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Researchers use graphene for converting waste to energy sources

Researchers use graphene for converting waste to energy sources

We have been concerned about the news of eruption of methane from the floor of the Arctic Ocean, however, the quantities released so far are relatively smaller than what comes out from our waste and landfills. A part of this is captured and burned for clean electricity, however, now graphene might be able to do more than that. 

Methane which is produced by anaerobic bacteria breaks down organic material in a lack of oxygen. The most suitable environment for this is the wastewater treatment plants in cities which produce more than 25 million tonnes every year. 

Methane is a stronger greenhouse gas than carbon dioxide so capturing and burning it helps from not reaching the atmosphere. We can displace fossil fuels if we are able to fully use the energy generated. Normally the biogas that is collected from waste facilities is impure so it cannot be used on a wide scale. 

Dr. Rakesh Joshi, University of New South Wales demonstrated that graphene membranes are more effective in separating methane than the systems currently in use, thus making use of waste methane viable where it is not currently present. Joshi was initially trying to use graphene for helping Sydney Water to improve the water purification process, to remove organic matter from the wastewater to make it fit for drinking. Graphene can remove 99 percent of the impurities which are not detected by other water purifying techniques. 

Graphene also helped in the filtering of biogas and it was used for powering the operations of Sydney Water. Graphene membranes are also cheaper than the other options. On burning, methane produces carbon dioxide but it is produced from wastewater by breaking down plants that draw the same amount of carbon from the atmosphere. This makes it a greenhouse neutral energy source that can balance the renewable electricity grids in low sun and wind conditions. 

The demonstration has been mainly effective in the scale of the laboratory till now. Dr. Heri Bustamante, Sydney Water said that using graphene will help in the increased capture of methane thus expanding its uses. Methane can ultimately be produced for fuelling buses in the near future.

Researchers are hopeful to ramp up the scale of its use. A near goal in the future is to capture the gases that are produced by natural wetlands and separate methane.

Curiosity obtains traces of salt in the last lakes of Gale Crater

Curiosity obtains traces of salt in the last lakes of Gale Crater

The lakes on Earth turn salty on drying out and the same incident happened when the Curiosity Mars climbed to identify the younger rocks. It found some of the salts which were left behind gathering insights on life could have prospered, rather than the mere survival on Mars. Gale crater was selected in part as it provides the possibility to investigate sedimentary rocks of different ages layered on top of each other. Curiosity has found periodic clay-bearing deposits containing 30-50 percent calcium sulfate by weight as reported in a Nature Geoscience paper.

All the rocks are 3.3-3.7 billion years old dating to the Hesperian period. Likewise, rich deposits have not been found in the older rocks of the crater. According to Dr. William Rapin of the California Institute of Technology and co-authors, the salts are present due to the percolation in the rocks by the waters of the bygone lakes which were very salty. Older rocks were much less salty although they were also exposed to the waters. Curiosity might detect more recent examples even though the younger ones were never touched by water.

Like a desert lake on Earth, the waters of the Gale crater evaporated, leaving a saltier residue, but it was an intermittent process on Mars that lasted 400 million years. The rocks have been subjected to forces of weathering over this vast time period even without water, and the calcium sulfate-enhanced portions are more resistant to erosion, producing mini versions of the formations in places such as Monument Valley, where harder rocks extend above the terrain.

Curiosity found a 10-meter (33-feet) slope containing 26-36 percent magnesium sulfate, in the 150 meters (500 feet) of calcium sulfate-enriched layers. Researchers believe that before the deposition of more soluble salts, it precipitated out first.

The paper mentions that their outcomes do not compromise the life search in the Gale crater. Terrestrial magnesium sulfate-rich and hypersaline lakes are known to sustain halotolerant biota while the preservation of biosignatures may be supported by crystallization of sulfate salts.

The occasional bursts of salty water are observed even today hence it is not unique to Gale crater in having such salts. As the planet dried, sulfate deposits have been identified by Martian orbiters across several places on Mars and it is the first instance where a rover has been operated its instruments over these samples. The periodic bursts of sulfate salts found by Curiosity showed Gale crater had many rounds of drying with several wet periods rather than one single great drought.

