Commercial and laboratory-prepared ZnO nanoparticles are assessed here as a photocatalyst in photodegradation of aqueous 2-chlorophenol under direct sunlight. Kaolinite is used as a support for ZnO to enable its recovery after reuse. The composite ZnO/kaolinite is prepared by growing ZnO nanoparticles directly on kaolinite surface and is characterized by a number of methods such as electronic absorption spectra, photoluminescence spectra, X-ray diffraction and scanning electron microscopy. All ZnO systems (commercial, synthetic and supported) exhibit the wurtzite phase. The composite ZnO/kaolinite shows higher photocatalysis efficiency in 2-chlorophenol degradation over both commercial and synthetic ZnO powders. The composite ZnO/kaolinite is also easier to recover and reuse, showing no observable loss in its catalyst efficiency even after five cycles. These features highlight the merit of using composite ZnO/kaolinite as photocatalyst in water purification with direct sunlight for the first time. All catalyst systems are more efficient in basic media (pH 8.5) than in neutral and acidic media, as rationalized by the point of zero charge concepts here. Moreover, the composite ZnO/kaolinite shows enhanced catalytic efficiency in 2-chlorophenol photodegradation in a wider pH range, compared to other counterparts, which shows another added value. © 2019, Islamic Azad University (IAU).