How Oxygen is produced and stored artificially?

     Oxygen is one of the most abundant elements on earth. Oxygen is a life sustaining element and is used by all the animals to survive. It also has many scientific, commercial and industrial applications. In this article we will learn how oxygen is manufacture artificially.

The most common method to produce oxygen is by cryogenic distillation in which argon and nitrogen is also produce along with oxygen. Cryogenic means something produce or store below -150°C to absolute zero. Let’s understand the whole process by looking at the given diagram.

  1.) First of all, the air is filtered to remove all dust particles and then is sucked inside a compressor.

  2.) In a compressor, there are two valves – inlet valve and discharge valve. Air comes inside through inlet valve and with the piston; it is compressed to a high pressure. As a result, it heats up (potential energy of piston converts to heat energy). This warm air goes to the freezing unit through discharge valve.

  3.) In the freezing unit, cooling effect is done by coil tube in which liquid nitrogen is been fed. Note that nitrogen is not mixed with compressed air but present in coil tube. Now, air becomes cold and its temperature drops by -200°C.

  4.) After that this cool air is sends to the separator in which carbon dioxide is got separated in the form of dry ice.

 5.) After this air goes inside expansion turbine, in which air turns into liquid air with temperature -200°C.

  6.) Now, liquid air goes in the air distillation column, where its warming starts. Air is a mixture of gases. Because of slow warming, different gases separate out. Nitrogen first separates out with boiling temperature of -196°C, below which argon with temperature -186°C and at last liquid oxygen gets collected with temperature -185°C.

    Nitrogen collected used in fertilizers and food processing industry. Argon mainly used in iron and steel industry. Liquid oxygen is collected and filled in cylinders.

    Oxygen Cylinders:

Oxygen stored in cylinders in liquid form and stored at high pressure almost at 200bar. These cylinders come with pressure regulator to regulate and fix the pressure needed. Today patients needed oxygen at lower pressure than 200bar, so from regulator you can fix or lower pressure.

The larger size cylinder that you see mostly, is 1.5 meters tall and contains 7800litres liquid oxygen. Patient admitted to hospital need 130litres/minute. This means that this cylinder in total will last about an hour.

India has lifted liquid oxygen from Singapore and from other countries in cryogenic liquid oxygen tanks, in which oxygen is stored at temperature -182°C or -185°C.  

Baikal GVD- telescope under water

Lake Baikal is deepest lake of the world. It is located in the region of Siberia in Russia. Russian scientists have developed world’s biggest underwater telescopes called Baikal- GVD (Gigaton Volume Detector). It is to be deployed in the waters of Lake Baikal. It is an international project in the field of neutrino astronomy. By this mission, it is possible to study about the most mysterious particle of our universe i.e. NEUTRINO. It will aid scientists to know about the origin of universe and even about the supernovas and nuclear reactions in the sun. Neutrinos are everywhere with no electric charge and no mass. They weakly interact or do not interact with the forces around them. So that’s why it is really challenging task to detect them.   

Just like Baikal- GVD, the other two largest neutrino detectors are deployed as ANTARES in Mediterranean Sea and other the IceCube at the South Pole.

Baikal- GVD: Its primary goal is to study the flux of high energy cosmic neutrinos and its sources. Telescope was submerged to 2500-4300 feet, about 4km from shore. Water is an effective medium to detect neutrinos. Lake Baikal is most suitable for this observation because of its depth.

What makes neutrino most interesting?

Neutrinos are second most abundant particle in our universe after photons. Trillions of neutrinos are passing through our body in every single second. Although their numbers are so huge, still it is so difficult to catch them. Why? This is because they do not posses any charge and does not interact with anything. Scientists also state that neutrinos might posses some unique properties which may helps us understanding that why this universe is made of matter rather than antimatter.

But why we are detecting neutrinos under water or in ice?

The answer is:  when one out of trillion neutrinos interacts, it may leave a flash of light or a line of bubbles which can be detected by large detectors like Baikal GVD. This telescope or we may say detector is designed to detect high energy neutrinos which may be coming from supernovas occurring somewhere in our universe, or may be from nuclear reactions in our sun, or may be from earth’s core.  

Nanophotonics- A new light of hope

Light causes us the sensation of sight and is essential for the existence of life. Researchers have been studying the nature of light and its behaviour at different levels, such discoveries has given to birth to a new field called NANOPHOTONICS.

          Nanophotonics is a branch of optics, optical engineering, electrical engineering and as well as a branch of nanotechnology. Nanophotonics investigates the behaviour of light on nanometer scale and interaction of nano particles with light. Its aim is to go beyond electronics and build up circuits which are totally run by light. Light travels in straight line so it is crucial to build a technology which can bend along what is require in the circuit.

