Optimization of acid pretreatment and enzymatic hydrolysis on the production of ethanol fuel from waste banana peels

2018 ◽  
Vol 29 (8) ◽  
pp. 1354-1364 ◽  
Author(s):  
Jiaxin Guo ◽  
Zhenchi Li ◽  
Lingcheng Su ◽  
Yiu-Fai Tsang ◽  
AK An ◽  
...  

This study investigated the application of waste banana peels as feedstock for the production of ethanol fuel as a second-generation biofuel. First, acid pretreatment followed by enzymatic hydrolysis converted both the cellulosic and hemicellulosic biomass of the peels into fermentable sugars, which eventually produced ethanol by yeast fermentation. The optimal conditions for the production of ethanol fuel were determined by orthogonal experimental design method. The results showed that 100 g of fresh banana would produce 31.4 g of banana peel which could be turned into 2.8 g dried peel powder. Under optimal conditions of acid pretreatment with 0.2% tartaric acid, enzymatic hydrolysis by cellulase and yeast fermentation, 115 mg of ethanol (95% purity) could be recovered by distillation from the fermentation broth, which was approximately 4% by weight of the dried peel powder. This study concluded that banana fruit, after the removal of peels for consumption or food processing, the discarded peels will no longer pose an organic waste problem to the environment if they could be recollected and converted into value-added products like ethanol fuel. We also demonstrated that tartaric acid, an organic acid used in the acid pretreatment, for the first time to our knowledge, outperformed the traditional sulfuric acid used commonly in other studies.

2020 ◽  
Author(s):  
Bawar Tahir ◽  
Xiaoqing Wang ◽  
Yuan Zhong ◽  
Hassan Mezori ◽  
Yan Liu ◽  
...  

Abstract Quercus infectoria is one of the most abundant native oak species in the Kurdistan region of Iraq. This study focused on utilizing leaves of Quercus infectoria for ethanol production in the region. A typical three-step conversion process of acid pretreatment, enzymatic hydrolysis, and yeast fermentation was investigated to produce ethanol from the leaves. Under the selected acid pretreatment and enzymatic hydrolysis conditions, the glucose and xylose concentrations in the hydrolysates reached 11.4 g/L and 16.8 g/L, respectively, with the corresponding sugar conversions of 42.8% and 99.8%. A yeast strain, Kluyveromyces marxianus, was used to ferment mono-sugars in the hydrolysates for ethanol production. The ethanol production rate and conversion of K. marxianus in the fermentation were 0.17 g/L/h and 27%. The techno-economic analysis further concluded that a regional ethanol biorefinery can be established in the Zawita sub-district, Iraq to utilize Q. infectoria leaves to produce 200,000,000 kg ethanol/year with a positive energy balance of 745,052,623 MJ/year. The net annual revenue of the biorefinery is $123,692,804. The payback period of the biorefinery is 10 years.


Author(s):  
María Laura Montoro ◽  
María Herrero ◽  
Arminda Mamaní ◽  
María Sardella ◽  
Martha Vallejo ◽  
...  

Abstract Melon is one of the main horticultural crops in the province of San Juan, Argentina. An excess of 20% of its production is not marketed for various reasons. To take advantage of this biomass, acid pretreatments (PA), acid combined with ultrasound (PAU), were applied to evaluate increases in the bioavailability of sugars for the production of 2G bioethanol. The results showed that under the optimal conditions of both pretreatments: concentration of 2% sulfuric acid, time of 30 minutes, the temperature of 55 °C and solid: liquid ratio11:1, followed by enzymatic hydrolysis using cellulase, hemicellulose and pectinase, increases of 111 and 576% are achieved in the content of fermentable sugars, compared to untreated melon. Acid pretreatment combined with ultrasound and enzymatically hydrolyzed, using cellulase, hemicellulase, and pectinase, turned out to be the best alternative in terms of increasing fermentable sugars, obtaining 38.99 mL of bioethanol per kg of melon.


