Combination of pre-freezing and supercritical CO2 dewatering for producing non-collapsing dried porous oil palm wood

Abstract Palm oil production is a major economic driver in Southeast Asia, but responsible forestry practices are essential to mitigate deforestation. One promising approach is to repurpose oil palm wood (OPW) into commercial materials, providing economic incentives for sustainable logging and replanting of mature trees. However, converting OPW into solid materials presents significant challenges, particularly in drying, where previous attempts have largely been unsuccessful. Recently, scientists at Walailak University in Thailand pioneered a method to successfully dry OPW without collapse. Building on this breakthrough, the present study investigates the technical feasibility of dewatering pre-frozen OPW using supercritical carbon dioxide (scCO₂). We compared the extent of OPW collapse across various treatment groups and assessed the effects of scCO₂ dewatering following different pretreatment conditions. Our findings indicate that combining freezing with scCO₂ dewatering is the most effective method in preventing OPW collapse, requiring fewer cycles to initiate dewatering and leaving less residual water for subsequent drying. The resulting pre-frozen and dewatered OPW maintains a highly porous structure with minimal cellular damage after drying. The results highlight the potential of scCO₂ treatment as an environmentally friendly and efficient approach to enhance the use of OPW in construction and other commercial applications.