Advanced Oxidation Enters a New Stage: A Patented Heterogeneous Ozone Catalytic System Drives Wastewater Treatment Innovation

In wastewater treatment, advanced oxidation processes rely on their ability to generate hydroxyl radicals (·OH, with an oxidation potential of 2.8 V) to completely decompose and mineralise refractory organics. This technology family covers the Fenton process, ozone oxidation, photocatalysis and electrochemical oxidation, among others. Among them, ozone oxidation delivers outstanding oxidising performance: it can act through direct reaction (the oxidation potential of O₃ is 2.07 V) or indirectly promote the generation of ·OH, thereby efficiently decomposing the organic components of wastewater. Because it reacts rapidly, produces no secondary pollution and also provides disinfection and decolourisation, ozone technology has been widely used to treat municipal wastewater, industrial effluent, papermaking waste liquor, dye wastewater and other complex systems.

However, conventional ozone processes still face a series of challenges in practice, including low gas-phase ozone utilisation, poor reaction selectivity and incomplete oxidation of organic pollutants. To overcome these limits, the industry is working to develop intensified ozonation systems that raise both ozone mass transfer efficiency and radical yield. Studies show that introducing a catalyst into the ozone reaction significantly promotes the generation of ·OH and enhances the effectiveness of direct ozone oxidation, thereby driving deeper pollutant removal.

Figure 1. Classification of ozone catalytic oxidation technologies

Adding a homogeneous catalyst can work in synergy with ozone oxidation, and the catalytic mechanism falls into two categories:

① Transition metal ions catalyse ozone to produce more ·OH;

② A complex is formed between the catalyst and the organics or ozone, extending the contact time between ozone and pollutants and improving reaction efficiency.

In practice, however, the metal ions of the catalyst are difficult to recover, generate large volumes of sludge that cause secondary pollution, and entail high water treatment costs, which has limited homogeneous ozone catalysis.

Figure 2. Pathways by which the catalyst and ozone act on organics in a heterogeneous catalytic oxidation system

To solve these problems, SINOKLE independently developed a heterogeneous Fenton catalyst and obtained a patent for it, fixing transition metal ions with catalytic properties onto a solid catalyst carrier by doping, adsorption, grafting modification and other means; the transition metal ions used include one or more of Cu, Fe, Mn, Co, Zn, Ce, Ni and Cr.

The main mechanisms by which such catalysts catalyse ozone oxidation are:

① The solid catalyst catalyses ozone to produce more ·OH that oxidises pollutants;

② Organic pollutants adsorb onto the solid catalyst, making it easier for ozone and pollutants to react;

③ The adsorption and catalysis of the catalyst act together to degrade organic pollutants;

As shown in Figure 2, ozone decomposes at the Lewis acid centres of metal oxides (such as Al2O3 and TiO2); ozone decomposition takes place on the hydroxyl groups of the metal oxide surface, and these active sites are all regarded as potential catalytic centres that promote ozone decomposition. The performance of a supported catalyst therefore depends mainly on the synergy between the catalyst and the carrier.

Figure 3. The patented heterogeneous ozone oxidation catalyst independently developed by SINOKLE

Verified through extensive experiments and engineering practice, the heterogeneous catalyst developed by SINOKLE builds a material system that combines high catalytic activity with broad adaptability by optimising the proportion of each component. A multi-stage precisely controlled sintering process significantly strengthens material stability while maintaining catalytic activity, effectively suppressing the leaching of active components and avoiding secondary pollution. With a special pore-forming technology, the specific surface area of the catalyst reaches more than 250 m²/g and the oxidation efficiency is raised by 2 to 5 times compared with a plain ozone process. The material offers excellent resistance to fouling, scaling and plugging, with a service life of more than five years and support for stable long-cycle operation.