Cellulose Carbamate Synthesis and Dissolution from Wheat Straw: Influence of Biomass Origin and Inorganic Removal Compared to Softwood Dissolving Pulps

Growing concerns over sustainability are driving innovation in textiles, especially as demand and waste increase with population growth and fast fashion. Agricultural residues such as wheat straw (WS) have emerged as promising alternatives to wood-based feedstocks; however, their use in indirect dissolution routes for man-made cellulosic fiber production remains underexplored. Cellulose carbamate (CC) offers a safer alternative to viscose due to its lower reactant toxicity. In this study, CC was synthesized from one softwood and two WS-based prehydrolysis kraft dissolving pulps (untreated and EDTA-chelated) at ~130 ºC for 1–6 h to determine optimal conditions for derivatization and dissolution in an alkali solvent system. Maximum CC solubility was achieved after 2 h of reaction. The EDTA-chelated WS pulp reached degrees of substitution comparable to softwood, while untreated WS performed worse. Results suggest that metal ions in WS catalyze undesirable triuret side reactions, forming cyanuric acid and crosslinks that reduce solubility. EDTA treatment mitigated this effect, lowering insoluble content and improving suitability for fiber spinning. The findings demonstrate that WS is a viable feedstock for CC-based MMCFs, provided that targeted pretreatments remove interfering inorganics.