Boiled tap water always carries an indescribable disinfectant odor, while the new filter cartridge of your water purifier starts emitting strange smells after just three months. Occasionally, chemical odors waft from rivers in summer, and news reports frequently expose organic contamination and antibiotic detection in water sources—these incidents make you hesitate when holding a glass of water: Just how many invisible "enemies" lurk in the water we drink and use every day? You may not know that conventional tap water treatment processes—coagulation, sedimentation, filtration, and chlorine disinfection—can handle most sediment, bacteria, and common pollutants. But when it comes to "stubborn molecules" like pesticide residues, antibiotics, endocrine disruptors, and disinfection byproducts, these century-old methods fall short. Regular chlorine disinfection can kill bacteria but struggles against these chemically stable small-molecule organic compounds, some of which even react with chlorine to form more toxic byproducts. Boiling only eliminates microorganisms and is largely ineffective against chemical pollutants. While your RO reverse osmosis membrane can filter them out, the high cost of cartridges, high wastewater rates, and the loss of beneficial minerals in water make it impractical. Not to mention that urban sewage treatment plants and industrial wastewater facilities process tens of thousands of tons of water daily—can we really rely solely on reverse osmosis membranes? **Advertisement** In-service postgraduate (2026) New Knowledge Education View After decades of research, environmental scientists have finally discovered a cutting-edge weapon against these "persistent toxins"—catalytic ozone technology. Today, we’ll break down this seemingly high-tech environmental solution in plain language. **1. Meet the star player: Ozone—More Than Just a Disinfection Cabinet Odor** When you hear "ozone," do you immediately think of summer ozone pollution alerts or the peculiar metallic scent from your disinfection cabinet? This "notorious" gas is actually a true "disinfection and oxidation powerhouse" in water treatment. **1.1 What Exactly Is Ozone?** Ozone has the chemical formula O₃—essentially just one extra oxygen atom compared to the O₂ we breathe. Don’t underestimate this additional atom; it makes ozone exceptionally reactive: prone to decomposition at room temperature and actively "attacking" many organic compounds, with oxidation power twice that of chlorine. As early as the early 20th century, European cities began using ozone for tap water disinfection. It kills bacteria dozens of times faster than chlorine, avoids the unpleasant chlorine odor, and effectively targets chlorine-resistant microbes like cryptosporidium and giardia. But as scientists continued using it, they discovered a "bug" in ozone
• The first issue is "selectivity": ozone oxidation is selective. When encountering phenols, pesticides, antibiotics, and other structurally stable organic compounds, it either oxidizes slowly or can only break down large molecules into smaller ones, failing to completely convert them into carbon dioxide and water. These intermediate products may even be more toxic than the original pollutants. • The second issue is "waste": ozone is highly unstable in water and decomposes into oxygen within minutes at room temperature. Much of it escapes before reacting with pollutants, requiring several grams of ozone to treat one ton of water, driving up electricity costs and resulting in alarmingly high treatment expenses. At this point, someone might wonder: Could we give ozone a "helper" to make it react faster, more thoroughly, and without waste? This helper is the catalyst. 1.2 Boosting Ozone: What is Advanced Oxidation Technology? Here, we need to explain a key concept in environmental science—Advanced Oxidation Technology. Simply put, conventional oxidation techniques (such as chlorination or ozone injection) rely on the oxidant itself to treat pollutants, while the core of Advanced Oxidation Technology involves generating a "super oxidant" called hydroxyl radicals (·OH) through various methods. How powerful are hydroxyl radicals? Their oxidation capacity is twice as strong as ozone, making them almost "non-selective." They can directly break down organic compounds of any structure into carbon dioxide and water, with reaction speeds up to 10⁶ to 10⁹ times faster than ozone, leaving no chance for intermediate products to form. The catalytic ozone technology we're discussing today is one of the most promising applications within Advanced Oxidation Technology: using catalysts to accelerate and enhance the decomposition of ozone into hydroxyl radicals while concentrating pollutants for more efficient reactions. This is like giving ozone an "aim assist" and "damage boost," perfectly addressing all the shortcomings of conventional ozone oxidation. II. The "School Feud" of Catalytic Ozone Technology: Homogeneous vs. Heterogeneous Based on the form of catalysts, catalytic ozone technology is currently divided into two "schools": homogeneous catalytic ozonation and heterogeneous catalytic ozonation. The difference between these schools boils down to whether the catalyst can be separated from water. 2.1 Homogeneous Catalysis: Early Origins, Strong Capabilities, But Fatal Flaws "Homogeneous" means the catalyst and water are in the same phase, typically achieved by adding soluble metal ions (e.g., iron or manganese ions) to water. These ions dissolve uniformly, ensuring full contact with ozone and pollutants, resulting in exceptionally high catalytic activity and well-defined reaction mechanisms. This makes research and development particularly convenient for scientists. However, the drawbacks of this technology are too fatal: • The catalyst is mixed in water and cannot be recovered after the reaction, rendering it unusable once it's gone. Treating one ton of water requires adding several hundred grams of catalyst, making the cost prohibitively high. • These metal ions remain in the water, which was originally intended to treat wastewater for environmental protection but instead causes secondary heavy metal pollution. Additional processes are then needed to remove the metals, making the effort counterproductive. Thus, homogeneous catalysis is now largely confined to laboratory research, while heterogeneous catalysis remains the only viable option for large-scale applications.
