SYNTHESIS OF COPPER NANOPARTICLE

CuSO4 and EDTA were dissolved in Distilled Water. KBH4 was added to above solution as reducing agent and then the solution was heated to reaction temperatures. After stirring at different temperatures for certain time, the aqueous solution was spilled out and filtered. After that the product was washed 3 times with ethanol and acetone separately, and finally dried in vacuum drying oven.

Mechanism of reaction
 Cu2+ + 2e- → Cu (Metallic copper in nm)

Overall reaction:

 4CuSO4 + KBH4 + 8KOH→ 4Cu +4K2SO4 + KBO2 + 6H2O

KOH is used as alkaline medium in the experiment and EDTA is added as ingredient agent in order to avoid the formation of CuSO4 ppt. in alkaline medium Characterization: Formation of Copper Nano particle can be confirmed using tool such as SEM (scanning electron microscope), TEM (transmission electron microscope) and AFM (atomic force microscope).

APPLICATIONS:
1. Alloys.
2. Automotive.
3. Building materials.
4. Electrical material.
5. Hardware.
6. Marine material.

SYNTHESIS OF SILVER NANOPARTICLE

In a typical experiment 50 ml of 3M AgNO3 was heated to boiling. To this solution 5 ml of 1% trisodium citrate was added drop by drop. During the process solution was strirred vigorously. Solution was heated until colours change is evident (pale yellow). Then it was removed from heating elementand stirred until cooled to room temperature. Mechanism of reaction

 Ag + + e → Ag (Metallic silver in nm)

Overall reaction:
 4Ag+ + C6H5O7Na3 + H2O→ 4 Ag + C6H5O7H3 + 3Na+ + H+ +O2

Characterization:
Formation of silver nano particle can be confirmed using tool such as SEM (scanning electron microscope), TEM (transmission electron microscope) and AFM (atomic force microscope).

APPLICATIONS:
1. These nanoparticles are used in biomedical nanotechnology for example in cancer therapy.
2. These nanoparticles are used in nanoelectronics.
3. They are used in water purification. 

SYNTHESIS OF GOLD NANOPARTICLE

A facile (simple) approach involves the reduction of hydrogen Tetrachloroaurate , [HAuCl4] with trisodium citrate dehydrate, [Na3C6H5O7.2H2O], in aqueous solutions at elevated temperatures. The citrate donates electrons to the gold ions producing gold metal and then adsorbs on the surface of the particle preventing growth of large particles. The charges on the citrate molecules help stabilize the gold nanoparticles by electrostatic repulsion and prevent aggregation.

 Au 3+ + 3e → Au (Metallic gold in nm)

Overall reaction:

6Au3+ + C6H5O7 3- + 15OH- → 6 Au + 6CO2 + 10H2O

Procedure 

Dilute solution of HAuCl4 is heated to boil at constant stirring using magnetic stir bar. After the solution begins to boil, 1% solution of trisodium citrate dehydrate, is added continue to boil and stir the solution. The gold nanoparticles will gradually form the citrate reduces the AuCl4. Following color changes observed during reaction which confirms formation of gold nano particle.

YELLOW COLOUR → COLOURLESS → PURPLE → WINE RED

Characterization:
Formation of gold nano particle can be confirmed using tool such as SEM (scanning electron microscope), TEM (transmission electron microscope) and AFM (atomic force microscope). APPLICATIONS:
1. These nanoparticles are used in biomedical nanotechnology for example in cancer therapy.
2. These nanoparticles are used in nanoelectronics.
3. They are used in water purification. 

Classification of nano materials

1. Zero dimensional nanomaterials(OD): Nanoparticle which have nano dimension (1 – 100 nm) in all the three direction like fullerene.
2. One dimensional nanomaterials(1D): Nanosheet or layers which have nano scale (1 – 100 nm) in two dimensions where as other one dimension have macro scale (either m or mm).
3. Two dimensional nanomaterials (2D): Carbon nanotubes which have nanoscale (1 – 100 nm) in one dimension whereas in two dimension it has macro scale (either m or mm).
4. Three dimensional nanomaterials(3D): Materials which have all three dimension in macro scale (either m or mm) with coating / dispersion of nanoscale (1 – 100 nm). 