Journal Reference: Nature Geoscience

Researchers develop catalytic reactor for converting greenhouse gas into pure liquid fuel

Researchers develop catalytic reactor for converting greenhouse gas into pure liquid fuel

Rice University has come up with an invention that converts carbon dioxide into valuable fuels. Carbon Dioxide was turned to liquid fuel in an environment-friendly manner by using an electrolyzer and renewable energy. The catalytic reactor was developed by Haotian Wang, a chemical and biomolecular engineer at Rice University.

It uses carbon dioxide as feedstock and the latest prototype produces highly purified concentrated formic acid. Traditional ways of producing formic acid are costly and require energy-intensive purification steps. The direct production of pure formic acid will help in promoting commercial carbon dioxide conversion technologies. The work appears in Nature Energy journal.

Wang and his group pursue all those technologies that convert greenhouse gases into useful products. In experiments, the electrocatalyst reached an energy conversion efficiency of nearly 42%. So almost half the electrical energy can be stored as liquid fuel in the formic acid. Formic acid an energy carrier and a fuel cell that can generate electricity and emit carbon dioxide which can be recycled again. It is a fundamental unit in chemical engineering as a feedstock for other chemicals and also a storage material for hydrogen that can hold 1000 times the energy of the same amount of hydrogen gas, which is also difficult to compress.

Chuan Xia, postdoc researcher at Rice said that this was possible due to two advancements. The first being the development of robust, two-dimensional bismuth catalysts and the second, a solid-state electrolyte which eliminates the need for salt in the reaction. Bismuth is a heavy atom with lower mobility and stabilizes the catalyst. The structure of the reactor prevents contact of water from the catalyst. Currently, catalysts are produced on a milligram or gram scale but Xia and his team have developed a way to produce them in the kilograms thus scaling up the industry.

The polymer-based electrolyte is coated with sulphonic acid ligands to conduct positive charge or amino functional groups for negative ions. Carbon dioxide is usually reduced in a liquid electrode using salty water and for the conduction of electricity, pure water is too resistant. Salts like sodium chloride or potassium bicarbonate have to be added so that ions can move freely.

Formic acid generated in this manner mixes with salts. But for most of the applications, salts have to eliminated from the end product which consumes energy and cost. Instead, solid electrolytes made up of insoluble polymers, inorganic compounds were used thus cancelling the need for salts.

The rate of water flow through the chamber determines the concentration of the solution. Researchers have expectations to achieve higher concentration from next-generation reactors accepting gas flow to generate pure formic acid.

The Rice lab worked with Brookhaven National Laboratory to view the process in progress. “X-ray absorption spectroscopy, a powerful technique available at the Inner Shell Spectroscopy (ISS) beamline at Brookhaven Lab’s National Synchrotron Light Source II. It enables us to probe the electronic structure of electrocatalysts during the actual chemical process.

They followed the bismuth’s oxidation states at different potentials and were able to identify the catalyst’s active state during the reduction process of carbon dioxide. The reactor can generate formic acid for 100 hours without any degradation of its components. Carbon dioxide reduction is a big step towards the effect of global warming and with renewable energy, we can make a loop that turns carbon dioxide to useful products without emitting it.

Journal Reference: Nature Energy

clean drop of water liquid

Scientists discover spontaneous production of hydrogen peroxide from water

Water is a strange molecule and even after centuries of research, irrespective of the number of strange things discovered about it, there are still unexpected results waiting to be unearthed. In a new case study, researchers in the United States have discovered that under the proper circumstances, water can spontaneously produce hydrogen peroxide which is a strange aspect of fundamental chemistry that was hiding in plain sight, unnoticed till now.  The work appears in PNAS journal.

Richard Zare, a chemist at Stanford University says that since water is one of the most commonly found elements which has been studied for several years, it is normally expected that there is nothing else to learn about it.

Scientists observed the phenomena with pure water, and just any form of water will not do. According to the team, hydrogen peroxide can be produced when water is atomized into microdroplets which measure between 1 micrometer to 20 micrometers in diameter. One micrometer is one-thousandth of a millimeter, hence it is understood that the droplets are very small in size. At this infinitesimal scale, hydrogen peroxide is formed spontaneously even when there is nothing else present apart from water.

