Improvement of Cellulose Hydrolysis Process and Cost Savings

The hydrolysis process to obtain the so-called ＂reducing sugars＂ represents the main step involved in the production of the second generation bioethanol. This product can be obtained directly from various types of green biomass, replacing the use of cereals cultivations, with obvious benefits to the environment and the economy of agricultural production. However, it is necessary to improve the hydrolysis process of the cellulose to achieve this goal. To this purpose, we applied a chemical process formerly used. The values of sugars yield were increased by about 40% with respect to the previous study. Further significant cost savings were accomplished, resulting from the recovery of the by-product, calcium sulfate, commercially known as gypsum.

Hydrolysis of cellobiose catalyzed by zeolites—the role of acidity and micropore structure

The roles of acidity and micropore structure of zeolite were studied in the hydrolysis of the model oligosaccharide of cellulose–cellobiose. HZSM-5, HY, HMOR and Hβ zeolites were selected as model catalysts for the hydrolysis of cellobiose. The effect of acidity of zeolite, including the strength, type and location, on its catalytic activity was investigated. The strong Br？nsted acid sites located in micropores are the active sites for the hydrolysis of cellobiose to glucose. Meanwhile, the catalytic performance of zeolite is also dependent on the micropore size of zeolite.

Simultaneous Extraction of Carboxylated Celulose Nanocrystals and Nanofibrils via Citric Acid Hydrolysis--A Sustainable Route

In this study, cellulose nanocrystals(CNC) with surface carboxylic groups were prepared from bleached softwood pulp by hydrolysis with concentrated citric acid at concentrations of 60 wt%~80 wt%. The solid residues from acid hydrolysis were collected for producing cellulose nanofibrils(CNF) via post high-pressure homogenization. Citric acid could be easily recovered after hydrolysis reactions through crystallization due to its low water solubility or through precipitation as a calcium salt followed by acidification. Several important properties of CNC and CNF, such as dimension, crystallinity, surface chemistry, thermal stability, were evaluated. Results showed that the obtained CNC and CNF surfaces contained carboxylic acid groups that facilitated functionalization and dispersion in aqueous processing. The recyclability of citric acid and the carboxylated CNC/CNF give the renewable cellulose nanomaterial huge potential for a wide range of industrial applications. Furthermore, the resultant CNC and CNF were used as reinforcing agents to make sodium carboxymethyl cellulose(CMC) films. Both CNC and CNF showed reinforcing effects in CMC composite films. The tensile strength of CMC films increased by 54.3% and 85.7% with 10 wt% inclusion of CNC and CNF, respectively. This study provides detailed information on carboxylated nanocellulose prepared by critic acid hydrolysis; a sustainable approach for the preparation of CNC/CNF is of significant importance for their various uses.

Multi-objective regulation in autohydrolysis process of corn stover by liquid hot water pretreatment

Increasing reducing sugars(xylose and glucose) yield for bioethanol from corn stover depends strongly on optimization of pretreatment conditions. The optimum reaction conditions of two-stage liquid hot water(LHW) pretreatment based on total sugars yield were investigated. Under optimal conditions, the recovery of glucose of corn stover after two-stage LHW pretreatment and 72 h enzymatic digestion, reached 89.55%. In addition, acetic acid-rich spent liquor pretreatment and one-stage LHW pretreatment have been carried out to make comparisons with two-stage LHW treatment. Glucose yield 89.55% is superior to the recovery 83.38% using acetic acidrich spent liquor pretreatment or 80.58% using one-stage LHW pretreatment. The production of total sugars was increased by 7.8% when compared with one-stage pretreatment. Moreover, the structural features of the treated corn stover solid residues were also investigated by XRD and SEM technology in order to clarify the effects of the reaction on corn stover. The results indicated that the two-stage LHW pretreatment was an effective pretreatment method of corn stover to get most massive resource utilization, and it could be successfully applied to corn stover.

Potential aspect of rice husk biomass in Australia for nanocrystalline cellulose production

Nanocrystalline cellulose(NCC) was produced from rice husk biomass(Oryza sativa) by a chemical extraction process to explore the potential aspect of agro-waste biomass in Australia. In this work, the delignified rice husk pulp(D-RHP) was produced by alkaline delignification of raw rice husk biomass(R-RHB) using 4 mol·L^(-1) alkali solutions(Na OH) in a jacketed glass reactor under specific experimental conditions. D-RHP was bleached using 15% sodium hypochlorite, and the bleached rice husk pulp was coded as B-RHP. Finally,raw suspension of NCC was produced by the acid hydrolysis of B-RHP using 4 mol·L^(-1) sulphuric acid. The raw suspension of NCC was neutralized by a buffer solution and analyzed by TAPPI, FT-IR, XRD, SEM, AFM, and TEM. FT-IR spectra of NCC are different to R-RHB but similar with B-RHP and D-RHP. From XRD results, the crystallinity of NCC was found to be approximately 65%. In AFM analysis particle thicknesses have been confirmed to be in the range of(25 ± 15.14) nm or(27 ± 15.14) nm which is almost the same. From TEM analysis particle dimensions have been confirmed to be in the range of(50 ± 29.38) nm width and(550 ± 302.75) nm length with the aspect ratio ~ 11:1(length/diameter) at a 500 nm scale bar. On the other hand, at a 200 nm scale bar the particle dimensions have been confirmed to be in the range of(35 ± 17) nm width and(275 ± 151.38)nm length with the aspect ratio ~ 8:1. The aspect ratio of individual crystalline domain was determined in TEM analysis which is 10:1(100/10). Therefore the aspect ratios and dimensions of nanoparticles in NCC suspension are almost the same and in nano-meter scale, as confirmed from both AFM and TEM results. The yield of NCC from B-RHP was found to be approximately 95%, and the recovery of cellulose from R-RHB is about 90%.

