Organo-modification of bentonite is necessary for enhancement of its adsorption capacity toward the organic dyes pollutants due to its negative-charged surface. In this study, novel adsorbent, carboxymethyl cellulose (CMC) grafted by poly(2-(dimethylamino) ethyl methacrylate) modified bentonite (Bent/CMC-g-P(DMAEMA)) composite, was synthesized. Its structure was characterized by SEM, TEM, XRD, TG, FT-IR, Zeta potential and nitrogen sorption measurements. The tunable adsorption property of Bent/CMC-g-P(DMAEMA) toward the anionic dyes(congo red (CR) and methyl orange (MO)) was investigated by changing the mass ratio of CMC to Bent + CMC in Bent/CMC-g-P(DMAEMA) composite. The adsorption property of 20CMC-Bent (20% of CMC in total amount of CMC + Bent) in the cationic and anionic binary dyes system, methylene blue (MB)/MO was also investigated. The results showed that both MO and MB could be removed effectively and sodium dodecyl sulfate exhibited selective suppressing effect toward MO in the binary system. Three isotherm models in linear and non-linear regressions were employed and assessed by various error functions. Considering all these unique characteristics, Bent/CMC-g-P(DMAEMA) can be considered as potential material for anionic dye removal from textile wastewater in industry. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.