Rapid and Efficient Removal of Rhodamine B by a Novel Nickel Oxide/Attapulgite Fenton-like Catalyst: Improved Adsorption and Fenton-like Oxidation

A nickel oxide/attapulgite (A-ATP/NiO) nanocomposite was synthesized and evaluated for the adsorption and Fenton-like degradation of Rhodamine B (Rh-B) in an aqueous solution. The composite was characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and Brunauer-Emmett-Teller (BET), confirming the successful immobilization of NiO nanoparticles into the attapulgite framework. The attapulgite modification results in enhanced surface properties, including increased surface area (from 68.9 to 111.3 m² g⁻¹), pore volume, and the availability of active sites. Batch experiments demonstrated a high affinity of A-ATP/NiO toward Rh-B, achieving 52% adsorption within 60 min. Upon addition of Fenton reagent (H₂O₂), the composite exhibited excellent catalytic performance, achieving 97% Rh-B degradation in 10 min and almost complete removal (99.39%) within 60 min under optimized conditions (pH 3, 303 K, H₂O₂ 5 mmol L⁻¹, catalyst dose 0.03 g L⁻¹, dye concentration 50 ppm). The synergistic combination of adsorption and catalytic oxidation significantly enhanced dye removal, with reactive hydroxyl radicals (•OH) driving the degradation process. Kinetic analysis indicated that the removal followed a pseudo-first-order model, suggesting that physisorption and surface diffusion are the primary mechanisms for Rh-B degradation. These findings highlight A-ATP/NiO as a low-cost, environmentally friendly, and highly efficient material for the rapid and sustainable remediation of Rh-B-contaminated wastewater.