Category Chemistry

What are the contributions of Binoy Kumar Saikia?

In all our minds, coal is dark black and useful only for burning. Would you like to see fluorescent blue coloured coal? Well, meet this chemist from Assam who developed the technology to make blue fluorescent carbon quantum dots (CQDs) from Indian coal. Binoy Kumar Saikia is a Senior Scientist at the North East Institute of Science and Technology, Jorhat (NEIST).

The blue CQDs are nano particles, meaning very small in size, though they have high stability, good conductivity, low toxicity and are environmental friendly. They are used for various applications especially for medicine and environmental science. The CQD technology patented by Dr. Saikia helps to reduce imports from other nations.

Saikia got the Shanti Swarup Bhatnagar Prize in 2021. It is given for seven categories by CSIR and he alone received it in the category of Earth, Atmosphere, Ocean and Planetary Sciences. Dr. Binoy Kumar Saikia was the first one from Assam who won this award after a gap of twenty years.

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Is there methane in clouds?

Methane is a very potent greenhouse gas that gets released into the atmosphere due to anthropological activities. It is responsible for about 30% of the Earth’s warming.

Methane clouds have been in the news recently with large plumes of methane being spotted over countries such as China, India, Jordan, Pakistan, Turkmenistan, and so on. The recent methane hotspots were attributed to waste sectors in these countries. And the scenario is alarming.

Methane is the primary component of natural gas and is responsible for about 30% of the Earth’s warming. According to scientists, the potent greenhouse gas has 84 times the warming power of carbon dioxide during its first two decades in the atmosphere. As such, reducing emissions of methane is one of the fastest ways to cool the planet.

Waste sector triggering methane clouds

A cloud of methane near a waste site in India was observed earlier this month. According to the satellite images taken, the methane plume is the result of the landfill in the country. The estimated emissions rate was 1.328 kg per hour of methane. These clouds of methane can cover vast areas and sometimes stretch for even 200 miles. All these observations were made through the satellite images released by the GHGSat, which is involved in high-resolution remote-sensing of greenhouse gas from space. Garbage and landfills can generate the potent greenhouse gas. This happens when organic material such as food waste breaks down in the absence of oxygen Landfills and wastewater are responsible for about 20% of the methane emissions generated from human activity. Not doing enough to stop these emissions can affect the global climate goals.

Sources of methane leak

Methane gets released into the atmosphere due to anthropological activities. It is also generated as a byproduct of oil and coal production and as part of agricultural activities. If not properly sealed, closed or abandoned coal mines can leak methane. This can go on for years.

Monitoring methane from space

Satellites can identify and track methane from anywhere, thereby aiding in tracking the methane footprint. This helps in climate transparency, bringing in accountability for countries and companies releasing methane. Greenhouse gases can be quantified and attributed in real-time. A total of 120 countries are part of the global methane pledge, which aims to cut the release of the gas by 30% by the end of this decade from the 2020 levels.

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WHAT IS NUCLEAR POWER AND ENERGY?

An atom is the building block of all matter. Nuclear energy is the energy that exists at the core of the atom called the nucleus. Nuclear energy can be accessed through two kinds of atomic reactions nuclear fission and nuclear fusion. In the first reaction, atoms are broken apart whereas in the latter they are forced to fuse together. However, to date, nuclear power plants do not have a safe and reliable way to generate energy through nuclear fusion. Therefore, nuclear reactors use uranium as fuel to produce energy by nuclear fission.

World nuclear power

Nuclear power provides almost 15 percent of the world’s electricity. The first nuclear power plants, which were small demonstration facilities, were built in the 1960s. These prototypes provided “proof-of-concept” and laid the groundwork for the development of the higher-power reactors that followed.

The nuclear power industry went through a period of remarkable growth until about 1990, when the portion of electricity generated by nuclear power reached a high of 17 percent. That percentage remained stable through the 1990s and began to decline slowly around the turn of the 21st century, primarily because of the fact that total electricity generation grew faster than electricity from nuclear power while other sources of energy (particularly coal and natural gas) were able to grow more quickly to meet the rising demand. This trend appears likely to continue well into the 21st century. The Energy Information Administration (EIA), a statistical arm of the U.S. Department of Energy, has projected that world electricity generation between 2005 and 2035 will roughly double (from more than 15,000 terawatt-hours to 35,000 terawatt-hours) and that generation from all energy sources except petroleum will continue to grow.

In 2012 more than 400 nuclear reactors were in operation in 30 countries around the world, and more than 60 were under construction. The United States has the largest nuclear power industry, with more than 100 reactors; it is followed by France, which has more than 50. Of the top 15 electricity-producing countries in the world, all but two, Italy and Australia, utilize nuclear power to generate some of their electricity. The overwhelming majority of nuclear reactor generating capacity is concentrated in North America, Europe, and Asia. The early period of the nuclear power industry was dominated by North America (the United States and Canada), but in the 1980s that lead was overtaken by Europe. The EIA projects that Asia will have the largest nuclear capacity by 2035, mainly because of an ambitious building program in China.

A typical nuclear power plant has a generating capacity of approximately one gigawatt (GW; one billion watts) of electricity. At this capacity, a power plant that operates about 90 percent of the time (the U.S. industry average) will generate about eight terawatt-hours of electricity per year. The predominant types of power reactors are pressurized water reactors (PWRs) and boiling water reactors (BWRs), both of which are categorized as light water reactors (LWRs) because they use ordinary (light) water as a moderator and coolant. LWRs make up more than 80 percent of the world’s nuclear reactors, and more than three-quarters of the LWRs are PWRs.

