Sunlight light-driven degradation of anthracene and naphthalene on robust Cu2+doped ZnO nanoparticles from simulated rainwater: optimization factors, kinetics, and reusability

Abstract

This research investigated the detection and removal of priority polycyclic aromatic hydrocarbons (PAHs) from metropolitan rainwater runoff through photocatalytic degradation. The ubiquitous distribution of PAHs in all environment matrices has gained scientific interest because of the risk for the security of drinking water which is a growing concern to the next generation worldwide. Anthracene and naphthalene are primarily used in the petrochemical, chemical, and food industries and are suspected to have carcinogenic and persistent properties and have been detected in rainwater runoff. Herein, a Cu doped ZnO nanocomposite is green synthesized via facile precipitation and used for photodegradation of NAP and ANT in simulated rainwater under natural light exposure. Sharp PXRD peaks confirmed that the spherical nanocomposite had great crystallinity and purity. XPS analysis, PXRD, and FE-SEM confirmed the effective doping of Cu with ZnO. Following this, under various reaction conditions (pollutant: 10-60 mg L−1; catalyst: 2-12 mg; pH: 3-9, dark sunlight, humic acid, and chloride ion: 0.1-1 M), the Cu@ZnO nanocomposite was assessed for the efficient removal of NAP and ANT. Cu@ZnO displayed maximum degradation of NAP (96%) and ANT (94%) at 10 mg L−1 conc. of each PAH with a 10 mg catalytic dose at neutral pH in the presence of direct sunlight. First-order kinetics followed by initial Langmuir adsorption constituted the degradation process. The efficiency of green fabricated Cu@ZnO for the removal of NAP and ANT in real rainwater samples was analyzed by HPLC. Predominant reactive species and safer metabolite formation in the photocatalysis process of PAHs were studied by scavenger and GC-MS analysis. The reusability of the nanocomposite up to nine cycles demonstrated the remarkable sustainability and cost-effectiveness of the nanocomposite. Thus, the Cu@ZnO nanocomposite has good catalytic properties for pollutant remediation, and industrial and other applications in laboratory control as well as real systems.