          Researchers from university of Hyderabad have discovered a technique which is called mechanophotonics which allow to move, bend, slice, lift micron sized waveguiding crystals with the help of atomic force microscopy. Researchers have also developed crucial photonic elements like microresonators which are light trapping elements. They also developed organic photonic integrated circuit or OPIC using the same technique.

Nanophotonics can be used in many fields ranging from biochemistry to electrical engineering. It is now possible to go beyond current electronics and building up of photonic circuits.

Applications of Nanophotonics

Microelectronics: Circuits can be squeezed into the small volumes. Micro photodetecors have various properties like- high speed, low noise, low power and low voltage.

Microscopy: with this technology it is possible to build lens called superlens which provide a better image that are more precise and accurate.

Solar cells: nanophotonics can intensify the light absorbed by the solar cells and hence will enhance its efficiency.

Optical technology: miniaturization can be achieved by nanophotonics. It is helpful in the devices like of wearable devices which will be operated entirely by light.

Fibre optics: fibre optics can be made at nano scale level with the help of organic materials.

Spectroscopy: in the traditional spectroscopy, we can get measurements of average billion or million of molecules but with nanophotonics, we get high intensity peaks of even single molecule.

          Researchers believe that Nanophotonics is wonderful discovery and will surely gain momentum with new molecular materials and new microscopy techniques. 

NANOMICELLES - big things come in small packages

With the advancement in nanotechnology, scientists have been in search to find the use of nanoparticles for efficient drug delivery. Nanomicelles, like nanoshells and nanovesicles are extremely small sized particles and have been noted as a new emerging platform in the field of science and medicine. Nanomicelles are stable at room temperature and are less than 100nm in size. They have ultramicroscopic globular structures and consists of hydrophilic exterior and a hydrophobic core of fatty acyl chain.

Shape of nanomicelles  Shape and size of nanomicelles are decided by molecular geometry of the particle. Shapes formed depend on pH of solution, ionic strength and surfactant concentration. Nanomicelles are mostly spherical in shape but some are cylindrical and ellipsoid also.

Formation   Nanomicelles can be formed in aqueous or non-aqueous solution. Hydrophobic or non polar region forms interior and hydrophilic or polar region forms exterior. Nanomicelles may be developed from the mixture of lipids and detergents or from surfactant molecules that can be ionic, non-ionic and cationic detergents.

Factors affecting nanomicelles

• Chain length of surfactant molecules- longer molecular chain length results in the formation of nanomicelles with low concentration.
• Temperature- increase in temperature leads to increase in critical micelle concentration (CMC).
• Dissolved salts- solutions containing dissolved salts decrease CMC.
• Addition of alcohol to water- presence of alcohol in water increases CMC.

Uses of nanomicelles

• Drug delivery- Nanomicelles will be deployed as an effective drug carrier. Team of Nano-drug delivery systems (NDDSs) has developed a nanomicelle that can be used to deliver a drug called docetaxel. This drug is used for the treatment of cancers. In cancer treatment, it is always expected to kill cancer cells without harming healthy cells of body. Docetaxel is hydrophobic drug and is dissolved in mixture of polysorbate-80 and alcohol. This mixture is toxic for liver, lungs and blood cells. So, there was a need of effective drug delivery vehicle for docetaxel without any extra damage. Nanomicelles are suited best in this work.
• Nanomicelles can also be used therapeutic interventions involving protein and peptide delivery.
• Hydrophobic part of nanomicelles facilitates solubilisation of hydrophobic drugs in water.
• Hydrophilic shell itself acts as protector for the drug and enables prolonged circulation.
• Nanomicelles have lower toxicity and have an ability to minimize drug degradation.
• Nanomicelles are extremely cost effective and can establish itself as a next generation chemotherapeutic.

Giant Metrewave Radio Telescope

How galaxies form and how they evolve thus requires measurements of various parameters. Although scientists have successfully studied about stellar masses and formation of stars at different epochs. But still there is little known about the fuel of star formation.   

 A Giant Metrewave Radio Telescope has been set up by NCRA, centre of school of natural sciences of TIFR. It is a versatile instrument which study various astronomical problems such as concerning pulsars, radio galaxies and regarding evolution of universe. It is one of the largest radio telescopes in the world. Galaxies are made up of stars and gas. To understand galaxies, there is need to know about the evolution of gas and stars with time. For this purpose GMRT was built to observe many different astronomical objects.  GMRT consists of 30 fully steerable gigantic parabolic dishes of 45m diameter each spread over distances of upto 25 km.  The number and configuration of the dishes was so selected to have high angular resolution as well as ability to image radio emission from diffuse extended regions. GMRT is being designed to operate in six different frequency bands between 38 and 1420 MHz. All these provides a purpose of dual polarization.

GMRT is an indigenous project. The construction of 30 large dishes at a relatively small cost has been possible due to an important technological breakthrough achieved by Indian Scientists.

