Facile synthesis and characterization of microporous-structured activated carbon from agro waste materials and its...

Biomass-derived activated carbon was prepared from the agro waste materials, (wild sugarcane (WS) and saw dust (SD)) by chemical activation using phosphoric acid. The crystallinity, morphology, functional groups of the synthesized activated carbon were investigated. The effects of contact time (10-60 min), mass of adsorbent (0.05-0.2 g) and concentrations of CO₂ (1 × 10^-4 to 10 × 10^-4M) were analysed and the optimum adsorption conditions were found. Freundlich, Langmuir, Temkin, Dubinin-Radushkevich and Sips isotherm were used to analyse the adsorption data. The adsorption process was fitted with the Freundlich model. Adsorption capacity of agro waste-based sorbent was 5.225 × 10^-3mol/g. Thermodynamic parameters, such as ΔH⁰, ΔG⁰, ΔS⁰ , were calculated and it was found that the present system was a spontaneous process. From the kinetic studies, it was inferred that the Pseudo-second-order kinetics describes the kinetics of CO₂ on AC-WSSD with an equilibrium point attained at 50 minutes with a high R² value of 0.9602. The Brunauer Emmett Teller (BET) surface area of 1220 m²/g and an iodine value of 1360 m²/g were better indications for adsorption process. The interaction between CO₂ and functional groups on the surface of the activated carbon was confirmed by FTIR. Desorption studies were carried out for three cycles with an efficiency of 93.2%.