From Oil Palm Residues to Engineered Carbon: Biochar and Activated Carbon Pathways for Carbon Removal, Environmental Purification, and a Circular Bioeconomy

Abstract

The rapid expansion of palm-oil processing has created a parallel challenge of managing large volumes of lignocellulosic residues, including empty fruit bunches, palm kernel shells, mesocarp fibre, oil palm fronds, and oil palm trunks. This qualitative literature review examines whether these residues can be repositioned from low-value wastes into feedstocks for biochar and engineered activated carbon. The review synthesizes recent literature published from 2020 onward across biomass conversion, materials engineering, environmental remediation, carbon sequestration, and techno-economic assessment. The evidence indicates that feedstock composition and thermochemical processing conditions jointly determine carbon yield, aromaticity, pore development, surface chemistry, adsorption performance, and long-term carbon stability. Biochar offers comparatively high carbon retention and promising applications in soils, nutrient management, remediation, and carbon sequestration, whereas further physical, chemical, or hybrid activation can produce higher-value porous carbons for wastewater purification, heavy-metal adsorption, organic-pollutant removal, CO₂ capture, gas purification, catalysis, and energy applications. However, maximum surface area is not synonymous with maximum sustainability because severe activation can reduce product yield and increase energy, reagent, washing, and wastewater burdens. The review therefore proposes an integrated oil-palm carbon platform based on feedstock–process–product matching, selective upgrading, coproduct energy recovery, credible life-cycle carbon accounting, and market segmentation. Such a portfolio approach can transform oil-palm residues into complementary agricultural, environmental, industrial, and climate products while strengthening circular-bioeconomy development.