Chemical Pretreatment of Lignocellulosic Biomass for the Production of Bioproducts: An Overview

Lignocellulosic biomass has attracted great interest from researchers. It was due to the abundance of this valuable material which can be converted into value-added materials such as nanocellulose, biocomposites, bioelectricity, biohydrogen and biosugars. Lignocellulosic biomass is consisting of the three major components which are cellulose, hemicellulose and lignin. In order to utilize lignocellulosic biomass for bioproducts manufacturing, they need to be pretreated prior to further processing. Pretreatment can be carried out either by mechanical, chemical, biological or combination of all these methods. Chemical pretreatment are the common method used to pretreat the lignocellulosic biomass in order to completely or partially remove the components. During the past few years, a large number of chemical pretreatment including lime, acid, steam explosion, sulfur dioxide explosion, ammonia fiber explosion, ionic liquid and others have been discovered for efficient pretreatment of biomass. Several types of chemical pretreatment of fibers and their future direction and also challenges were tackled in this review. This review could be beneficial for future directions in the pretreatment of fiber for the development of several products.

Pretreatment Ethanol From Cellulosic

<p><strong>Abstract.</strong> Pre-treatment is an important tool for practical cellulose conversion processes and can be carried out in different ways such as mechanical pre-treatment, steam explosion, ammonia fiber explosion, supercritical CO2 treatment, alkali or acid pretreatment, ozone pre-treatment, physicochemical pretreatment, dilute-acid pretreatment and biological pre-treatment. Biomass pretreatment with hot water (HW) is the most investigated physicochemical method use the differences in the thermal stabilities of the major components of lignocellulosic materials. Acid pretreatment of lignocellulosic biomass aims at increasing the sugar substrate digestibility, defined as the concentration of reducing sugars after the hydrolysis, by microorganisms. Acid hydrolysis is an attractive pretreatment method as the hemicellulose degradation runs with the efficiency of approximately 20-90%, depending on the process conditions. Dilute acid (DA) processes with continued research and development, no significant breakthroughs have been made to raise the glucose yields much higher than 65-70%. Acid pretreatment is much more effective than water and alkaline pretreatment in terms of cellulose accessibility increase compared with DA and HW pretreatment.</p><p> </p><p><strong>Keywords:</strong> ethanol, cellulosic, pre-treatment</p>

Reflowed Aqua Ammonia Explosion Pretreatment for Corn Stover

Based on ammonia recycled percolation (ARP) and combined with the advantage of ammonia fiber explosion (AFEX), a set of reflowed aqua ammonia explosion pretreatment (RAAEP) equipment was developed. According to the previous orthogonal experiment experimental results, the optimal pretreatment conditions were at 90°C, 9 min retention time, water to dry corn stover loading of 0.8:1(w/w), and aqua ammonia flow rate is 1.5L/min. The cellulose content of the pretreated corn stover was 50.46 % and the glucan and xylan enzymatic digestibility was 86.45 % and 95.77% respectively. The reflowed aqua ammonia not only caused fiber swelling and an efficient delignification (up to 62.5%) of biomass, but also altered the cellulose crystalline structure. The SEM picture and FTIR spectra confirmed swelling and significant delignification effects of the RAAEP process. The X-ray crystallography data indicated that the rigid structure of corn stover was disrupted with more crystallization fiber being exposed after the pretreatment process, but the crystallinity increased due to the removal of amorphous materials (lignin and hemicelluloses).