2.2 Multiphase catalysis: A rising star, the practical optimal solution "Multiphase" means that the catalyst is a solid and in a different phase state from water and ozone. During the reaction, the solid catalyst is filled in the reaction tank. Sewage flows through, ozone comes up from the bottom of the tank, and the three phases react on the surface of the catalyst. After the reaction, the water flows away directly, while the catalyst remains in the tank and can be reused for several years. The three major advantages of heterogeneous catalysis are: • The catalyst is solid and will not run into the water, there is no secondary pollution, and no additional treatment is required; The catalyst does not need to be added every time, and can be used for 3-5 years with a loading time. The operating cost is less than one tenth of that of homogeneous catalysis; The reaction process is simple, just fill the traditional ozone oxidation tank with catalyst, and the transformation of the old process is also particularly convenient. No wonder both the research and engineering communities now consider multiphase catalytic ozone as the core technology for the next generation of water treatment. 3, The "superpower" of catalysts: Three unique activities that increase ozone efficiency tenfold. Many people may be curious: Isn't it just adding some solid materials to the pool? How can we double the effectiveness of ozone? In fact, these seemingly inconspicuous solid catalysts all have "superpowers", which can be summarized into three main skills. Trick one: act as an "adsorption net" to gather pollutants around oneself. Many catalysts themselves have many micropores, with a particularly large specific surface area. The surface area of one gram of catalyst can expand to several basketball courts. When sewage flows through, the organic matter in the water will be adsorbed onto the surface of the catalyst, like a large net grabbing all the surrounding pollutants, with a concentration dozens of times higher than in the water. Think about it, ozone used to float around in water and waste if it didn't come into contact with pollutants. Now that pollutants gather on the surface of catalysts, ozone can come into contact with them, and the reaction efficiency naturally increases. And some organic compounds, when combined with catalysts, weaken their chemical bonds. Originally, ozone couldn't bite them, but now it breaks with just one bite, making oxidation easier. Trick 2: As a "decomposer", it turns ozone into stronger hydroxyl radicals, which is the core function of the catalyst. Some catalysts have special active sites on their surfaces, and when ozone molecules touch these sites, they will be "broken" and decomposed into hydroxyl radicals, which are super oxidants. For example, ordinary ozone is just an ordinary bullet that can only penetrate thinner targets, but not thicker ones; Catalysts are like bullet processing factories, converting ordinary ozone bullets into armor piercing bullets that can penetrate no matter how stable organic matter is. According to research calculations, with the addition of suitable catalysts, the proportion of ozone converted into hydroxyl radicals can increase from less than 10% to over 60%, and the oxidation efficiency can directly increase several times. Tip 3: "Adsorption+Activation" Double buff superposition, with 1+1>2 being the most powerful catalyst, often possessing both of the above abilities: while adsorbing surrounding pollutants to its surface, it turns passing ozone into hydroxyl radicals, which is equivalent to opening a "pollutant slaughterhouse" on the surface of the catalyst. As soon as pollutants are captured, they are oxidized by hydroxyl radicals waiting nearby, with higher efficiency than adsorption or activation alone
4, Catalyst family: Who is the 'best partner' for treating wastewater?
There are various catalytic ozone catalysts on the market now, all of which appear to be black and gray particles, but in fact, there are many tricks inside. The three most commonly used types currently are (loaded) metal catalysts, metal oxide catalysts, and activated carbon catalysts, each with their own characteristics and suitable for different water quality scenarios.
