ISO 22197-2:2019

Overview

ISO 22197-2:2019 defines a laboratory test method for evaluating the air‑purification performance of semiconducting photocatalytic materials with respect to the removal of acetaldehyde (a representative volatile organic compound, VOC). The standard covers continuous exposure of a planar or structured test piece to a controlled acetaldehyde‑containing air stream while irradiated by near‑UV (UV‑A) light, and quantifies removal as percent removed and micromoles converted (including CO formed as an oxidation product). It is intended for performance testing of advanced ceramic (fine ceramics) photocatalytic materials and coatings commonly based on titanium dioxide and similar metal‑oxide semiconductors.

Key topics and technical requirements

• Scope and materials: Applies to flat sheets, boards, plates, honeycomb/structured filters, woven and non‑woven fabrics, and plastic or paper composites that contain ceramic microcrystals. Does not apply to powder or granular photocatalysts.
• Test principle: Flow‑type photoreactor exposes the test piece to model polluted air under UV‑A irradiation; photocatalytic oxidation and adsorption of acetaldehyde are monitored. Dark‑condition tests separate simple adsorption from photocatalytic activity.
• Apparatus: Includes test gas supply (humidifier, gas mixer, mass‑flow controllers), photoreactor with a 5.0 mm ± 0.5 mm air gap between sample and optical window, a UV‑A light source (per ISO 10677), and analytical systems for acetaldehyde and CO (referenced standards ISO 16000‑3 and ISO 4224).
• Gas and flow control: Acetaldehyde standard gas typically 50–250 µl/l before dilution; flow rates are expressed at standard state and should be controlled within ±5% (thermal mass‑flow controllers recommended).
• Measured outputs: Removal percentage of acetaldehyde, removed quantity in µmol, and conversion to CO. The method includes procedures for sample pretreatment and acceptable adsorption criteria.
• Limitations: Not suitable for evaluating photocatalytic effects on water contaminants, self‑cleaning, antifogging or antibacterial properties.

Applications and users

• Manufacturers of photocatalytic building materials, coatings and filters validating air‑purification claims.
• Independent testing and calibration laboratories seeking ISO‑compatible VOC performance data.
• Product developers and R&D teams optimizing photocatalyst formulations (e.g., TiO2‑based ceramics).
• Specifiers, architects and indoor‑air quality consultants comparing materials for VOC mitigation.
• Regulatory bodies and certification schemes requiring standardized VOC removal metrics.

Related standards

• ISO 22197 series (other pollutant test parts; e.g., ISO 22197‑1 for NO removal)
• ISO 10677 (UV light source for testing photocatalytic materials)
• ISO 16000‑3 (sampling/analysis of carbonyls)
• ISO 4224 (CO determination)
• ISO/IEC 17025 (laboratory competence)

Keywords: ISO 22197‑2, photocatalytic materials, acetaldehyde removal, air purification, fine ceramics, titanium dioxide, UV‑A photoreactor, VOC removal, indoor air quality.