Non-Linear Kinetic, Isotherm Models Approach for Mercury Adsorption on Facile Synthesized Activated Carbon from Zea Mays Roots

Carbonization of Zea mays roots at 600˚C in the presence of nitrogen atmosphere and its activation at 800˚C under the hydraulic environment for an hour was used for mercury adsorption studies. Activated carbon (AC) was characterized by P-XRD, Raman, SEM, EDX, BET, and pH methods. By the inductively coupled plasma-mass spectrometer technique, mercury adsorption on AC was investigated under optimum conditions (at a pH of 5, 1mg/mL of adsorbent, 10 ppm of mercury, and 60˚C for 60 min). Evaluation of the statistical parameters for non-linear isotherm and kinetic models has disclosed that mercury adsorption on AC obeyed a pseudo-first-order kinetic model and Freundlich adsorption isotherm which was further confirmed by the Sips isotherm at equilibrium. The surface area of AC is 422 m2/g and has shown an adsorption capacity of 40.8 mg/g mercury and 99.43% removal efficiency. The dimensionless separation factor (RL) was 0.018 which pronounces favorable adsorption of mercury. The larger C value (7.3675 mg/g) and not passing the plot through the origin (R2 =0.9872) in Web Morris intraparticle diffusion model evidenced that IPD is not only rate-limiting step and other kinetic models (PFO) were also involved in the mercury sorption on AC. Desorption experiments were carried out in warm water and the percentage of mercury that has been restored was 6% due to the quasi-chemical bond between AC and mercury.