Applicability of Hydrogenated Castor Oil-Impregnated Wood as a Raw Material to Produce Shelters Used in Abalone Aquaculture

This study was conducted to examine the viability of using wood as an alternative to plastic as the source material for the fabrication of shelters used in abalone aquaculture. Various wood species were treated with hydrogenated castor oil (HCO) using a pressure treatment. To quantify the effectiveness and longevity of the wood shelters, HCO uptake, volumetric swelling, moisture absorption, and Janka hardness were measured. The weights of all HCO-impregnated specimens increased ranging from 26% to 154% after saline water leaching, indicating that HCO did not leach out. Total volumetric swellings (TVS) of the HCO-impregnated specimens immersed in saline water were less than 1%. HCO-impregnated strips showed lower moisture absorption and TVS than control strips after outdoor exposure for 2 weeks. Additionally, HCO-impregnated strips had increased Janka hardness and bending strength. Lower amounts of microplastics (MPs) were found in the saline water samples immersed with wooden shelters fabricated with HCO-impregnated wood than those with plastic shelters, as expected. Unlike wooden shelters, the more MPs were detected in plastic shelters samples, the longer the shelter was immersed in the saline water. HCO-impregnated wood, particularly Japanese cedar, can be an environmentally friendly alternative to plastics for fabricating shelters as it reduces a source of MPs in abalone aquaculture.