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Applications of Nanomaterials and Technologies in Environmental Protection Author: Peng Zifei and Yu Xiafei from Shanghai University As research on the use of nanomaterials and nanotechnologies in environmental protection advances, it will bring new opportunities for addressing environmental pollution in our country and around the world. ★Applications of nanotechnology in controlling harmful gases. Air pollution has always been a problem that countries need to address. Excessive levels of sulfur dioxide (SO2), carbon monoxide (CO), and nitrogen oxides (NOX) in the air are harmful gases that affect human health, and the use of nanomaterials and nanotechnology can help eliminate the sources of these pollutants. Gasoline and diesel used in industrial production, as well as those used as vehicle fuels, produce SO2 gas when sulfur-containing compounds burn, and this is the main source of SO2 pollution. Therefore, there is a desulfurization process in the petroleum refining industry to reduce its sulfur content. Cobalt nanotitanate (CoTiO3) is an excellent catalyst for petroleum desulfurization. Catalysts using cobalt titanate with a radius of 55–70 nm as the catalytic active component, supported on porous silica gel or A1203 ceramic, exhibit extremely high catalytic efficiency. The sulfur content in the oil catalyzed by it is less than 0.01%, meeting international standards. The burning of coal used in industrial production also generates S02 gas. If a nanoscale catalyst is added during combustion, it not only enables the coal to burn completely without producing sulfur monoxide, thereby improving energy efficiency, but it also converts sulfur into solid sulfides instead of sulfur dioxide, thus preventing the formation of harmful gases. Recent research findings show that nanoscale powders of composite rare earth compounds possess extremely strong redox properties, which are unmatched by any other catalysts for automotive exhaust purification. Its application can completely solve the pollution problem caused by carbon monoxide (CO) and nitrogen oxides (NOx) in vehicle exhaust. An automobile exhaust purification catalyst that uses activated carbon as a carrier and nano-Zr0.5 Ce0.5 O2 powder as the catalytically active component possesses strong electron transfer capabilities and redox properties due to the presence of Zr4+/Zr3+ and Ce4+/Cr3+ ions on its surface, allowing electrons to be transferred between these trivalent and tetravalent ions. Additionally, nanomaterials have a large specific surface area, numerous dangling bonds, and strong adsorption capacity; therefore, this catalyst can oxidize carbon monoxide while reducing nitrogen oxides, converting them into gases that are harmless to humans and the environment—carbon dioxide and nitrogen. The next generation of nanocatalysts will act as catalysts in automobile engine cylinders, preventing the production of CO and NOx during gasoline combustion, thus eliminating the need for exhaust gas purification. ★Applications of nanotechnology in wastewater treatment: Wastewater usually contains toxic and harmful substances, suspended solids, sediment, rust, odor-causing pollutants, bacteria, viruses, and more. Wastewater treatment involves removing these substances from water. Due to the low efficiency, high costs, and issues such as secondary pollution associated with traditional water treatment methods, wastewater treatment has not been effectively addressed. The development and application of nanotechnology are likely to completely solve this problem. Precious metals in wastewater are substances that are extremely harmful to the human body. It is lost in wastewater, which is also a waste of resources. A new nanotechnology can completely extract precious metals from wastewater, such as gold, ruthenium, palladium, platinum, etc., turning what was once harmful into a valuable resource. A new type of nanoscale water purifier possesses strong adsorption capacity. Its adsorption and flocculation capacities are 10 to 20 times those of the common water purification agent aluminum trichloride. Therefore, it can completely adsorb and precipitate the suspended solids in wastewater, first removing any suspended solids from the water. Then, by using a purification system that includes nano-magnetic materials, fibers, and activated carbon, it is possible to effectively remove pollutants such as rust, sediment, and unpleasant odors from the water. After the first two purification steps, the water becomes clear, odorless, and has a better taste. After passing through a special water treatment membrane with nanopores and a treatment device composed of ceramic balls with various nanopore sizes, bacteria and viruses in the water can be removed 100%, resulting in high-quality purified water that is completely safe for drinking. This is because bacteria and viruses are larger in diameter than nanometers, so they are filtered out when passing through membranes and ceramic beads with nanoscale pores, while water molecules as well as minerals and elements smaller in diameter than water molecules remain. This technology has already been applied in hemodialysis in the medical field, and is known as an \"artificial kidney.