Optimizing Dye Adsorption Onto a Waste-Derived (Modified Charcoal Ash) Adsorbent Using Box–Behnken and Central Composite Design Procedures

The objective of this work was to optimize the experimental conditions for adsorption of reactive azo dye using a waste-derived adsorbent, modified charcoal ash. With this aim, Box–Behnken and Central Composite Design models were applied to achieve maximum dye adsorption and minimum operation costs. In the models studied, independent variables were pH (1–12), ash dosage (0.02–0.1 g/50 ml), dye concentration (10–200 mg/L), and operation time (10–130 min). The quadratic models were developed for the predetermined responses (dye removal and operation cost), and it was clearly seen that the experimental data fit well to model predictions statistically ( R 2 ≥ 0.89 and “Prob > F ”