Abstract
As the removal of toxic dyes by catalytic degradation is interestingly growing field, diverse types of nanomaterials are used intensively as a catalyst to enhance the catalytic degradation of toxic dyes in the last decades. The unique property of ionic crosslinking of the biopolymer sodium alginate (Na-ALG) in presence of CaCl2 solution is exploited to prepare Ca-alginate (Ca-ALG) microbeads, which further used as precursor for in situ silver nanoparticles (Ag NPs) formation by the effect of gamma radiation to obtain Ca-ALG/Ag nanocomposite beads. The amount of silver ions adsorbed by the Ca-ALG beads before reduction was evaluated by using ultraviolet-visible spectrophotometer (UV-Vis). The physicochemical properties of prepared Ca-ALG/Ag nanocomposite beads were studied by various techniques as X-ray diffraction (XRD) and transmission electron microscopy (TEM) for approving the creation of Ag NPs and assessing its morphology and particle magnitude. The catalytic reduction ability of the resulting Ca-ALG/Ag nanocomposite beads is studied toward the degradation of basic blue 3 dye as a model anionic dye by the aid of the reducing agent NaBH4 under various factors including time, pH, catalyst's dosage, NaBH4 contents, and dye's initial concentration. Various kinetics and isothermal models were applied for forecasting the mechanism of the degradation process using the prepared catalyst beads. The kinetics and isothermal study revealed that the degradation process using Ca-LG/Ag nanocomposite beads as a catalyst in presence of NaBH4 as a reducing agent was best fit the pseudo-second-order model and Langmuir isotherm model.