Wheat straw bio-refining. Part II: Optimization of the microwave radiation with sulphuric acid pre-treatment and its enzymatic hydrolysis for fermentable sugars

Festus, Onome; Skoulou, Vasiliki K; Zein, Sharif H.

Abstract

Background: The potential of microwave-assisted heating for enhancing the alkaline pretreatment of lignocellulosic waste is highlighted in this work.

Objective: To maximize separation of fermentable sugars from wheat straw.

Methods: Wheat straw hydrolysis assisted by microwave was carried out by setting up a statistical experimental design method and further investigating the main process parameters, namely: temperature (°C), microwave power (W), NaOH concentration (M) and wheat straw pre-treatment time (min) towards maximization of fermentable sugars extraction from wheat straw. The reducing sugars yield (response) of the alkaline pre-treated and microwaved wheat straw in lab scale provided data for building a predictive model which reflected interactions, significance and impact of the process parameters (factors) on the wheat straw hydrolysis yield.

Results: SEM and FTIR images of untreated and alkaline pre-treated wheat straw were studied for investigating the morphological changes of wheat straw surface quality and structure resulting from the microwave and/or alkaline pre-treatment. In addition reducing sugars yield of 87%wt. from wheat straw pre-treated at 180°C, 550W microwave power, 0.65M of NaOH for 25min was achieved. This result was significantly higher compared to the one from the straw which was only hydrolysed enzymatically (30 %wt).

Conclusion: It was found that shorter pre-treatment times were obtained at higher temperatures, alkali concentration and moderate microwave power levels. The results obtained were further optimized and indicated that the microwave-assisted alkaline pre-treatment of wheat straw technique is an attractive pre-treatment method which reduces the wheat straw pre-treatment time and enhances the hydrolysis yield.

Citation

Festus, O., Skoulou, V. K., & Zein, S. H. (2017). Wheat straw bio-refining. Part II: Optimization of the microwave radiation with sulphuric acid pre-treatment and its enzymatic hydrolysis for fermentable sugars. Current Microwave Chemistry, 4(4), 306-316. https://doi.org/10.2174/2213335604666171103123459

• Journal Article Type: Article
• Acceptance Date: Nov 28, 2017
• Publication Date: Nov 30, 2017
• Deposit Date: Feb 4, 2018
• Publicly Available Date: Oct 27, 2022
• Journal: Current Microwave Chemistry
• Print ISSN: 2213-3356
• Publisher: Bentham Science Publishers
• Peer Reviewed: Peer Reviewed
• Volume: 4
• Issue: 4
• Pages: 306-316
• DOI: https://doi.org/10.2174/2213335604666171103123459
• Keywords: Bioethanol; Enzymatic hydrolysis; Experimental design; Fermentable sugars; Lignocellulose; Microwave-assisted pre-treatment; Wheat straw
• Public URL: https://hull-repository.worktribe.com/output/481575
• Publisher URL: http://www.eurekaselect.com/156781/article
• Contract Date: Feb 8, 2018