Adsorptive removal of phenol from aqueous solutions by copper (cu)-modified scoria powder: process modeling and kinetic evaluation

摘要

Phenol compounds are regarded as hazardous pollutants due to their toxicity and carcinogenic properties to human health at low concentrations. So, this study was aimed to investigate the phenol adsorption by copper (Cu)-modified scoria powder, which is a low-cost adsorbent for the removal of organic compounds. All the experiments were performed based on the full face-centered central composite design experimental plan and analyzed using response surface methodology. The samples were analyzed using various conditions including adsorbent dose (0.1-1g/l), phenol concentration (50-250mg/l), and contact time (5-100min). Three-dimensional plots reveal the relationship between the phenol removal efficiency and the paired factors, which describe the behavior of scoria powder in the removal of phenol from aqueous solution. The models showed that phenol removal efficiency in aqueous solution affected by four studied factors. A maximum removal efficiency of phenol achieved was more than 96% at the optimum conditions (scoria dosage of 1g/l, phenol concentration of 50mg/l, and contact time of 100min). Process of kinetic parameters were also evaluated and modeled using five kinetic models including pseudo-first-order equation, second-order equation, modified Freundlich, pore diffusion, and Elovich. The best fit of experimental adsorption data was calculated by means of the pseudo-second-order model. Equilibrium data obeyed the Freundlich and Langmuir isotherms, and found that the equilibrium data well obeyed the Langmuir isotherm.