Removal of malachite green from aqueous solution using Ficus benjamina activated carbon-metal oxide synthesized by pyrocarbonic acid microwave

Abstract

Activated carbon has a high adsorption feature because it contains a specific high surface area, as this property helps it to adsorb organic, inorganic, and colloidal substances, whether these substances are liquid or gaseous. In this research, Ficus benjamina plant residues were selected as a precursor for preparation of the activated carbon (AC), and composite photocatalyst (AC-TiO2) adsorbents using pyrocarbonic acid microwave technique. The Ficus benjamina and activated carbon was characterized using Fourier-transform infrared spectroscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy and Brunauer–Emmett–Teller techniques. A certain range of conditions (impregnation time, acid concentration, impregnation ratio, microwave power, and microwave exposure time,) has been identified and analyzed for the production of activated carbon using STATISTICA 12.5 software with Taguchi method. The results showed that the best productivity of activated carbon in a specific range of condition was 80% phosphoric acid concentration, 1:2 impregnation ratio (weight ratio), 6-h impregnation time, 20-min microwave exposure time and 700-watt microwave power. Likewise, Taguchi method was used to identified and analyzed the experimental adsorption data of initial dye concentration, mixing time, and adsorbent dosage. In addition, the adsorption data were analyzed and fitted by Langmuir and Freundlich isotherm models, and the result was well fitted with the Freundlich model. Likewise, the adsorption kinetics were fitted with pseudo-first-order and pseudo-second-order models and the results were well represented by the pseudo-second-order model.