How do chemical filters compare with photocatalytic purification equipment?

In discussions about air purification solutions, chemical filters and photocatalytic purification equipment are often compared together.

Both technical routes can treat gaseous pollutants, but their working mechanisms are different and their applicable conditions are also different. It is difficult to judge which one is more suitable for a certain project based only on the name of the equipment or the manufacturer's introduction. The premise of comparison is to align the target pollutants, operating conditions and acceptance requirements, and then look at the respective treatment performance. For specific selection logic, please refer to Discussion of what chemical filters are and what problems they are mainly used to solve .

Different processing mechanisms

There are fundamental differences in the way the two technologies deal with gaseous pollutants.

Chemical filters rely on media adsorption or reaction. When air flows through the filter material, the target gas is adsorbed by the surface of the media or chemically reacts with the impregnated material. The treatment effect depends on the suitability of the medium to the target gas, contact time and inlet concentration. The medium has capacity limits and needs to be replaced after adsorption saturation or reaction consumption.

Photocatalytic purification equipment usually uses catalysts and specific light sources to produce substances with oxidizing capabilities and decompose organic pollutants into products such as carbon dioxide and water. Its effectiveness depends on catalyst activity, light conditions, contact time, and the chemical nature of the contaminant.

The two mechanisms have different scopes of application. Chemical filters have corresponding media solutions for various gases such as acids, alkalis, and organic vapors, but they need to be selected according to the gas. Photocatalysis may have a decomposition effect on some organic matter, but its ability to process certain gases (such as small molecules with low concentrations and stable structures) is limited. For specific comparison, please refer to Discussion on why chemical filters should be selected according to the target gas .

By-products also need attention

During photocatalytic treatment, organic matter may not be completely decomposed, but intermediate products may be generated.

Some intermediates may still have an odor or have different chemical properties. If the project has strict requirements on the composition of the outlet air, it is necessary to confirm the product composition of the photocatalytic process and not just look at the removal rate of the target pollutants.

Similar problems exist with chemical filters. After adsorption is saturated, already adsorbed substances may desorb when concentration or temperature changes. Reactive media may also produce by-products if the reaction is incomplete. Both types of technology require a focus on the composition of the treated air, not just removal efficiency.

When comparing, both 'what is removed' and 'what is generated' should be included in the evaluation scope. Only the target gas concentration at the inlet and outlet is measured, and intermediate products or by-products may be missed. For specific detection methods, please refer to Discussion of why chemical filter performance reports list specific target gases .

Sustained operating performance

After the equipment is installed, whether it can continue to operate stably is another comparison dimension.

Chemical filter capacity decreases as media is consumed. The outlet concentration may gradually increase, and replacement needs to be arranged according to the gas processing capacity. The change in pressure difference is not necessarily obvious and cannot be judged solely by pressure difference.

The catalyst activity of photocatalytic devices may decay over time. If the catalyst surface is covered with dust or contaminated with certain substances, the activity may decrease. The intensity of the light source also decays over time. These factors need to be monitored during operation.

Both types of technologies have maintenance requirements, but the basis for judgment is different. The chemical filter depends on the gas processing capacity, and the photocatalytic equipment depends on the catalyst status and light source intensity. Maintenance intervals, replacement costs, and downtime should all be taken into consideration when comparing.

involving For projects of the chemical filter product series , it is recommended to clarify the maintenance basis and inspection cycle during the planning stage.

System matching and operating costs

No matter which option you choose, check the system conditions.

Resistance and fan margin. Chemical filters and photocatalytic equipment both increase system resistance. When selecting a model, it is necessary to calculate the impact of the new resistance on the fan operating point and confirm whether the air volume can still meet the requirements. The accounting method can be referred to Discussion of how much the added resistance of the chemical filter will increase the fan's electricity consumption .

Installation space. The size of the chemical filter depends on the air volume and media usage. The photocatalytic equipment also needs to consider the installation conditions of the light source and power supply. Projects with limited space must be confirmed in advance.

Operating energy consumption. The chemical filter itself does not consume electricity, but the resistance will affect the energy consumption of the fan. In addition to fan energy consumption, photocatalytic equipment also consumes electricity from light sources. Take this into account when comparing running costs.

Maintenance costs. Media replacement of chemical filters is the main cost, and catalyst and light source replacement, cleaning and maintenance of photocatalytic equipment also need to be included. The long-term costs of the two options should be calculated based on actual working conditions.

Project judgment example

A certain project requires the treatment of organic waste gas generated by the spray painting process.

The preliminary plan considers photocatalytic equipment, which is believed to be able to decompose organic matter. After running for a period of time, it was found that the outlet smell had improved, but the test could still detect some organic matter, and the composition was different from that at the entrance.

Investigation and confirmation: The photocatalytic process produced intermediate products, and some intermediate products still smell. The original solution had limited processing capabilities for intermediate products.

Adjustment plan: Add a chemical filtration section after the photocatalytic equipment to adsorb residual organic components and intermediate products. After adjustment, the outlet concentration meets the requirements.

This case shows that the two technologies can be used in combination or alone. The key is to look at the target pollutants and export requirements. There is no default that one technology can solve all gas problems. involving For projects where FFU is equipped with chemical filters or equipment-side applications, the solution selection should be based on the equipment structure and air flow conditions.

Key points for selection and acceptance inspection

About Aili Industrial’s solution packages

The core of selecting an air purification solution is to align the target pollutants, operating conditions and acceptance requirements, and then compare the treatment performance of different technical routes.

Aili Industrial has independent manufacturing capabilities in filters, motors, fans, control systems and sheet metal processing, and can provide chemical filter product series and supporting air supply equipment. For projects that need to compare or combine different treatment technologies, the target gas, concentration, air volume and installation space can be combined to assist in checking the filter section configuration. When the filter is matched with MAU, FFU, EFU and other equipment, the resistance, interface and maintenance methods can be confirmed uniformly.

Related products:Chemical filter product series、MAU box chemical filter、FFU comes with chemical filter . Providing a list of target contaminants, system conditions and acceptance requirements when enquiring, can help identify suitable solutions. The specific selection is subject to the technical documents and test results confirmed by the project.