GECH119 Recycling

1. GECH119Recycling Dr. Ralph C. Gatrone Virginia State University Department of Chemistry and Physics

2. Chapter Objectives • Waste • Recycling • Natural Recycling • Recycling Aluminum • Recycling Plastic • Green Chemistry

3. Technology’s Cost • What is the cost of a comfortable life? • How many of you have a cell phone? • How many have more than one? • Your cell phone is powered by a rechargeable nickel-cadmium battery. • How long does a battery last?

4. Nickel-Cadmium Batteries • Rechargeable for about 2 years • Then what? • Disposal. • Where? • In California (2002) all batteries are considered hazardous waste.

5. Battery Disposal • 3 Billion batteries are sold in US per year • All must be disposed of at some point. • Batteries have potential environmental issues, including • pollute the lakes and streams as the metals vaporize into the air when burned; • contribute to heavy metals that potentially may leach from solid waste landfills; • expose the environment and water to lead and acid; • contain strong corrosive acids; • may cause burns or danger to eyes and skin.

6. Today’s Situation • Currently, most batteries collected through household battery collection programs are disposed of in hazardous waste landfills. • Even stores and chains that have established take-back programs admit that it often ends up in the trash

7. Waste • How much waste do you generate? • This includes: • Left-over food • Wrappers • Plastic • Glass • Cans (aluminum and steel) • Paper • Dirty water

8. Waste • In the US, we generate • 4 pounds of waste per person per day • ~ 1 billion pounds per day • What happens to this waste?

9. What happens to trash? • It does not disappear once it is picked up. • Depending on where you live it may: • Buried • Burned • Thrown in the ocean (illegal now) • Sending it into space has been considered • RECYCLE

10. Composition of a Landfill

11. Nature’s Recycling • Mother Nature has organized the biggest recycling programs. • It recycles water, carbon matter, and oxygen (the 3 most important ones). • Humans have impacted these recycling processes.

12. Type of Systems • There are three different types of systems. • Open System: one where both mass and energy are free go in and out. • Closed System: one where energy is allowed in and out but mass is not. • Isolated System: one where neither mass nor energy can go in or out.

13. The Earth • In our planet we have energy coming in from the sun and energy going out. There is usually no mass going out (unless we send the space shuttle to space). And unless we have a meteor coming into our atmosphere there is no mass coming in. • The Earth is a Closed System.

14. Energy from the sun • What does the energy from the sun do for us? • Ever notice when you feel like you are coming down with something • during the day you feel ok • but at night you feel sick again? • Like plants you are sucking up energy from the sun • Provides energy for plants

15. Carbon Cycle • Energy from the sun is absorbed by plants. • Fruits or vegetables grow. • We eat fruits/vegetables. • We produce waste. • Goes to landfill. • Organic matter goes into the soil where it decomposes. • Organic matter is used by plants again.

16. Water Cycle • The sun provides the energy required to evaporate water form large bodies of water (seas, lakes, and streams). • Evaporated water forms clouds. • It rains • Water go into reservoirs or underground • Perspiration of the soil • Evaporation…

17. Oxygen and CO2 Cycles • The oxygen and carbon dioxide cylcles are the basis of life on earth. • During respiration oxygen is consumed and CO2 is produced • During Photosynthesis CO2 is consumed and oxygen is produced. • Respiration and photosynthesis are chemical reactions.

18. Chemical Reactions • There are two misconceptions about chemical reactions: • 1. A chemical reaction represents what actually happens. • Writing chemical reactions is like looking at the ingredients for a meal and the final product. • They do not provide any idea as to the intermediate steps.

19. Chemical Reaction • There are two misconceptions about chemical reactions: • 2. Chemical reactions go to completion • Unlike cooking where everything that goes into the pot is cooked, in a chemical reaction not all the starting materials are used by the time we are done. • Even when you start with the exact amount of what you need, there will be unused chemicals at the end.

20. Human Intervention • Interference with nature’s processes. • Trees have been cut down • This reduces the amount of O2produced and the amount of CO2 removed. • We continue to use non-replenishableresources. • It is time we try to slow down our damage and if possible reverse it.

21. Recycling • Recycling does not mean mending the damage. • But it mitigates some of the daily damage. • We can recycle just about everything • lets concentrate on Aluminum.

22. Aluminum cans • Cans are made of Al, Mn, Fe, Mg, Si, Cu. • The aluminum used in new cans comes from the ore Bauxite, Al2O3. • Aluminum is the third most abundant element in the earth’s crust. • The two most abundant are Si, and O in the form or SiO2, SAND.

