Optimization, Equilibrium and Kinetic Studies of Basic Red ۲ Removal onto Waste Gossypium hirsutum Seeds

Cationic dye - basic red ۲ (BR۲) was removed from aqueous solutions by sulfuric acid activated waste Gossypium hirsutum seeds (WGSAB). The main and interactive effects of five process variables such as, adsorbent dose (۱.۲۵ – ۵ g/L), initial dye concentration (۱۰۰–۳۰۰ mg/L), contact time (۱–۳ h),  pH (۲ – ۱۲) and temperature (۲۰ – ۴۰۰C) were investigated via  response surface methodology (RSM) based on Box–Behnken statistical design.  The optimum values of the key variables were estimated using Derringer’s desirability function. The optimal values were found to be at an adsorbent dose ۲.۴۱ g, initial dye concentration ۱۵۰ mg/L, pH ۸.۶۹, temperature ۳۳.۵۷۰C, and contact time ۱.۴۲ h with the maximum desirability of ۹۱%. The equilibrium data obeyed Redlich-Peterson isotherm which showed that the WGSAB was heterogeneous and BR۲ was adsorbed in multilayers. The kinetic investigation showed that the BR۲ was chemisorbed on WGSAB surface following Avrami fractional order kinetics. The thermodynamic parameters revealed that the BR۲ adsorption process was spontaneous and endothermic. Regeneration of exhausted WGSAB found to be possible via acetic acid as elutant.

کلیدواژه ها:

Adsorption ، Box–Behnken ، Derringer’s desirability ، Gossypium hirsutum seed ، equilibrium