Cellulose Nanoparticles Extracted from Sugarcane Bagasse and Their Use in Biodegradable Recipients for Improving Physical Properties and Water Barrier of the Latter

The present work firstly aimed to obtain cellulose from sugarcane bagasse by using alkaline methods in pulping/delignifying and, at bleaching stages, using sodium chlorite, glacial acetic acid, and hydrogen peroxide, associated to NaOH/KOH. The process was carried out at temperatures varying from 55°C to 110°C, under magnetic stirring in various steps lasting from 2 h to 12 h. The yields of the two cellulose extracted, SCB24-Na-I and SCB24-Na-II, were 37% and 41%, respectively, from samples of ca. 15 g of the bagasse. Secondly, it is to extract nanoparticles from the obtained celluloses via acid hydrolysis (with 77% H2SO4) to lately be tested as reinforcement in biodegradable packagings. Both celluloses and their respective nanoparticles were characterized by several techniques, among them ATR-FTIR, DSC-TGA, XRD, SEM, and TEM. Despite that the yields of cellulose nanoparticles have been low, the preliminary studies of their use in biodegradable films coated on biodegradable pots were promising.

Enzymatic saccharification of cellulose using an ionic liquid [Amim] [COOH] pretreatment

In this study we used l-allyl-3-methyl imidazole formate （[Amim][COOH]） as ionic liquid to pre-treat the cellulose and determined the rate of polymerization and enzymatic hydrolysis. The results showed that pretreatment with （[Amim][COOH]） significantly decreased the cellulose polymerization. As the pretreatment temperature went up, the enzymatic hydrolysis rate was first increased and then decreased The maximal enzymatic hydrolysis rate was achieved when the pretreatment temperature was 90 ℃. Under the ultrasonic condition, the initial rate of enzmatic hydrolysis for the ionic liquid-treated cellulose was up to 11.10 gL-1h-1, which was 33% increase compared to the untreated cellulose. Scanning Electronic Microscopy （SEM） and Fourier Transform Infrared-Raman Spectroscop （FT-IR） analysis showed that ionic liquidtreated cellulose started to depolymerize. In addition, the cr3＇stallinity of the cellulose was significantly decreased after pretreatment with ionic liquid.

Process development for producing a food-grade glucose solution from rice straws

In this paper, processes for producing a food-grade glucose solution through enzymatic hydrolysis of celluloserich solids obtained from rice straws are presented. The rice straws were pretreated by acid-catalyzed steam explosion, and the reaction efficiency, toxicity control, and process economic feasibility were studied. Mass transfer resistance to the hydrolysis reaction was reduced by grinding with glass beads. A higher glucose concentration could be obtained by feeding more cellulose in the hydrolysis reaction; however, this also resulted in the production of undesired byproducts. Thus, a soaking process for the cellulose solids in water was developed to effectively reduce the generation of byproducts in the hydrolysis reaction. The resulting food-grade glucose solution can provide 414 kilocalories per liter, and could be used during a food-shortage crisis in the future.The current production cost is estimated to be 0.82 USD·L^(-1).

A boronate-modified renewable nanointerface for ultrasensitive electrochemical assay of cellulase activity

The saccharification of cellulosic biomass to produce biofuels and chemicals is one of the most promising industries for gree n-power production and sustainable development.Cellulase is the core component in the saccharification process.Simple and efficient assay method to determine cellulase activity in saccharification is thus highly required.In this work,a boronate-affinity surface based renewable and ultrasensitive electrochemical sensor for cellulase activity determination has been fabricated.Through bo ronate-sugar interaction,celluloses are attached to the electrode surface,forming the cellulose na nonetwork at the sensing interface.Cellulase degradation can lead to the variation of electrochemical impedance.Thus,electrochemical impedance signal can reflect the cellulase activity.Importantly,via fully utilizing the boronate-affinity chemistry that enables reversible fabrication of cellulose nanonetwork,a renewable sensing surface has been firstly constructed for cellulase activity assay.Thanks to interfacial diffusion process of electrochemical sensor,the product inhibitory effect in the cellulase activity assays can be circumvented.The proposed electrochemical sensor is ultrasensitive for label-free cellulase activity detection with a very simple fabrication process,showing great potential for activity screen of new enzymes in saccharification conversion.

Ethanol production from sweet sorghum residual

In this work,the ethanol production from sweet sorghum residue was studied.Sweet sorghum res-idue was hydrolyzed with phosphoric acid under mild conditions.The liquid hydrolysate was fermented by Pachysolen tannophilus,and the hydrolysis residue was fermented by the simultaneous saccharification and fer-mentation(SSF)using Saecharomyces cerevisiae with cel-lulase(60 FPU/g dry materials).Orthogonal experiments were carried out to investigate the effects of main reaction condition factors,such as temperature,acid concentra-tion,time and dry-matter content,on the reducing sugar yield.The results show that the optimal reaction condi-tions should be 120℃,80 g/L,80 min and 10%,respect-ively.Under these conditions,0.3024 g reducing sugar/g dry material was obtained.The liquid hydrolysate was then fermented by P.tannophilus with the highest ethanol concentration of 14.5 g/L.At a water-insoluble solid con-centration of 5%,5.4 g/L ethanol was obtained after 12 h of SSF.The total ethanol yield was 0.147 g/g dry material,which would be beneficial for the application of ethanol production from sweet sorghum residue.