Zinc oxide nanorod-loaded activated carbon for ultrasound-assisted adsorption of safranin O: Central composite design and genetic algorithm optimization

This paper focuses on the development of an effective methodology to obtain the optimum ultrasonic-assisted removal of a dye, safranin O (SO), under optimum conditions that maximize the removal percentage, using ZnO nanorod-loaded activated carbon (ZnO-NRs-AC) in aqueous solution. Central composite design coupled with genetic algorithm was used for parameter optimization. The effects of variables such as pH, initial dye concentration, mass of ZnO-NRs-AC and sonication time were studied. The interactive and main effects of these variables were evaluated using analysis of variance. The structural and physicochemical properties of the ZnO-NRs-AC adsorbent were investigated using field emission scanning electron microscopy and X-ray diffraction. Adsorption equilibrium data were fitted well with the Langmuir isotherm and the maximum monolayer capacity was found to be 32.06 mg g(-1). Studies of the adsorption kinetics of the SO dye showed a rapid sorption dynamic with a (pseudo-)second-order kinetic model, suggesting a chemisorption mechanism.