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Separation Processes

Capture ammonia reversibly with this new MOF

Production of ammonia by the Haber-Bosch process not only requires a lot of energy for the high-temperature (300–500°C) synthesis of NH3 itself, but the recovery of ammonia takes place by condensation at –20°C. As a result, large changes in both…

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Hydrogen-enabled recovery of raw materials from ‘red mud’ and other metallurgical waste

Bauxite residue (red mud) is a byproduct from the smelting of aluminum. Like other waste slags from the metallurgy industry, bauxite residue is traditionally put into hazardous-waste landfills, although it contains a mixture of valuable raw materials in low concentrations.…

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Supercritical extraction drives ‘molecular washing machine’ for plastic waste

A new recycling process has been developed for scrap polypropylene (PP), a waste stream that is currently underserved by many plastics-recycling facilities. The process, developed by PureCycle (Orlando, Fla.; www.purecycle.com), aims to “wash the plastic molecules” using a series of…

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Making more from mining water with electrowinning

A new electrowinning process is being field-trialed at the Prieska copper-zinc mine operated by Orion Minerals Ltd. (Melbourne, Australia; www.orionminerals.com.au) in South Africa, which will enable the production of valuable products, including calcium, magnesium, iron and others, from contaminated mine…

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Recycling halogens electrochemically

Next April, a six-year, €4-million project will begin that aims to develop an electrochemical process to recover halogens (chlorine, bromine and fluorine) from waste products. Funded as part of the CZS Breakthrough program of the Carl Zeiss Foundation (CZS; Heidenheim…

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New method selectively extracts magnesium salt from seawater

Magnesium metal is important for several emerging potential sustainability-related applications, including carbon capture, low-carbon cement and energy storage. These potential applications are driving efforts to efficiently produce magnesium hydroxide, the raw material for manufacturing Mg metal. It is possible to…

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Facts At Your Fingertips: Crossflow Membrane Filtration Module Types

In crossflow membrane filtration (CMF), feed flow is parallel to the filtration surface (rather than perpendicular to it, as in conventional filtration). During a given pass, a portion of the feed permeates the membrane, while a larger portion is retained…

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Carbonized polymer membrane exhibits improved performance, stability

Organic-solvent nanofiltration (NF) uses membranes with tiny pores to remove dissolved molecules. “Although NF is more energy efficient than alternative separation methods, such as distillation, the majority of polymer-based membranes exhibit poor chemical stability,” says Rifan Hardian, a post-doctoral researcher…

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CO2 reduction aided by DNA

Electrochemically reducing carbon dioxide to carbon monoxide offers a pathway to use CO2 as a feedstock, but the reaction is challenging because it requires catalyst molecules and dissolved CO2 to meet on the electrode surface. One approach to help this…

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Rare-earth recovery from magnet scrap is being scaled up

Rare-earth materials are a crucial part of high-performance magnets in many electronic devices. Right now, only about 5% of these magnets are recycled, but tapping into end-of-life electronics is a promising and more sustainable source for rare-earth materials, the vast…