Dye wastewater possess immense toxicity with carcinogenic properties and they persist in environment owing to their stability and resistance to chemical and photochemical changes. The bio degradability of dye-contaminated wastewater is low due to its complex molecular structure. Nano-photocatalysts based on zinc oxide are reported as one of the effective metal oxides for dye remediation due to their photostability, enhanced UV and visible absorption capabilities in an affordable manner. An electron–hole pair forms when electrons in the valence band of ZnO nano-photocatalyst transfer into the conduction band by absorbing UV light. The review article presents a detailed review on ZnO applications for treating acidic and basic dyes along with the dye degradation performance based on operating conditions and photocatalytic kinetic models. Several acidic and basic dyes have been shown to degrade efficiently using ZnO and its nanocomposites. Higher removal percentages for crystal violet was reported at pH 12 by ZnO/Graphene oxide catalyst under 400 nm UV light, whereas acidic dye Rhodamine B at a pH of 5.8 was degraded to 100% by pristine ZnO. The mechanism of action of ZnO nanocatalysts in degrading the dye contamination are reported and the research gaps to make these agents in environmental remediation on real time operations are discussed.

染料废水具有巨大的毒性和致癌性，并且由于其稳定性以及对化学和光化学变化的抵抗力而在环境中持续存在。染料污染废水由于其分子结构复杂，生物降解性较低。据报道，基于氧化锌的纳米光催化剂是用于染料修复的有效金属氧化物之一，因为它们具有光稳定性、以经济的方式增强了紫外线和可见光吸收能力。当 ZnO 纳米光催化剂的价带中的电子通过吸收紫外光转移到导带时，形成电子空穴对。该综述文章详细综述了 ZnO 在处理酸性和碱性染料方面的应用，以及基于操作条件和光催化动力学模型的染料降解性能。一些酸性和碱性染料已被证明可以使用 ZnO 及其纳米复合材料有效降解。据报道，在 400 nm 紫外光下，ZnO/氧化石墨烯催化剂在 pH 12 时对结晶紫的去除率较高，而酸性染料罗丹明 B 在 pH 5.8 时被原始 ZnO 降解至 100%。报道了 ZnO 纳米催化剂降解染料污染的作用机制，并讨论了这些试剂在实时环境修复中的研究空白。