Comparison of the Application of Three Methods for the Determination of Outdoor PM2.5 Design Concentrations for Fresh Air Filtration Systems in China

Comparative Filtration Performance of Composite Air Filter Materials Synthesized Using Different Impregnated Porous Media

Indoor environment quality is currently a hot research topic. In this study, composite air filter materials were synthesized using different impregnated porous medium materials, and their filtration performance and structural parameters were analyzed. The results showed that composite filter materials' structures changed at the fibers' surfaces when synthesized using different porous medium material layers. The filtration efficiency of composite filter materials synthesized using different porous media reached a maximum 0.8 m/s filtration velocity, and PM₁₀, PM_2.5, and PM_1.0 increased by 1.67~26.07, 1.19~26.96, and 1.10~21.98%, respectively. The filtration efficiencies of reduced graphene oxide composite for PM₁₀, PM_2.5, and PM_1.0 were 21.26, 20.22, and 18.50% higher, respectively, than those of carbon black composite. In addition, the filtration efficiency of the composite material synthesized by reducing graphene oxide improved for 0 to 1.0 μm particulates and was more effective by comparison. Filtration efficiency and resistance were comprehensively considered during air filter use to provide useful values for the selection and preparation of composite filter materials in the future.

Experimental Study of the Factors Influencing the Regeneration Performance of Reduced Graphite Oxide Filter Materials under Water Cleaning

With the normalization of epidemic prevention and control, air filters are being used and replaced more frequently. How to efficiently utilize air filter materials and determining whether they have regenerative properties have become current research hotspots. This paper discusses the regeneration performance of reduced graphite oxide filter materials, which were studied in depth using water cleaning and the relevant parameters, including the cleaning times. The results showed that water cleaning was most effective using a 20 L/(s·m²) water flow velocity with a 17 s cleaning time. The filtration efficiency decreased as the number of cleanings increased. Compared to the blank group, the filter material's PM₁₀ filtration efficiency decreased by 0.8%, 19.4%, 26.5%, and 32.4% after the first to fourth cleanings, respectively. The filter material's PM_2.5 filtration efficiency increased by 12.5% after the first cleaning, and decreased by 12.9%, 17.6%, and 30.2% after the second to fourth cleanings, respectively. The filter material's PM_1.0 filtration efficiency increased by 22.7% after the first cleaning, and decreased by 8.1%, 13.8%, and 24.5% after the second to fourth cleanings, respectively. Water cleaning mainly affected the filtration efficiency of particulates sized 0.3-2.5 μm. Reduced graphite oxide air filter materials could be water washed twice and maintain cleanliness equal to 90% of the original filter material. Water washing more than twice could not achieve the standard cleanliness equal to 85% of the original filter material. These data provide useful reference values for the evaluation of the filter materials' regeneration performance.