Tag Archives: water desalination

Bristly hybrid materials

Caption: [Image 1] A carbon fiber covered with a spiky forest of NiCoHC nanowires. Credit: All images reproduced from reference 1 under a Creative Commons Attribution 4.0 International License© 2018 KAUST

It makes me think of small, cuddly things like cats and dogs but it’s not. From an August 7, 2018 King Abdullah University of Science and Technology (KAUST; Saudi Arabia) news release (also published on August 12, 2018 on EurekAlert),

By combining multiple nanomaterials into a single structure, scientists can create hybrid materials that incorporate the best properties of each component and outperform any single substance. A controlled method for making triple-layered hollow nanostructures has now been developed at KAUST. The hybrid structures consist of a conductive organic core sandwiched between layers of electrocatalytically active metals: their potential uses range from better battery electrodes to renewable fuel production.

Although several methods exist to create two-layer materials, making three-layered structures has proven much more difficult, says Peng Wang from the Water Desalination and Reuse Center who co-led the current research with Professor Yu Han, member of the Advanced Membranes and Porous Materials Center at KAUST. The researchers developed a new, dual-template approach, explains Sifei Zhuo, a postdoctoral member of Wang’s team.

The researchers grew their hybrid nanomaterial directly on carbon paper–a mat of electrically conductive carbon fibers. They first produced a bristling forest of nickel cobalt hydroxyl carbonate (NiCoHC) nanowires onto the surface of each carbon fiber (image 1). Each tiny inorganic bristle was coated with an organic layer called hydrogen substituted graphdiyne (HsGDY) (image 2 [not included here]).

Next was the key dual-template step. When the team added a chemical mixture that reacts with the inner NiCoHC, the HsGDY acted as a partial barrier. Some nickel and cobalt ions from the inner layer diffused outward, where they reacted with thiomolybdate from the surrounding solution to form the outer nickel-, cobalt-co-doped MoS2 (Ni,Co-MoS2) layer. Meanwhile, some sulfur ions from the added chemicals diffused inwards to react with the remaining nickel and cobalt. The resulting substance (image 3 [not included here]) had the structure Co9S8, Ni3S2@HsGDY@Ni,Co-MoS2, in which the conductive organic HsGDY layer is sandwiched between two inorganic layers (image 4 [not included here]).

The triple layer material showed good performance at electrocatalytically breaking up water molecules to generate hydrogen, a potential renewable fuel. The researchers also created other triple-layer materials using the dual-template approach

“These triple-layered nanostructures hold great potential in energy conversion and storage,” says Zhuo. “We believe it could be extended to serve as a promising electrode in many electrochemical applications, such as in supercapacitors and sodium-/lithium-ion batteries, and for use in water desalination.”

Here’s a link to and a citation for the paper,

Dual-template engineering of triple-layered nanoarray electrode of metal chalcogenides sandwiched with hydrogen-substituted graphdiyne by Sifei Zhuo, Yusuf Shi, Lingmei Liu, Renyuan Li, Le Shi, Dalaver H. Anjum, Yu Han, & Peng Wang. Nature Communicationsvolume 9, Article number: 3132 (2018) DOI: https://doi.org/10.1038/s41467-018-05474-0 Published 07 August 2018

This paper is open access.

 

Nanopores and a new technique for desalination

There’s been more than one piece here about water desalination and purification and/or remediation efforts and at least one of them claims to have successfully overcome issues such as reverse osmosis energy needs which are hampering adoption of various technologies. Now, researchers at the University of Illinois at Champaign Urbana have developed another new technique for desalinating water while reverse osmosis issues according to a Nov. 11, 2015 news item on Nanowerk (Note: A link has been removed) ,

University of Illinois engineers have found an energy-efficient material for removing salt from seawater that could provide a rebuttal to poet Samuel Taylor Coleridge’s lament, “Water, water, every where, nor any drop to drink.”

