Adsorption of Organic Pollutants

Reproduced from ref. 33 with permission from The Royal Society of Chemistry. 

Material Sbett (m g Benzene (mmol Toluene (mmol g ) Methanol (mmol g ) 

PAF-2 and the benzene molecule. The organic vapor sorption of PAFs are summarized in Table 8.2 it can be clearly seen that PAFs show great potential in the sorption of organic vapor and all are superior to the very famous MOF-5 (10.3 mmol g of benzene at 295 K).  

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Construction and use of adsorption isotherms from equilibrium sorption data has been employed by numerous researchers to describe adsorption of organic pollutants on a solid matrix [131-137]. An isotherm represents a relation between the amount of solute (i.e., the pollutant of interest) adsorbed per unit weight of solid adsorbent (i.e., soil, sediment) and the solute concentration in solution at equilibrium. 

SPME, a variant of SPE, involves the adsorption of organic pollutants from the matrix onto the solid-phase coating. The adsorbed analytes are then directly transferred to a gas chromatography (GC) injector using a modified syringe assembly or can be stored for a certain period of time.141... 

Effect of Water Vapor on Photocatalytic Air Treatment. Several studies have reported on the effects of water vapor on the photocatalytic treatment of air (101-108). The effect of water vapor very much depends on the type of pollutant and, obviously, on the partial pressure of water against that of the pollutant. On one hand, water can compete with the adsorption of organic pollutants, especially those that are structurally related, such as alcohols. On the other hand, water can behave as a reactant in some of the successive steps of the degradation of organics and, in particular, can limit the formation of products that inhibit the photocatalytic activity. Water can be at the origin of the formation of hydroxyl radicals however, the importance of these radicals in gas-phase photocatalytic reactions is being debated on (109-111). The conclusion is that some humidity seems necessary for optimum photocatalytic activity. 

Wolfe, T.A., Demirel, T. and Bauman, E.S. (1985). Interaction of aliphatic amines with montmorillonite to enhance adsorption of organic pollutants. Clays Minerals, 33 301-311. 

For applications like the adsorption of organic pollutions, selectivity is also an important feature that an absorbent should possess. PAF-2 can adsorb 138 mg g benzene vapor at room temperature but little cyclohexane (7 mg g Figure 8.5). This excellent selective sorption of benzene can be directly attributed to the n-n interaction between the aromatic framework of... 

In conclusion, owing to the high surface area and excellent stability, PAFs show great potential in gas storage and separation, the adsorption of organic pollutants, molecular reorganization, as electrode materials for batteries and... 

In conclusion, as a new generation of porous materials, PAFs are a class of material with intrinsic micropores composed of covalent bonds. Both experiments and theoretical simulation and calculation have shown the potential applications of PAFs in gas storage and separation, the adsorption of organic pollutions and many other fields. Besides, due to their high physicochemical stability and surface area, PAFs are good candidates as host materials that can be loaded with guest molecules or be modified by incorporation of functional groups for specific applications. 

Coughlin R, Ezra FS. Role of surface acidity in the adsorption of organic pollutants on the surface of carbon. Environ Sci Technol 1968 2 291-297. 

B. Dragoi, V. Rakic, E. Dumitriu, A. Auroux, Adsorption of organic pollutants over microporous solids investigated by microcalorimetry techniques. J. Therm. Anal. Calorim. 99, 733-740 (2010). doi 10.1007/sl0973-009-0353-4... 

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