23. Bauxite • It is so abundant that we probably can go on using new cans and never run out of Al. • But the abundance of Bauxite is not the only factor? • Consider the energy needed to make a new aluminum can.

24. Making a can • The bauxite is mixed with other chemicals and must be heated to 1000 C. • Is it cheaper, energy wise to recycle the can we just used? • To make 1 metric ton (2000 kg) of aluminum from bauxite we used the energy equivalent to burning 240,000 kg of coal.

25. Making a can • That is about ¼ of a million pounds of coal • We use about 110 billion cans a year • We recycle about 60 million cans a year (~60%) • It requiers about 10% of the energy to recycle. • While we may not run out of bauxite to make new cans we may run out of coal to process the bauxite.

26. Making a can • How is a soda can made? • It is mostly aluminum but there are other materials needed as well. • The can is made out of an alloy of Mg, Mn, Fe, Si, and Cu. The lid which is a bit harder contains slightly more Mg. • Now, I am sure you do not want your soda tasking like aluminum so a coating of plastic is applied to the inside. • We must know what kind of soda we are about to buy so some paint is used in the outside.

27. Recycling the can • Before melting the can it must be dry. If liquid water comes into contact with molten Aluminum an explosion can occur. • The paint must be removed in a furnace. • The can is melted; due to the higher content of Mg on the can’s lid the resulting molten alloy is not suitable for new cans.

28. The Aluminum Can

29. Recycling the can • Because the can contains less Mg than the lid the molten alloy is not suitable for lids. • Add Mg to make it suitable for lids • Add Aluminum to make it suitable for cans. • Alloy: A physical homogeneous blend of metals with different properties than the initial components.

30. To Be Recycled

31. Recycling Metals • It is possible to recycle metals even when they are “lost” in solution. • Silver, Gold, etc (precious metals) are recovered making use of the reactivity metal series through Redoxreactions. • Reactivity Series: a list that ranks how “reactive metals are in solution”

32. Reactivity Series • A metal that is more reactive than another will “push” the less reactive metal out of solution. • For example, Copper is more reactive than silver; therefore, a copper wire put into a solution containing silver ions will push the silver out. Cu(s) + 2Ag+(aq) Cu2+(aq) + Ag(s)

33. RedoxReactions • Redoxreactions are arguably the most important type of reactions there are. • They are responsible for transforming breathable oxygen to usable oxygen. • They are responsible for most cellular reactions. • They are responsible for the ATP-ADP cycle.

34. RedoxReactions • A Redoxreaction is broken down into two parts • REDuction Reaction: A reaction in which electrons are gained. • Ag+(aq) + e- Ag(s) • OXidation Reaction: A reaction in which electrons are lost. • Cu(s) Cu2+(aq) + 2e-

35. Redoxreactions • We cannot have one without the other • the electrons gained in the reduction reaction • must had to have come from somewhere • oxidation reaction

36. Plastics • Plastics is just the common name for a group of chemicals. • The general common name of plastics is POLYMERS. • A polymer is a long chain of MONOMER units. • They are separated (recycling) by a number.

37. Plastic Recycling • The number inside the triangle determines which type of plastic you have. Not all plastics are recycled everywhere. Some processes are more expensive than others.

38. Uses of Recycled Plastic • Used to make: • Rugs • Sleeping Bag Fillings • Clothing (jackets) • Packing (Styrofoam beans) • Bottles

39. State of Recycling • Paper of Plastic? • This decision should depend on many things not only in if you are environmentally conscious. • The biggest contributor to landfills is paper. • Not all cities recycle plastic (Chesterfield county does not recycle plastic bags)

40. State of Recycling • The aluminum recycling industry is thriving and will continue to do so until other recycling processes catch on with the public. • Plastic Recycling is a relatively new industry and many cities still need to develop programs to recycle a larger number of plastic types.

41. Green Chemistry • Green Chemistry is a philosophy that is in tune with environmental efforts to reduce the amount of waste we produce. • It is based on “Atom Economy” • We must used as many atoms from the initial chemicals as possible. • It is based on Six guidelines

42. Green Chemistry Guidelines • Prevention is better than cleanup • And it is also cheaper. • Maximizing the atom economy. • Use as much as possible and you may profit more. • Use safer chemicals in the production process. • Less likely to create a problem.

43. Green Chemistry Guidelines • Use non hazardous solvents • If an accident happens it does not harm the environment • Reduce use of energy • Pay attention at secondary resources • Biodegradable Products • If a product will cease to serve its purpose make sure it will be absorb by the earth quickly.