4.1 Category 1: Metal Catalysts - Installing a "Starter" for Ozone
This type of catalyst generally involves loading transition metals such as titanium, copper, zinc, iron, nickel, and manganese onto inert carriers such as alumina and ceramic particles. The outermost electrons of metal atoms are relatively active and easily react with ozone, decomposing it into hydroxyl radicals.
For example, many industrial wastewater treatment plants use iron-based catalysts that load iron oxide onto ceramic particles, which are low-cost and particularly effective in treating azo dyes and phenolic substances in printing and dyeing wastewater and chemical wastewater. Previously, ozone oxidation alone took 2 hours to reach the standard, but with the addition of catalysts, it can be completed in 40 minutes.
However, this type of catalyst also has its drawbacks: if the loading process is not good, the metal ions are prone to slowly fall off into the water, and the activity will decrease after one or two years of use. Therefore, the current research focus is on how to firmly "stick" the metal to the carrier and extend its service life.
4.2 Second category: Metal oxide catalysts - stable and durable "main players"
Metal oxides are currently the most researched and widely used type of catalyst. The hydroxyl groups on the surface of general metal oxides are the active sites for catalytic reactions. They adsorb anions and cations from water through ion exchange reactions by releasing protons and hydroxyl groups into water, forming Br ø nsted acid sites, which are usually considered as the catalytic centers of metal oxides.
The most representative ones are three types: titanium dioxide (TiO ₂), aluminum oxide (Al ₂ O3), and manganese dioxide (MnO ₂). They have many hydroxyl groups on their surface, which are the active sites for catalytic reactions and are particularly stable, not easily lost, and can be used for three to five years without any problems.
(1) Titanium dioxide (TiO ₂): an old acquaintance in photocatalysis, also proficient in catalyzing ozone
Speaking of titanium dioxide, many people know that it is a star material in photocatalysis, used for making anti fouling coatings and air purifier filters. In fact, its ability to catalyze ozone is not bad at all.
Scientists have conducted experiments using ozone alone to oxidize oxalic acid (a particularly difficult to oxidize organic acid, often used to test oxidation ability), with a removal rate of only about 10% after 1 hour of reaction. After adding titanium dioxide powder, the removal rate can reach over 90% under the same conditions, almost entirely turning into carbon dioxide and water. If ultraviolet light is added, titanium dioxide can also undergo photocatalytic reactions simultaneously. The synergy of the two reactions can further enhance the effect, making it particularly suitable for deep treatment of drinking water without secondary pollution and with high safety.
(3) Manganese dioxide (MnO ₂): the "top student" in transition metal oxides. If metal oxides are the main force in catalysts, then manganese dioxide is the top student in the main force. Among all transition metal oxides, its catalytic activity is widely recognized as the best, and it can treat the most types of organic compounds. Whether it is complex organic compounds in pesticides, antibiotics, dyes, or pharmaceutical wastewater, it can catalyze ozone to remove them. Moreover, manganese dioxide itself is cheap, and there are already a large amount of manganese ore in nature, which is easy to modify. Nowadays, many industrial wastewater treatment projects have begun to use manganese based catalysts, which are more than 30% more effective than traditional iron-based catalysts. 4.3 Third category: Activated carbon catalyst - adsorption+catalysis dual skilled activated carbon is more familiar to everyone, and it is used in water purifiers and formaldehyde removal bags at home. It is a carbon material composed of a mixture of small crystalline and amorphous parts, with a large number of acidic or alkaline groups on the surface, especially hydroxyl and phenolic hydroxyl groups, which make activated carbon not only have adsorption ability but also catalytic ability. In the synergistic process of ozone/activated carbon, the adsorption of activated carbon accelerates the conversion of ozone into hydroxyl radicals, thereby improving oxidation efficiency. However, the catalytic mechanism of activated carbon is different from that of metal oxides: the Lewis base on the surface of activated carbon plays a major role; The Lewis acid on the surface of metal oxides is the active site of the catalytic process. In addition, for activated carbon catalytic systems, the adsorption performance of the activated carbon surface plays a significant role, so the efficiency of ozone oxidation degradation is greatly affected by the acidity or alkalinity of the medium. The most commonly used process now is the ozone/activated carbon synergistic process. Activated carbon adsorbs pollutants while catalyzing the decomposition of ozone into hydroxyl radicals, and can also adsorb ozone to prevent it from escaping. It is used in deep treatment of drinking water, which can remove odors and organic matter without adding metals, and has particularly high safety. However, activated carbon will become saturated after prolonged use and requires regular regeneration, which is also a minor drawback of it. Advertising Mobile Selfie Stick Selfie Live Streaming Stand Bluetooth Telescopic Tripod Z8 [Cool Black] Extended by 1 meter+Stable Tripod 30 yuan Coupon ¥ 40.9 Buy JD
5, Nanocatalysts: Empowering Catalysts with Wings of 'Performance Leap'
In the past decade, nanotechnology has become popular and has brought new breakthroughs to catalytic ozone technology. Think about it, the reactions of catalysts all occur on the surface. The smaller the particles, the larger the specific surface area, the more active sites on the surface, and naturally the higher the catalytic efficiency.
