{"id":182076,"date":"2026-10-08T07:23:00","date_gmt":"2026-10-08T05:23:00","guid":{"rendered":"https:\/\/renewable-carbon.eu\/news\/?p=182076"},"modified":"2026-10-02T14:09:44","modified_gmt":"2026-10-02T12:09:44","slug":"carboxymethyl-cellulose-from-coconut-fiber-via-sequential-pretreatment","status":"publish","type":"post","link":"https:\/\/renewable-carbon.eu\/news\/carboxymethyl-cellulose-from-coconut-fiber-via-sequential-pretreatment\/","title":{"rendered":"Carboxymethyl cellulose from coconut fiber via sequential pretreatment"},"content":{"rendered":"\n\n\n<ul class=\"wp-block-list\">\n<li>Sustainable valorization of coconut residue for carboxymethyl cellulose (CMC) production<\/li>\n\n\n\n<li>Efficient extraction of lignin and hemicelluloses from coconut fiber via sequential chemical pretreatment<\/li>\n\n\n\n<li>Enrichment of cellulose content in coconut fiber pulps following the proposed sequential pretreatment<\/li>\n\n\n\n<li>Effective CMC synthesis, validated by high yield, and structural analyses (FT-IR and SEM)<\/li>\n\n\n\n<li>Advancement in the industrial processing of lignocellulosic biomass<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"577\" src=\"https:\/\/renewable-carbon.eu\/news\/media\/2026\/10\/1-s2.0-S0141813026036809-ga1_lrg-1024x577.jpg\" alt=\"\" class=\"wp-image-182091\" style=\"width:623px;height:auto\" srcset=\"https:\/\/renewable-carbon.eu\/news\/media\/2026\/10\/1-s2.0-S0141813026036809-ga1_lrg-1024x577.jpg 1024w, https:\/\/renewable-carbon.eu\/news\/media\/2026\/10\/1-s2.0-S0141813026036809-ga1_lrg-300x169.jpg 300w, https:\/\/renewable-carbon.eu\/news\/media\/2026\/10\/1-s2.0-S0141813026036809-ga1_lrg-150x85.jpg 150w, https:\/\/renewable-carbon.eu\/news\/media\/2026\/10\/1-s2.0-S0141813026036809-ga1_lrg-768x433.jpg 768w, https:\/\/renewable-carbon.eu\/news\/media\/2026\/10\/1-s2.0-S0141813026036809-ga1_lrg-1536x866.jpg 1536w, https:\/\/renewable-carbon.eu\/news\/media\/2026\/10\/1-s2.0-S0141813026036809-ga1_lrg-400x225.jpg 400w, https:\/\/renewable-carbon.eu\/news\/media\/2026\/10\/1-s2.0-S0141813026036809-ga1_lrg.jpg 1572w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">\u00a9 Federal University of Sergipe<\/figcaption><\/figure><\/div>\n\n\n<p>The recalcitrant structure and high lignin content of coconut fiber limit its use as a raw material for synthesizing carboxymethyl cellulose (CMC). This study examined the application of sequential pretreatments, autohydrolysis, alkaline extraction, and organosolv (AH-AE-OG), to valorize coconut lignocellulosic biomass for producing CMC. The pretreatment process effectively removed hemicelluloses, reducing their content from 16.88% in untreated coconut fiber to 0.59% after AH-AE-OG and bleaching steps. Cellulose content increased from 42.09% in the untreated sample to 80.71% after AH-AE-OG and 86.13% following bleaching. The Kappa number decreased from 44.20 to 6.77, indicating lignin removal and a CMC yield of 38.05%. The TGA showed the expected mass loss for cellulose, and FTIR and SEM confirmed the presence of cellulose and the formation of CMC fibers, validating the effectiveness of the pre-treatment and chemical modification. These findings highlight the potential of sequential pretreatment to extract a high-quality cellulosic pulp and to produce CMF from coconut fiber. The proposed pretreatment process (AH-AE-OG) represents a potential innovation, as it employs a two-step methodology to eliminate hemicelluloses and partial lignin, followed by a third step characterized by high-efficiency lignin extraction and enhanced preservation of the cellulose structure, thereby facilitating improved conversion to CMC.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Introduction<\/h3>\n\n\n\n<p>The coconut tree (<em>Cocos nucifera<\/em>) is a widely cultivated tropical crop that stands out for the significant production of lignocellulosic residues. Given the global annual production of approximately 65.5 million metric tons of coconuts in shell [1], wherein most of the fruit becomes underutilized residues, the valorization of these discarded materials offers an opportunity to develop sustainable, value-added byproducts. Coconut fruit primarily comprises edible fractions, the solid and liquid albumen, and the external residues, which consist of the endocarp, mesocarp, and epicarp [2]. Among these, the mesocarp, the fibrous layer, and a major component of the residues are of particular interest for biotechnological valorization due to their abundant availability and distinct physicochemical properties. This residue, known as coconut fiber (CF), is made up of 38% cellulose, 15% hemicellulose, and 41% lignin, making it a robust feedstock for producing important cellulose derivatives, such as carboxymethyl cellulose (CMC) [3].