NO₂ Scrubber | 98%+ NOₓ Removal Efficiency | XICHENG EP LTD

While both use alkaline absorption, a NO₂ scrubber requires specialized design features to handle the unique properties of nitrogen oxides. Most importantly, NO (nitric oxide) is insoluble in water and cannot be removed by simple alkali washing—it must first be oxidized to NO₂ using a chemical oxidizing agent.

A standard acid mist scrubber will only remove 30-40% of total NOₓ, while our dedicated NO₂ scrubber achieves 98%+ removal through integrated oxidation and absorption processes. Learn more about configuration options in our multi-stage NOx scrubber design guide.

NO is treated through a two-step process: first, it is oxidized to NO₂ using a specialized oxidizing agent (typically sodium hypochlorite or hydrogen peroxide) in the oxidation section of the scrubber. The resulting NO₂ is then easily absorbed and neutralized by the sodium hydroxide solution in the packed bed section.

Our ORP control system automatically maintains the optimal oxidation potential to ensure complete conversion of NO to NO₂, maximizing overall NOₓ removal efficiency.

Our NO₂ scrubbers use two primary chemicals: sodium hydroxide (NaOH) for neutralizing NO₂ and an oxidizing agent (sodium hypochlorite or hydrogen peroxide) for converting NO to NO₂. The exact concentration and dosage depend on the inlet NOₓ concentration and NO/NO₂ ratio.

Our automatic dosing system precisely controls both chemical feeds to maintain optimal performance while minimizing waste and operating costs.

ORP (Oxidation-Reduction Potential) is a measure of the oxidizing power of the scrubbing solution. For NOₓ treatment, maintaining the correct ORP level (typically 500-700 mV) is critical to ensure complete oxidation of NO to NO₂.

If the ORP is too low, NO will not be fully oxidized and will pass through the scrubber untreated. If it is too high, excess oxidizing agent is wasted. Our integrated ORP controller automatically adjusts oxidant dosage to maintain the optimal range.

NO₂ scrubber sizing depends on four critical factors: total exhaust air volume, inlet NOₓ concentration, NO/NO₂ ratio, and required outlet emission limit. For NOₓ treatment, it is essential to account for the additional oxidation requirement in the design.

Our engineers can provide a detailed sizing calculation based on your specific operating conditions. You can also refer to our NO2 scrubber sizing calculation guide for more information.

The wastewater from a NO₂ scrubber contains sodium nitrate, sodium nitrite, and excess sodium hydroxide. This solution is typically alkaline and may require neutralization and reduction of nitrates before discharge.

Most facilities either send the wastewater to their existing industrial wastewater treatment plant or use a dedicated biological denitrification system. Our engineers will help you develop a wastewater management plan that meets local discharge regulations.

With proper operation, our NO₂ scrubber systems require minimal maintenance. We recommend daily checks of pH and ORP levels, weekly inspections of spray nozzles and packing, and quarterly calibration of sensors.

A complete annual service, including pump inspection and electrical system testing, is also recommended. Download our NOx system maintenance checklist for a detailed schedule.

The most common issues are insufficient NO oxidation (caused by low ORP levels), nozzle clogging, and packing fouling. Insufficient oxidation is usually the result of improper chemical dosing or sensor calibration issues.

Regular maintenance and proper system monitoring can prevent most of these issues. For troubleshooting guidance, see this comprehensive guide on common NO2 scrubber troubleshooting.

Yes, our NO₂ scrubbers are designed to meet or exceed all relevant OSHA and EPA regulations for nitrogen oxide treatment. The 98%+ removal efficiency ensures that outlet concentrations are well below the OSHA NO2 permissible exposure limit of 5 ppm.

Our systems have been installed in over 30 countries and comply with all major international environmental standards, including EU BREF and India CPCB.

Yes, in many cases, existing acid mist scrubbers can be upgraded to treat NOₓ by adding an oxidation section and ORP control system. For facilities requiring higher removal efficiency, we can add a second absorption stage or an activated carbon polishing stage for final treatment.

For facilities with both SO₂ and NOₓ emissions, we recommend upgrading to a combined SOx/NOx scrubber system that handles both pollutants in a single unit.