For this process, there is no necessity of chemical reagent, catalyst, electrical potential or radiation. The only requirement is pure water in microdroplet form. This phenomenon was discovered accidentally in previous research while investigating how gold nanoparticles and nanowires can be produced using water droplets. Those experiments revealed that water microdroplets besides accelerating the synthesis of the gold nanostructures also results in their spontaneous formation.

Zare’s team conducted several tests such as spraying pure water microdroplets on a test strip which turned blue if hydrogen peroxide was present. The yield of hydrogen peroxide production was inversely proportional to the size of microdroplet. Researchers think that the spontaneous oxidation of water takes place due to the presence of strong intrinsic electric field between water and air microdroplets, where hydroxyl radicals combine to form hydrogen peroxide in the presence of an electric field.

Further research is needed to test this hypothesis, although there is no ambiguity regarding the generation of hydrogen peroxide itself. This could lead to more eco-friendly ways of producing hydrogen peroxide. Research like this opens doors to innovative opportunities such as green and affordable production of hydrogen peroxide, environment-friendly synthesis of chemicals, safe cleaning and food processing. This is a surprising discovery even to someone such as Zare who himself holds 11 honorary doctorates and considers it to be one of the most significant discoveries.

Research Paper: Spontaneous generation of hydrogen peroxide from aqueous microdroplets

plate tectonics

Ancient water drops helps in calculating the timeline of plate tectonics of earth

Ancient water drops might have changed the timeline of the Earth’s tectonic plates as researchers have analyzed a series of drops from ancient seawater and arrived at an estimate that the process which underpins the plate tectonics of the Earth might have started 600 million years earlier than previously considered. The study has been published in Nature journal.

The constant movement of tectonic plates is a crucial part of renewing the surface of the planet and flourishing of life. By analyzing the levels of water in microscopic melt inclusions trapped in volcanic rock sample called komatiites, researchers calculated a new timeline when the seawater got pushed down from surface to the mantle, the point when convection started to occur. The ancient water droplets were captured in the mineral olivine found in the komatiites from the Komatiite lava flow which remained after the hottest magma was produced in Archaean Eon.

Geologist Alexander Sobolev from the Russian Academy of Sciences said the mechanism that caused the crust to sink into the mantle started 3.3 billion years ago. A global cycle of the matter was established within the first billion years and the excess water in mantle’s transition zone came from the ancient oceans.

Factors like atmospheric conditions and minerals deposited underground have been affected by shifting of the Earth’s plates along with the earthquakes and volcanoes. The plate tectonics always recycles the matter on Earth without which our Earth would end up looking like Mars. Plate tectonics started 3.3 billion years before which coincides with the time life began on Earth.

The geological landscape which was formed by these tectonic movements provides an excellent record of what happened in the past. The komatiite was dug up from Weltevreden Formation in the Barberton greenstone belt in South Africa.

After examining the piece of melt of close to 10 microns and analyzing the chemical indicators like water content, chlorine and hydrogen/deuterium ratio, it was found that the Earth’s recycling process started close to 600 million years earlier than what was thought initially. It was found that the seawater was transported deep into the mantle and later re-emerged through volcanic plumes from the core-mantle boundary.

The chemical signature of the lithographic mantle matches with that of the analyzed rocks from the Archaean, despite coming from further down in the transition zone between upper and lower mantle. The komatiites grabbed so much water from deep underground before being shot up to the surface, which in turn indicates that the tectonics plate cycle happened earlier than 2.7 billion years ago which is the currently accepted starting point.  The chemical mixes, pressure, geological processes have many variations to account in the readings. More research is needed to figure out exactly when the material of the Earth’s crust started shifting.

Journal Reference: Nature

Curiosity Cradled by Gale Crater

Curiosity has sent the images of the ideal place to find evidence of life on Mars

Although Mars looks like a dry and dusty planet, science says that it used to be warm and wet along with an atmosphere. It was in this condition for billions of years, suitable for the development of life. However, we are not sure if life existed there or not. 

