Aminothiol supported dialdehyde cellulose for efficient and selective removal of Hg(II) from aquatic solutions

The increasingly serious problem of mercury pollution has caused wide concern, and exploring adsorbent materials with high adsorption capacity is a simple and effective approach to address this concern. In the recent study, dialdehyde cellulose (DAC), cyanoacetohydrazide (CAH), and carbon disulfide (CS₂) are used as raw materials for the (DAC@CAH@SK₂) preparation material through the three-steps method. By utilizing the following characterization techniques; thermogravimetric analysis (TGA), N₂ adsorption-desorption isotherm (BET), elemental analysis, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD), ¹HNMR and Energy Dispersive X-ray Spectroscopy (EDS) of DAC@CAH@SK₂ composite. The point of zero charge (pH_PZC) for the prepared DAC@CAH@SK₂ also was examined. From the batch experiments, the optimum conditions were found to be pH (5-8), an Hg²⁺ concentration of 150 mg/L, a DAC@CAH@SK₂ dose of 0.01 g, and a contact time of 180 min with a maximum adsorption quantity of 139.6 mg/g. The process of Hg²⁺ adsorption on the DAC@CAH@SK₂ material was spontaneous exothermic, monolayer chemisorption, and well-fitted to Langmuir and pseudo-2nd-order models. The DAC@CAH@SK₂ selectivity towards the Hg²⁺ was examined by investigating the interfering metal ions effect. The DAC@CAH@SK₂ was successfully applied for the Hg²⁺ removal from synthetic effluents and real wastewater samples with a recovery % exceeding 95%. The prepared DAC@CAH@SK₂ was regenerated using a mixture of EDTA and thiourea. Also, FT-IR analysis indicates that the synergistic complexation of N and S atoms on DAC@CAH@SK₂ with Hg(II) is an essential factor leading to the high adsorption capacity.