Properties at Nanoscale

As particle sizes and layer thicknesses approach the nm size scale, special properties begin to emerge. For example as particles get smaller in diameter a greater percentage of the atoms in the particle reside on the surface of the particle as shown below. Smaller than 10nm, the number of surface atoms dramatically increases, increasing the reactivity of these particles. At below 2nm diameter 50% of the atoms in the particle, and hence have more degree of freedom because they have fewer constraints and they become more active additionally as the particle become smaller, their relative surface areas increases, again making them more chemically active. When heated, the atoms in a crystal begin to oscillate with increasing degree of amplitude, when the temperature is hot enough to increase the amplitude of atomic oscillation to break the crystal structure, the material will spontaneously melt. In nanoscale particles, the surface atoms are not as strongly bound as core atoms. When most of the atoms in the particle reside on the surface, the melting point of the particle can be few nm gold particle can melt at room temperature. Following are examples of the special properties of nanomaterials.
1. By varying the size of the materials to nanoscale the emission wavelength can be adjusted to any color. This technology can be used in dyes, paint display and chemical sensitive, sunscreen for example Zno and Tio2 – both metal oxide in sunscreen because they absorb UV that dangerous to skin Tio2 (50nm) particle absorb high energy UV radiation and transparent to visible light.
 2. By varying the size of the materials to nanoscale the emission wavelength can be adjusted to any color from blue up through IR. This technology can be used in dye, paint, display and sunscreen. NOTE: Particle of TiO2 and ZnO both metal oxides used in su7nscreen because they absorb UV radiation that damages skin. TiO2 (50 nm) particle absorb high energy UV radiation and are transparent to visible light. Whereas normal sized TiO2 turns skin white.
3. Nanoscale components have very high surface area to volume ratio making them ideal for use in composite material, chemical energy storage.
 4. At nanoscale gravitational force diminishes whereas electrostatic force is prominent.
5. At nanoscale tensile strength is more for example carbon nanotube 100 times stronger than steel.
 6. At nanoscale material like Al become combustible.
7. At nano dimension opaque metal like copper become transparent.
8. Noble metals like Au, Hg become more active.
9. Nano structured macroscopic systems which have higher density can be employed in smaller and faster circuit with reduced power consumption.
10. At nanoscale metals like gold, silver etc. shows excellent anti microbial activity. Note: catheters are usually soaked with Ag nano particle which helps in destroying infection producing bacteria/germs.

Air conditioning

Air conditioning is the process of altering the properties of air (primarily temperature and humidity) to more favorable conditions. More generally, air conditioning can refer to any form of technological cooling, heating, ventilation, or disinfection that modifies the condition of air.
An air conditioner (often referred to as AC) is a major or home appliance, system, or mechanism designed to change the air temperature and humidity within an area (used for cooling and sometimes heating depending on the air properties at a given time). The cooling is typically done using a simple refrigeration cycle, but sometimes evaporation is used, commonly for comfort cooling in buildings and motor vehicles. In construction, a complete system of heating, ventilation and air conditioning is referred to as "HVAC".
The basic concept behind air conditioning is known to have been applied in ancient Egypt where reeds hung in windows had water trickling down. The evaporation of water cooled the air blowing through the window, though this process also made the air more humid. In Ancient Rome, water from aqueducts was circulated through the walls of certain houses to cool them down. Other techniques in medieval Persiainvolved the use of cisterns and wind towers to cool buildings during the hot season. Modern air conditioning emerged from advances inchemistry during the 19th century, and the first large-scale electrical air conditioning was invented and used in 1911 by Willis Haviland Carrier. The introduction of residential air conditioning in the 1920s helped start the great migration to the Sunbelt.

   

      

 An air conditioning unit:

1.    The coils and pipes in an air conditioning unit contain refrigerant gas. The refrigerant gas enters the compressor as warm, low-pressure gas and leaves it as hot, high-pressure gas.

2.    In the condenser coils, hot, compressed refrigerant gas loses heat to the outdoor air and becomes liquid while it is still warm.

3.    The warm, liquid refrigerant passes through the tiny opening of the expansion valve, expands, and partly turns to gas at a low temperature.

4.    In the cooling coils, the refrigerant takes up heat from the indoor air and leaves the coils as warm, low-pressure gas.

5.    The indoor air gives up heat to the refrigerant in the cooling coils and also loses moisture as it is chilled. The moisture condenses on the coils and trickles down to outside drain holes. Cooled air is blown back into the room.