The material, a nanometer-thick sheet of molybdenum disulfide (MoS2) riddled with tiny holes called nanopores, is specially designed to let high volumes of water through but keep salt and other contaminates out, a process called desalination. In a study published in the journal Nature Communications (“Water desalination with a single-layer MoS2 nanopore”), the Illinois team modeled various thin-film membranes and found that MoS2 showed the greatest efficiency, filtering through up to 70 percent more water than graphene membranes. [emphasis mine]

I’ll get to the professor’s comments about graphene membranes in a minute. Meanwhile, a Nov. 11, 2015 University of Illinois news release (also on EurekAlert), which originated the news item, provides more information about the research,

“Even though we have a lot of water on this planet, there is very little that is drinkable,” said study leader Narayana Aluru, a U. of I. professor of mechanical science and engineering. “If we could find a low-cost, efficient way to purify sea water, we would be making good strides in solving the water crisis.

“Finding materials for efficient desalination has been a big issue, and I think this work lays the foundation for next-generation materials. These materials are efficient in terms of energy usage and fouling, which are issues that have plagued desalination technology for a long time,” said Aluru, who also is affiliated with the Beckman Institute for Advanced Science and Technology at the U. of I.

Most available desalination technologies rely on a process called reverse osmosis to push seawater through a thin plastic membrane to make fresh water. The membrane has holes in it small enough to not let salt or dirt through, but large enough to let water through. They are very good at filtering out salt, but yield only a trickle of fresh water. Although thin to the eye, these membranes are still relatively thick for filtering on the molecular level, so a lot of pressure has to be applied to push the water through.

“Reverse osmosis is a very expensive process,” Aluru said. “It’s very energy intensive. A lot of power is required to do this process, and it’s not very efficient. In addition, the membranes fail because of clogging. So we’d like to make it cheaper and make the membranes more efficient so they don’t fail as often. We also don’t want to have to use a lot of pressure to get a high flow rate of water.”

One way to dramatically increase the water flow is to make the membrane thinner, since the required force is proportional to the membrane thickness. Researchers have been looking at nanometer-thin membranes such as graphene. However, graphene presents its own challenges in the way it interacts with water.

Aluru’s group has previously studied MoS2 nanopores as a platform for DNA sequencing and decided to explore its properties for water desalination. Using the Blue Waters supercomputer at the National Center for Supercomputing Applications at the U. of I., they found that a single-layer sheet of MoS2 outperformed its competitors thanks to a combination of thinness, pore geometry and chemical properties.

A MoS2 molecule has one molybdenum atom sandwiched between two sulfur atoms. A sheet of MoS2, then, has sulfur coating either side with the molybdenum in the center. The researchers found that creating a pore in the sheet that left an exposed ring of molybdenum around the center of the pore created a nozzle-like shape that drew water through the pore.

“MoS2 has inherent advantages in that the molybdenum in the center attracts water, then the sulfur on the other side pushes it away, so we have much higher rate of water going through the pore,” said graduate student Mohammad Heiranian, the first author of the study. “It’s inherent in the chemistry of MoS2 and the geometry of the pore, so we don’t have to functionalize the pore, which is a very complex process with graphene.”

In addition to the chemical properties, the single-layer sheets of MoS2 have the advantages of thinness, requiring much less energy, which in turn dramatically reduces operating costs. MoS2 also is a robust material, so even such a thin sheet is able to withstand the necessary pressures and water volumes.

The Illinois researchers are establishing collaborations to experimentally test MoS2 for water desalination and to test its rate of fouling, or clogging of the pores, a major problem for plastic membranes. MoS2 is a relatively new material, but the researchers believe that manufacturing techniques will improve as its high performance becomes more sought-after for various applications.

“Nanotechnology could play a great role in reducing the cost of desalination plants and making them energy efficient,” said Amir Barati Farimani, who worked on the study as a graduate student at Illinois and is now a postdoctoral fellow at Stanford University. “I’m in California now, and there’s a lot of talk about the drought and how to tackle it. I’m very hopeful that this work can help the designers of desalination plants. This type of thin membrane can increase return on investment because they are much more energy efficient.”

