Green Chemistry: Definition and Concepts of green chemistry, principles of green chemistry, waste or pollution prevention hierarchy, green chemistry and sustainability development, use of alternative feed stock (Bio fuel), green solvents, alternative sources of energy: use of microwaves and ultrasonic energy

4. Unit-5: Green Chemistry
• Definition and Concepts of green
chemistry
• Principles of green chemistry,
waste or pollution prevention
hierarchy
• Green chemistry and sustainability
development,
• Use of alternative feedstock (Bio
fuel),
• Green solvents,
• Alternative sources of energy: use
of microwaves and ultrasonic energy.

32. Straw

33. Heating and treating with microwave energy is a green and
highly efficient technique for various thermal processes.
Microwave (MW) Energy

34. Microwaves ovens use electromagnetic energy and generate electromagnetic waves that
heats up the food kept in the appliance. Unlike a conventional oven, they do not heat up
the whole space inside the appliance and just use the waves to heat the food kept in it.
Myths regarding Microwave Ovens
Some people believe that using microwave ovens contaminates food with radioactive
element. But FDA (Food and Drug association) of America states that microwave ovens do
not contaminate food. Microwaves just cause water molecules in food to vibrate
producing heat that cooks food and thus food having high water content like vegetables
cook faster. The energy waves generated by microwave oven are converted to heat and
thus they do not contaminate food.
Difference in usage of microwave and conventional oven
Both the types of ovens can be used for heating but have very different
purposes. Conventional Ovens are good for any cooking that requires baking
or browning of food. A microwave does not bake or brown properly but is good
for re-heating, roasting and almost all other kind of cooking. Microwaves are a
good replacement for conventional cooking rather than to all types of cooking
requiring ovens (like baking)

36. WHAT IS THE DIFFERENCE BETWEEN INDUCTION STOVE AND A
MICROWAVE OVEN?

37. Working mechanism of induction stove:
1. Under the ceramic plate of the induction stove, there’s a coil of metal. When you turn
on the power, an alternating current flows through the coil and produces an invisible
magnetic field above, below, and all around it. Unless there’s a pan on the cooking
zone, no heat is produced: the cooking zone remains cold.
2. Place a pan on the cooking zone and the magnetic field produced by the coil
penetrates the iron inside it.
3. The magnetic field induces whirling electrical (eddy) currents inside the pan turning
the pan into a heater.
4. Heat from the pan flows directly into the food or water inside it.
Note: Induction cooking only works properly with cooking pans
containing iron—the only metal that efficiently produces electrical (eddy)
currents and heat from magnetic fields. Copper and aluminium pans
and glass cookware don’t work.

39. Elephants can communicate using very low frequency sounds, with pitches below the
range of human hearing. We can't hear most of the sounds they make. The
creatures produce low-frequency noises between 1 to 20 Hertz, known as
infrasounds, that help them keep in touch over distances as large as 10 kilometers.

40. As we know, a bat emits ultrasonic waves of high pitch to avoid from obstacles or for
hunting their preys. Frequencies higher than 20 kHz are called ultrasonic sound. ...
Hence, we are unable to hear the sound made by them.