Phenol adsorption equilibrium and kinetics on zeolite X/activated carbon composite

• The zeolite X-activated carbon composite is used as adsorbent for removal of phenol.
• The adsorption kinetic data is best described by pseudo-second-order model.
• The equilibrium adsorption data follows Redlich–Peterson isotherm.
• Adsorption of phenol onto the composite is spontaneous, favorable and endothermic.

The zeolite X/activated carbon composite (X/AC) was prepared from elutrilithe by adding pitch powder and solid SiO2 was used to adsorb phenol from aqueous solutions. To investigate the influences of solution pH, contact time and temperature on the phenol adsorption capacities of the composite material, batch experiments were conducted under different conditions. The adsorption performances of 13X, the activated sample (AC) and X/AC were also compared. The results showed X/AC exhibited better adsorption performance for the removal of phenol than 13X and AC. Furthermore, the adsorption ability of X/AC was revealed by equilibrium, kinetics and thermodynamic parameters. The adsorption kinetic data could be better represented by pseudo-second-order equation and the intra-particle diffusion model. It is shown that the adsorption rate was controlled by both the pore diffusion and the external layer diffusion. The equilibrium adsorption data were better described by Redlich–Peterson and Freundlich equations, indicating that X/AC possessed various functional groups. The obtained thermodynamic parameters demonstrate that adsorption of phenol was spontaneous, favorable, endothermic, and realized by the electron donor-acceptor complex and the solvent effects.

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