Efficiency of response surface methodology for optimizing Reactive Blue 21 dye removal with modified bentonite

Abstract

Bentonite was modified with cetyltrimethylammonium bromide by a simple method and was used as an adsorbent for the removal of Reactive Blue 21 dye. Reactive Blue 21 is an important dye used in the textile industry, which is very harmful for living creatures, especially humans. The response surface methodology (RSM) was used to study the effect of independent variables such as dye concentration (20, 40, 60, 80 and 100 mg/dm 3), time (10, 20, 30, 40 and 50 min), initial pH (2, 4, 6, 8, 10) and modified bentonite dosage (1, 2, 3, 4 and 5 g/dm 3) on Reactive Blue 21 dye removal efficiency from aqueous solutions. At the optimum conditions (modified bentonite dosage 5 g/dm 3 , dye concentration 61.3 mg/dm 3 , pH 4.78; time14.31 min), the predicted removal of Reactive Blue 21 on modified bentonite was 93.22%. In a confirmatory experiment, 92.01% dye removal has been obtained. Thus, the experimental investigation and statistical approach enabled us to model adsorption of Reactive Blue 21 on modified bentonite.