Renewable Energy Global Innovations features: Room temperature hydrogen production from Hg contaminated water, with desirable throughput, and simultaneous Hg-removal

Significance Statement

Fossil fuels produce toxic byproducts on oxidation; hydrogen on the other hand yields water vapor making it a better source of energy. Today industrial hydrogen production primarily adopts an approach using steam reforming of fossil fuels. However carbon monoxide and carbon dioxide are emitted as byproducts of this process. Given this an obvious and simple way of getting hydrogen would be by splitting water, since it is abundant globally. Researchers world over are attempting development of hydrolytic reagents that result in high throughput hydrogen production through splitting of water (also called hydrolysis).

Currently there are numerous methods used for generating hydrogen which include: water decomposition at high temperature, photo electrochemical water splitting, decomposition of water electrochemically, and metal hydrolysis. Heat and electrochemical based water splitting approaches tend to be energy intensive. Light based approaches (i.e photo electrochemical or photochemical) tends to require very pure water, is usually low efficiency, and not yet robust as a process. Metal hydrolysis tends to be expensive and if carefully looked at, is high on carbon footprint (since metal extraction is energy intensive too).

Furthermore post production of hydrogen, its storage, transportation, and handling presents many safety issues. Hence hydrogen fuel though seemingly ideal, is fraught with many engineering challenges. Consequently, there is need to improve techniques of production. It would be ideal to have a process that generates hydrogen on demand; better still if this could be done using dirty water!  Abdul Malek, Edamana Prasad, Subrahmanyam Aryasomayajula, and Tiju Thomas at the Indian Institute of Technology Madras (IITM) in India have developed an approach that does just that. The approach uses nanoscience based ideas to achieve this engineering outcome. – The team developed a novel method with high hydrogen production efficiency using water contaminated with mercury (usually an issue in effluents from several industries, including mines, leather industries etc). The researchers aimed at generating hydrogen through ‘in situ’ formation of nanoaluminum amalgam by simultaneously reducing aluminum (obtained from inexpensive salts) and mercury (present as a contaminant) using a powerful reducing agent. The research work is now published in the journal, International Journal of Hydrogen Energy.

The experiment works well with tap water and would do just as well with dirty water contaminated with mercury. The process cleans up mercury from water, while at the same time producing hydrogen. The process works since the nano-alloy they synthesize using this in situ approach has many galvanic couples on its surface (think of them as ‘nano batteries’ sitting on the nanoparticle surface). In the lab scale,  researchers observed rampant production of hydrogen gas (720 mL per minute of hydrogen for every 0.5 mg of Al salt used). The presence of other contaminants (eg. salts) did not seem to affect the rate nor the amount of hydrogen gas produced. The process scales rather easily with the amount of aluminium salt used; this makes it in principle useful for point of use production of hydrogen (providing a plausible way out for the transportation and storage problem).

Scaling up in the next step, and the team is excited to further their work towards this end. Dr. Tiju Thomas, one of the senior authors said “Getting fuel while purifying water is a very good example of how design thinking and nanoscience can solve some major problems. I particularly enjoy doing this. We, as a team, are excited about the possibility of using this technology is parts of the world wherein mercury is a major contaminant in water. The team behind this story believes that we have just gotten the right lead. Scaling up is the way to go, and partnering with process, water and energy engineers in industry is essential to take this technology to the real world. We have made a good start – the science is there; the next step is to make it available to change makers and innovate along with them”.

In conclusion, Abdul Malek and his co-workers have shown a possible way to overcome some of the major setbacks in current water and hydrogen energy sectors. It offers a possibility for scale up, and improve the efficiency of generating hydrogen using dirty water (mercury contaminated as of now). This method also helps to address the problem of storage and transportation of material, while also cleaning up the mercury from water. The technology lends itself to point of use hydrogen production; the challenges that remains are at the device and systems level. The team envisions their invention to give way to a multi-functional technology.  This procedure is possibly applicable to ocean water and effluents from industries with more complex contaminant composition because of the inability of salts to affect the process. Therefore, more work along these lines are anticipated, and hence development of suitable devices and reactors are the way to go. Everything herein suggests that this novel technique is viable and suitable for adoption. It is important to note here that the technique developed by Abdul Malek and his co-workers is patented (PCT/ IN2017/ 050334) and available for licensing. They are also happy to discuss industry relevant and academic questions with their professional colleagues world over.

Reference

Abdul Malek, Edamana Prasad, Subrahmanyam Aryasomayajula, Tiju Thomas. Chimie douce hydrogen production from Hg contaminated water, with desirable throughput, and simultaneous Hg-removal. International Journal of Hydrogen Energy, Volume 42 (2017) page 15724-15730.

 

Go To International Journal of Hydrogen Energy

 

Malek, A.; Thomas, T.; Prasad, E. Hydrogen generation from waste water via galvanic corrosion of in-situ formed aluminum amalgam, Indian Patent Office, Application No. 201641027502; International application no: PCT/ IN2017/ 050334.

A. Malek, T. Thomas, E. Prasad, Visual and optical sensing of Hg²⁺, Cd²⁺, Cu²⁺, and Pb²⁺ in water and its beneficiation via gettering in nanoamalgam form. ACS Sustain Chem Eng, 4 (2016), pp. 3497-3503.

 

 

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