Utilization of a cadmium sulfide/nickel–ferric layered double hydroxide nanocomposite decorated with silver nanoparticles for efficient adsorption and photocatalytic degradation of 2,4-dichlorophenoxyacetic acid

Abstract

This study examined the efficacy of the hydrotalcite-like materials of Zn–Fe, Mg–Fe, and Ni–Fe layered double hydroxides as adsorbents of 2,4-dichlorophenoxyacetic acid (2,4-D) by synthesizing them using a coprecipitation process at an M²⁺/M³⁺ molar ratio of 3. This study presents a novel cadmium sulfide/Ni–Fe LDH and its decorated form with silver nanoparticles as a plasmonic element, Ag@CdS/Ni–Fe LDH, to overcome conventional photocatalyst limitations such as weak photoresponsivity and unstable structure. The physicochemical characteristics of Ag@CNFL were analyzed, revealing a hierarchical pore structure, a large specific surface area (113.10 m² g⁻¹), a particle size of 68 nm, a total pore volume of 0.1658 cm³ g⁻¹, an average pore size of 5.8638 nm, a pH_PZC of 8.34, and a band gap of 1.96 eV. Our findings showed a notable maximum adsorption capacity of 203.75 mg g⁻¹ at 23 °C for NFL and fast adsorption kinetics within 8 h. The exothermic and spontaneous adsorption process was well described by Avrami and pseudo-second-order kinetics, Redlich–Peterson, and Langmuir isotherms. Under visible irradiation, the Ag@CNFL heterojunction demonstrated remarkable photocatalytic activity in the 2,4-D degradation, reaching a 100% degradation percentage at 15 mg L⁻¹ and 110 min. Additionally, following eight cycles of 2,4-D photodegradation, the efficiency of NFL, C, CNFL, and Ag@CNFL was only decreased by 8.4, 3.4, 3.2, and 7.0%, respectively. It was shown that the produced materials were very effective at removing 2,4-D from water.