlich. The Isotherm model was fitted to the Freundlich, and this indicated multilayer adsorption with R2 = 0.9869.

Review

This manuscript presents a valuable investigation into the utilization of activated boiler bottom ash, a waste product from palm oil production, for the removal of free fatty acids (FFA) from crude palm oil (CPO) recovery. The work addresses an important environmental issue by proposing a sustainable application for industrial waste, while simultaneously offering a practical solution for improving the quality of CPO. The primary objective was to evaluate the performance of both non-activated and phosphoric acid-activated bottom ash as an adsorbent for FFA removal, optimizing key process parameters relevant to industrial application. The experimental design systematically explored the influence of two critical parameters: adsorbent activator concentration (ranging from 0% to 15% phosphoric acid) and contact time (from 1 to 4 hours). The study effectively identified optimal conditions, reporting that a 10% phosphoric acid concentration for activation coupled with a 3-hour contact time yielded the highest efficiency and capacity for FFA removal. Significantly, the adsorption process also contributed to a substantial reduction in water (0.05-0.22%) and impurity (0.01-0.04%) content in the CPO recovery, demonstrating a multifaceted improvement in oil quality. Furthermore, the robust fit of the experimental data to the Freundlich isotherm model (R2 = 0.9869) provides valuable insight into the adsorption mechanism, suggesting a multilayer adsorption process. While the study clearly demonstrates promising results and a practical application, further enhancement could be achieved by including detailed characterization of the activated bottom ash (e.g., surface area, pore size distribution, SEM, FTIR) to corroborate the proposed multilayer adsorption mechanism. Elaboration on the specific "CPO recovery" source and its initial FFA content would also provide crucial context for the reported removal efficiencies. Future work could benefit from exploring the reusability of the adsorbent and conducting a comparative analysis with commercial adsorbents to establish its economic viability and competitive advantage. Despite these potential areas for expansion, this research offers a compelling and environmentally conscious approach to valorize industrial waste for significant improvements in crude palm oil quality, representing a valuable contribution to sustainable processing.

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