<\/p>\n\n\n\n<p>CMC is a versatile biopolymer used in various industries, including food, pharmaceuticals, textiles, and construction [4]. Traditionally, the production of CMC relies on the use of wood pulp [5] or cotton linter [6] as cellulosic feedstock. Cotton linter is preferred for the resulting high-quality CMC; however, it may be contaminated with genetically modified organisms from the world&#8217;s cotton supply chain [6]. Wood pulp serves as a well-established alternative to cotton linter, but it raises environmental concerns due to water consumption, soil erosion, reduction of soil nutrients and quality, and impacts on hydrological systems [7]. Therefore, despite their natural origin, both biomass sources are linked to unsustainable practices.<\/p>\n\n\n\n<p>For producing CMC, the main methods employed are chemical treatments, such as the Kraft, sulfite, and soda processes, which are used to remove lignin and produce cellulosic pulp from lignocellulosic material [8]. After cellulosic pulp is obtained, CMC is synthesized by cellulose etherification employing chloroacetic acid or its sodium salt, in the presence of an alkali and an inert solvent [9], [10]. This reaction modifies the cellulose hydroxyl group, converting it to a carboxymethyl group [11]. Different from cellulose, the resulting product is water-soluble and exhibits several interesting rheological properties, including viscosity, thickening, and thixotropy, making it suitable for various industrial applications [12].<\/p>\n\n\n\n<p>Given the importance of CMC to the industry, there is an extensive search for more sustainable pathways to produce this biopolymer with reduced environmental impact. In particular, there are efforts to utilize alternative non-wood lignocellulosic feedstock and to implement less intensive chemical treatments. In this sense, the exploration of lignocellulosic residues, such as coconut residues, represents a strategic approach for producing CMC and advancing the biocircular economy. Nonetheless, coconut residues require prior chemical pretreatment to remove lignin and hemicelluloses, yielding a cellulose-rich pulp suitable for CMC production.<\/p>\n\n\n\n<p>Despite their potential, the efficient use of coconut residues for CMC production remains challenging due to their high lignin content and compact lignocellulosic structure. These characteristics make the selective isolation of cellulose difficult and reduce the efficiency of the CMC synthesis. In some cases, single pretreatments are insufficient to achieve simultaneous delignification, hemicellulose removal, and preservation of the cellulosic structure [13], which may compromise the quality of precursor pulp to CMC.<\/p>\n\n\n\n<p>Among pretreatments reported in the literature for lignocellulosic biomass, autohydrolysis (AH), alkaline extraction (AE), and organosolv processes (OG) stand out. The AH process is an environmentally friendly method that uses only water at high temperatures. This process facilitates the breakdown of certain primary linkages, thereby solubilizing part of the hemicelluloses and enhancing the solid&#8217;s susceptibility to further treatments [14]. The AE is highly effective at removing hemicelluloses and a significant fraction of lignin under tailored chemical conditions, resulting in an enriched cellulose solid. Organosolv, on the other hand, uses organic solvents often combined with acids and bases to remove lignin, yielding a solid pulp with high cellulose content [15].<\/p>\n\n\n\n<p>Since each pretreatment method affects the lignocellulosic structure through different chemical mechanisms, integrating a sequence of pretreatments can promote complementary fractionation effects. A recent study highlighted that the inherent limitations of single methods have driven the development of integrated or sequential strategies aimed at maximizing the efficiency of lignocellulosic fractionation [16]. Thus, AH drives the selective depolymerization of hemicellulose and enhances biomass accessibility, AE promotes partial delignification by cleaving the linkages within the lignin-carbohydrate complex, while OG enables extensive delignification while preserving the integrity of the cellulosic structure. Consequently, the combination of AH-AE-OG sequential pretreatment can maximize the production of high-purity cellulosic pulp by extensively minimizing non-cellulosic components, which is highly advantageous for subsequent CMC synthesis. Based on this framework, this study hypothesizes that the sequential AH-AE-OG pretreatment promotes complementary biomass fractionation effects, favoring a cellulose-rich fraction suitable for CMC synthesis via etherification of carboxymethyl groups within the polysaccharide chain.