Characterizations and n-Hexane Vapor Adsorption of a Series of MOF/Alginates

Abstract

Four different kinds of metal−organic framework (MOF) materials Zn-BTC, Cu-BTC, Cr-BTC, and Fe-BTC are incorporated into alginate, forming various hydrogels for n-hexane vapor adsorption. The cross-link networks between center cations of MOFs and alginate are verified by comparing the Fourier transform infrared characteristic peaks of the MOF/alginates with that of bare alginate. Interestingly, the MOF/alginate composites cross-linked by trivalent cations (Cr 3+ and Fe 3+ ) contain micropores while those cross-linked by divalent cations (Zn 2+ and Cu 2+ ) do not. The specific surface parameters of the as-prepared hydrogels are affected by the concentration of the alginate. In addition, the Fe-BTC/alginate performs the best n-hexane vapor adsorption capacity among the four kinds of composites. This study would be helpful for a better understanding of the effect of ionic cross-linking on the alginate hydrogel surface area parameters and provide basic knowledge and reference for expanding the applications of the MOF/ alginate hydrogels.

The Complexity of Comparative Adsorption of C6 Hydrocarbons (Benzene, Cyclohexane, n-Hexane) at Metal–Organic Frameworks

“…In the literature uptake values for n -hexane near p p 0 −1 = 1 were noted as high for MOF-5 (249 mg g −1 at 298 K), MIL-101(Cr) (504 mg g −1 at 298 K), or Cu-BTC (175 mg g −1 at 303 K) [ 80 ]. Here, an n -hexane uptake above 500 mg g −1 at p p 0 −1 = 0.9 (293 K) is seen with DUT-4, DUT-5, MIL-53, UiO-66, UiO-66-NH 2 , UiO-67, MIL-125 and MIL-101(Cr) ( Table S2 , Figure 4 ).…”

Advances in metal–organic framework-based hydrogel materials: preparation, properties and applications

“…MOFs, as dispersed substances, scattered in a continuous medium (hydrogel matrix), thereby forming composite structures to perform multiple functions. The fabrication methods of MOF-based hydrogels are roughly classified into three categories: 102–108 (1) simple mixing method, (2) in situ growth method, and (3) other methods.…”

“…In addition, the three-dimensional mesh of the hydrogel can be utilized to facilitate the dispersion of MOFs in the hydrogel matrix, while the MOFs can interact with hydrophilic polymers or affect the mechanical properties, freeze resistance and stability of the hydrogel. 102–104 The most significant advantage of hydrogels and MOFs is their functional diversity. More precisely, the introduction of MOFs into hydrogels can excellently combine the functional characteristics of both, resulting in novel and efficient functional materials.…”

Green Synthesis of Hierarchically Porous Alginate/ZIF‐8 Composite Beads for Water Treatment

“…The polysaccharides/MOFs composites have found diverse applications in the fields of adsorption, [22–24] catalysis, [25,26] thermal insulation & fire retardancy, [27,28] energy, [29] controllable release, [30] and electromagnetic shielding [31] . To construct these porous polysaccharides/MOFs composites, MOFs are usually introduced through three different ways, i. e. (i) direct blending MOFs powders with polysaccharides in solution before gelation and drying, [32–40] (ii) in situ formation of MOFs on pre‐prepared porous polysaccharide supports, [41–44] and (iii) in situ formation of MOFs in polysaccharide‐based hydrogels [45–49] . Based on previous reports, the third method exhibits its unique advantages.…”

“…Sodium alginate (SA) is a kind of natural polysaccharide extracted from brown algae, which consists of β‐D‐mannuronic acid (M unit) and α‐L‐guluronic acid (G unit). Hydrogels can be easily formed with SA cross‐linked by different divalent and trivalent metal ions under mild conditions, which have been proved to be excellent candidates as matrices for in situ growth of MOFs and the subsequent preparation of porous alginate/MOFs composite materials [45,48,50] . However, it failed to avoid the employment of either organic solvents or elevated temperature during the in situ growth of MOFs in these works, which may cause large amounts of waste, air pollution, fire hazard, and other environment impacts.…”