Cellulose was isolated from cotton by scouring in sodium hydroxide, and bleaching. Percentage cellulose obtained was about 96.0% ± 0.70 with a moisture content of about 4.80% ± 0.43. Heterogeneous carboxymethylation in an organic solvent was carried out on the cellulose to produce carboxymethylated cellulose (CMC). These derivatives labelled as CMC-20, CMC-30, and CMC-40 of different degree of substitution of 0.060, 0.078, 0.096 produced using 20%, 30%, and 40% sodium hydroxide concentrations respectively. Carboxymethylation was confirmed using FT-IR spectroscopy. Presence of characteristic bands of cellulose, and absorption bands for CMC were observed in the spectra data of the carboxymethylated cellulose fibers. The presence of strong absorption bands at around 1600−1640 cm-1 and 1400−1450 cm-1 were observed for the three carboxymethylated derivatives due to symmetric and asymmetric vibrations of ionized −COO− group. This indicated that carboxyl groups were grafted onto the cellulose backbone. The anionic carboxymethylated cellulose prepared was used in sorption of a cationic dye, methylene blue. Sorption study of a cationic dye was carried out to determine effect of pH, equilibrium contact time, initial concentrations, and adsorption isotherm models of Langmuir and Freudlich were tested. The uptake of methylene blue was minimal at pH of 2 and increased with increasing pH due to deprotonation of the –COOH introduced onto the cellulose by carboxymethylation reaction as the alkalinity of the sorption medium increases. Effects of contact time shows the carboxymethylated cellulose reached equilibrium sorption capacity of about 70% within 30 minutes, while just about 34% reached equilibrium sorption at about 40 minutes of contact time for the cellulose. Results shows an increase in sorption capacity of the carboxymethylated cellulose as sodium hydroxide concentration increases and sorption equilibrium reaches optimal at concentration of 150mg/l for a sorbent dose of 0.5g. Equilibrium data fitted well to the Langmuir model than Freudlich model for the cellulose, CMC-20, CMC-30, and CMC-40, with CMC-40 showing the maximum sorption capacity of 111.1mg/g. That is, introduction of the carboxylate functional group on cellulose backbone is an efficient method of improving the sorption capacity of cellulose towards removal of cationic industrial effluent containing dye which would have polluted the environment.

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