Template Method for Synthesizing Hierarchically Porous MIL-101(Cr) for Efficient Removal of Large Molecular Dye

Abstract

As one of the most important prototypical chromium-based MOFs, MIL-101(Cr) is well-studied and widely employed in various scientific fields. However, due to its small capture window sizes and curved internal apertures, its application in large molecular removal is quite limited, and given its high stability and high synthetic temperature (> 200 °C), it is difficult to achieve hierarchically porous MIL-101(Cr). In our study, hierarchically porous MIL-101(Cr) involving a high macro-/meso-/micropores ratio was designed and synthesized using acetic acid as an additive and silicon dioxide (SiO2) nanoparticles as a template. The optimal hierarchically porous MIL-101(Cr) (A-4) possessed a high specific surface area (2693 m2·g−1) and an abundant macro-/mesoporous structure with the addition of SiO2 of 200 mg. Compared with the control sample (A-0) with a less macro-/mesoporous structure, A-4 showed good adsorption properties for both coomassie brilliant blue R-250 (CBB, 82.1 mg g-1) and methylene blue (MB, 34.3 mg g-1) dyes, which were 1.36 times and 9.37 times higher than those of A-0. Moreover, A-4 also had good recyclability, and the removal rate of CBB was still higher than 85% after five cycles of adsorption.

A Novel P@SiO2 Nano-Composite as Effective Adsorbent to Remove Methylene Blue Dye from Aqueous Media

“…The proposed adsorption mechanism is illustrated in Figure 8 . The electrostatic attractions between the positive MB species and the negative active sites of P@SiO 2 nanocomposite mainly depends on the reaction pH [ 49 , 50 ]. In an acidic environment, the H-atom will convert Si=O into Si-OH which will enhance the activity of these groups towards interaction with the positive MB species.…”

“…A comparative evaluation of the maximum adsorption capacity of P@SiO 2 nanocomposite to adsorb MB dye according to the Langmuir isotherm and other adsorbent materials in the literature is listed in Table 7 [ 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 ]. Referring to the recent literature, equilibrium time and adsorption capacities are the main goals for scientists to investigate and develop many novel adsorbent materials.…”

Superior Adsorption Efficiency of MIL‐101 (Cr) and Nano‐MIL‐101 (Cr) in Anionic and Cationic Dye Removal from Aqueous Solution

“…Adsorption is a widely used technique for dye removal, in which particles are attached to the surface of the adsorbent by physical or chemical forces [28] . In recent years, it has been reported in adsorption studies that MIL‐101 (Cr) is a potential adsorbent and shows very high efficiency in the treatment of dye‐contaminated wastewater [29–34] …”

“…[28] In recent years, it has been reported in adsorption studies that MIL-101 (Cr) is a potential adsorbent and shows very high efficiency in the treatment of dye-contaminated wastewater. [29][30][31][32][33][34] In this work, MIL-101 (Cr) and nano structured MIL-101 (Cr) samples were synthesized using two different hydrothermal protocols. XRD, TG-DTA-DTG, FTIR and SEM analyses were performed and pHpzc points and Zeta potentials were determined to characterize MIL-101 (Cr) and nano-MIL-101 (Cr) samples.…”