Efforts to understand the ancient habitability of Mars has increased in recent years. MSL Curiosity is looking to find evidence of life which existed billions of years before around the Gale Crater, which is a dried-up lake bed and a prime spot to find evidence. 

Christopher House, Geoscience Professor at Penn State University who is also a participating scientist with the Mars Science Laboratory of NASA said that Gale Crater appeared to have been a lake environment, as the mission found finely layered mudstones in the crater. It is estimated that water would have persisted for more than a million years. Gale Crater is a complex place. Besides being a lake bed, there are minerals which provide clues to habitability in Mars. However, it was finally filled with sediment, which turned to stone and then eroded. This same process also led to the creation of Mt. Sharp in the middle of Gale Crater. However, the entire system lasted more than a billion years. Sulfate has filled many fractures, indicating that water went through the rocks, even after no lakes were being formed in the planet.

House works with Sample Analysis at Mars (SAM) and stratigraphy, sedimentology teams of Mars Science Laboratory. SAM uses instrument to heat the rock samples and mass spectrometer for measuring the molecules released by heated samples which helps to identify the types of gases released. 

Researchers are interested in the sulfur gases from sulfate and sulfide minerals as the presence of decreased sulfur minerals such as pyrite would mean that the environment might have supported life previously. This is partially due to the fact that formation of pyrite needs organic matter in the sediment. The sedimentology and stratigraphy team studies the rock layers on Mars for understanding the environment they were formed. House directs daily teleconference with the researchers few times every month for planning the operations of Curiosity on Mars for the next day.

He said that it is fun to be involved in its everyday operations for taking decisions such as where to take measurements, where to drive or which measurement to be prioritised over another one in a limited time. Each day’s time is limited by the power which the rover contains and how much it requires. He feels that it has been an important learning experience in how missions are operated and collaborate with researchers all over the world. The daily operations of Curiosity is very fast and detailed. This is a golden age of planetary science. Every new driving operation brings different fields of view with different rocks and new questions to ask. 

It is similar to a new world every time it moves, but bringing into discussion the same questions about the events which occurred months before. However, it is necessary to deal with the new landscape and perform the operations for that day. Although we know a whole lot about Mars, it is still a dynamic and fascinating place. Similar missions have shown that it was a habitable environment in the past. Missions have also shown that there occurs methane releases in Mars and volcanic eruptions not so long ago. There is a lot of interest in Mars as it is quite similar to Earth than other planets in the solar system. Venus has fully different conditions, Jupiter is a planet filled with radioactive gases and the remaining planets are far away from Sun. 

In 2014, Curiosity detected methane spikes associated with organic processes along with organic carbon compounds. The rover also found evidences of ancient stream bed on Mars in 2013 proving the presence of water in the past on Red Planet. 

Initially, the mission length of MSL Curiosity was targeted at 687 days since its landing on August 2012. However it has been going on even after 2500 days. It will keep going on until its radioisotope thermoelectric generator loses its power. 

New imaging method aids in water decontamination

New imaging method aids in water decontamination

A breakthrough imaging technique developed by Cornell researchers shows promise in decontaminating water by yielding surprising and important information about catalyst particles that can’t be obtained any other way.

Peng Chen, the Peter J.W. Debye Professor of Chemistry, has developed a method that can image nonfluorescent catalytic reactions – reactions that don’t emit light – on nanoscale particles. An existing method can image reactions that produce light, but that applies only to a small fraction of reactions, making the new technique potentially significant in fields ranging from materials engineering to nanotechnology and energy sciences.

The researchers then demonstrated the technique in observing photoelectrocatalysis – chemical reactions involving interactions with light – a key process in environmental remediation.

“The method turned out to be actually very simple – quite simple to implement and quite simple to do,” said Chen, senior author of “Super-Resolution Imaging of Nonfluorescent Reactions via Competition,” which published July 8 in Nature Chemistry. “It really extends the reaction imaging to an almost unlimited number of reactions.”

First author of the paper is Xianwen Mao, a postdoctoral researcher in Chen’s lab.

