Cu nanoparticles-decorated beidellite: Synthesis, characterization, and catalytic reduction of wastewater pollutants

This study focused on immobilizing copper nanoparticles (CuNPs) with an average diameter of 9.98 nm onto natural beidellite (BD). Initially, the adsorption behaviour of beidellite for copper ions (Cu²⁺) was investigated, showing optimal adsorption at pH = 5.20 ± 0.12 and a capacity of 25.31 mg·g⁻¹ . Additionally, the cation exchange capacity was determined to be 89.80 meq/100 g. The synthesis of the (CuNPs)/BD nanocomposite involved an adsorption step, followed by chemical reduction by sodium borohydride (NaBH₄) as the reducing agent. The resulting material was comprehensively characterized using various analytical techniques, including X-ray fluorescence (FX), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), UV vis spectroscopy, and Fourier transform infrared spectroscopy (FTIR). The synthesized nanocomposites demonstrated exceptional catalytic performance, achieving reduction efficiencies of more than 98 % for various organic pollutants , including nitrophenols (within 12 min for 4-nitrophenol), cationic dyes (within 14 min for Rhodamine B), and anionic dyes (within 12 min for methyl orange), using sodium borohydride (NaBH₄) as the reducing agent at room temperature. The reduction followed first-order kinetics, with activity factors (k′) calculated as 144 s⁻¹ . g⁻¹ , 240 s⁻¹ . g⁻¹ , and 196 s⁻¹ . g⁻¹ for 4-NP, MO, and RhB, respectively. The catalysed reaction spectrum displayed a rapid decrease in absorbance, confirming the catalytic ability of the CuNPs. Conversely, the uncatalyzed reaction exhibited minimal absorbance changes, suggesting a notably sluggish reduction rate of organic pollutants . A noteworthy aspect was the reusability of the catalyst, which displayed consistent catalytic efficiency over multiple cycles without significant degradation. • This study presents the eco-friendly synthesis of copper nanoparticles (CuNPs) supported on acid-treated beidellite. • The catalyst demonstrated exceptional catalytic activity in the reduction of organic pollutants in aqueous solutions. • The composite exhibits high stability and cost-effectiveness, offering a promising solution for wastewater treatment. • The catalyst retained its efficiency over multiple reuse cycles, indicating its durability and reusability.