Adsorption of basic red 9 on activated waste Gossypium hirsutum seeds: Process modeling, analysis and optimization using statistical design

•Basic red 9 was adsorbed onto H2SO4 activated waste Gossypium hirsutum seeds.•The key factors controlling batch adsorption were identified and discussed using 25 FFD.•A quadratic model developed using BBD and illustrated by 3D response surface plots.•Optimized conditions with key factors were evaluated using Derringer's desirability.•Isotherm and kinetic models describing the adsorption process were examined.

Sulfuric acid activated immature Gossypium hirsutum seed was utilized as adsorbent for the batch adsorption of basic red 9. The main and interactive effects of five process factors like, adsorbent dose, initial dye concentration, contact time, pH and temperature were investigated to select the influencing key factors via 25 two-level full factorial design. Box–Behnken statistical design with the selected key factors employed for process optimization. The simultaneous optimization by Derringer's desirability function indicated that 54.27% removal of BR9 could be possible at the optimal conditions. Isotherm and kinetic studies confirmed the chemisorption on homogeneous and heterogeneous patches.

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