Volatile organic compounds (VOCs) are air pollutants that contribute to ozone sphere damage and threaten human health after high-concentration exposure.vocs adsorb Adsorption is an effective environmental remediation technique that can effectively remove VOCs from the environment.vocs adsorb However, the performance of adsorption depends on the physicochemical characteristics of the adsorbent material. Therefore, scientists are constantly pursuing advanced materials with excellent adsorption performance for the abatement of VOCs.
In recent years, many researches on VOCs adsorption have focused on porous materials with abundant specific surface area and chemical functional groups.vocs adsorb Among these materials, metal-organic frameworks (MOFs) are promising for their outstanding adsorption properties. They have a unique porous structure, large surface chemical functional groups, and adjustable pore size. In addition, they can be flexibly modified with different ligands and structures to optimize the adsorption behavior of VOCs.
Currently, the most common VOCs adsorption materials are activated carbon, zeolites, and crosslinked polymer resins.vocs adsorb The adsorption capacities of these materials vary due to their different physicochemical properties, such as the pore size, the number of pore channels, and the molecular diameter. Furthermore, the adsorption process is greatly affected by the boiling point of VOCs. The adsorption process is most efficient when the pore volume of the adsorbent is slightly larger than that of the adsorbate.
In addition, the adsorption capacity of zeolites varies depending on their pore size and cation exchange.vocs adsorb The adsorption capacities of zeolite adsorbents can be enhanced by the introduction of cations into the zeolite skeleton during synthesis. The cations can neutralize the negative charge on the adsorbent and change its active cationic center to improve its adsorption behavior.
Another method for improving the adsorption efficiency of zeolite is to introduce a covalent bond between the cation and the silica atom.vocs adsorb The interaction between the cation and the silica results in the formation of an unsaturated metal ion site on the adsorbent, which enhances the adsorption ability by increasing the number of surface active sites.
A recently developed adsorbent, DESVOCANT, is an air-permeable clay with strong VOCs adsorption capacity.vocs adsorb The free-flowing granules of this adsorbent are completely contained in an air-permeable package, so that they can be safely used in households and workplaces without the risk of dusting or staining light-colored goods.
The adsorption capacity of MOFs is superior to that of traditional adsorbents, including activated carbon, zeolite, and crosslinked polymer resins.vocs adsorb In fact, the adsorption capacity of MOFs for VOCs is 1.7 times greater than that of activated carbon, and 5.8 and 2.1 times greater than that of zeolite and super crosslinked polymer resins, respectively. Considering the high adsorption efficiency and environmentally friendly nature, MOFs have great potential as an adsorbent for VOCs removal from the environment. Their adsorption capacity also increases with the addition of more metal ions or covalent ligands on the skeletal structure. In addition, the adsorption efficiency of zeolite can be improved by combining it with an organometallic framework.
