Chelating Ability and Microbial Stability of an l-Arginine-Modified Chitosan-Based Environmental Remediation Material

Abstract

To improve the heavy metal ion chelating ability and the microbiological stability of chitosan (CS), l-arginine (l-Arg) was grafted on CS polymer in the presence of the condensing agent 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDC) and the coupling reagent N-hydroxysuccinimide (NHS) to prepare a natural polymer-based environmental rehabilitation material: l-arginine-grafted chitosan (CA). The graft mechanism is discussed, and the reaction conditions were optimized. The product was characterized using elemental analysis, infrared spectroscopy (FT-IR) and 13C-NMR spectroscopy (13C-NMR). The optimal reaction conditions were a reactant molar ratio nCS:nArg:nEDC:nNHS of 3:3:3:1, a reaction time of 12 h, and a reaction system pH = 5. Under these conditions, the grafting ratio (GR) was 16.85%, while the product yield (PY) was 90.48%. The results of the adsorption experiments showed that the CA (GR = 16.85%) had a better removal capacity for highly concentrated Cu2+ and Ni2+ ions than CS. The antibacterial activity of the CA was also enhanced. When the GR reached 16.85%, the CA almost completely inhibited the growth of colibacillus and Staphylococcus aureus. Due to its high chelating ability and microbiological stability, this novel metal-ion adsorption material, CA, can be considered to have broad application potential in heavy metal ion-polluted water and soil remediation.