Saccharification of Brazilian sisal pulp: evaluating the impact of mercerization on non-hydrolyzed pulp and hydrolysis products

Abstract

Cultivation of sisal, a plant with a short growth cycle, is highly productive in Brazil. This work is part of extensive research in which sisal is valued. In these studies, sisal fibers are used in the preparation of bio-based composites and in the derivatization of the pulp, including posterior preparation of films. This study aimed to examine the use of sisal pulp in the production of bioethanol, which can potentially be a high efficiency process because of the cellulose content of this fiber. A previous paper addressed the hydrolysis of sisal pulp using sulfuric acid as a catalyst. In the present study, the influence of the mercerization process on the acid hydrolysis of sisal pulp was evaluated. Mercerization was achieved in a 20% wt NaOH solution, and the cellulosic pulp was suspended and vigorously mixed for 1, 2 and 3 h, at 50°C. The previously characterized mercerized pulps were hydrolyzed (100°C, 30% H 2 SO 4 , v/v), and the results are compared with those obtained for unmercerized pulp (described in a companion paper). The starting sample was characterized by viscometry, a-cellulose content, crystallinity index and scanning electron microscopy. During the reactions, aliquots were withdrawn, and the liquor was analyzed by HPLC. The residual pulps (non-hydrolyzed) were also characterized by the techniques described for the initial sample. The results revealed that pretreatment decreases the polyoses content as well as causes a decrease of up to 23% in the crystallinity and up to 21% in the average molar mass of cellulose after 3 h of mercerization. The mercerization process proved to be very important to achieve the final target. Under the same reaction conditions (30% and 100°C, 6 h), the hydrolysis of mercerized pulp generated yields of up to 50% more glucose. The results of this paper will be compared with the results of subsequent studies obtained using other acids, and enzymes, as catalysts.

Bio-based Films from Linter Cellulose and Its Acetates: Formation and Properties

“…The delignification of lignocellulosic fibers, such as wood or annual non-woody fibers, has been widely investigated because of the interest of the paper industry [7,8], and other interests such as those of biorefineries that produce cellulosic ethanol [9,10,11,12,13,14,15], or the area of materials focused on cellulose and its derivatives [16,17,18,19,20]. It is expected that the availability of celluloses from different sources, hence with different properties, will increase significantly.…”

Composites based on renewable materials: Polyurethane‐type matrices from forest byproduct/vegetable oil and reinforced with lignocellulosic fibers

“…The use of renewable raw material (biomass) to produce chemical substances, materials and energy is an interesting topic, both in basic and applied research. Currently, the use of lignin is even more important because lignin is a by‐product of biorefineries that produce ethanol from cellulose found in wood and lignocellulosic fibers 2–4…”

Adding value to the Brazilian sisal: acid hydrolysis of its pulp seeking production of sugars and materials

“…In this context, in other paper (Lacerda et al 2012) it has been considered the influence of prior mercerization of the pulp on the hydrolysis process.…”

“…Sulfuric acid (H 2 SO 4 ) was chosen for the first stage of the study due to its efficiency in pulp hydrolysis: future comparisons will be made with other acids. Another part of this study (Lacerda et al 2012) evaluates the effect of prior mercerization (treatment with aqueous alkali solution) on the acid hydrolysis of sisal pulp.…”