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ARS Home » Northeast Area » Wyndmoor, Pennsylvania » Eastern Regional Research Center » Sustainable Biofuels and Co-products Research » Research » Publications at this Location » Publication #397630
Research Project: Integrated Biological/Chemical Biorefining for Production of Chemicals and Fuels

Location: Sustainable Biofuels and Co-products Research

Title: Effects of NaOH and Na2CO3 pretreatment on the saccharification of sweet sorghum bagasse

Author
item Garcia-Negron, Valerie
item Stoklosa, Ryan
item Toht, Matthew

Submitted to: Frontiers in Chemical Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/14/2024
Publication Date: 10/29/2024
Citation: Garcia-Negron, V., Stoklosa, R.J., Toht, M.J. 2024. Effects of NaOH and Na2CO3 pretreatment on the saccharification of sweet sorghum bagasse. Frontiers in Chemical Engineering. 6:1449114. https://doi.org/10.3389/fceng.2024.1449114.
DOI: https://doi.org/10.3389/fceng.2024.1449114

Interpretive Summary: Sweet sorghum is an environmentally adaptable feedstock containing high sugar content suitable for bioethanol and chemical production. This work evaluates the composition and sugar release of sweet sorghum bagasse (SSB) biomass after chemical pretreatment and enzymatic hydrolysis. Multiple samples of SSB biomass were pretreated with varying concentrations of sodium hydroxide (NaOH) and sodium carbonate (Na2CO3) alkaline solutions and exposed to two heating treatments. Results demonstrate that pretreatment methods were effective at promoting biomass conversion and increasing sugar recovery. Moreover, pretreatments with high volumetric ratios of NaOH were more effective than Na2CO3, as composition analysis indicated additional changes in the structure and degradation of hemicellulose and lignin. On the other hand, pretreatment solutions with more Na2CO3 reached a higher hydrolysis rate and outperformed NaOH for glucose and arabinose yields. Sugar yields from samples treated at higher temperature were more effective and stable. This study helps to understand and improve the conversion of lignocellulosic biomass into sugars for potential conversion to biofuels or value-added products.

Technical Abstract: The continuing need for liquid transportation fuels requires development of sustainable alternatives to fossil-fuels and ways to improve cost of energy generation while reducing greenhouse gas emissions. Sweet sorghum is an environmentally adaptable feedstock containing high sugar content suitable for bioethanol and chemical production. This work evaluates the composition and sugar release of sweet sorghum bagasse (SSB) biomass after chemical pretreatment and enzymatic hydrolysis. Five different ratios of 2M sodium hydroxide (NaOH) and sodium carbonate (Na2CO3) solution were used for pretreatment. The biomass was pretreated for two heat treatment conditions at 85 Celsius and 150 Celsius for 1 hour which increase biomass conversion and sugars yields. Enzymatic hydrolysis studies were conducted to understand the sugar yields of the biomass at different durations up to 72 hours. Results show pretreatments were effective in promoting biomass conversion and optimizing sugar recovery. SSB samples pretreated with 100% NaOH were favorable to cellulose content while samples pretreated with high Na2CO3 concentrations favored hemicellulose. Nevertheless, pretreatment solutions with 25 and 50% Na2CO3 resulted at over 80% of that achieved with NaOH's cellulose content and produced similar or higher glucose yields. Pretreatment solutions with Na2CO3 reached approximate maximum yields faster than those of NaOH, 48 versus 72 hours. The higher temperature pretreatment produced higher and more stable sugar yields.