Scientists of TIFR and IISER Mohali have used the upgraded GMRT to carry out the distant measurements of atomic hydrogen content of galaxies in the early universe. They found that the star formation efficiency of galaxies appear to have not changed significantly over the last 4 billion years.

Why there was a need to upgrade GMRT?

Scientists answered that most of the atomic gas is in the form of hydrogen, which emits spectral line at the radio length of 21.11cm. This emission is so weak that it is not even detected by powerful telescopes like GMRT. That’s why GMRT has been extended to wide range frequency covering range even of hydrogen spectrum.

The upgraded version of GMRT has made possible to have a direct measurements of gas masses of distant galaxies.

Light electrons- Photoelectric Effect

 

Metals consist of: - positively charged ions called kernals and negatively charged electrons. Kernals are fixed on their positions and does not move whereas electrons are free and they move in between positively charged ions but still they do not allow to leave the metal surface. Now the question arises that is it possible to knock out these free electrons from metal surface? The answer will be YES.

          If we want to eject electrons from the metal surface, it is necessary to give some energy to these free electrons. There are some methods which can cause the ejection of electrons-

First is THERMIONIC EMISSION-

It is the phenomenon of emission of electrons from the metal surface with the help of thermal energy. When we heat the metal surface the free electrons start getting energy and they excited and consequently start ejecting out of the metal surface. More thermal energy will cause more ejection of electrons. Electrons ejected are called thermal electrons.

Second is FIELD EMISSION- It is the phenomenon of ejection of electrons from the surface of metal by applying strong electric field. Battery (denoted by B) connected with metal surface (denoted by A). Positive ions of battery will start attracting electrons from metal surface. First electrons will along battery side of metal and as electric field goes on increasing, it will cause the ejection of electrons out of metal.

Now let’s think- Is it possible to eject electrons from metal surface with the help of light?

Answer will be- YES

This process is named as PHOTOELECTRIC EMISSION

Photoelectric emission is a phenomenon of emission of electrons from the surface of metal when light of suitable frequency falls on it.

When light falls on metals, electrons get energy and get excited after that will ultimately comes out of the metal surface. This phenomenon was explained by Hertz, when he was conducting an experiment related to Maxwell electromagnetic radiation.

HERTZ OBSERVATION - Hertz prepared an apparatus in which he used two plates, one is cathode C and other is anode A. Plate C is photosensitive plate and is given negative potential and plate A is given positive potential. Whole apparatus is evacuated in glass tube. Through a window, light of suitable frequency is made to fall on plate C. Electrons get energy and will start coming out of the plate C and will start attracting towards positive anode A and thus will constitute current. Electrons thus ejected are called photoelectrons and current formed is called photo current.

Supercapacitor vs Battery & Capacitor

In this era of climate change, there is a need to switch from fossil fuels to electric power. Electricity is a versatile form of electricity but it has one problem associated with it. As I had raised same concern in my last post that there is a problem to store electricity for a long time (https://imbibephysics5794.blogspot.com/2020/08/decarbonisation-and-storing-thermal.html). For capacitors and batteries we need to look for two different things, one is amount of charge stored and other is how quickly the energy is delivered. Capacitors deliver energy instantaneously but cannot able to store large amount of charge. Batteries have an ability to store large charge and cannot give energy quickly. So in order to overcome these drawbacks, we need to look for other alternatives. This problem can now be solved by supercapacitors.

SUPERCAPACITORS

Supercapacitor also known as ultracapacitor is an electronic device which is used to store large amount of electric charge. According to following formula, it is cleared that capacitance is directly proportional to surface area and is inversely proportional to distance between the plates.

C = Ɛ_oA/d

How supercapacitors are different from conventional capacitors and batteries?

    Supercapacitors consist of electrodes of large surface area and a thin dielectric plate between electrodes so to have large capacitance. Supercapacitors can store 100 times more charge than a conventional capacitors. Here, electrodes are made up of some porous substance which provides more surface area for storage of charge. In supercapacitors there is no dielectric material between the plates. Both electrodes are soaked in specific electrolyte and are separated by very thin layer of insulator. Plastic, paper or carbon can be used as insulator. That’s why supercapacitors could able to store larger charge because of large surface area of electrodes and lesser distance between them.

    Supercapacitors rely on static charges resting on solid electrodes while batteries rely on the charges which produced through chemical reactions of liquids present in batteries. Batteries have higher energy density while supercapacitors have higher power density. All these factors gave us conclusion that supercapacitors releases energy very quickly as compare to batteries.

Future of supercapacitors

Scientists believe that supercapacitors may replace lithium ion cells as it charges more quickly and can recharge multiple numbers of times.

Scientists are exploring the concept of designing lightweight supercapacitors by designing ECs with graphene which will have high storage capabilities.

Supercapacitors can widely be used in automobiles where regenerative braking is used, in wind turbines, motors and also it been employed in hybrid buses.

By looking its applications it seems that supercapacitors or ultracapacitors are a most promising energy storage device.