Abstract
Gel adsorption is an efficient method for the removal of metal ion. In the present study, a functional chitosan gel material (FCG) was synthesized successfully, and its structure was detected by different physicochemical techniques. The as-prepared FCG was stable in acid and alkaline media. The as-prepared material showed excellent adsorption properties for the capture of Cu2+ ion from aqueous solution. The maximum adsorption capacity for the FCG was 76.4 mg/g for Cu2+ ion (293 K). The kinetic adsorption data fits the Langmuir isotherm, and experimental isotherm data follows the pseudo-second-order kinetic model well, suggesting that it is a monolayer and the rate-limiting step is the physical adsorption. The separation factor (RL) for Langmuir and the 1/n value for Freundlich isotherm show that the Cu2+ ion is favorably adsorbed by FCG. The negative values of enthalpy (ΔH°) and Gibbs free energy (ΔG°) indicate that the adsorption process are exothermic and spontaneous in nature. Fourier transform infrared (FTIR) spectroscopy and x-ray photoelectron spectroscopy (XPS) analysis of FCG before and after adsorption further reveal that the mechanism of Cu2+ ion adsorption. Further desorption and reuse experiments show that FCG still retains 96% of the original adsorption following the fifth adsorption–desorption cycle. All these results indicate that FCG is a promising recyclable adsorbent for the removal of Cu2+ ion from aqueous solution.
Highlights
Water pollution caused by heavy metal ion poses a significant threat to environment and human health due to its non-degradability and toxicity [1,2]
The results indicate that qm and KL decrease with increasing temperatures, implying that the exothermic nature of the adsorption process
functional chitosan gel (FCG) is stable at room temperature (RT) in acidic or basic solution, in contrast to most supramolecular gels, due to the formation of
Summary
Water pollution caused by heavy metal ion poses a significant threat to environment and human health due to its non-degradability and toxicity [1,2]. Improper disposal of wastewaters containing Cu2+ ion can bring human health issues and serious environmental problems. Many techniques have been used for the removal of Cu2+ ion from various industrial effluents, such as chemical precipitation, ion exchange, membrane filtration, and adsorption [8,9,10] Among these methods, biosorption offers an effective method for the removal of Cu2+ ion from aqueous solution because it has obvious advantages, such as good stability and selectivity, biocompatibility, and biodegradability [11,12]
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