Friday, October 7, 2022

Simple course of extracts helpful magnesium salt from seawater

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Researchers can isolate magnesium feedstocks from the ocean, vital for renewable vitality purposes. Credit: Composite picture by Cortland Johnson, Pacific Northwest National Laboratory

Since historic occasions, people have extracted salts, like desk salt, from the ocean. While desk salt is the simplest to acquire, seawater is a wealthy supply of various minerals, and researchers are exploring which of them they will pull from the ocean. One such mineral, magnesium, is considerable within the sea and more and more helpful on the land.

Magnesium has rising sustainability-related purposes, together with in carbon seize, low-carbon cement, and potential next-generation batteries. These purposes are bringing renewed consideration to home magnesium manufacturing. Currently, magnesium is obtained within the United States by way of an energy-intensive course of from salt lake brines, a few of that are at risk because of droughts. The Department of Energy included magnesium on its lately launched list of critical materials for home manufacturing.

A paper printed in Environmental Science & Technology Letters reveals how researchers at Pacific Northwest National Laboratory (PNNL) and the University of Washington (UW) have discovered a easy technique to isolate a pure magnesium salt, a feedstock for magnesium steel, from seawater. Their new methodology flows two options side-by-side in an extended stream. Called the laminar coflow methodology, the method takes benefit of the truth that the flowing options create a continually reacting boundary. Fresh options circulation by, by no means permitting the system to achieve a stability.

This methodology performs a brand new trick with an outdated course of. In the mid-20th century, chemical corporations efficiently created magnesium feedstock from seawater by mixing it with sodium hydroxide, generally often known as lye. The ensuing magnesium hydroxide salt, which supplies the antacid milk of magnesia its identify, was then processed to make magnesium steel. However, the method ends in a fancy combination of magnesium and calcium salts, that are arduous and expensive to separate. This current work produces pure magnesium salt, enabling extra environment friendly processing.

“Normally, people move separations research forward by developing more complicated materials,” mentioned PNNL chemist and UW Affiliate Professor of Materials Science and Engineering Chinmayee Subban. “This work is so exciting because we’re taking a completely different approach. We found a simple process that works. When scaled, this process could help drive the renaissance of U.S. magnesium production by generating primary feedstock. We’re surrounded by a huge, blue, untapped resource.”

Simple process extracts valuable magnesium salt from seawater
Seawater from the PNNL-Sequim campus fueled this analysis mission. Credit: Andrea Starr, Pacific Northwest National Laboratory

From Sequim water to strong salt

Subban and the workforce examined their new methodology utilizing seawater from the PNNL-Sequim campus, permitting the researchers to benefit from PNNL services throughout Washington State.

“As a Coastal Sciences staff member, I just called a member of our Sequim chemistry team and requested a seawater sample,” mentioned Subban. “The next day, we had a cooler delivered to our lab in Seattle. Inside, we found cold packs and a bottle of chilled Sequim seawater.” This work represents the collaboration that may occur throughout PNNL’s Richland, Seattle, and Sequim campuses.

In the laminar coflow methodology, the researchers circulation seawater alongside an answer with hydroxide. The magnesium-containing seawater shortly reacts to kind a layer of strong magnesium hydroxide. This skinny layer acts as a barrier to resolution mixing.

“The flow process produces dramatically different results than simple solution mixing,” mentioned PNNL postdoctoral researcher Qingpu Wang. “The initial solid magnesium hydroxide barrier prevents calcium from interacting with the hydroxide. We can selectively produce pure solid magnesium hydroxide without needing additional purification steps.”

The selectivity of this course of makes it significantly highly effective. Generating pure magnesium hydroxide, with none calcium contamination, permits researchers to skip energy-intensive and costly purification steps.

Simple process extracts valuable magnesium salt from seawater
The laboratory-scale circulation gadget for extracting magnesium salt. Credit: Qingpu Wang, Pacific Northwest National Laboratory

Sustainability for the longer term

The new and mild course of has the potential to be extremely sustainable. For instance, the sodium hydroxide used to extract the magnesium salt could be generated on web site utilizing seawater and marine renewable vitality. Removing magnesium is a vital pre-treatment for seawater desalination. Coupling the brand new course of with current applied sciences may make it simpler and cheaper to show seawater into freshwater.

The workforce is especially enthusiastic about the way forward for the method. Their work is the primary demonstration of the laminar coflow methodology for selective separations. This new strategy has many further potential purposes, however extra work must be performed to grasp the underlying chemistry of the method. The information hole presents new prospects and analysis instructions for powering the blue financial system.

“We want to take this work from the empirical to the predictive,” mentioned PNNL supplies scientist Elias Nakouzi. “There is an exciting opportunity to develop a fundamental understanding of how this process operates while applying it to important problems like creating new energy materials and achieving selective separation of hard-to-separate ions for water treatment and resource recovery.”


Extracting high-quality magnesium sulphate from seawater desalination brine


More info:
Qingpu Wang et al, Flow-Assisted Selective Mineral Extraction from Seawater, Environmental Science & Technology Letters (2022). DOI: 10.1021/acs.estlett.2c00229

Provided by
Pacific Northwest National Laboratory


Citation:
Simple course of extracts helpful magnesium salt from seawater (2022, September 23)
retrieved 23 September 2022
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