Optimization of sugar recovery efficiency using microwave assisted alkaline pretreatment of cassava stem using response surface methodology and its structural characterization
Graphical abstract
Introduction
Lignocellulosic materials and agricultural residues are the most attractive and abundant renewable biomass source available in nature. These materials constitute three main polymers namely cellulose, hemicellulose and lignin [1,2]. Cassava (Manihot esculenta Crantz) is an everlasting woody shrub belongs to the family Euphorbiaceae grows well in tropical and subtropical areas and is generally regarded as a third largest carbohydrate source [3]. It is mainly used ad food (48%) and feed (34%), feedstock (18%) for biofuels and biochemical [4,5]. Globally, cassava stem waste have today reached about 6.7 Pg; 60% of this is available for biofuel production, yielding ca. 64.8 EJ/of energy (given the net heat value of 16.2 MJ/kg). This reported value equals the annual energy use of about 840 million people based on the global average of energy use per capita [6]. A detailed phytochemistry report and a case study on above ground carbon stocks of cassava were found elsewhere in the world. Previous studies reported that non-edible parts of cassava especially stem can be feasibly utilized for fermentable sugars and bioethanol production [7,8].
The major advantage of using non-edible part is neglecting food versus fuel conflict and non-compete with the food supply. To increase the yield of fermentable sugars, an efficient pretreatment method should be incorporated into the lignocellulosic conversion process. Various researchers have reported that pretreatment methods are able to change the efficient lignocellulosic conversion and enhance the biofuel production [7,9,10]. Among the methods, alkaline pretreatment was shown to be more effective and advantageous since it operates at lower temperatures [2] utilizing readily available low-cost chemicals such as sodium hydroxide (NaOH), calcium hydroxide (Ca(OH)2), potassium hydroxide (KOH) and ammonia. However, long retention time and neutralizing pretreated slurry fetch drawbacks to this method. Application of microwaves on pretreatment of lignocellulosic has been considered as an alternative to conventional methods [11,12]. Microwave, a high-frequency electromagnetic radiation offers uniform and rapid heating leading to improved digestibility and disruption of recalcitrant structures in biomass [13].
Various researchers on several different lignocellulosic feedstocks such as switch grass, wheat straw, water hyacinth, banana waste, sugarcane bagasse, catalpa sawdust, are canut husk [1,3,7,[14], [15], [16], [17], [18]], and so on. Overview of fundamentals, recent advances in microwave assisted pretreatment methods and the importance of microwave reactor development was also available in the literature [11,19].
The present study involves the optimization of MAASHP using cassava stem powder as raw material to increase sugar recovery using response surface methodology. This study aimed to develop the model using cassava stem powder as output and reaction time, NaOH concentration, solid to liquid ratio and microwave frequency as input. The parameters influencing pretreatment conditions were statistically optimized to enhance sugar production. FTIR, XRD and SEM were investigated for determination of functional group modifications, structure of cassava stem and cellulose crystallinity.
Section snippets
Sample collection and preparation
Lignocellulosic biomass is a substrate for the production of bioethanol was cassava stem from a local farm in Namakkal District (latitude 11.378476; longitude 77.894493), Tamil Nadu, India and the collected material was stored at room temperature for their further analysis. The procured sample was initially shredded into small pieces and then followed by grinding using mixer grinder (Preethi Trio, India). The resultant was sieved using a standard mesh to get fine particles (≤1 mm) and
Optimization of MAASHP
In the present work, the relationship between the yield of reducing sugars and four process variables (reaction time, NaOH concentration, solid to liquid ratio, and microwave frequency) was developed by using RSM. The results at each point based on the experimental Box-Behnken design template are presented in Table 1. The experimental and predicted values of TRS and xylose yield are shown in Table 2. Design Expert 10.0.6 software was employed to determine and evaluate the coefficients of the
Conclusion
The application of response surface methodology on the effect of alkaline NaOH pretreatment on cassava stem powder under microwave conditions was investigated. The optimal process parameters for maximum TRS and xylose yield (43.6% and 91.56% respectively) was found to be: reaction time of 116.4 s, NaOH concentration of 3.21%, solid to liquid ratio of 1:62.07, and a microwave frequency of 719.86 Hz. An XRD study indicates the increase in values of crystallinity index signifying the effect of
References (41)
- et al.
Application of pretreatment, fermentation and molecular techniques for enhancing bioethanol production from grass biomass–a review
Renew. Sust. Energ. Rev.
(2017) Production of bioethanol from lignocellulosic materials via the biochemical pathway: a review
Energy Convers. Manag.
(2011)- et al.
Enhancing saccharification of cassava stems by starch hydrolysis prior to pretreatment
Ind. Crop. Prod.
(2017) - et al.
Cassava stem wastes as potential feedstock for fuel ethanol production: a basic parameter study
Renew. Energy
(2015) - et al.
Pretreatment technologies for an efficient bioethanol production process based on enzymatic hydrolysis: a review
Bioresour. Technol.
(2010) - et al.
Microwave heating processing as alternative of pretreatment in second-generation biorefinery: an overview
Energy Convers. Manag.
(2017) - et al.
Development of a steam or microwave-assisted sequential salt-alkali pretreatment for lignocellulosic waste: effect on delignification and enzymatic hydrolysis
Energy Convers. Manag.
(2017) - et al.
Review of microwave-assisted lignin conversion for renewable fuels and chemicals
J. Anal. Appl. Pyrolysis
(2016) - et al.
Combined production of bioethanol and biogas from peels of wild cassava Manihot glaziovii
Chem. Eng. J.
(2015) - et al.
Environmental sustainability of bioethanol production from wheat straw in the UK
Renew. Sust. Energ. Rev.
(2013)
Efficient sugar production from sugarcane bagasse by microwave assisted acid and alkali pretreatment
Biomass Bioenergy
Hydrothermal and microwave assisted alkali pretreatment for fractionation of arecanut husk
Ind. Crop. Prod.
Microwave irradiation–a green and efficient way to pretreat biomass
Bioresour. Technol.
Statistical based media optimization and production of naringinase using Aspergillus brasiliensis 1344
Int. J. Biol. Macromol.
Development of experimental design approach and ANN-based models for determination of Cr (VI) ions uptake rate from aqueous solution onto the solid biodiesel waste residue
Bioresour. Technol.
Study on chemical compositions of Manihot esculenta Crantz (M. utilissima Pohl) stalks
Adv. Mater. Res.
Investigation of the glycosidic linkages in several oligosaccharides using FT-IR and FT Raman spectroscopies
J. Mol. Struct.
Short duration microwave assisted pretreatment enhances the enzymatic saccharification and fermentable sugar yield from sugarcane bagasse
Renew. Energy
Physicochemical characterization of cellulose from perennial ryegrass leaves (Lolium perenne)
Carbohydr. Res.
Structural characterization and isolation of lignin and hemicelluloses from barley straw
Ind. Crop. Prod.
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