Tailoring Defect Density in UiO-66 Frameworks for Enhanced Pb(II) Adsorption

Abstract

Defect engineering of metal organic frameworks offers potential prospects for tuning their features toward particular applications. Herein, two series of defective UiO-66 frameworks were synthesized via changing the concentration of the linker and synthetic temperature of the reaction. These defective materials showed a significant improvement in the capability of Pb­(II) removal from wastewater. This strategy for defect engineering not only created additional active sites, more open framework, and enhanced porosity but also exposed more oxygen groups, which served as the adsorption sites to improve Pb­(II) adsorption. A relationship among degree of defects, texture features, and performances for Pb­(II) removal was successfully developed as a proof-of-concept, highlighting the importance of defect engineering in heavy metal remediation. To investigate the kinetic and adsorption isotherms, we performed adsorption experiments influenced by the time and concentration of the adsorbate, respectively. For the practicality of the materials, the most significant parameters such as pH, temperature, adsorbent concentration, selectivity, and recyclability as well as simulated natural surface water were also examined. This study provides a clue for the researchers to design other advanced defective materials for the enhancement of adsorption performance by tuning the defect engineering.

Zr-Based Metal–Organic Framework Nanocrystals for Water Remediation

“…In all the studies performed, the reference adsorbent UiO-66-0FA had the lowest Q max , further confirming previous conclusions on the role of defects and/or the carboxyl functional groups on the linker as adsorption sites. This is further confirmed in previous studies that showed the effect of the increase in the defect number on the increased Pb­(II) adsorption in UiO-66 adsorbents . In fact, the UiO-66-0FA sample shows a similar Q max of Pb­(II) compared to previously synthesized UiO-66 samples with HCl as a modulator (48.7 mg/g), while it performed much better than a sample synthesized to have as little as 0.1 defects per cluster (19.4–25.5 mg/g) .…”

Highly Efficient and Simultaneous Removal of Cr(VI) and Imidacloprid through a Ferrocene-Modified MIL-100(Fe) Composite from an Aqueous Solution

“…Prior to the batch adsorption experiments, the compositions of the materials, for instance, Fc 1 -MIL-100(Fe), Fc 2 -MIL-100(Fe), and Fc 4 -MIL-100(Fe), were compared with their removal efficiency. After the selection of the optimized material, the effects of adsorption conditions were evaluated with the added amounts of materials (10, 20, 30, 40, and 50 mg), adsorption times (20,40,60,120,180,240,300,360,480, 600, 720, and 1440 min), and adsorption temperatures (283, 293, 303, 313, and 323 K). In addition, the effects of pH (2.0, 4.0, 6.0, 8.0, 10.0, and 12.0) and coexisting ions (20 mM Cu 2+ , Cd 2+ , Pb 2+ , NO 3 − , CI − , and H 2 PO 4 − ) on the removal efficiencies (REs) of Cr(VI) and imidacloprid were also researched.…”

“…Meng et al used a nitrogen-doped MoS 2 nanoflower to effectively remove Cr­(VI) . Ali et al prepared defective UIO-66 to adsorb Pb­(II) in wastewater . Yang et al studied the effect of pH on the adsorption of pesticide at black carbon as adsorbents .…”

High Performance of UiO-66 Metal-Organic Framework Modified with Melamine for Uptaking of Lead and Cadmium from Aqueous Solutions

“…inorganic cations and organic linkers (10). Such materials have quickly moved to the forefront of materials research due to their extraordinary internal surface areas and porosity, chemical stability, and surface capability to selectively capture of guest species (10)(11)(12)(13)(14)(15)(16)(17)(18)(19). Accordingly, MOFs can be used in many applications such as gas storage, separation, catalysis, sensing, drug delivery, biological and proton conduction.…”

“…These materials are recognized to be considerably superior adsorbents as compared to conventional materials such as activated carbons and zeolites (14). Among various MOFs, UiO-MOF formulations (UiO-66, UiO-67, UiO-68, and UiO-69) have superior stability in different chemical media with large porosity (11,(16)(17)(18)(19)(20)(21). Thus they can be emerged as effectively adsorbents for removal of heavy metal ions from a variety of wastewater samples (11,16).…”