Bioinspired Metal‐Organic Frameworks in Mixed Matrix Membranes for Efficient Static/Dynamic Removal of Mercury from Water

Abstract

The mercury removal efficiency of a novel metal‐organic framework (MOF) derived from the amino acid S‐methyl‐L‐cysteine is presented and the process is characterized by single‐crystal X‐ray crystallography. A feasibility study is further presented on the performance of this MOF—and also that of another MOF derived from the amino acid L‐methionine—when used as the sorbent in mixed matrix membranes (MMMs). These MOF‐based MMMs exhibit high efficiency and selectivity—in both static and dynamic regimes—in the removal of Hg2+ from aqueous environments, due to the high density of thioalkyl groups decorating MOF channels. Both MMMs are capable to reduce different concentration of the pollutant to acceptable limits for drinking water (<2 parts per billion). In addition, a novel device, consisting of the recirculation and adsorption of contaminated solutions through the MOF–MMMs, is designed and successfully explored in the selective capture of Hg2+. Thus, filtration of Hg2+ solutions with multiple passes through the permeation cell shows a gradual decrease of the pollutant concentration. These results suggest that MOF‐based MMMs can be implemented in water remediation, helping to reduce either contaminants from accidental unauthorized or deliberate metal industrial dumping and to ensure access for clean and potable freshwater.

Synthesis and Enhanced Capture Properties of a New BioMOF@SWCNT‐BP: Recovery of the Endangered Rare‐Earth Elements from Aqueous Systems

“…It is known that both SWCNT‐BP [ 33 ] and BioMOF in polymer matrices [ 47 ] are stable after regeneration processes showing integrity and reusability over several successive cycles of adsorption and regeneration. Such properties were also confirmed for BioMOF@SWCNT‐BPs, which were reused thrice after regeneration in 250 mL ethanol for the release of adsorbed lanthanides.…”

Emerging Materials to Prepare Mixed Matrix Membranes for Pollutant Removal in Water

“…To minimize the detrimental impacts brought about by heavy metals, the World Health Organization has imposed strict standards for the concentration of heavy metals in drinking water (e.g., <10 ppb of arsenic) [39]. Unlike organic pollutants that can be degraded naturally or through treatment by advanced oxidation processes (AOPs), heavy metals cannot be removed and is thus persistent in the environment if they are not physically removed [38]. Membrane-based technologies have been adopted to remove heavy metals from aqueous solutions because of their ease of operation, decent removal efficiencies, and most importantly, modest energy consumption [27,37].…”

“…Heavy metals are known to be highly soluble in water and tend to be absorbed by living organisms. The pollution and contamination of aquatic systems due to the presence of heavy metals are a cause for concern because of their harmful effects as well as the non-biodegradability, which will eventually accumulate onto living organisms and lead to detrimental health effects such as skin cancer, cardiovascular diseases and brain damage [ 38 , 39 ]. To minimize the detrimental impacts brought about by heavy metals, the World Health Organization has imposed strict standards for the concentration of heavy metals in drinking water (e.g., <10 ppb of arsenic) [ 39 ].…”

“…The latter trait is particularly important because adsorption is deemed the most suitable removal method in treating feeds with a low concentration of heavy metals. For instance, Bruno et al reported the success (>98% Hg 2+ rejection) of MMMs incorporated with MOFs when removing trace amounts of mercury in the feed solution (2.61 ppm) [ 38 ]. The key message here is that the trait of large surface area per unit volume is typically desired when treating feeds with a low concentration of heavy metals to enhance the adsorption rate of the latter.…”

“…( B ) Schematic illustration of the filtration process in which wastewater containing mercury ions is filtered through the MMM. The adsorption of mercury ions onto the MOFs occurs as a result of the interaction between mercury ions and functional groups in the interior of the MOFs channels [ 38 ]. ( C ) The fabrication procedure of a hollow fiber MMM incorporated with UiO-66 filler materials [ 39 ].…”