The advanced oxidation process of the water organic contaminants is amongst the promising technologies for water purification. In this work, ZnO nanoparticles have been supported on natural clay particles. The prepared composite ZnO/Clay has been characterized by solid-state electronic absorption spectra, X-ray diffraction, and scanning electronic microscopy. It is used in photodegradation of aqueous 2-chlorophenol (2-CP) with direct solar radiation. As the catalyst surface charge and point of zero charge presumably, influence adsorption uptake and photodegradation of the 2-CP molecules, these two properties have been studied here. For the composite, the optimal contaminant adsorption pH is 8.7, which is the optimal photodegradation value as well. Compared to naked ZnO, the composite ZnO/Clay shows enhanced adsorption and photodegradation efficiency in 2-CP degradation, at all working pH values. This highlights the future practicality of using this composite catalyst under various natural conditions. Moreover, the ZnO/Clay can be easily recovered and reused for the third cycle with no significant loss of efficiency. Complete mineralization of the 2-CP has been confirmed after enough time (2 h). This has been manifested by analysis for remaining organic materials inside the reaction mixture, using UV-visible spectra, high-performance liquid chromatography, and total organic carbon measurements.