Catalytic reactions occur when a catalyst, such as a solid particle, accelerates a molecular change. Imaging these reactions at the nanoscale as they happen, which the new technique allows scientists to do, can help researchers learn the optimal size and shape for the most effective catalyst particles.

In the paper, the researchers applied the new technique to image the oxidation of hydroquinone, a micropollutant found in water, on bismuth vanadate catalyst particles, and discovered previously unknown behaviors of catalysts that helped render hydroquinone nontoxic.

“Many of these catalyzed reactions are environmentally important,” Chen said. “So you could study them to learn how to remove pollutants from an aqueous environment.”

Previously, Chen’s research group pioneered the application of single-molecule fluorescence imaging, a noninvasive, relatively inexpensive and easily implemented method that allows researchers to observe chemical reactions in real time. Because the method was limited to fluorescent reactions, however, his team worked for years on a more widely applicable method.

The technique they discovered relies on competition between fluorescent and nonfluorescent reactions. The competition suppresses the fluorescent reaction, allowing it to be measured and mapped, which in turn provides information about the nonfluorescent reaction.

The researchers named their method COMPetition Enabled Imaging Technique with Super-Resolution, or COMPEITS.

“This highly generalizable technique can be broadly applied to image various classes of nonfluorescent systems, such as unlabeled proteins, neurotransmitters and chemical warfare agents,” Peng said. “Therefore, we expect COMPEITS to be a breakthrough technology with profound impacts on many fields including energy science, cell biology, neuroscience and nanotechnology.”

Co-authors include research associate Chunming Li, former postdoctoral researcher Madhi Hesari and Ningmu Zou, Ph.D. ’17. The research was partly supported by the Army Research Office and the U.S. Department of Energy, and made use of the Cornell Center for Materials Research, which is supported by the National Science Foundation.

Journal: https://www.nature.com/articles/s41557-019-0288-8

Materials provided by Cornell University

Daphnis saturn moon

NASA’s Cassini reveals new sculpting in Saturn’s rings

The beautiful planet, Saturn, popular for its complex rings was found to have more hidden details on intrinsic textures, colours and temperatures by NASA’s Cassini spacecraft.

The Cassini mission was concluded two years ago but the spacecraft’s trip to the ring planet is still transferring data to the planet about Saturn and its evolution through all these years. A paper which was published in the Science journal had followed four of the Cassini’s major instruments and observed the interaction between Saturn’s main rings and its tiny moons. Using the observational data of this, scientists have an elucidate picture of how Saturn’s rings are part of astrophysical disk processes that have been impacting the solar system.

Cassini also took into notice the fine details that were sculpted by masses within these rings. New maps that were released revealed how do chemical, colour, and temperature-related changes are, across the rings of Saturn.

The observation made by the spacecraft enabled scientists to attain a better grasp of the complexity of Saturn. It enabled the scientists to hypothesize the outer edge of the main rings of the ringed planet are formed due to impacts of the celestial bodies hitting the ring. This information also tells us that the rings were also shaped by material streams that are known to circle the planet. The close-ups of the rings highlights that the textures happen in belts which possess sharp boundaries and these belts are not connected to any of the planet’s rings.

The way these rings look tells that there is some peculiar characteristic particles present that affect whatever takes place between any two rings. Another mystery uncovered by Cassini’s VIMS( Visible and Infrared Mapping Spectrometer ) was that it detected unusually weak water-ice bands in the A ring’s outermost area. It was shocking to find the water-ice bands, because the vicinity is known to be very reflective, which could be a sign of less-contaminated ice and fortified water-ice bands.

The new spectral map that the scientists found also provided insights to the composition of the ring, confirming that ammonia ice and methane ice are not the contents but water ice is the major content of the planet’s rings. The drawback was that it could not spot any organic compounds.

According to the scientist of the Cassini project, Linda Spilker, it was like turning up the power by one more time to know what was inside the ring so that everyone could actually get to see it as an extra resolution which answered many questions but most tantalizing ones, however, remain.