Traditional bulk catalysts have particles in the millimeter range, with a maximum specific surface area of only a few tens of square meters per gram, while nanocatalyst particles are in the nanometer range, with a specific surface area of several hundred or even thousands of square meters per gram. With several times more active sites, the catalytic efficiency naturally increases.
There are currently many researched nanocatalysts, including cobalt trioxide (Co∝ O ₄), iron oxide (Fe ₂ O ∝), nano titanium dioxide (TiO ₂), nano zinc oxide (ZnO), and so on. Experimental data shows that the efficiency of nanoscale manganese dioxide in catalyzing the degradation of phenol by ozone is more than three times that of ordinary bulk manganese dioxide, and the ozone consumption can be reduced by 40%.
Of course, there is also a problem with nanocatalysts now: the nanoparticles are too small, easily washed away by water, and difficult to recover. So now scientists are working on "loaded nanocatalysts", which load nanoparticles on large particle carriers such as alumina and activated carbon, retaining the high activity of nanomaterials and solving the problem of difficult recycling. It is estimated that they will be widely used in a few years.
6, How does catalytic ozone react? Explain three mechanisms to you clearly
Many people may ask: how do catalysts, ozone, and pollutants react together? In fact, the scientific community has summarized three typical reaction mechanisms, with different catalysts and water quality following different mechanisms.
Mechanism 1: Adsorption followed by oxidation
This mechanism is easy to understand: firstly, pollutants are chemically adsorbed on the surface of the catalyst, forming surface chelates with certain nucleophilicity, which is equivalent to being "fixed" on the catalyst surface. Then ozone or hydroxyl radicals come over and directly react with these fixed pollutants, oxidizing them. The intermediate products after oxidation may be further oxidized on the surface or desorbed into the solution for further oxidation.
Catalysts with relatively large adsorption capacity, such as activated carbon and macroporous alumina, basically follow this mechanism. You can understand it as a catalyst first "grabbing" pollutants to its side, and then waiting for oxidants to come and "eliminate" them, to avoid pollutants running around in the water without touching oxidants.
Mechanism 2: Catalyst directly participates in the reaction
In this mechanism, the catalyst is not just a bystander, but also directly participates in the reaction: the catalyst can not only adsorb organic matter, but also directly undergo redox reactions with ozone, producing oxidized metals and hydroxyl radicals that can directly oxidize organic matter.
You see, the catalyst is actually a "carrier" throughout the entire process, transferring the oxidation ability of ozone to pollutants without being consumed. This is why the catalyst can be reused repeatedly. Many supported metal catalysts and metal oxide catalysts conform to this mechanism.
To sum up, in actual reaction processes, these three mechanisms often do not exist alone, and often two or even three occur simultaneously, working together to achieve such high efficiency in catalyzing ozone.
7, What can this technology be used for? There are many more application scenarios than you think
Seeing this, you may ask: This technology sounds so powerful, where is it being used now? In fact, it is not far from our lives at all. Many familiar scenes have the presence of catalytic ozone technology behind them.
7.1 Deep treatment of drinking water, making tap water more reassuring to drink
Nowadays, many newly built water plants in China are adopting the ozone activated carbon deep treatment process, and many of them have already switched to catalytic ozone technology. The original ordinary ozone process, with the addition of 3mg/L ozone, had a removal rate of only about 20% for organic matter. After switching to catalytic ozone, with the same dosage, the removal rate can reach over 60%, and the generation of disinfection by-products can be reduced by 80%. The resulting tap water has almost no disinfectant taste and can be consumed directly without any problems.
There are also water sources that are slightly polluted, such as those with pesticide residues and antibiotic detection, which cannot be treated with conventional processes. Adding a catalytic ozone unit can completely degrade these trace pollutants without worrying about drinking water safety issues.
