Adsorption Characteristics of Mercury(II) Ions from Aqueous Solution onto Chitosan-Coated Diatomite

The prepared chitosan-coated diatomite (CCD) was characterized using Fourier transform infrared spectroscopy and SEM techniques. The effects of pH, contact time, sorbent dosage, metal concentration, and temperature on the adsorption (%) of mercury (Hg(II)) from aqueous solution using the CCD sorbent were studied systemically. The monolayer sorption capacities of raw diatomite and CCD sorbents at pH 5 were found to be 68.1 and 116.2 mg/g, respectively. The mean adsorption energy (8.2 kJ/mol) calculated from the Dubinin-Radushkevich (D-R) model indicated that the sorption process occurred via chemisorption. The modified sorbent had good adsorption and desorption performance with respect to reusability after 10 repeated cycles. The thermodynamic calculations revealed that the sorption was viable, spontaneous, and exothermic in nature under the conditions studied. The kinetic calculations indicated that the sorption mechanism was well-explained by a pseudo-second-order model. All results demonstrated that the prepared CCD is an effective sorbent for the removal of Hg(II) from aqueous solution.