<\/p>\n\n\n\n<p>Some studies in the literature report the use of sequential pretreatment to improve the breakdown process of lignocellulosic biomass. However, no study reports the AH-AE-OG sequence for producing CMC from coconut residues or any other source. Nath et al. [17] conducted a sequential AE-OG process to treat sugarcane bagasse, aiming to achieve delignification and cellulose recovery. This sequence resulted in a cellulose recovery of 66.1% and a delignification of 83.2%. Fialho et al. [18] employed the AH-OG sequence on wheat straw, achieving 75.6% delignification. Similar CMC from coconut residues has been explored using different sequential processes. Joyline et al. [19] obtained microcrystalline cellulose from AE pretreatment followed by treatment with peracetic acid and chloric acid to synthesize CMC. Gupta et al. [20] produced CMC from groundnut shells and coconut fiber pretreated with an alkaline solution, followed by acid hydrolysis and bleaching. Salehudin et al. [21] first treated coconut residue with an alkaline solution to extract cellulose, then synthesized CMC using an alkaline solution and chloroacetic acid.<\/p>\n\n\n\n<p>This study evaluates the efficacy of the sequential AH-AE-OG process for isolating a cellulose-rich pulp from coconut fiber and investigates the chemical and structural modifications induced at each consecutive step. This approach contributes to the valorization of agricultural residues as sustainable feedstocks for producing alternative biopolymers, specifically CMC. Furthermore, it provides critical insights into the development of multi-stage pretreatments for the fractionation of recalcitrant biomass. The primary novelty of this work lies in its integrated, sequential pretreatment design to fractionate coconut fiber, a strategy supported by tracking the chemical composition, structural modifications, and thermal properties of both the intermediate solid fractions and the final CMC product.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Section snippets<\/h3>\n\n\n\n<div style=\"height:17px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h3 class=\"wp-block-heading\">Coconut fiber (CF) obtention and initial analysis<\/h3>\n\n\n\n<p>Mature CF were sourced from an industrial unit in the northeast region of Brazil, washed, dried, manually cut into pieces approximately 2.5&nbsp;cm in size, and then homogenized. The raw CF was characterized chemically to determine lignin, holocellulose, \u03b1-cellulose, hemicelluloses and Kappa number, and structurally by thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), as described in Fig. 1.<\/p>\n\n\n\n<p>&#8230;<\/p>\n\n\n\n<p>please read the complete article under <a href=\"https:\/\/www.sciencedirect.com\/science\/article\/abs\/pii\/S0141813026036809\">https:\/\/www.sciencedirect.com\/science\/article\/abs\/pii\/S0141813026036809<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>The recalcitrant structure and high lignin content of coconut fiber limit its use as a raw material for synthesizing carboxymethyl cellulose (CMC). This study examined the application of sequential pretreatments, autohydrolysis, alkaline extraction, and organosolv (AH-AE-OG), to valorize coconut lignocellulosic biomass for producing CMC. The pretreatment process effectively removed hemicelluloses, reducing their content from 16.88% [&#8230;]<\/p>\n","protected":false},"author":59,"featured_media":182091,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_seopress_robots_primary_cat":"none","nova_meta_subtitle":"The recalcitrant structure and high lignin content of coconut fiber limit its use as a raw material for synthesizing carboxymethyl cellulose (CMC)","footnotes":""},"categories":[5572],"tags":[5842,13702,12690,11323],"supplier":[28671],"class_list":["post-182076","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-bio-based","tag-biomass","tag-cellulosics","tag-lignocellulosics","tag-naturalfibers","supplier-federal-university-of-sergipe-universidade-federal-de-sergipe"],"_links":{"self":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/182076","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/users\/59"}],"replies":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/comments?post=182076"}],"version-history":[{"count":2,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/182076\/revisions"}],"predecessor-version":[{"id":182122,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/182076\/revisions\/182122"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/media\/182091"}],"wp:attachment":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/media?parent=182076"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/categories?post=182076"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/tags?post=182076"},{"taxonomy":"supplier","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/supplier?post=182076"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}