Bio-based products from xylan: A review (original) (raw)
Related papers
Polymers
In this paper, we describe an experimental study on the hot alkali extraction of hemicelluloses from wheat straw and corn stalks, two of the most common lignocellulosic biomass constituents in Romania. The chemical compositions of the raw materials were determined analytically, and the relevant chemical components were cellulose, hemicelluloses, lignin, and ash. Using the response surface methodology, the optimum values of the hot alkaline extraction parameters, i.e., time, temperature, and NaOH concentration, were identified and experimentally validated. The physicochemical characterization of the isolated hemicelluloses was performed using HPLC, FTIR, TG, DTG, and 1H-NMR spectroscopy. The main hemicellulose components identified experimentally were xylan, arabinan, and glucan. The study emphasizes that both corn stalks and wheat straw are suitable as raw materials for hemicellulose extraction, highlighting the advantages of alkaline pretreatments and showing that optimization meth...
Alkaline extraction and carboxymethylation of xylans from corn fiber_Cellulose_2019.pdf
Cellulose, 2019
In the corn crop industry, of all the biomass produced, about 80% are residues. The so-called corn fibers, one of the most important residues of the corn processing industry, represent about 9% of the corn kernel weight, being a low value material that could, potentially, be used for making higher added value products. This work aimed to extract the hemicelluloses present in the corn fiber via alkaline extraction, with their subsequent functionalization for production of carboxymethyl xylans in mild conditions. The corn fibers were characterized for their contents of carbohydrates, lignin, extractives, total uronic acids, acetyl groups, and ash. Their arabinoxylans were extracted by 2–18% (w/v) sodium hydroxide at room temperature, for 5 h at 10% consistency, precipitated with ethanol, washed and then vacuum dried. The resulting extract was characterized by FT-IR, viscosity, arabinoxylan content and purity. It was demonstrated that CCE treatment provides a high purity and little degraded xylan, but the extraction yields are relatively low, in the range of 4.0–23.9% wt/wt depending upon extraction conditions. The use of corn fiber arabinoxylans to obtain hemicellulosic derivatives through chemical modification reactions was also evaluated. The arabinoxylans were derivatized by carboxymethylation with sodium monochloroacetate in a 2-propanol alkaline medium using different proportions of alcohol and alkali. The product carboxymethyl xylan was characterized by degree of substitution, FT-IR, DSC, and yield, and showed high degree of substitution, yield and enthalpy of fusion. This work proved the feasibility of producing hemicellulosic derivatives from corn fibers, which excludes the use of extreme conditions of solvents and temperature.
Green synthesis of xylan hemicellulose esters
Carbohydrate Research, 2011
The esterification of xylan type hemicelluloses, isolated from birchwood, was carried out firstly in homogeneous conditions using N,N-dimethylformamide (DMF) and lithium chloride (LiCl) in the presence of 4-dimethylaminipyridine (DMAP). The degree of substitution (DS) of xylan acetates ranged between 0.9 and 2.0 as a function of experimental conditions. Due to the problems of toxicity and recycling of DMF, an alternative method of esterification is reported in the second part of this work, performing in the absence of organic solvent and using DMAP or methanesulfonic acid (MSA) as catalysts. Acetylation reaction catalyzed by MSA was developed through an experimental design in order to achieve the highest DS under the mildest conditions. The significant factors and their interactions were identified. The optimization of reaction parameters allowed to obtain a high DS (1.6) and maximal yield (85%). Moreover, the reactivity of propionic and hexanoic anhydrides was evaluated and hydrophobic xylan esters with low degrees of substitution were obtained.
Extraction of xylan from wood pulp and brewer’s spent grain
Industrial Crops and Products, 2015
Hemicelluloses are potential raw materials for different types of biobased materials. Alkaline extraction of bleached birch kraft pulp yields pure, high molecular weight hemicellulose (xylan) and hemicellulosepoor pulp. In this work, the concentration of alkali and the extraction temperature were studied as parameters for xylan yield and mass balance in the extraction. Extraction at room temperature using 1 molar aqueous sodium hydroxide (NaOH) showed the highest value for the mass balance with 98.5 wt.% on dry matter of pulp-16.1 wt.% xylan in the extract and 82.4 wt.% extracted pulp. Recycling of 90% of the NaOH used for the extraction was demonstrated by ultrafiltration. The ultrafiltration process is thus a highly potential tool offering an economical way to simultaneously recycle chemicals and separate products from process liquids in xylan extraction and other biorefinery processes. The concept of alkaline extraction was also demonstrated for brewer's spent grain (BSG). Arabinoxylan comprised 80% of the carbohydrates in the alkaline extract of BSG. However, the selectivity of the extraction was poor as proteins, lipids and some lignin were also efficiently extracted from BSG in alkaline conditions.
2011
Humicola lanuginosus produced xylanase 1100 U/ mL in liquid state culture at optimum condition like pH 5, temperature 35°C, inoculum size 2mL, time period 4 days, Vogel's media 160 mL, 1 g corn steep liquir as best nitrogen source using sugar cane bagasse (5g) as a substrate. Xylanase passing from gel filteration obtained with an average specific activity of 379 U/mg protein, purification fold 1.9 and recovery yield of xylanase 10%. Patially purified xylanase has optimum pH 5.0, stability range of pH 6 to 7 and optimum temperature 45°C, stability range of temperature 35 to 40°C for 24 hours incubation. Km and Vmax of partially purified xylanase oxidize xylan were obtained 2 mM, 450 mM/min. MgCl enhanced the activity of partially 2 purified xylanase but silver nitrate strongly inhibited. Crude xylanase (2-10 mL) removed the reducing sugar 20 mg/mL from rice polish as compared with lignocellulosic substrates such as rice husks, corn stover and corn cobs.
Bioresource technology, 2017
The viability of single-step microwave-induced pressurized hot water conditions for co-production of xylan-based biopolymers and bioethanol from aspenwood sawdust and sugarcane trash was investigated. Extraction of hemicelluloses was conducted using microwave-assisted pressurized hot water system. The effects of temperature and time on extraction yield and enzymatic digestibility of resulting solids were determined. Temperatures between 170-200°C for aspenwood and 165-195°C for sugarcane trash; retention times between 8-22min for both feedstocks, were selected for optimization purpose. Maximum xylan extraction yields of 66 and 50%, and highest cellulose digestibilities of 78 and 74%, were attained for aspenwood and sugarcane trash respectively. Monomeric xylose yields for both feedstocks were below 7%, showing that the xylan extracts were predominantly in non-monomeric form. Thus, single-step microwave-assisted hot water method is viable biorefinery approach to extract xylan from li...