Grafting of regenerated cellulose films with fibrous polymer and modified into phosphate and sulfate groups: Application for removal of a model azo-dye

Regenerated cellulose films (RCF) were functionalized with bromoacetyl bromide as atom transfer radical polymerization (ATRP) initiator. Then, poly(glycidyl methacrylate), p(GMA), as a functional polymer was grafted via surface initiated ATRP (SI-ATRP) on the RCF. The polymer grafted RCF was modified into phosphate [i.e.,(RCF-g-p(GMA)-PO3H2)] and sulfate [i.e.,(RCF-g-p(GMA)-SO3H)] groups using H3PO4 and H2SO4, respectively. The synthesized composite adsorbents were characterized using FTIR, SEM and analytical methods to evaluate the structural and morphological characteristics of the modified cellulose based films. The effectiveness of both cation exchange films [(RCF-g-p(GMA)-PO3H2) and (RCF-g-p(GMA)-SO3H)] for the removal and recovery of Chlorazole Black E (CBE) dye was investigated from aqueous solutions. The adsorbent dosage, pH, ionic strength, initial concentration of dye, and contact time were studied to optimize the conditions for maximum adsorption. The adsorption process was pH dependent, shows maximum removal at pH 5.5 and 2.0 for RCF-g-p(GMA)-PO3H2 and RCF-g-p(GMA)-SO3H, respectively. The maximum adsorption capacities were found to be 165.7 and 268.6 mg/g for the RCF-g-p(GMA)-PO3H2 and RCF-g-p(GMA)-SO3H, respectively. Kinetic studies showed that pseudo-second-order kinetic model described well the kinetics of adsorption of the CBE dye. Adsorption equilibrium data were correlated with the Langmuir, and Freundlich isotherm models. Adsorption/desorption for 10 cycles showed the possibility of repeated use of modified RCF for removal and recovery of the dye from aqueous solutions. These presented both cationic adsorbents had several operational advantages for the dye removal from aqueous medium indicating that they are talented materials to be used in wastewater treatment. Finally, the RCF-g-p(GMA)-SO3H adsorbent with strong acidic groups can be utilized for the removal of basic dyes from industrial wastewaters in sight of its favorable high adsorption capacity.