2021 ◽  
Author(s):  
Qibo Zhang ◽  
Ali Nawaz ◽  
Kankan Jiang ◽  
Xin Zhou ◽  
Yong Xu

Abstract Corncob as an abundance and low-cost waste resource has received increasing attention to produce value added chemicals, it is rich in xylan and regarded as the most preferable feedstock for preparing xylooligosaccharides, which possesses highly commercial value due to a range of health benefits. The strategy with xylooligosaccharides as core products can cut costs and improve economic efficiency of biorefinery. Therefore, a cascade processing for converting corncob to xylooligosaccharides and glucose by sequential maleic acid pretreatment and enzymatic hydrolysis was design. Based on overarching aim of this study that maximally yielding xylooligosaccharides, corncob was first subjected to response surface methodology experimental procedure for optimizing the conditions. Correspondingly, a maximum xylooligosaccharides yield of 52.9% was achieved with 0.5% maleic acid at 155 °C for 26 min. Maleic acid, a non-toxic and edible catalyst, was able to effectively hydrolyze xylan into xylooligosaccharides and simultaneously generate a positive pretreated effect for improve the enzymatic hydrolysis efficiency. Finally, an enzymatic hydrolysis yield of 87.5% was achieved from maleic acid-treated corncob at 10% solids loading. This cascade processing may provide a novel strategy for the other biomass wastes utilization.


2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Qibo Zhang ◽  
Lu Cheng ◽  
Xutong Ma ◽  
Xin Zhou ◽  
Yong Xu

Abstract Background Sunflower stalk pith, residue from the processing of sunflower, is rich in pectin and cellulose, thereby acting as an economic raw material for the acquisition of these compounds. In order to increase the commercial value of sunflower processing industry, a two-step dilute sulfuric acid treatment process was conducted on spent sunflower stalk pith to obtain the value-added products, pectin and glucose. Results In this study, pectin was firstly extracted under mild acid condition to avoid pectin degradation, which was conducted at 90 °C with a pH of 2.0 for 2 h, and ~0.14 g/g of pectin could be recovered. Then the remaining solids after pectin extraction were subjected to the reinforced treatment process with 0.75% H2SO4 at 150 °C for 30 min to further improve enzymatic hydrolysis efficiency. Moreover, by combining a fed-batch enzymatic hydrolysis strategy, a solid loading content of 16% was successfully achieved and the glucose titer reached 103.1 g/L with a yield of 83.6%. Conclusion Finally, ~140 g pectin and 260 g glucose were produced from 1 kg of raw sunflower stalk pith using the integrated biorefinery process. This work puts forward a two-step dilute acid pretreatment combined with enzymatic hydrolysis method to produce pectin and glucose from sunflower spent waste.


2021 ◽  
Author(s):  
Qibo Zhang ◽  
Xutong Ma ◽  
Xin Zhou ◽  
Yong Xu

Abstract Background: Sunflower stalk pith, residue from the processing of sunflower, is rich in pectin and cellulose, thereby acting as an economic raw material for the acquisition of these compounds. In order to increase the commercial value of sunflower processing industry, a two-step sequential dilute sulfuric acid treatment combined with subsequent enzymatic hydrolysis was conducted on spent sunflower stalk pith to obtain the value-added products, pectin and glucose. Results: In this study, pectin was firstly extracted with a mild condition to avoid pectin degradation, which conducted at 95℃ with a pH of 2.0 for 2 h, and approximately 0.12 g/g of pectin could be recovered. Then the remaining solids followed by extracted pectin were subjected to the reinforced treatment process with 0.75% H2SO4 at 150 oC for 30 min to further improving enzymatic hydrolysis efficiency. Moreover, a fed-batch enzymatic hydrolysis was successfully performed with a solid 16% content, the glucose titer reached 103.1 g/L with a yield of 83.6 %.Conclusion: Finally, approximately 140 g pectin and 260 g glucose were produced from 1 kg of raw sunflower stalk pith using the integrated biorefinery process. This work put forward a two-step dilute acid pretreatment combined with enzymatic hydrolysis method to produce pectin and glucose from sunflower spent waste.


Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1360
Author(s):  
Ekaterina Budenkova ◽  
Stanislav Sukhikh ◽  
Svetlana Ivanova ◽  
Olga Babich ◽  
Vyacheslav Dolganyuk ◽  
...  

Enzymatic hydrolysis of cellulose-containing raw materials, using Aspergillus niger, were studied. Filter paper, secondary cellulose-containing or starch-containing raw materials, miscanthus cellulose after alkaline or acid pretreatment, and wood chip cellulose, were used as substrates. The study focused on a wild A. niger strain, treated, or not (control), by ultraviolet (UV) irradiations for 45, 60, or 120 min (UV45, UV60, or UV120), or by UV irradiation for 120 min followed by a chemical treatment with NaN3 + ItBr for 30 min or 80 min (UV120 + CH30 or UV120 + CH80). A mixture of all the A. niger strains (MIX) was also tested. A citrate buffer, at 50 mM, wasthe most suitable for enzymatic hydrolysis. As the UV exposure time increased to 2 h, the cellulase activity of the surviving culturewas increased (r = 0.706; p < 0.05). The enzymatic activities of the obtained strains, towards miscanthus cellulose, wood chips, and filter paper, were inferior to those obtained with commercial enzymes (8.6 versus 9.1 IU), in some cases. Under stationary hydrolysis at 37 °C, pH = 4.7, the enzymatic activity of A. niger UV120 + CH30 was 24.9 IU. The enzymatic hydrolysis of secondary raw materials, using treated A. niger strains, was themost effective at 37 °C. Similarly, the most effective treatment of miscanthus cellulose and wood chips occurred at 50 °C. The maximum conversion of cellulose to glucose was observed using miscanthus cellulose (with alkaline pretreatment), and the minimum conversion was observed when using wood chips. The greatest value of cellulase activity was evidenced in the starch-containing raw materials, indicating that A. niger can ferment not only through cellulase activity, but also via an amylolytic one.


2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Lin Dai ◽  
Tian Huang ◽  
Kankan Jiang ◽  
Xin Zhou ◽  
Yong Xu

Abstract Background Pretreatment is the key step for utilizing lignocellulosic biomass, which can extract cellulose from lignin and disrupt its recalcitrant crystalline structure to allow much more effective enzymatic hydrolysis; and organic acids pretreatment with dual benefic for generating xylooligosaccharides and boosting enzymatic hydrolysis has been widely used in adding values to lignocellulose materials. In this work, furoic acid, a novel recyclable organic acid as catalyst, was employed to pretreat sugarcane bagasse to recover the xylooligosaccharides fraction from hemicellulose and boost the subsequent cellulose saccharification. Results The FA-assisted hydrolysis of sugarcane bagasse using 3% furoic acid at 170 °C for 15 min resulted in the highest xylooligosaccharides yield of 45.6%; subsequently, 83.1 g/L of glucose was harvested by a fed-batch operation with a solid loading of 15%. Overall, a total of 120 g of xylooligosaccharides and 335 g glucose could be collected from 1000 g sugarcane bagasse starting from the furoic acid pretreatment. Furthermore, furoic acid can be easily recovered by cooling crystallization. Conclusion This work put forward a novel furoic acid pretreatment method to convert sugarcane bagasse into xylooligosaccharides and glucose, which provides a strategy that the sugar and nutraceutical industries can be used to reduce the production cost. The developed process showed that the yields of xylooligosaccharides and byproducts were controllable by shortening the reaction time; meanwhile, the recyclability of furoic acid also can potentially reduce the pretreatment cost and potentially replace the traditional mineral acids pretreatment.


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