Nanofibrous Aerogel Extracts Metal Elements From Water Like Lithium, Gold, Uranium, Among Others

A research team led by Professor LI Chaoxu from the Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, recently revealed that biological nanofibrils could effectively extract useful metal elements from water.

Essentially, a lot of valuable metals such as lithium, gold, silver, and Uranium are vital to the modern and high technology industry, a Nanowerk report specified.

The terrestrial mineral resources of these said metals are generally extremely limited or experience high mining costs.

Even though most of these useful metal ions could be found in the ocean, high-efficiency and low-cost adsorbents remain the key to the development of extracting such metals from seawater.

Exfoliation and Self-Assembly of Biological Nanofibrils

The study Encapsulating Amidoximated Nanofibrous Aerogels within Wood Cell Tracheids for Efficient Cascading Adsorption of Uranium Ions was published in ACS Nano.

In previous years, the team performed much research on "exfoliation and self-assembly of biological nanofibrils," as indicated in this Nanowerk report.

The researchers discovered that cyanoethyl substitution or alternative could allow for rapid exfoliation of cyanoethyl cellulose nanofibrils by mild shear, for instance, manual shake and homogenization, within half an hour with a 90-percent conversion.

Recently, the team discovered that cellulose fibrils were preferentially exfoliated from the secondary cell walls of balsa wood's lignin-poor layer during an in-situ amidoximation process, and these said fibrils were filled in the wood cell tracheids.

Biofibrous Nanomaterials

When the cell tracheids are aligned perpendicular to the flow, the resultant woods could function as effective and high-pressure filtration membranes to catch aquatic uranium ions, in analog to a standard cascading filtration, allowing for a rejection ratio of less than 99 percent and flux ~920 L m-2 h-1 for a 2 mm-thick free-standing membrane below six bar pressure.

One of the corresponding authors of the study, Prof. LI Mingjie, explained that this research does not only offers an in-situ approach to generating biological nanomaterials.

Rather, it provides a sustainable route as well, "for high-efficiency extraction for aqueous uranium," the corresponding author continued explaining.

In their study, Biofibrous nanomaterials for extracting strategic metal ions from water, published in Exploration, the team reported that functional groups like carboxyl, amino phosphonate, and hydroxy, for instance, of biological nanofibrils, enabled the reduction of chemicals and the capturing of noble ions like Au, Ag, and platinum from water, providing a sustainable and green route for noble metals recovery.

Absorption Attraction

Among the extraction methods used in this research, adsorption attracted specific interest because of its low cost, ease of operation, "low risk of secondary pollution, and adsorbent recyclability."

Essentially, a variety of absorbents such as carbon materials of activated graphene and carbon, inorganic materials of metal oxides and molecular sieves, organic polymers of ion, and metal/covalent-organic frameworks all have been endeavored to attain massive adsorption capacity, fast dynamics, and high selectivity in terms of capturing aquatic metal ions.

Lastly, according to a similar Phys.org report, nanostructured materials like graphene, carbon nanotubes, zeolite-based nanosorbents, and oxide nanoparticles have been considerably examined as adsorbents with bigger specific surface area, super binding affinities, distinctive nanoscale impacts, and interfacial phenomena.

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