ISO 17168-4:2025

Overview

ISO 17168-4:2025 - Fine ceramics (advanced ceramics) - Test method for air‑purification performance of semiconducting photocatalytic materials under indoor lighting environment - Part 4: Removal of formaldehyde specifies a laboratory method to quantify how effectively photocatalytic materials remove formaldehyde (HCHO) from air under typical indoor illumination. The standard covers semiconducting photocatalysts (for example, titanium dioxide and other ceramic materials) in sheet, board, plate, honeycomb, or composite forms - but excludes powder or granular photocatalysts.

Key topics and technical requirements

• Test principle: Continuous exposure of a test piece in a flow‑type photoreactor to a model formaldehyde‑containing air stream while illuminated by an indoor light source; measurement of removed HCHO (µmol) and removal percentage.
• Apparatus components: test gas supply, photoreactor, light source, UV sharp cut‑off filter, airtight optical window, and analytical measurement system.
• Reactor geometry & materials:
  • Planar test piece placed in a 50 mm wide trough with a 5.0 mm ± 0.5 mm air gap to the window.
  • Window materials: quartz or borosilicate glass (minimal absorption > 300 nm).
  • Recommended construction materials for low adsorption: acrylic resin, stainless steel, glass, fluorocarbon polymers.
• Gas supply & concentrations:
  • Continuous humidified test gas flow with stable formaldehyde supply (standard cylinder gas ≈ 20 µl/l typically used).
  • Typical flow controller capacities noted (e.g., pollutant gas ~100 ml/min; dry/wet air ~1 000 ml/min).
• Controls & corrections: Dark tests to separate simple adsorption from photocatalytic oxidation; calculations for removal quantity and percentage; reporting requirements and procedures for lower‑performance test pieces.
• Safety & competence: Addresses hazardous gas handling and references laboratory competence (ISO/IEC 17025).

Applications and who uses it

• Manufacturers of photocatalytic building materials, coatings, tiles and composite panels use ISO 17168-4:2025 to validate formaldehyde removal performance for indoor‑use products.
• Test and calibration laboratories apply the standardized method for product certification, R&D benchmarking and quality control.
• Material scientists and product developers use the method during formulation and scale‑up to quantify indoor‑light‑activated air purification.
• Indoor air quality (IAQ) specialists, architects and building product specifiers rely on results from this method when assessing material contributions to formaldehyde mitigation in occupied spaces.

Related standards

• ISO 17168-1 (NO removal method)
• ISO 14605 and ISO 24448 (light source specifications for indoor testing)
• ISO 16000-3 (formaldehyde sampling and analysis)
• ISO/IEC 17025 (laboratory competence)

ISO 17168-4:2025 provides a reproducible, application‑focused test method for evaluating formaldehyde removal by semiconducting photocatalytic materials under realistic indoor lighting - a practical tool for manufacturers, labs and IAQ professionals.