Pretreatment Of Barley Straw Research Articles

Nanocellulose separation from barley straw via ultrasound-assisted choline chloride – Formic acid deep eutectic solvent pretreatment and high-intensity ultrasonication

The present study aims at investigating the application of ultrasound assisted choline chloride (ChCl) – formic acid (FA) deep eutectic solvent (DES) pretreatment of Barley straw. In addition, the efficiency of a wet grinding followed by high intensity ultrasound (HIUS) treatment for production of cellulose nanofibers (CNF) has been evaluated. The DES (using ChCl: FA at 1:9 M ratio) treatment at 45 kHz ultrasound frequency and 3 h of treatment duration resulted in 84.68 ± 1.02 % and 82.96 ± 0.79 % of lignin and hemicellulose solubilisation, respectively. The purification of DES treated solid residue resulted in cellulose with more than 90 % purity. Further, 10 min of wet grinding followed by 40 min of HIUS treatment resulted in more than 80 % nano-fibrillation efficiency. The produced CNF had diameters less than 100 nm in number size distribution and type I cellulose structure. This study confirmed that the developed process offers a sustainable method for producing nanocellulose from agricultural waste.

Pretreatment of barley straw with acid and alkaline solutions to boost the efficiency of fermentable yield enzymatic degradation in the separated fermentation technique for ethanol production

Barley straw is a lignocellulose agricultural waste material that can be utilized as a raw material for ethanol production since it is easy to find, cheap, and has the potential to produce ethanol yield. This research aims to select the optimum pretreatment conditions to increase fermentable sugar production during enzymatic hydrolysis for bioethanol production. Initially, sulfuric acid at a concentration of 0.5, 1.0, 1.5, and 2.0% (v/v) pre-treated barley straw biomass was applied by autoclaving at 121℃ for 15 lb/in2 pressure for 15 min. Furthermore, acid-treated barley straw under the alkaline condition with calcium hydroxide concentrations of 1, 2, 3, and 4% (w/v) was autoclaved at 121℃ for 15 lb/in2 pressure for 15 min. Subsequently, the pretreatment of barley straw in the acetic and alkaline processes was compared. It was found that calcium hydroxide at a concentration of 2% (w/v) gave more sugar concentrations. Finally, combined acid and alkaline pretreatment with 2% of cellulase enzymatic hydrolysis had the highest total sugar concentration of 205.43 g/L and reducing sugar of 134.42 g/L, producing the highest ethanol yield (16.17 g/L) by 24 hours of fermentation.

Enhanced Enzymatic Saccharification of Wheat Flour Arabinoxylan and Barley Straw Using Recombinant Hemicellulases

Enzymatic hydrolysis of hemicelluloses in biomass feedstocks requires multiple enzymes for sacchari-fication to fermentable monosaccharides. Considering the high cost of enzymes, the need for enzymes in the cocktail for maximum saccharification can be minimized using a statistically significant experimental design. In the present study, response surface methodology was used to optimize the saccharification of wheat arabinoxylan and pretreatment of barley straw. A hemicellulase enzyme mixture consisting of recombinant xylanase (rPcXynC), arabinanase (rPcAra), and bifunctional β-xylosidase/L-arabinofuranosidase (rPcXyl) was used. A central composite design was used to evaluate and confirm the effectiveness and interactions of these enzymes along with reaction time. A 100% sacchari-fication of 1 g of wheat arabinoxylan was achieved using 21.85 U, 6.025 U, and 182 U of rPcXynC, rPcAra, and rPcXyl, respectively, for 11.46 h. Subsequently, using pretreated barley straw as a substrate, a maximum saccharification of 42% was achieved in 12 h using an enzyme cocktail of 25 U rPcXynC, 5 U rPcAra, and 200 U rPcXyl. The total hydrolysis of pretreated barley straw was increased to 1.71% by the addition of acetyl xylan esterase as a pretreatment factor followed by optimization of enzyme cocktail. The experimental values under the optimum conditions were consistent with the predicted values and a minimum cocktail was involved for a synergistic effect of the enzymes.

