Removal of Orange G dye from water using halloysite nanoclay-supported ZnO nanoparticles
Ahlam A. Al-Beladi, Samia A. Kosa, Roswanira Abdul Wahab, Mohamed Abdel Salam
Abstract
ABSTRACT Zinc oxide nanoparticles (ZnO NPs) supported over halloysite nanoclay (ZnO/HS) were investigated for the removal of Orange G (OG) dye in simulated water and real water samples. This study aimed to synthesize ZnO NPs/HS to photo-catalytically degrade OG dye in the aforementioned water samples. In addition to establishing the kinetics and thermodynamics of the reaction. Surface and physicochemical characterizations affirmed the ZnO NPs/HS were meso- porous (61.0 m 2 g –1 ) with the rod-shaped nanoparticles homogeneously dispersed over the surface of HS. Employment of ZnO/HS at a mass ratio of 3:47 (w/w) degraded the highest quantity of the dye, amounting to a mass loss of >100 mg in just 2 h (pH < 12). The UV-irradiated and direct sunlight-activated photodegradation of aqueous OG dye by ZnO/HS followed a first-order kinetic model with the latter exhibiting a higher rate constant (4.87 × 10 –3 min –1 ). Meanwhile, values of ΔG (-4.60 kJ mol –1 ), ΔH (+42.8 kJ mol –1 ), and ΔS (+159 J mol –1 K –1 ) indicated that the ZnO/HS-UV- irradiated photodegradation process was entropically driven. The ZnO NPs/HS photocatalyst efficiently degraded OG dyes (49.78%-94.36%) dissolved in various real water samples, thus envisaging its applicability for convenient in situ photocatalytic treatment of contaminated water bodies.