eng Oriental Scientific Publishing Company Material Science Research India 0973-3469 2026-06-20 23 1 20 38 24146 article Abu Mahmud 1 Lila Dipto Joy 2 Md. Habibul Islam 3 Shamsad Sharmin 4 Department of Materials Science and Engineering, University of Rajshahi, Rajshahi, Bangladesh Water hyacinth (Pontederia crassipes), an invasive aquatic weed with severe negative ecological impacts, represents an abundant and low-cost biomass resource due to its high cellulose content. In this study, cellulose was extracted from water hyacinth through degreasing, alkaline treatment, and bleaching, followed by chemical conversion into carboxymethyl cellulose (CMC) via mercerization and etherification. Structural modification was confirmed by FTIR spectroscopy which indicated successful etherification without degradation of the cellulose backbone. X-ray diffraction analysis and morphological examination by SEM of cellulose and CMC showed a clear transformation from well-aligned fibrillar structures in cellulose to a more fragmented, rough, and flaky surface in CMC. Both SEM and X-ray diffraction analysis revealed a pronounced reduction in crystalline order after carboxymethylation, reflecting disruption of the hydrogen-bonded cellulose lattice and increased amorphous character. EDX analysis also revealed a systematic increase in oxygen content consistent with incorporation of oxygen-bearing carboxymethyl groups. Thermogravimetric analysis demonstrated major CMC degradation onset at approximately 250°C suggesting its robust thermal degradation capabilities suited for industrial applications. The synthesized CMC achieved a degree of substitution of 0.69 ± 0.03 (n = 3) indicating a moderate degree of carboxymethyl substitution. From Atomic Absorption Spectroscopy (AAS), a significant decrease in total residual chromium is observed after CMC was introduced and found that CMC can remove 98.69% of total chromium within 30 minutes from water when used at a concentration of 0.75 g/L. Previous works mainly focus on either cellulose or CMC-modified cellulose derived from water hyacinth for water treatment. But here we report the use of CMC extracted from water hyacinth in its nascent form without further chemical modification or composite formation for chromium removal from wastewater for the very first time. https://www.materialsciencejournal.org/vol23no1/removal-of-chromium-from-wastewater-using-carboxymethyl-cellulose-derived-from-water-hyacinth/ CMC Chromium removal Tannery effluent Wastewater Water hyacinth