Potential of barley straw for high titer bioethanol production applying pre-hydrolysis and simultaneous saccharification and fermentation at high solid loading

Barley straw (BS) is considered a good candidate for fuel-ethanol production due to its abundance and high carbohydrate content. Economic viability of the process requires ethanol titer in fermentation broth >4% (w/v) which is considered to be the benchmark for an efficient distillation. Mild alkaline pretreatment of BS resulted in 74% and 45% lignin and hemicellulose removal, respectively. Alkali treated barley straw (ATBS) was hydrolyzed at 15% (w/v) substrate concentration, using commercial cellulases (Cellic® CTec2). Highest glucose release was 91.19 g/L (hydrolysis yield 82%). Models based on first and second order cellulase deactivation kinetics satisfactory predicted the behavior of glucose release during enzymatic hydrolysis of ATBS, however the first order model appears to fit better. ATBS, at high solids loading (15% and 20% w/v), was converted to bioethanol applying pre-hydrolysis and simultaneous saccharification and fermentation (PSSF). Highest ethanol production was achieved after 16 h pre-hydrolysis. As substrate loading increased from 15% to 20%, ethanol concentration increased from 39.55 to 46.62 g/L. Mass balance of PSSF showed that the reduction of ethanol yield when solid loading increases could be attributed to the decrease in cellulose enzymatic conversion.

Second-Generation Bioethanol Production Combining Simultaneous Fermentation and Saccharification of IL-Pretreated Barley Straw

Ionic liquid dissolution/precipitation pretreatment of barley straw was used to improve the yield to produce ethanol. The pretreatment with ionic liquid greatly improves the enzymatic hydrolysis co...

Microwave and microwave-alkali effect on barley straw for total sugar yield

Lignocellulose is the most remarkable plant material resource for obtaining energy; however, its utility is restrained by its recalcitrant structure. Therefore, it is necessary to apply a convenient pretreatment method to increase the sugar yield. Microwave pretreatment method assists to break down hard lignin structure for improved degradation of cellulose and releasing of sugar. The objectives of this study are to investigate microwave and microwave-alkali pretreatment efficiency of barley straw before enzymatic hydrolysis. In both pretreatment methods, remarkable findings were obtained as sugar concentration. The maximum reducing total sugar concentration of 354.1 mg/L was achieved after ten minutes of pretreatment time in 30 mL of 3% NaOH solution (w/v) at microwave power of 200 W. The evaluations of scanning electron microscopy (SEM) images were carried out within pretreatment of barley straw as well. The results suggest that microwave and microwave-alkali pretreatment can increase total sugar concentration.