Here’s a link to and a citation for the paper,

Water desalination with a single-layer MoS2 nanopore by Mohammad Heiranian, Amir Barati Farimani, & Narayana R. Aluru. Nature Communications 6, Article number: 8616 doi:10.1038/ncomms9616 Published 14 October 2015

Graphene membranes

In a July 13, 2015 essay on Nanotechnology Now, Tim Harper provides an overview of the research into using graphene for water desalination and purification/remediation about which he is quite hopeful. There is no mention of an issue with interactions between water and graphene. It should be noted that Tim Harper is the Chief Executive Officer of G20, a company which produces a graphene-based solution (graphene oxide sheets), which can desalinate water and can purify/remediate it. Tim is a scientist and while you might have some hesitation given his fiscal interests, his essay is worthwhile reading as he supplies context and explanations of the science.

Egypt steps it up nanowise with a Center for Nanotechnology

Dec. 16, 2014 Egypt’s Prime Minister Ibrahim Mahlab along with other ministers and Dr. Ahmed Zewail, Chairman of the board of Zewail City of Science and Technology (this seems to be a campus with a university and a number of research institutes), announced Egypt’s Center for Nanotechnology (from a Zewail City of Science and Technology Dec. 16, 2014 press release),

The Center, funded by the National Bank of Egypt, cost over $ 100 Million and is, till this moment, the biggest research Center Egypt has seen. This center is hailed as a turning point in the development of scientific research in Egypt as it will allow researchers to develop nanoparticles and nanostructured applications that will improve, even revolutionize, many technology and industry sectors including: information technology, energy, environmental science, medicine, and food safety among many others.

During the visit, Dr. Zewail gave Mahlab and the Cabinet members a brief introduction about the City’s constituents, achievements, and how it is going to improve Egypt’s economic development.

Impressed by the magnitude of Zewail City, Mahalab expressed his excitement about the effect this project is going to have on the future of scientific research in Egypt.

Following the opening ceremony, they all moved to the construction site of the soon-to-be Zewail City new premises, in Hadayk October, to evaluate the progress of the construction process. This construction work is the result of the presidential decree issued on April 9, 2014 to allocate 200 acres for Zewail City in 6th of October City. The construction work is expected to be done by the end of 2015, and will approximately cost $ 1.5 billion.

The end of 2015 is a very ambitious goal for completion of this center but these projects can sometimes inspire people to extraordinary efforts and there seems to be quite a bit of excitement about this one if the video is any indication. From a Dec. 22, 2014 posting by Makula Dunbar, which features a CCTV Africa clip, on AFKInsider,

I was interested to learn from the clip that Egypt’s new constitution mandates at least 1% of the GDP (gross domestic product) must be earmarked for scientific research.

As for Ahmed Zewail, in addition to being Chairman of the board of Zewail City of Science and Technology, he is also a professor at the California Institute of Technology (CalTech). From his CalTech biography page (Note: A link has been removed),

Ahmed Zewail is the Linus Pauling Chair professor of chemistry and professor of physics at the California Institute of Technology (Caltech). For ten years, he served as the Director of the National Science Foundation’s Laboratory for Molecular Sciences (LMS), and is currently the Director of the Moore Foundation’s Center for Physical Biology at Caltech.

On April 27, 2009, President Barack Obama appointed him to the President’s Council of Advisors on Science and Technology, and in November of the same year, he was named the First United States Science Envoy to the Middle East.

The CalTech bio page is a bit modest, Zewail’s Wikipedia entry gives a better sense of this researcher’s eminence (Note: Links have been removed),

Ahmed Hassan Zewail (Arabic: أحمد حسن زويل‎, IPA: [ˈæħmæd ˈħæsæn zeˈweːl]; born February 26, 1946) is an Egyptian- American scientist, known as the “father of femtochemistry”, he won the 1999 Nobel Prize in Chemistry for his work on femtochemistry and became the first Egyptian scientist to win a Nobel Prize in a scientific field. …

If you watched the video, you may have heard a reference to ‘other universities’. The comment comes into better focus after reading about the dispute between Nile University and Zewail City (from the Wikipedia entry),

Nile University has been fighting with Zewail City of Science and Technology, established by Nobel laureate Ahmed Zewail, for more than two years over a piece of land that both universities claim to be their own.

