Adsorption of dye from wastewater using chitosan-CTAB modified bentonites

► Adsorption capabilities of Na-Bent are low, but higher for 1CTS-10CTAB-Bent. ► The removal efficiency of weak acid scarlet on 1CTS-10CTAB-Bent was higher than 85%. ► The adsorption capacity of the 1CTS-10CTAB-Bent was 102.0 mg g−1. ► The adsorptions are spontaneous. ► The Langmuir and Temkin models both described the adsorption isotherm data well.