Chelating cellulose functionalized with four amino acids: A comparative study on the enhanced adsorptive removal of cadmium and lead ions

Cellulose, a regenerative superior material, has been attracted an increased interest for extending its area to use. Here, some chelating celluloses functionalized with four amino acids: cysteine, histidine, aspartic acid, and methionine (as named Cys-CL, His-CL, Asp-CL and Met-CL) were prepared through a Schiff base reaction, and analyzed by several means of characterization for the purpose of enhanced adsorptive removal of Cd2+ and Pb2+ from aqueous solution. For the Cd2+ ions, the saturated adsorptive capacities of the Cys-CL, His-CL, Asp-CL and Met-CL at 30 ? in the optimal pH range of 4.5-5.5 were found to be 130.7, 87.0, 75.5 and 37.1 mg g(-1), respectively. For the Pb(2+ )ions, the saturated adsorptive capacities of the Cys-CL, His-CL, Asp-CL and Met-CL at 30 ? in the optimal pH range of 4.0-5.5 were found to be 180.9, 119.0, 111.0 and 51.1 mg g(-1), respectively. The results clearly illustrated adsorption capacities conformed to Cys-CL > His-CL > Asp-CL > Met-CL. Cys-CL exhibited the obvious advantages and was sensitive to the initial concentrations of both the metal ions, solution pH and temperature. The rapid uptakes of the Cd2+ and Pb2+ by the Cys-CL were observed within 30 min. The adsorption of both the metal ions by the Cys-CL was described reliably by the Langmuir and pseudo second-order models and occurred spontaneously and endothermically in nature. The Cys-CL with good adsorptive characteristics and recyclability owns great potential for the adsorptive removal of the Cd2+ and Pb2+ from aqueous solution.

Automated summary

In this study, chelating celluloses functionalized with four amino acids were prepared and their adsorption capacities towards Cd2+ and Pb2+ were investigated. The results showed that Cys-CL exhibited the highest adsorption capacity and sensitivity towards the metal ions, demonstrating good adsorptive characteristics and recyclability.