The earth is facing momentous environment challenges to improve the quality of air, soil and water. It is now generally acknowledged that the main source for global warming is the dischargeof the so called greenhouse gases into the atmosphere. A major greenhouse gas is carbon dioxide (CO2), which is released predominantly from ignition of fossil fuels such as coal, petroleum and natural gas.Itsconsequence is now considered to be irreversible and this could escort to the demise of human society. This is a complex issue without a single solution, yet from the rapidly increasing global research activity and expansion in the field of CO2 capture and consumption, there is brightness at the end of the tunnel. Although the conventional methods for transforming (CO2) include biological (e.g., photosynthesis and enzymatic biochemistry), chemical (e.g., amine capture), electrochemical, and photochemical (e.g., sunlight driven photo catalysis)are reported in literature review, However very few drawbacks have been reported on carbon capturing through Nanofluids or with help of nanobased particles.This review firstly sheds the light on the nanoparticles, its elementary properties; categorizationand the latest developments in nanotechnology enabled carbon dioxide capture processes along with an overview of the conventional technologies for carbon capture are described. Key words:Nanoparticles, green house gases, Carbon dioxide, conventional methods.
It is a field that combines of chemistry, physicsand biology so it can be called as multifunctional field. Among many definitions the U.S Environmental Protection Agency define it as research development in atoms, macromolecular levels using a length scale of 100 nm in any dimension; creation of devices and system having novel properties of small size .The technology is being applied in various industries such as pharmaceutical, engineering, IT sector, Medicinal field.
1.1 History of nanotechnology:
Enormity does not come close toas of size;surprises can come from small size. The word “Nano” was derived from Greek word that stands for “Dwarf”. Nanotechnology word was presented by Nobel Lauterate Richard P.Feynman know as father of nanoscience in his lecture delivered at the session of the American Physical Society in 1959. Feynman described a route in which scientists would be able to employ and manage single atoms and molecules. It wasn't until 1981, with the progress 2 inventions: Scanning tunnelling microscope that could "spot" single atoms and birth of cluster science, innovative nanotechnology started . These lead to breakthrough of Fullerenes (1985) and Carbon Nanotubes in 1991.
In the second half of 1980s and early 1990s a number of significant discoveries were made, this created a crucial impact on the further enlargement of nanotechnology. In 1991, the first nanotechnological program of National Scientific Fund started to operate in USA. In 2001, the National Nanotechnological Initiative (NNI) of the USA was approved. Since then, lots of scientific and technical research developments have been taking place all over the world especially in countries like Japan, Germany, England, France, China, and South Korea and recently in the CIS countries. Thus, the nanotechnology paradigm was formed at the turn of the 1960s, while the 1980s and 1990s are the start of development of nanotechnology in its own right. Hence the whole period up to the 1950s may be considered as pre-history of nanotechnology. In 2003, Samsung introduced an antibacterial technology with the trade name Silver Nano™ in their washing machines, refrigerators, air purifiers and vacuum cleaners, which use ionic Ag NPs . In 2005, Abraxane™, which is a human serum albumin NP material containing paclitaxel, was manufactured, commercialized and released in the pharmaceutical market. In 2014, there were about 1814 nanotechnology-based consumer products that are commercially available in over 20 countries. Nowadays it is widely accepted that nanotechnology is budding as a key aspect for commercial success in 21st century and is regarded as the “Next industrial revolution”.
1.2. Classification of nanoparticles:
On Basis of dimensions: Pokropivny and Skorokhod in 2007 classified nanoparticles on basis of dimensions.Figure( 1) such as; Zero dimensional (0D) that is measured within the nanoscale. These nanostructure ranges between 1-100 nm in each direction. Ex: nanoparticles. In one dimensional (1D) one direction remain large and other two be in nanometric range, having shape like rods. Ex: Nano tubes and rodes. Two Dimensional (2d) have plate like shape and have 2 dimensions outside the nanoscale. This class includes graphene, nanofilms, and nanocoatings. Three Dimensional (3D) are materials that are not confined to nano scale in any dimension. This class includes nanotubes, bundles of nanowires . Figure 1:structure of nanoparticles on basis of dimensions.
On basis of structure: Nanoparticles are generally classified into the organic, inorganic and carbon based described below:
- Organic nanoparticles: These NPs are recyclable and non lethal. Examples are:Dendrimers, micelles, liposome and ferritin etc. Among these some has a empty core (Figure1), known as nanocapsules and are perceptive to thermal and electromagnetic radiation like heat and light. This exceptional quality makes them aperfect choice for drug delivery. The organic nanoparticles are most broadly used in the biomedical field for example drug delivery system as they are competent and can be injected on definite parts of the body identified as targeted drug delivery.