Curiosity Aberlady Kilmarie Mars

Clay containing rocks detected by Curiosity on Mars

On any surface, if clay is found it indicates the presence of water nearby. Hence, finding clay on Mars is a very big thing. The historical, present water conditions of the planet are very crucial to understand the planet and to know if it supported life at any point. Currently, MSL Curiosity is present at Mt Sharp for inspection of the rocks and to find evidence of clay. Detecting evidence of clay at Mt Sharp was one of the main reasons for choosing Gale Crater as a landing site for MSL Curiosity.

Curiosity has sampled two rocks as a clay-bearing unit and it confirmed that clay is indeed present there. Among the rocks checked by Curiosity so far, these two rocks have the greatest clay concentration. The rocks are named as “Aberlady” and “Kilmarie“. They are situated at Mt Sharp’s lowest region, which has been the primary objective of the mission.

The height of Mt Sharp above the crater floor is 5.5kms, which means that it contains a layered record of the geology of Mars. With the passage of time, it was weathered down by winds and thus has been an easy target for Curiosity. Scientists have been interested in Mt Sharp which is also known as Aeolis Mons due to its formation. Gale Crater is an impact crater which was most probably filled with water, and according to scientists, the formation of Mt Sharp took place over 2 billion years with the deposition of the sediments at the bottom.

There are some doubts about the timeline of the formation of Mt Sharp. MSL Curiosity hopes to clear out this confusion. Mt Sharp appears as an eroded, sedimented mountain and scientists hope as the work of Curiosity continues a clearer view of its formation will be obtained.

It is being considered that the interaction of water and sediment at the bottom of the lake took place for the formation of clay. Since, a mountain has various layers containing different kinds of minerals, specific types of clay at given layers gives the information on the timeline of water on Mars. The layers above clay-containing layers have sulphur and above it, there are layers which contain minerals bearing oxygen.

There is also a river named Gediz Vallis Channel in Gale crater. It formed after the layers of clay and sulphur. It presents a different type of puzzle and the work of Curiosity is to collect all the clues of the puzzle, process it and generate the final information on Martian geology and history.

nucleus ice freezing

Researchers accidentally discover unique property of crystalline ice

Water ice is not always produced equally. Under specific circumstances, its neat arrangement of lattice molecules in a crystalline fashion get disordered and then it resembles the structure of amorphous solids like glass, plastic.

This was the general idea behind the working however a recent finding has made scientists turn into a confused state.

A specific type of amorphous ice was discovered in the ’80s. It was produced by freezing water to form ice at very extreme temperatures. And immediately this ice was subjected to high amounts of pressure. It was taken that consequent amorphous material was similar to liquid water since water could be frozen to form amorphous ice and then melted back to its previous state. But researchers are not so certain about this anymore.

While trying to study about amorphous ice with very high density, a group of researchers at the Oak Ridge National Laboratory accidentally produced different forms of crystalline ice. Dennis Klug, a material science researcher at the National Research Council of Canada remarked that if the data from the experiment conducted was true then it would signify that the amorphous ice is not connected to liquid water, instead, it is a transformation between two phases which has been interrupted. This is a wide variation from the theory which has been usually accepted. The study was published in Nature.

What actually took place was that the research group planned to study the changes in the amorphous ice with an increase in the temperature. After that, it was considered that the molecules in the disordered state would fall back to the regular ordered lattice with the “melting” of amorphous ice to a crystal form.

Researchers had to first manufacture the amorphous ice. For this, a three-millimeter sphere of heavy water (which has an additional neutron in the nucleus of hydrogen) was frozen. This property of heavy water helps in the analysis of neutron scattering. Next, the temperature was lowered to -173 degrees Celsius and simultaneously the pressure was increased to 28000 times the value at sea level.

When the molecular structure was observed, scientists found that the transformation of ice had taken place through four forms. It started with the regular form and ended up at the form ice XIII, while passing through ice IX and ice XV.

Initially, the team felt that the water sample was not pure. Hence they repeated with another new sample and observed the same result every time. Just by slowly increasing the pressure, scientists had a completely new observation.

The transition of water phase from low-density state to high-density state is thought to occur at a second critical point. However, as per this research, this critical point may not exist. The unexpected results have given scientists a new way to understand the dynamics of water.