Cellulose Nanofiber Preparation Combined with Bioethanol Production from Fermented Sweet Sorghum Bagasse

Abstract

In order to achieve cost-competitive industrial production of cellulose nanofibers (CNFs), bioethanol extraction and lignocellulose pretreatment from fermented sweet sorghum bagasse were combined with alkaline distillation in this study. CNFs were further prepared from an alkaline-distilled substrate after washing, bleaching, and a high-pressure homogenization process. Lignin-containing cellulose nanofibers (LCNFs) were simultaneously prepared without bleaching. The effects of different alkali loadings on the ethanol quality and performances of CNFs and LCNFs were investigated. Results showed that only 12.94 mg/L of alkali residue was found in extracted ethanol at the highest alkali dosage, which can be removed in the subsequent purification process. Cellulose fibers can be prepared from sweet sorghum bagasse during alkaline distillation, and the crystallinity of pretreated samples increased from 37.2 to 59.5%. It is observed by transmission electron microscopy that the obtained nanofibrils aggregated and formed a network in suspension. The degradation temperature of the CNFs can be increased up to 352 °C, which is 34 °C higher than that of LCNFs due to less hemicellulose content. Wastewater was only generated in the washing process during alkali distillation, which is far less than that generated in a conventional pulping making process. The process scale-up simulation indicates that the coproduction of bioethanol and CNFs or LCNFs by alkaline distillation is environment-friendly and energy-efficient for industrialization.

Using a Novel Pervaporative Sequential-Co-immobilized Two-Sectional Bioreactor with an Ultralow Fouling–Biofouling Superhydrophobic Silicallite-1/PDMS Membrane to Enhance Bioethanol Production

“…Specific growth rates for Z. mobilis on glucose (0.3−0.48 h −1 ) and P. stipitis on xylose (0.22−0.28 h −1 ) have so far been reported in the literature for single cultures at low levels of sugars. 39,40,61 Similarly, specific growth rates of about 0.43 and 0.21 h −1 for Z. mobilis and P. stipitis in single glucose and xylose media were obtained in this work. However, in the sequential-co-culture fermentation, no report on the specific growth rate of individual species was available.…”

“…This was a sign of the robust stability of PITB throughout the fermentation and lower bioethanol level in the culture and hence less inhibition via its in situ removal. However, some researchers reported that using pervaporation played a dominant role only at the beginning of coupling. ,,,, The stable permeation flux and separation factor of TSP could have resulted from permanent antiswelling and anti-fouling–biofouling properties during 161 h. However, they fell to average values of 30.34 and 1.73 kg/m 2 ·h in the real fermentation broth compared to the synthetic solutions (34.6 and 1.95 kg/m 2 ·h, respectively). Xue et al used self-flocculating yeast and CNT/PDMS membrane at the same time and found out that the stable performance of the integrated process significantly decreased the production cost.…”

“…In the literature, the performance of single cultures of S. cerevisiae to ferment single glucose media was surveyed mostly at low sugar levels in PMBR, ,,− ,,,, which are not in accordance to sugar levels in the real hydrolysate of lignocellulosic materials. , In fact, the low level of sugar and ignoring xylose provide unaffordable bioethanol production . A suspended cell was often used, and this could have led to fouling/biofouling formation. , In the pervaporation part, considerable differences were observed in the separation factor and pervaporative separation index of TSP compared to the use PDMS and zeolite/PDMS membranes in the literature. ,,,,, This disagreement can be related to having simultaneous antiswelling properties, ultralow fouling–biofouling formation, and high inherent pervaporation performance of TSP (high performance in separating ethanol from the synthesis solution) compared to others. In fact, high membrane hydrophobicity (contact angle) has not been addressed in the literature.…”

“…35,36 In the pervaporation part, considerable differences were observed in the separation factor and pervaporative separation index of TSP compared to the use PDMS and zeolite/PDMS membranes in the literature. 10,13,14,16,61,64 This disagreement can be related to having simultaneous antiswelling properties, ultralow fouling−biofouling formation, and high inherent pervaporation performance of TSP (high performance in separating ethanol from the synthesis solution) compared to others. In fact, high membrane hydrophobicity (contact angle) has not been addressed in the literature.…”

Compacted Silage Fermentation on Whole Sweet Sorghum Plant for Distributed Bioethanol Production

“…Chemical composition analysis of fermentation residues cited the literature data. 31 The quality of vinasse feed was analyzed according to AOAC standards. 32 ■ RESULTS AND DISCUSSION Tolerance with Sulfur Dioxide.…”