High-performance materials for effective sorptive removal of formaldehyde in air

As formaldehyde (FA) is well-known for its carcinogenic potential, various techniques for its removal have been developed based on recovery (e.g., adsorption/absorption and condensation) or destructive treatment (e.g., incineration and thermal/ catalytic oxidation). Among them, adsorption has been one of the most preferable options due to its low price and simplicity. In this review, we summarize state-of-the-art knowledge about adsorption mechanisms with respect to its key controlling variables (e.g., surface chemical properties of adsorbent, temperature, and relative humidity) and adsorption performance of materials with particular emphasis on advanced materials (e.g., carbon nanotubes, metal-organic frameworks, graphene oxides, and porous organic polymers) and their modified forms in comparison with conventional sorbents (e.g., AC and zeolite). However, it is yet difficult to assess the adsorption capacity of each material on a parallel basis because adsorption experiments of each material were conducted under different conditions (e.g., large differences in the initial loading concentrations). The partition coefficient (PC) was employed for evaluating adsorption performance between different materials at an equivalent level to overcome the limitation based on adsorption capacity concept. For instance, among the list of the surveyed materials, the highest PC was recorded by γ-CD-MOF-K (31.2 mol kg^-1 Pa^-1). This study should offer valuable insights into the selection and development of outstanding materials for the sorptive removal of FA.