Smart nanocomposite of V/Pd-layer double hydroxide encapsulated with double-layer hydrogel for optimum adsorption of basic yellow 28 dye

The synthesis of V/Pd-LDH/CD-Alg hydrogel beads was achieved by encapsulating Vanadium-Palladium-layered double hydroxide (V/Pd-LDH), β-cyclodextrin, and alginate, using epichlorohydrin as a cross-linking agent. The purpose of these hydrogel beads was to purposefully remove the basic yellow 28 (BY28) dye from wastewater. To thoroughly characterize the V/Pd-LDH/CD-Alg, an array of analytical techniques was employed in the examination of hydrogel beads, including powder-X-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray (EDX), and Fourier transform-infrared (FT-IR). The textural characteristics of V/Pd-LDH/CD-Alg hydrogel beads were evaluated using nitrogen adsorption and desorption isotherms. According to the research, V/Pd-LDH/CD-Alg has a surface area of 88.6 m2/g, a pore volume of 1.68 cc/g, and a regular pore size of 3.38 nm. These parameters indicate the presence of a well-defined mesoporous architecture, which is conducive to the adsorption of small molecular entities. Following adsorption of BY28, significant alterations in the properties of the hydrogel beads were observed. The surface area was reduced to 64.2 m2/g, accompanied by a decrease in pore size to 2.84 nm. Additionally, there was a decline in pore volume to 1.12 cc/g. These changes support the theory that dye molecules entered the pore structures, filled open spaces, and reduced the material’s total porosity. This research investigated the effects of several variables, including dosage, pH level, temperature, and original concentration, on the adsorption procedure. An inclusive assessment of the adsorption was conducted through detailed equilibrium analyses and the investigation of adsorption kinetics. The adsorption procedure monitored the Langmuir isotherm model, which represents surface saturation conditions. The kinetics followed a pseudo-second-order mechanism. The adsorption rate was dependent on adsorbate concentration. Analysis concluded that chemisorption was the primary mechanism, supported by an adsorption energy value of 27.8 kJ·mol–1, indicating strong adsorbate-adsorbent interaction. An analysis of the thermodynamic limits ΔG°, ΔH°, and ΔS° indicates that the adsorption procedure was spontaneous, as demonstrated by the consistently negative ΔG°. The positive ΔH° shows that the adsorption process is endothermic. The variable nature of the adsorption process indicates that multiple factors may contribute, including electrostatic forces, π-π interactions, hydrogen bonding, and pore filling. The integration of a Box-Behnken design (BBD) with Response Surface Methodology (RSM) has improved the results of the adsorption procedure.