Effect of Processing Time of Steam-Explosion for the Extraction of Cellulose Fibers from Phoenix canariensis Palm Leaves as Potential Renewable Feedstock for Materials

Abstract

This paper briefly discusses the utilization of pruning wastes as a lignocellulosic source of cellulose fibers, which could be of potential use in the development of valuable materials such as sustainable textiles and fillers for footwear components including uppers and soles. Phoenix canariensis palm leaves, one of the most common plants found in the local environment of the Alicante region (Spain), was used as a biomass raw material. Determining appropriate processing parameters and their desired range of maximum cellulose extraction states is key to improving yields. Therefore, this study aimed at determining the effect of processing conditions on cellulose extraction by optimizing the hydrothermal process, as a part of overall combined processes involving several steps. Specifically, the time of the steam-explosion stage was varied between 15 and 33 min in order to maximize the cellulose extraction yield. The composition of both the extracted fibers and the resulting by-product solutions generated during the different steps were determined by FTIR and TGA in order to analyze the effectiveness of removing hemicellulose, lignin and extractives as well as the removed substances at each stage for their further valorization. Additionally, the morphology of cellulosic fibers was evaluated by SEM and their crystallinity by XRD. Crystalline cellulose fibers were successfully extracted from pruning biomass wastes, achieving more efficient removal of hemicellulose and lignin when the hydrothermal process was assessed over 25–33 min. This resulted in finer and smoother fibers, but the crystallinity of α-cellulose decreased as the time of steam-explosion increased to 33 min. The characterization of waste solutions generated after the different extraction steps confirmed that the most effective treatments to remove lignin and hemicellulose from the cell wall are alkaline pretreatment and a hydrothermal process.

Steam Explosion-Based Method for the Extraction of Cellulose and Lignin from Rice Straw Waste

“…In this study, a multistep method, based on the sequential execution of several chemical and physical processes, was employed for the isolation of cellulose fibres from rice straw. The methodological framework, adapted from Pérez-Limiñana et al [32], was comprehensively optimised to enhance the extraction efficacy while striving for a reduction in the number of stages, duration, and reagent use.…”

“…In line with the circular economy principles, the process aims to utilise all constituents of rice straw. The refined method detailed herein builds on the procedures established by Pérez-Limiñana et al (2022) [32] while introducing new process optimisations suitable for the rice straw feedstock. The process efficiency has been evaluated based on the yield and purity of the extracted cellulose and the utility of the byproducts in lignin valorisation.…”

“…The standard initial process consisted of an alkaline pretreatment followed by a 33 min steam explosion, a 5 h oxidation period, and finally, a bleaching stage [32]. From this baseline, modifications were explored, such as omitting the pretreatment, varying the steam explosion duration (33 min, 1 h, 2 h, and 4 h), implementing or excluding ScCO 2 , and adjusting the oxidation times (3, 4, and 5 h).…”

“…These processes also generate large amounts of residues and require expensive and resistant processing equipment as well as considerable waste treatments, thus increasing their environmental footprint. This has driven the scientific community to seek more sustainable and eco-friendly alternatives for cellulose and lignin extraction, such as steam explosion, ultrasound-assisted pretreatment, supercritical fluid pretreatment, and others, in addition to combining both green and conventional methods in order to reduce the impact and optimise the process [31][32][33][34][35][36]. Furthermore, the extraction of cellulose and lignin from biomass such as rice straw is fraught with challenges, including effectively removing silica and developing a practical method to isolate its key components [37].…”

“…This research conducts a thorough assessment and refinement of the multistep cellulose and lignin extraction protocol previously developed at INESCOP [32], particularly focusing on rice straw waste from the Albufera of Valencia. This study not only adapts but significantly enhances the steam explosion technique, specifically targeting the valorisation of rice straw, a biomass source hitherto underexplored in this context.…”