Fixed-bed adsorption of copper from aqueous media using chitosan-coated bentonite, chitosan-coated sand, and chitosan-coated kaolinite.

Abstract

Fixed-bed studies were performed to evaluate the removal efficiency of copper (Cu(II)) from aqueous solution using chitosan-coated bentonite (CCB), chitosan-coated sand (CCS), and chitosan-coated kaolinite (CCK). The thermal and morphological properties of CCB, CCK, and CCS were characterized using thermogravimetric analysis, Fourier transform infrared spectroscopy, and the Brunauer-Emmett-Teller method. Dynamic experiments were carried out to investigate the effect of solution pH (3.0 to 5.0) and initial Cu(II) concentration (200 to 1000 mg/L) on the time to reach breakthrough (tb), total volume of treated effluent (Veff), and adsorption capacity at breakthrough (qb). Results show that increasing the initial Cu(II) concentration inhibits the column performance where lower Veff, tb, and qb were obtained. Decreasing the pH from 5.0 to 3.0 led to improved removal efficiency with higher values of Veff, tb, and qb. Under pH 3.0 and 200 mg/L, the maximum removal efficiency of 68.60%, 56.10%, and 58.90% for Cu(II) was attained using CCB, CCS, and CCK, respectively. The Thomas model was determined to adequately predict the breakthrough curves based on high values of coefficient of determination (R2 ≥ 0.8503). Regeneration studies were carried out using 0.1 M HCl and 0.1 M NaOH solution in the saturated column of CCB, CCK, and CCS.