7.2 Upgrading municipal sewage treatment to make the discharged water cleaner
Nowadays, most municipal sewage treatment plants in China implement Class A discharge standards, but many places have higher requirements to meet Class IV or even Class III standards for surface water. The original biochemical treatment process simply cannot achieve this because biochemical treatment has no way to deal with difficult to degrade dissolved organic matter.
At this point, the catalytic ozone process comes into play: the effluent after biochemical treatment is first treated with catalytic ozone to decompose difficult to degrade organic matter into small molecules that can be biodegraded. After subsequent filtration, it can stably meet the Class IV standard for surface water. This water can be directly discharged into rivers as ecological water replenishment, used for greening, road flushing, and as recycled water. According to data, using catalytic ozone for wastewater upgrading only costs 0.3-0.5 yuan per ton of water, which is more than half cheaper than reverse osmosis technology.
7.3 Industrial wastewater treatment, tackling the toughest challenges
Industrial wastewater is the hardest nut to crack in water treatment, especially in industries such as printing and dyeing, pharmaceuticals, chemical engineering, and coking. The concentration of pollutants is high, the toxicity is high, and the structure is stable. Conventional processes cannot treat it at all. In the past, many companies either illegally discharged or spent a lot of money on steam distillation and reverse osmosis, with exorbitant costs.
Now with catalytic ozone technology, these problems are easily solved: for example, in printing and dyeing wastewater, the color is still very dark after biochemical treatment, and the COD is still over 100 mg/L. After one hour of catalytic ozone treatment, the COD can be reduced to below 50mg/L, the color completely fades, and the discharge can directly meet the standard; There is also pharmaceutical wastewater, which contains antibiotic residues and drug intermediates. After catalytic ozone treatment, the degradation rate can reach over 99%, and there is no need to worry about drug resistance issues caused by discharge into the environment.
8, Technology outlook: In the future, water treatment will become cheaper and safer. Although catalytic ozone technology has many applications, it is still developing rapidly and there is still a lot of room for imagination in the future. 8.1 Catalysts with higher performance and lower cost. Currently, most catalysts still use metal oxides or metal supports. In the future, with the development of nanotechnology and materials science, there may be catalysts with lower cost, higher activity, and longer lifespan, such as modified non-metallic catalysts that do not even need to add metals and have no risk of secondary pollution. The cost can be further reduced by half. 8.2 More integrated process and smaller footprint. Currently, most catalytic ozone reaction tanks are separate tanks, and in the future, they may be integrated with biochemical tanks and filtration tanks to form an integrated device, reducing the footprint by half and lowering the construction cost. They are particularly suitable for small sewage treatment plants and decentralized drinking water treatment plants in villages and towns. 8.3 Wide application scope: Currently mainly used in water treatment, it may also be used in fields such as flue gas treatment, soil remediation, and exhaust gas treatment in the future. For example, catalytic ozone decomposition of VOCs (volatile organic compounds) and oxidation of organic pollutants in soil are much more efficient and cost-effective than current technologies. The most important thing about the continuous decline in water treatment costs is that with the popularization of this technology, the cost of water treatment will become lower and lower. We don't have to spend a lot of money on expensive water purifiers anymore, we don't have to worry about the smell of disinfectant in tap water, and we don't have to worry about industrial wastewater being illegally discharged into rivers. Every sip of water we drink and every river around us becomes cleaner and safer. At the end: Environmental black technology has never been superior. Many people think that "catalytic ozone", "advanced oxidation", and "hydroxyl radicals" are high-tech far away from themselves when they hear these words, but they are not. All environmental protection technologies ultimately aim to make our lives better, allowing us to drink clean water, breathe fresh air, and see clear rivers. The cup of clean water you are holding now may be backed by decades of research by countless environmental scientists, countless engineers debugging processes on site, and countless operators maintaining equipment every day. This seemingly advanced catalytic ozone technology is actually an invisible defense line built by countless environmentalists for our lives, quietly eliminating those "stubborn toxins" in the water and safeguarding our drinking water safety. Of course, environmental protection is never just the responsibility of technicians. Each and every one of us is a participant: using less plastic bags, throwing less batteries, saving every drop of water, and reducing pollutant emissions can reduce the pressure of these water treatment technologies and speed up the improvement of our environment.
After all, every sip of water we drink, every breath of air we breathe, and ultimately the quality, are actually in our own hands.