A March 22, 2014 ruling turned down challenges to a verdict issued in April 2013 submitted by Zewail City. The court also ruled in favour of the return of Nile University students to the contested buildings.

In a statement released by Nile University’s Student Union before Saturday’s decision, the students stated that the verdict would test the current government’s respect to the judiciary and its rulings.

Zewail City, meanwhile, stressed in a statement released on Saturday that the recent verdict rules on an urgent level; the substantive level of the case is yet to be ruled on. Sherif Fouad, Zewail City’s spokesman and media adviser, said the verdict “adds nothing new.” It is impossible for Zewail City to implement Saturday’s verdict and take Nile University students into the buildings currently occupied by Zewail City students, he said.

If I understand things rightly, the government has pushed forward with this Zewail City initiative (Center for Nanotechnology) while the ‘City’ is still in a dispute over students and buildings with Nile University. This should make for some interesting dynamics (tension) for students, instructors, and administrators of both the institutions and may not result in those dearly hoped for scientific advances that the government is promoting. Hopefully, the institutions will resolve their conflict in the interest of promoting good research.

Water desalination to be researched at Oman’s newly opened Nanotechnology Laboratory at Sultan Qaboos University

Before getting to the news, here’s some information (for those who may not be familiar with the country) about the Sultanate of Oman and why this water desalination project is very important. From the Oman Wikipedia essay (Note: Links have been removed),

Oman (Listeni/oʊˈmɑːn/ oh-MAAN; Arabic: عمان‎ ʻUmān), officially called the Sultanate of Oman (Arabic: سلطنة عُمان‎ Salṭanat ʻUmān), is an Arab state in southwest Asia on the southeast coast of the Arabian Peninsula. It has a strategically important position at the mouth of the Persian Gulf. It is bordered by the United Arab Emirates to the northwest, Saudi Arabia to the west, and Yemen to the southwest and also shares a marine border with Iran. The coast is formed by the Arabian Sea on the southeast and the Gulf of Oman on the northeast. The Madha and Musandam exclaves are surrounded by the UAE on their land borders, with the Strait of Hormuz and Gulf of Oman forming Musandam’s coastal boundaries.

From the 17th century, Oman had its own empire, and vied with Portugal and Britain for influence in the Persian Gulf and Indian Ocean. At its peak in the 19th century, Omani influence or control extended across the Strait of Hormuz to Iran, and modern-day Pakistan, and as far south as Zanzibar.[7] As its power declined in the 20th century, the sultanate came under heavy influence from the United Kingdom, though Oman was never formally part of the British Empire, or a British protectorate.

Oman has a hot climate and very little rainfall. Annual rainfall in Muscat averages 100 mm (3.9 in), falling mostly in January. The Dhofar Mountains area receives seasonal rainfall (from late June to late September) as a result of the monsoon winds from the Indian Ocean saturated with cool moisture and heavy fog.[39] The mountain areas receive more plentiful rainfall, and annual rainfall on the higher parts of the Jabal Akhdar probably exceeds 400 mm (15.7 in).[40] Some parts of the coast, particularly near the island of Masirah, sometimes receive no rain at all within the course of a year. The climate generally is very hot, with temperatures reaching around 50 °C (122.0 °F) (peak) in the hot season, from May to September.

The Sultanate of Oman’s Ministry of Information’s Omanet.om website offers this about water (from the Water webpage),

Oman is in the world’s arid belt and depends on groundwater and its limited rainfall . The demand for water continues to rise.   A national water resources conservation plan has been drawn up to further rationalise and improve water consumption practices and explore for new groundwater reserves. The Sultanate now has a complete, up-to-date and properly documented database covering all the country’s available and potential water resources, together with details of their status and conditions. Studies on new ways of rationalising water consumption are ongoing.

