Ag decorated Zn-Al layered double hydroxide for adsorptive removal of heavy metals and antimicrobial activity: Numerical investigations, statistical analysis and kinetic studies

Abstract

Ag nanoparticles have been decorated with Zn-Al layered double hydroxide (LDH) using a simple synthetic procedure. The structural and morphological characterization result confirms the formation of the layered structure Ag@Zn-Al LDH. Ag@Zn-Al LDH has been evaluated for adsorptive elimination of hazardous heavy metal ions like Pb2+ and Cd2+ from an aqueous solution. pH, initial concentration, and contact time are well-studied adsorption conditions as independent variables. The Response Surface Model was used to describe the optimization of the variables (RSM). The optimal conditions for Pb2+ and Cd2+ removal under the constraints are 200 ppm heavy metal levels (concentration), pH 8.0, a reaction duration of 90 min, and a response of 98.9 % by Ag@Zn-Al LDH. With exceptional adsorption efficiencies of 537.63 and 401.62 mg/g, the Langmuir isotherm fitted the adsorption of Pb2+ and Cd2+ well. Studies on thermodynamics demonstrate the exothermic spontaneity and pseudo-second-order kinetic model was determined to be more appropriate. Ag@Zn-Al LDH exhibits more antibacterial activity than Zn-Al LDH, with MIC values that are similar to those of standard streptomycin. The examination indicates that the synthesised Ag@Zn-Al LDH has good adsorption and antibacterial activity.