Effective removal of cefixime using VCu-layered double hydroxide encapsulated with chitosan-carboxymethyl cellulose nanocomposite: Adsorption models and optimization by box-behnken design

The investigation employed a co-precipitation method to fabricate Vanadium and Copper-layered double hydroxide (VCu-LDH) as an adsorbent. Subsequently, VCu-LDH was combined with chitosan (CS) and carboxymethyl cellulose (CMC) to produce VCu-LDH/CS-CMC hydrogel beads via crosslinking with epichlorohydrin (ECH). Various characterization techniques, including scanning electron microscopy (SEM)-energy dispersive X-ray (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), Brunauer-Emmett-Teller (BET), and the zero point of charge (ZPC) (pHzpc) analysis, were employed to assess the effectiveness of these composite beads in removing cefixime (CFX) from wastewater. Additionally, the research examined the effects of several variables on the elimination of CFX, including adsorbent dosage, pollutant concentration (ranging from 0.8 to 10.0 g/L), pH levels (from 2 to 8), and contact time (from 5 to 100 min). The optimization of results was conducted using Response Surface Methodology (RSM). The identified optimal parameters for the adsorption process comprised an adsorbent concentration of 0.8 g/L, a pH of 4.0, and a reaction time of 100 min, leading to an impressive CFX removal efficiency of 97.5%. A thorough examination of the adsorption isotherm and kinetic models indicated that the pseudo-second-order kinetics and Langmuir isotherm effectively characterize the mechanism of CFX removal. Moreover, the impact of temperature was analyzed within the range of 20 to 45°C. At elevated temperatures, the thermodynamic parameters reflected a reduction in Gibbs free energy (ΔGo), coupled with an increase in both entropy and enthalpy, which implies a greater spontaneity of the process. During the assessment focused on regeneration and reusability, the adsorbent demonstrated a notable CFX removal efficiency of 88.4% even after undergoing six reuses. This finding indicates that the hydrogel beads VCu-LDH/CS-CMC represent a promising approach for the extraction of CFX from wastewater.