Investigation into the Role of Surface Modification of Cellulose Nanocrystals with Succinic Anhydride in Dye Removal

Abstract

Herein, the effect of surface modification of cellulose nanocrystals (CNC) on the sorption of dyes from waste textile effluent (methylene blue as a model) was achieved. The esterification of the isolated CNC from wood sawdust by acid hydrolysis was performed through melting with succinic anhydride (SA). At using 1:3–1:9 as the feeding ratios of CNC to SA, the succinylated CNC (CNC-SA) was obtained with degree of substitution of 1.6–2.2 and carboxylic content of 286.8–381.7 mmol/kg. Both of diameter size and zeta potential of the prepared CNC-SA were gradually enlarged by increasing the reactant feed ratio, indicating the successful modification of CNC surface with highly stable particles via increasing the negative charges on the outer surface. FTIR and XRD affirmed the change in the chemical structure as well as crystallinity of CNC after succinylation reaction. The prepared succinylated CNC was applied in the removal of methylene blue (MB) dye and the data showed that the sorption capacity is a direct proportional linear relation with the contents of carboxylic group. Within 120 min contact time, the sorption capacity was enlarged from 64.1 mg/g for CNC to 84.1 mg/g for CNC-SA3. The sorption data was fitted well to the first order kinetic model. Due to the esterification, the rate of sorption reaction is accelerated by double factor. These findings will maximize the benefit of esterified CNC in water treatment.