Lignocellulosic biomass is well known to inherently have a certain amount of inorganics that can be divided into two fractions: (1) structural inorganic constituents and (2) non-structural elements derived from the soil, whose contents vary depending on biomass species or harvesting operations. During the pretreatment using acid catalysts or only water, inorganic sin biomass tends to negatively affect its performance, because inorganics with the ash affect the neutralization of mineral acids such as sulfuric acid (H2SO4)viatheion-exchangereactionbetweencationsfortheinorganicsandH3O+,andtheirneutralizingcapacityisstronglycorrelatedtotheashcontentofthebiomass.In this study, the effect of water-extractable inorganic constituents (WEICs) of sunflower stalks (SS) on the hydrothermal treatment and enzymatic hydrolysis was investigated. To remove the inorganics, the SS was soaked in water at different temperatures, followed by dewatering. Then, each soaked-out SS was hydrothermally treated under diverse conditions. The result showed that the removal rate of inorganics was correlated to the soaking temperatures. To investigate the effect of WEICs on biochemical conversion, WEICs-rich powder was separated from the soaking solution using the membrane system. When empty fruit bunches (EFB), inherently containing much less amount of ash, was hydrothermally treated at 190 °ÆC for a variable time in the presence of increasing amount of the added WEICs, glucose yield via the enzymatic hydrolysis was decreased up to 30%. Furthermore, cellulose digestibility by cellulases was noticeably reduced in the presence of WEICs.
