The 3-chloro-2 hydroxypropyltrimethyl ammonium chloride was successfully introduced into the β-cyclodextrin-modified chitosan to create the multicomponent adsorbent O-HTACC-g-CD. The structure of sorbent was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy. The adsorption capacity of O-HTACC-g-CD toward phenol was investigated as a function of pH, temperature, contact time as well as adsorbent dosage. The Box-Behnken response surface methodology was employed to optimize the effects of experimental parameters including adsorbent dose, pH, and time on the adsorption of phenol at 298.15 K. The obtained optimal values for adsorbent dose, pH, and time were 0.06 g, 6, and 200 min, respectively. The obtained experimental data follows the pseudo-second-order kinetic and Langmuir model. The thermodynamic parameters such as free energy change, enthalpy change, and entropy change were calculated, revealing that adsorption of phenol on O-HTACC-g-CD is a spontaneous and exothermic process. The prepared O-HTACC-g-CD displayed high adsorption capacity (39.98 mg g-1) and excellent removal rate (96%) for phenol from the aqueous solution at 288.15 K. The gained removal rates of chemical oxygen demand (CODCr) were in the range of 60.6-61.2%. Considerable results of sorption could be attributed to the multicomponent structure of the adsorbent with more active sites including the cavities, amino, and carboxyl functional groups which provided better sites for the phenolic pollutant to adsorb on the adsorbent via Van der Waals force, hydrogen bond, and the inclusion effect. Therefore, the results obtained strongly suggest that O-HTACC-g-CD could be an effective adsorbent for the removal of phenol and CODcr from drilling wastewater.
Keywords: Adsorption; CODcr; Chitosan; Drilling wastewater; Phenol; β-cyclodextrin.