\" For those with liver or kidney failure, drinking this water will **reduce the burden on the liver and kidneys**. ★Nan TiO2 and environmental protection: Since nan TiO2 possesses not only the characteristics of nanomaterials but also photocatalytic properties, it will play an extremely important role in the treatment of environmental pollution. 1. Degradate harmful organic compounds in the air. In recent years, as the use of paints and coatings for interior decoration has increased, indoor air pollution has received growing attention. Surveys show that the concentration of organic compounds in the air of newly renovated rooms is higher than outside, and even higher than in industrial areas. Hundreds of organic substances have been identified in the air to date, many of which are harmful to the human body, and some are carcinogens. Studies on the main indoor gas pollutants such as formaldehyde and toluene have shown that photocatalysts can effectively degrade these substances, with nano-TiO2 exhibiting the highest degradation efficiency, approaching 100%. Its degradation mechanism is to convert these harmful substances into carbon dioxide, water, and organic acids under light exposure. Photocatalysts based on nano-TiO2 can also be used for treating industrial waste gases in industries such as petroleum and chemicals, thereby improving the air quality in the areas surrounding these facilities. 2. It can degrade organophosphorus pesticides. These pesticide varieties, developed in the 1970s, account for 80% of China’s pesticide production, and their production and use generate large amounts of toxic wastewater. This environmental challenge can be fundamentally solved by using nano-TiO2 to catalyze degradation. 3. Using nano-TiO2 catalytic degradation technology to treat wool dyeing and finishing wastewater offers advantages such as cost savings, high efficiency, and energy conservation; it also enables the complete mineralization of organic substances without causing secondary pollution, thus showing good prospects for application. 4. During the extraction, transportation, and use of oil, a considerable amount of petroleum-based substances are discarded on land, in rivers and lakes, and in marine waters. Nanoparticle TiO2 can be used to degrade oil, thereby addressing the problem of oil pollution in the oceans. 5. Nanosized TiO2 can accelerate the degradation of municipal solid waste, at a rate more than 10 times higher than that of larger particles of TiO2, thereby alleviating the pressure exerted on the urban environment by large amounts of waste. 6. Commonly used bactericides such as Ag and Cu can render cells inactive, but after the bacteria are killed, they can release febrile and toxic components such as endotoxins. Endotoxins are deadly substances that can cause diseases such as typhoid and cholera. Utilizing the photocatalytic properties of nano-TiO2 can not only kill bacteria in the environment but also degrade the toxic compounds released by these bacteria. Placing nanoscale TiO2 photocatalysts in areas of hospitals where bacteria are abundant, such as patient rooms, operating rooms, and living spaces, also has a deodorizing effect. 7. Due to its superhydrophilic and superoleophilic properties on the surface, nano TiO2 exhibits a self-cleaning effect; its surface features antifouling, anti-fogging, easy cleaning, and fast drying properties. If a TiO2-coated glass is placed in water vapor, mist will adhere to the surface of the glass; upon exposure to ultraviolet light, this mist disappears and the glass becomes transparent again. Coating TiO2 films on the surfaces of car windshields and mirrors can prevent fogging on those surfaces. Experiments show that, compared to surfaces without a TiO2 coating, surfaces coated with a nanoscale TiO2 film exhibit a high degree of self-cleaning capability. Once these surfaces are contaminated by oils and other substances, their superhydrophilic nature prevents the contaminants from sticking to them. The small amount of dirt that does adhere to the surface is removed automatically due to external forces such as wind, water flow, and its own weight. The ultraviolet rays in sunlight are sufficient to maintain the hydrophilic properties of the TiO2 surface, thereby ensuring that it retains its self-cleaning and decontaminating capabilities over time. The development and utilization of this feature will change people’s understanding of the functions of coatings, thereby bringing about a new revolution in coating materials. It will be widely used in automotive surface coatings, building exterior glass, and more in the future. Due to its good chemical stability, wear resistance, low cost, and the transparency of the films it can produce, nano TiO2 photocatalyst has become one of the most promising materials for environmental purification. More importantly, it can be used to purify the environment using sunlight, solar energy, or ordinary light sources. In short, as fundamental research on nanomaterials and nanotechnology progresses and their practical application expands, especially with the further integration of nanotechnology into environmental protection and management, many environmental challenges such as air pollution, wastewater treatment, and urban waste will be resolved. We will fully enjoy the clean environment that nanotechnology brings to humanity.