Efficient Wet Scrubber Solutions for Nitrogen Oxide and Aqua Regia Exhaust Gas Treatment

Client

Client is a leading manufacturer of printed circuit boards (PCBs) based in Silicon Valley, California. The company specializes in the design and production of high-tech PCBs for a wide range of applications, including consumer electronics, medical equipment, the automotive industry, and the aerospace sector.
The factory adheres to strict environmental standards in waste management and emissions control. In particular, it is equipped with a state-of-the-art gas treatment system that effectively neutralizes nitrogen oxides and other harmful substances released during the PCB etching process in nitric acid and aqua regia solutions. This ensures full compliance with all EPA emission requirements while also helping to maintain the safety and health of employees.
The company actively invests in research and development, allowing it to remain at the forefront of industrial innovation. Its research center develops new materials and technologies that enhance PCB performance and reduce manufacturing costs.

Production Process

Neutralization of exhaust gases containing nitrogen oxides (NOₓ) during the etching of copper hangers in electroplating production.

Problem

In the electroplating production process, including the etching of copper hangers in nitric acid or aqua regia, exhaust gases containing nitrogen oxides (NOx) are emitted. These gases can pose a serious threat to workers' health and the environment due to their high toxicity and ability to contribute to the formation of photochemical smog.
In the United States, nitrogen oxide concentration levels in work areas are strictly regulated by the Environmental Protection Agency (EPA) and the Occupational Safety and Health Administration (OSHA). The main requirements include the following:

• OSHA sets the permissible exposure limit (PEL) for NO2 at 5 ppm (parts per million) as an 8-hour time-weighted average for an 8-hour workday.
• NIOSH recommends a short-term exposure limit (STEL) for NO2 at 1 ppm for a 15-minute period.

Task

Develop and supply a wet scrubber system for neutralizing nitrogen oxide (NOₓ) exhaust gases generated during the etching of copper hangers in electroplating production using nitric acid and aqua regia. The system must comply with EPA and OSHA regulations, ensuring gas treatment efficiency while maintaining operational reliability.

Temperature

20—30 °С

Gas/Dust

Nitrogen oxide gases and aqua regia.

• Composition: Aqua regia is a mixture of HCl and HNO3, where the ratio is typically three parts HCl to one part HNO3.
• Appearance: In its freshly prepared state, aqua regia has a yellow-orange color due to the presence of dissolved chlorine and other gases released during the reaction.
• Odor: It has a sharp, characteristic odor due to the release of chlorine vapors and nitrogen oxides.
• Density: The density of aqua regia can vary depending on concentration and temperature, but it typically ranges from 1.0 to 1.2 g/cm³.
• Boiling point: The mixture boils at a temperature higher than that of pure hydrochloric or nitric acid, and can reach up to 120°C.
• Solubility: Aqua regia can dissolve many metals, including some that are resistant to other acids.