Chitosan-dosed adsorptive filter media for removal of formaldehyde from indoor air – Performance and cancer risk assessment

It is firmly established that contemporary building materials and indoor furnishings are associated with elevated concentrations of formaldehyde in indoor air, representing a hazard to human health. To mitigate this issue, formaldehyde and other pollutants in indoor air are removed via air conditioning systems fitted with appropriate filters. Based on positive results from earlier, relevant research, this study investigates the use of air conditioning filters treated with chitosan as potential eco-friendly absorbents for removal of formaldehyde, a significant indoor air pollutant. The filter is sprayed with different dosages of chitosan, in accordance with our previous work [8]. Removal rate and adsorption of formaldehyde are calculated for the health risk assessment. After twenty-four hours testing, the results showed the averaged concentration of formaldehyde is 1.146 ppm, 0.714 ppm, and 0.084 ppm with chitosan dosage of 2.6 mg m⁻², 5.3 mg m⁻², 8.0 mg m⁻², respectively. The averaged reduction of formaldehyde concentration is 64.9%, 80.0%, and 96.0%; the averaged absorption of chitosan on formaldehyde is 0.167 mg, 0.204 mg and 0.271 mg for chitosan dosage of 2.6 mg m⁻², 5.3 mg m⁻², 8.0 mg m⁻², respectively. The risk characterization figures without spaying chitosan are 2.94, 2.65 and 7.07 times higher when compared with the same figures associated with filters treated with 2.6 mg m⁻², 5.3 mg m⁻², and 8.0 mg m⁻² of chitosan. This study finds that chitosan has strong potential as a commercial adsorbent. Increasing the amount of chitosan applied to the filter substrate improves the efficacy of the absorbent and further reduces the indoor formaldehyde concentration and the associated carcinogenic risk.