The effects of boron derivatives as pretreatment chemicals for biodegradation of sunflower stalks

Abstract

This study examined the suitability of boron derivatives as pretreatment chemicals with regard to their efficiency in the enzymatic saccharification of sunflower stalks. It was hypothesized that the utilization of boron derivatives might improve enzymatic digestibility. The aim of this study was to examine the effect of NaOH and the boron derivatives sodium borohydride [NaBH4], calcined tincal [Na2B4O7(1-5)H2O], colemanite [CaB3O4(OH)3H2O], boron oxide [B2O3], borax decahydrate [Na2B4O710H2O], disodium octaborate tetrahydrate [Na2B8O134H2O] and boric acid [H3BO3] on enzymatic saccharification. Results showed that the boron derivatives prevented peeling reactions and preserved more glucan; however, the NaOH removed the highest amounts of xylan and lignin from the structure. Significant xylan removal was observed with H3BO3, while B2O3 was as effective as NaBH4 and NaOH for selective lignin removal. The highest enzymatic saccharification yield (59,5%) resulted with the 2% NaOH pretreatment, whereas slightly lower yields were achieved with some boron derivatives (1% NaBH4-45%; 2% B2O3-40,2%; and 2% H3BO3-36,7%).

Keywords

• Enzymatic hydrolysis
• enzymatic saccharification
• glucan
• lignin
• xylan.