- Inorganic nanoparticles: Inorganic nanoparticles are harmless, hydrophilic , biocompatible and highly stable as compared to organic nanoparticles.These are made up of metal and metal oxide such as gold nanoparticles, Iron oxide NPs , Silver Nanoparticles. Beneath these semiconductors such as ceramics, silicon are also categorised.
- Metal based nanoparticles: The particles which are synthesised from metals to nanometric sizes either by destructive or constructive methods are known as metal based nanoparticles , approximately all the metals can be converted into their nanoparticles. The frequently used metals for nanoparticle synthesis are aluminium (Al), zinc(Zn), cobalt (Co), Iron (Fe), gold (Au),cadmium (Cd), lead (Pb), Copper(Cu)and silver(Ag).
- Metal oxides based nanoparticles: The metal oxide based NPs are synthesised to amend the properties of their particular metal based nanoparticles, for instance Iron (Fe) straight away oxidises to iron oxide (Fe2O3) in the occurrence of oxygen at room temperature that boost its reactivity as compared to iron nanoparticles. Metal oxide nanoparticles are synthesised mostly due to their better reactivity and efficiency. These are used in fabrication of electronic circuits, sensors, fuel cells, coatings etc. The commonly synthesised nanoparticles are Aluminium oxide (Al2O3), Iron oxide (Fe2O3), Magnetite (Fe3O4), Zinc oxide(ZnO),Silicon dioxide (SiO2), Titanium oxide(TiO2).
- Carbon based nanoparticles: These are preparedentirely of carbon are knows as carbon based nanoparticles and originate in morphologies like hollow tubes, spheres.They can be classified into fullerenes(C60), grapheme, carbon nano tubes (CNT), carbon nanofibers.\nFig 1: Structures of Carbon based nanoparticles.
1.3 Properties of nanoparticles:
Once the particle size is compact below 100 nm, the solid particles begin to reveal unusual properties from the massive material based on Quantum mechanics.The surface related properties and the quantum properties play a elementary role in making the difference in the properties of the bulk material with that of the nanoparticles.Varying the particle size can change the properties like solubility, colour, and transparency .Other than this conductivity, optical and catalytic behaviour change with the alteration in surface of particle.The materials formed in a nanoparticle form have much high activity in catalytic processes than the bulk material .and material like gold which is one of poor catalyst, in form of nanoparticle give excellent catalytic properties .The reduction of the melting point of ultrafine particles is regarded as one of the unique features of the nanoparticles related with aggregation and grain growth of the nanoparticles.
Glance of Carbon dioxide
Brisk economic expansion has contributed to today's ever-increasingdemand for energy. An evidentconsequences of this is an increase inthe use of fuels, particularly conventional fossil fuels (i.e. coal, oil andnatural gas) that have become key energy sources since the IndustrialRevolution.Greenhouse effect occurs in the troposphere (the lower atmosphere layer), where life and weather occur. In the absence of greenhouse effect, the average temperature on Earth’s surface is estimated around -19°C, instead of the current average of 14°C . The greenhouse gas (GHG) effect has established that emittingextremely large amounts of carbon dioxide into the atmosphere has an alarming effect on Earth, resulting in catastrophic weather effects and unhealthy air quality . The last few years have witnessed a significant increase in the atmospheric CO2 level to more than 400 ppm, and the anthropogenic CO2 emissions are now higher than ever in history .
Carbon dioxide is accountable for 20% of the thermal absorption. Natural sources of CO2 include organic decomposition, ocean release and respiration. Anthropogenic CO2 sources are derived from activities such as cement manufacturing, deforestation, fossil fuels combustion such as coal, oil and natural gas, etc. Astonishingly, 24% of direct CO2 emission comes from agriculture, forestry and other land use, and 21% comes from industry. CO2 can potentially serve as a renewable feedstock that is it can be used both as a reagent in the synthesis of various chemicals and also as a viable solvent system that is environmentally benign. It provides a viable alternative to replace the depleting petroleum feedstock’s that are used to produce industrially important chemicals. Hence, expansion of novel uses for CO2 in chemical synthesis and purification would hold back global petroleum consumption.
Currently, many techniques are studied for capture,storage, and conversion of CO2 likewise depleted oil or onshore saline aquifers provide some potential CO2 storage facilities. Before CO2 can be stored, it must be separated from the waste gases, from flue gas (nitrogen, water, dust particles) is the main capture process for CO2 that usuallyinvolves capture through absorption with a solvent.Improved technologies are necessary to achieve thegoals of cost-eff ective and energy-efficient capture of carbon dioxide. Improvements over time have alsosparked research in direct conversion of carbon dioxide into useful products rather than simplesequestration. Nanotechnology can play an importantrole in global reduction of CO2.Nanotechnologies have the ability to produce innovative materials with unique properties that can be used in different environmental fields .
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