Issues affecting nuclear power

Countries may have a number of motives for deploying nuclear power plants, including a lack of indigenous energy resources, a desire for energy independence, and a goal to limit greenhouse gas emissions by using a carbon-free source of electricity. The benefits of applying nuclear power to these needs are substantial, but they are tempered by a number of issues that need to be considered, including the safety of nuclear reactors, their cost, the disposal of radioactive waste, and a potential for the nuclear fuel cycle to be diverted to the development of nuclear weapons. All of these concerns are discussed below.

Safety

The safety of nuclear reactors has become paramount since the Fukushima accident of 2011. The lessons learned from that disaster included the need to (1) adopt risk-informed regulation, (2) strengthen management systems so that decisions made in the event of a severe accident are based on safety and not cost or political repercussions, (3) periodically assess new information on risks posed by natural hazards such as earthquakes and associated tsunamis, and (4) take steps to mitigate the possible consequences of a station blackout.

Credit : Britannica 

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Do you know how uranium for nuclear reactors is produced?

Uranium in its state is found in quantities that average about 4 grammes to every ton of rock. It is an extremely process to extract this mineral, from the rocks that contain it even when the deposits are relatively rich.

The best material for nuclear fission is Uranium 235, but natural uranium has only one atom of this structure for every has been extracted from rocks, the element has to be further processed to get the portion with the atomic structure needed for nuclear reactors.

Once the atomic reaction has been set in motion, the energy which is released mostly takes the form of heat. This heat led to a type of boiler where it generates steam that is later put to several uses. One kilogramme of uranium yields as much energy as 3 million kilogrammes of coal.

 

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Describe how a nuclear reaction takes place?

We speak of nuclear reaction whenever the nucleus of an atom undergoes any change in its properties any change in properties. For example, this could be the loss of one or more protons or other particles from within the nucleus, which in turn is possibly caused by the impact of other particles. In nature this process can take place spontaneously in certain substances and gives rise to radioactivity.

Radioactivity was discovered in 1896 by the French scientist Henri Becquerel who proved that pitchblende, a mineral that contains uranium, could darken photographic plates even if they were wrapped in dark paper. It became evident to Becquerel that a very penetrating from of radiation was involved.

We now know that this radiation consists of alpha particles and that radioactive materials also give out two other types of radiation: beta and gamma. Alpha particles are not very powerful and they can be stopped by a thickness of a few sheet of paper or by a few centimeters of air. Beta rays are more penetration but can be stopped by thick cardboard, a few meters of air or thin sheet metal. Gamma rays, like X-rays, are extremely penetrating and can be very dangerous to plant and animal life. To stop them several centimeters of metal thickness is needed to reduce gamma radiation to an acceptable level.

It was not simple to produce these rays artificially and it took many years of difficult research and complicated experiments. In the end the scientists succeeded. They bombarded the atoms of certain materials with particles taken from naturally radioactive material. By increasing or decreasing this bombardment, the scientists were able to break aparkthe protective shell of electrons and reach the nucleus of an atom.

In this way nuclear fission, or the splitting of the atom, was achieved. Under such bombardment to atomic nucleus splits into two smaller nuclei. As this happens, some neutrons are rejected by the splitting atomic nucleus and collide with the nuclei of neighbouring atoms. This sets off a chain reaction, releasing enormous quantities of energy which can go out of control with disastrous results.

Nuclear reactors are complicated structures in which the chain reaction from atomic fission can be set off continued and kept under control. In this way, an atom can be split without the risk of a terrible destructive explosion. Instead, the process is done gradually and a large amount of energy is produced.

Nuclear reactors are fuelled in different ways. Nuclear fuel must always be substances which cab set off a chain reaction when bombarded with neutrons. The most commonly used elements in fueling reactors are uranium, plutonium and thorium.

At the heart of the reactor there is the moderator which is a substance that slows down the speed of the neutrons and regulates their flow. The reactor is called fast if it uses fast neutrons and thermal if the neutrons have been slowed down, thereby transferring much of their energy to the moderator.

 

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What makes an atom?

Everything is made up of atoms which are the smallest parts of an element still possessing the chemical properties of that element. It is difficult to realize how small atoms are. They have a diameter of about one-hundred-millionth of a centimeter. At one time scientists believed atoms were little spheres that could not be broken, but we know that atoms are composed of other particles which are even smaller. Each atom is like a miniature solar system: at the centre it has a nucleus which consists of protons and neutrons around which electrons revolve.

The atom consists almost entirely of empty space and its entire size is that of the orbit of its outer electron, which revolves at extremely high velocity, forms an impenetrable shield. A propeller going round very fast will give us an idea of an electron. The electron seems to be at every point of its orbit at the same time because it goes round the nucleus so fast. That is why we say the atom consists mostly of empty space. The spherical shield formed by the revolving electrons prevents the emptiness between their orbits and the nucleus from being filled in normal circumstances.

The nucleus and the electrons each have a diameter of about one-tenth of a millionth part of millionth part of one centimeter. Nearly all the mass of the atom is contained within the nucleus. The electrons are very light compared with the protons and the neutrons which are 1,837 times heavier than the electrons.

Electrons have a negative charge and they are fixed to the atom and cannot break away from their orbits through centrifugal force because protons have an equivalent positive charge and the two balance each other. Neutrons have no electrical charge.

 

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