 Water Resources Management

The approach here is the emphasis on making judicious use of available water resources and reducing waste.

The management plan includes:

Reduction of water loss to the sea or desert

Providing potable water in communities

Developing and improving aflaj systems

Intensification of studies

Changing land use in some regions

Increasing recovery rates of water loss

Implementation of awareness programs

The fact that there is a Middle East Desalination Research Center (MEDRC)suggests an important problem especially in this region. (If you know of any collaborative water projects for other regions, please do let me know about them in the Comments.) From the MEDRC homepage,

MEDRC is a Center of Excellence in Desalination and Water  Reuse Technology established in Muscat, Sultanate of Oman, December 1996.

MEDRC Mission Statement

The mission of MEDRC is to contribute to the achievement of peace and stability in the Middle East and North Africa by promoting and supporting the use of desalination to satisfy the needs of the people of this region for available, affordable, clean fresh water for human use and economic development. This is done through the advancement of desalination technology, education in the technology and training in its use, technology transfer, technical assistance, and building cooperation between nations to form the joint projects and international relationships necessary to meet the needs for fresh water.

The Peace Process to resolve the issues of Israel and the Palestinian National Authority that have troubled the Middle East for almost a century included the establishment of MEDRC to assist in meeting the fresh water needs of the parties involved. This is still the first priority of MEDRC. However, MEDRC’s activities extend to and benefit the entire region and beyond. MEDRC is advancing the use of desalination and waste water reuse thru regional and international cooperation to overcome current and future world water supply deficiencies.

The MEDRC also has a 6 pp. PDF titled: Overview on Desalinated Water in the Sultanate of Oman. So this news about a nanotechnology lab opening in Oman which is focused on water desalination is big news, from the Feb. 19, 2014 news item on Nanowerk,

The Nanotechnology laboratory at Sultan Qaboos University in Muscat, Oman, as a part of The Research Council (TRC ) Chair in Nanotechnology for Water Desalination, was officially opened yesterday under the patronage of Dr Hilal bin Ali al Hinai, Secretary-General of TRC. The state-of-the-art laboratory of the TRC Chair, contains wet-chemistry facilities and analytical equipment rooms, and has been built in a single workspace on the College of Engineering premises. Talking about the activities of the Chair in terms of research and related activities, Prof Joydeep Dutta, the Chair Professor, said that research and development focused on the application of nanoparticles, nanomaterials and desalination processes.

A Feb. 18, 2014 news item in the Oman Observer provides additional detail,

“The Chair aims at innovative research suited to the region, education and training of highly qualified personnel and in increasing public and industrial awareness of nanotechnology, amongst others. The current research group is involved in developing applications that address the needs of those who are without — clean drinking water, cheap energy, unspoiled food and the other necessities required to provide for a decent living. The Chair is focusing on dedicated research and development issues addressing water desalination-both of seawater as well as brackish water”, he said. At present, a few broad themes for research were identified in consultation with the technical committee and work is continuing along these themes. The research themes are “Designer metal-oxide nanostructures”, “Capacitive desalination with functionalised nanostructures”, “Condensation induced renewable desalting”, and “Functionalised micro or nano membranes”.

The unifying concept in the laboratory is to make use of inexpensive wet-chemical methods to fabricate innovative materials and futuristic device components with an eye on its application in water desalination and water treatment. …

Although dated Feb. 19, 2014, a news release on the Sultan Qaboos University (SQU) website appears to have originated the news item on the Nanowerk website and on the Osman Observer website.

I have previously written about water in the Middle East within the context of a June 25, 2013 post regarding a research collaboration between the University of Chicago and Ben Gurion University in Israel. I managed to include a bit about Palestine and its very serious water problem (the Gaza’s sole aquifer may be unusable by 2016) in that post, about 3/4 of the way down.