Wheat Straw Bio-refining Part II: Optimization of Alkali Pre-treatment Method with Microwave Radiation for Fermentable Sugars Separation

Author(s): Onome Festus, Vasiliki K. Skoulou, Sharif H. Zein*.

Journal Name: Current Microwave Chemistry

Volume 4 , Issue 4 , 2017

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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.

Keywords: Bioethanol, enzymatic hydrolysis, experimental design, fermentable sugars, lignocellulose, microwave-assisted pre-treatment, wheat straw.

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Article Details

VOLUME: 4
ISSUE: 4
Year: 2017
Page: [306 - 316]
Pages: 11
DOI: 10.2174/2213335604666171103123459
Price: $58

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