염기 용매를 이용한 보릿짚의 전처리 특성

최근의 식량자원과 충돌의 우려가 있는 전분질계 에탄올 생산에 문제점이 대두되고 있고, 기존의 화석에너지를 대신할 새로운 재생가능 에너지개발에 대한 요구가 지속적으로 증가하면서 새로운 에너지 자원으로서 셀룰로오즈 계열 바이오매스가 지속적인 주목을 받고 있다. 하지만 지난 수십 년 간의 연구에도 불구하고 셀룰로오직 에탄올이 가격 경쟁력을 가지지 못하는 이유는 셀룰로오스 계열 바이오매스의 구성성분인 셀룰로오스, 헤미셀룰로오스, 리그닌의 분리과정이 어렵고, 전처리 과정 중 생산되는 부산물질에 의한 당화 및 발효율이 낮다는 점과, 당화를 위해 다량의 효소가 필요하고 가격이 비싸다는 점이다. 바이오 에탄올 생산을 위한 전처리 공정 기술을 상용화 단계까지 효율적이고, 경제적으로 구축하기 위해서는 경제성이 확보되고 원천 기술 적용이 가능한 바이오매스의 선정과 더불어 기존 기술들의 문제점을 파악, 극복하면서 전체 생산 수율을 높이는 동시에 에너지 저감형태의 새로운 전처리 공정 기술 개발이 필요하다. 본 논문에서는 이러한 문제 점을 해결하기 위해 이전부터 많은 연구가 이루어진 농업 부산물 계열의 볏짚과 그 특성이 비슷할 것으로 보이는 보릿짚을 바이오매스로 선택하여 보편적으로 이용되고 있는 염기 전처리를 적용하여 그 특성에 대하여 파악해 보고자 하였다. 보릿짚은 볏짚과 비교하였을 때 셀룰로오스와 리그닌의 함량이 각각 41.60%와 17.56%로 그 함량이 비슷하게 나타났고 가축 사료로 사용되고 있는 볏짚에 비해 수급단가 또한 상대적으로 낮아 매우 경제적인 바이오매스로 보여진다. 보릿짚을 이용한 암모니아 침지 반응을 통한 볏짚과의 비교에서는 암모니아 농도; 15%, 반응온도; <TEX>$60^{\circ}C$</TEX> 반응시간; 24hr의 조건에서 전처리 후 리그닌 제거율 29.09%, 가수분해도 64.78%(16.01 g/L), 에탄올 수율 56.50%(8.65 g/L)로 나타나 볏짚에 비해 그 효과가 낮은 것으로 나타났지만 암모니아에 의한 전처리에 상당한 효과가 있는 것으로 보여진다. NaOH 침지 반응은 NaOH 농도; 2%, 반응온도; <TEX>$85^{\circ}C$</TEX>, 반응시간; 1hr 동안 반응하여 볏짚과 암모니아 침지 반응에 대한 비교를 통해 그 특성을 파악하였다. NaOH 침지 반응 후 보릿짚의 상대적인 리그닌 제거율; 24.15%, 가수분해도; 58.40%(15.39 g/L), 에탄올 수율 52.56%(8.35 g/L)의 결과를 얻어, 보릿짚이 암모니아를 이용한 전처리와 NaOH를 이용한 전처리 즉 염기 용매를 이용한 전처리에 있어 효과적인 리그닌 제거가 가능한 것으로 결론 지을 수 있고 본 연구 결과를 바탕으로 차 후 NaOH와 암모니아 침지 반응 및 침출 반응의 최적화 연구를 통해 각 전처리의 최적화 조건을 설정할 수 있을 것으로 보인다. Lignocellulose is difficult to hydrolyze due to the presence of lignin and the technology developed for cellulose fermentation to ethanol is not yet economically viable. However, recent advances in the extremely new field of biotechnology for the ethanol production are making it possible to use of Agriculture residual biomass, e.q., Barley straw, because of their several superior aspects as Agriculture residual biomass; low lignin, high contents of carbohydrates. Barley straw consists of 39.78% cellulose (glucose), 22.56% hemicelluloses and 19.27% lignin. Pretreatment of barley straw using NaOH pretreatment solutions concentration with 2%, temperature <TEX>$85^{\circ}C$</TEX> and reaction times 1 hr were investigates. <TEX>$NH_4OH$</TEX> pretreatment condition was solutions concentration with 15%, temperature <TEX>$60^{\circ}C$</TEX>, and reaction times 24hr were investigates. Furthermore, enzymatic saccharification using cellulose at <TEX>$50^{\circ}C$</TEX>, pH 4.8, 180 rpm for conversion of cellulose contained in barley straw to monomeric sugar. The pretreatment of barley straw using NaOH and <TEX>$NH_4OH$</TEX> can significantly improve enzymatic saccharification of barley straw by extract more lignin and increasing its accessibility to hydrolytic enzymes. The result showed NaOH pretreatment extracted yield of lignin was 24.15%. <TEX>$NH_4OH$</TEX> pretreatment extracted yield of lignin was 29.09%. Shaccharification of barley straw pretreatment by NaOH for 72hr and pH 4.8 result in maximum glucose concentration 15.39g/L (58.40%) and by <TEX>$NH_4OH$</TEX> for 72hr and pH 4.8 result in maximum glucose concentration 16.01g/L (64.78%).

Dilute acid pretreatment of barley straw and its saccharification and fermentation

In this study, the optimization of the major factors for efficient dilute acid pretreatment (DAP) of Korean barley straw was conducted by response surface method (RSM). In addition, saccharification of the optimized pretreated barley straw as well as fermentation of solubilized hemicellulose and enzymatic hydrolysates was performed for bioethanol production. The factors optimized by RSM were concentration of sulfuric acid, reaction time and temperature. Optimization experiments were carried out within the scope of 0.16 ∼ 1.84% sulfuric acid, 10 ∼ 20 min of reaction time, and 116 ∼ 183°C of temperature using a statistical program, and optimal conditions (1.16% of sulfuric acid, 16.9 min of reaction time, and 150°C) were determined based on reliable statistical indicators. The predicted value at stationary point and the experimental value were 81.38 and 80.66%, respectively. Saccharification was performed at 50°C using Celluclast (cellulase) and Novozyme 188 (β-glucosidase) as biocatalysts in an enzyme loading test. Conversion of the saccharification process was approximately 65%. In addition, fermentation of glucose after saccharification and solubilization of xylose solution by DAP were performed using Saccharomyces cerevisiae and Pichia stipitis at 30°C and 200 rpm for 12 h.