The search for efficient technologies empowering the selective capture of environmentally harmful heavy metals from wastewater treatment plants, at affordable prices, attracts wide interest but constitutes an important technological challenge. We report here an eco-friendly single-walled carbon nanotube buckypaper (SWCNT-BP) enriched with a multivariate amino acid-based metal–organic framework (MTV-MOF) for the efficient and selective removal of Pb 2+ in multicomponent water systems. Pristine MTV-MOF was easily immobilized within the porous network of entangled SWCNTs, thus obtaining a stable self-standing adsorbing membrane filter ( MTV-MOF/SWCNT-BP ). SWCNT-BP alone shows a moderately good removal performance with a maximum adsorption capacity of 180 mg·g –1 and a considerable selectivity for Pb(II) ions in highly concentrated multi-ion solutions over a wide range of lead concentration (from 200 to 10000 ppb). Remarkably, these features were outperformed with the hybrid membrane filter MTV-MOF/SWCNT-BP , exhibiting enhanced selectivity and adsorption capacity (310 mg·g –1 , which is up to 42% higher than that of the neat SWCNT-BP) and consequently enabling a more efficient and selective removal of Pb 2+ from aqueous media. MTV-MOF/SWCNT-BP was able to reduce [Pb 2+ ] from the dangerous 1000 ppb level to acceptable limits for drinking water, below 10 ppb, as established by the current EPA and WHO limits. Thus, the eco-friendly composite MTV-MOF/SWCNT-BP shows the potential to be effectively used several times as a reliable adsorbent for Pb 2+ removal for household drinking water or in industrial treatment plants for water and wastewater lead decontamination.
Although the discovery of plastic in the last century has brought enormous benefits to daily activities, it must be said that its use produces countless environmental problems that are difficult to solve.
Human society is facing—among other environmental threats—an enormous challenge due to human activities. The extensive use of high‐tech devices and electronics equipment in the daily life makes, among others, rare‐earth elements (REEs) recovery from secondary sources highly required. Here, a novel bioMOF‐based single‐walled carbon nanotube buckypaper (SWCNTBP) is presented as a new and efficient composite material (BioMOF@SWCNT‐BP). The flexible and highly crystalline metal–organic framework (MOF), prepared from the natural amino acid L‐threonine, has been homogeneously dispersed within the tangled net of a self‐standing SWCNT‐BP for lanthanides recovery from water. This MOF‐carbon‐based membrane exhibits high efficiency, either in static or dynamic regimes, in the recovery of lanthanides from aqueous streams outperforming the state‐of‐the‐art. The capture performances of BPs are successfully improved after incorporation of such MOF featuring hexagonal functional channels decorated with the threonine amino acid residues, pointing toward the accessible void spaces, which boosts the capture properties of the final membrane, providing the adaptable functional environment to interact with lanthanides. This material's preparation presents also a potential for large‐scale applications with a potential benefit on natural aquatic ecosystems as well. It is highly demanded because REEs from non‐recycled waste materials are potential pollutants for surface waters.
Photocatalytic materials, such as WO3, TiO2, and ZnO nanoparticles, are commonly linked onto porous polymer membranes for wastewater treatment, fouling mitigation and permeation enhancement. Buckypapers (BPs) are entanglements of carbon nanotubes, which have been recently proposed as innovative filtration systems thanks to their mechanical, electronic, and thermal properties. In this work, flexible membranes of single wall carbon nanotubes are prepared and characterized as efficient substrates to deposit by chemical vapor deposition thin layers of WO3 and obtain, in such a way, WO3/BP composite membranes for application in advanced oxidation processes. The photocatalytic efficiency of WO3/BP composite membranes is tested against model pollutants in a small continuous flow reactor and compared with the performance of an equivalent homogeneous WO3-based reactor.
Water decontamination is an important challenge resulting from the incorrect disposal of heavy metal waste into the environment. Among the different available techniques (e.g., filtration, coagulation, precipitation, and ion-exchange), adsorption is considered the cheapest and most effective procedure for the removal of water pollutants. In the last years, several materials have been tested for the removal of heavy metals from water, including metal-organic frameworks (MOFs), single-walled carbon nanotubes (SWCNTs), and graphene oxide (GO). Nevertheless, their powder consistency, which makes the recovery and reuse after adsorption difficult, is the main drawback for these materials. More recently, SWCNT buckypapers (SWCNT BPs) have been proposed as self-standing porous membranes for filtration and adsorption processes. In this paper, the adsorption capacity and selectivity of Pb2+ (both from neat solutions and in the presence of other interferents) by SWCNT BPs were evaluated as a function of the increasing amount of GO used in their preparation (GO-SWCNT buckypapers). The highest adsorption capacity, 479 ± 25 mg g−1, achieved for GO-SWCNT buckypapers with 75 wt.% of graphene oxide confirmed the effective application of such materials for cheap and fast water decontamination from lead.
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