1. 5.7 - Green chemistry In industry

2. What is chemistry
WHY GENERATE POLLUTION IF THERE IS A GREENING (LESS POLLUTING) ALTERNATIVE?
A step is designed in order to minimalize the environmental impact
Less-toxic chemicals are used or equipment upgrades may be necessary
Companies are more profitable and competitive and the environment is healthier and safer

3. 5 principles of green chemistry
PRINCIPLE #1: USE RENEWABLE RESOURCES AS STARTING MATERIALS
PRINCIPLE #2: USE CHEMICALS THAT HAVE LESS ENVIRONMENTAL IMPACT
PRINCIPLE #3: USE CATALYSTS TO INCREASE REACTION EFFICIENCY
PRINCIPLE #4: USE LESS ENERGY
PRINCIPLE #5: WASTE NOT

4. PRINCIPLE #1: USE RENEWABLE RESOURCES AS STARTING MATERIALS
* even if manufacturing processes are well established and accepted better starting materials can always be found
* EX. Benzene, C6H6, is a carcinogen often used in the production of plastic
* recently chemists have switched out benzene for glucose, which can be readily made from renewable resources with the use of a catalyst
* even though alternative production materials can be found, production of classic still has a negative impact on the environment and we should reduce our use of it

5. PRINCIPLE #2:USE CHEMICALS THAT HAVE LESS ENVIRONMENTAL IMPACT
* manufacturing process involves a step that is bad for the environment, therefore industries are dying with the desire to search for a better option
* fast food products are made by first injecting liquid polystyrene into a mould container
* gas is injected which causes it to expand
* CFCs were used in the past, but they discovered they were thinning the ozone layer which is bad for the environment
* Dow Chemical Company developed an alternative process that uses carbon dioxide instead of CFCs for an expanding agent
* carbon dioxide is cheaper, non-pollution
* carbon dioxide is a greenhouse gas so the process isn’t entirely benign

6. PRINCIPLE #3: USE CATALYSTS TO INCREASE REACTION EFFICIENCY
* a catalyst increases the speed of a reaction without being used up, so can be used repeatedly
ex. A catalyst, vanadium pentoxide, is used to make sulfuric acid during the contact process

7. PRINCIPLE #4: USE LESS ENERGY
* traditionally ore was smelted in a furnace fueled by the combustion of fossil fuels
* this process can be made more efficient if the equipment is updated
* this way energy costs would dive down, and there would be increased productivity
* since smaller quantities of fossil fuels are used, air pollutants would be reduced

8. PRINCIPLE #5: WASTE NOT
* a Canadian battery recycler has developed a recycling process that is totally enclosed
* old batteries go in; clean, recycled materials come out
* the process “closed loop” prevents hazardous substances from escaping into the environment
* results in less waste, safe working condition cleaner environment
* reduced waste clean up

9. Applying the 5 principles to pulp and paper
THE PAPER MAKING PROCESS
BLEACHING ALTERNATIVES
ENERGY USE
CONTROL OF EMISSIONS AND WASTE
Scrubbers

10. THE PAPER MAKING PROCESS
* used to use trees from Canada’s forest ecosystem, now we use specially planted, fast-growing trees to supply the needed amounts
* 70% of dry wood is made up of a compound called cellulose, the rest is called lignin
* to make the paper white the brown coloured lignin must be removed, this process is called kraft process
* wood is chopped into small chips then the chips are cooled in sodium sulfide and sodium hydroxide solution, the reaction that occurs removes 90% of the lignin from the wood

11. BLEACHING ALTERNATIVES
* to remove remaining lignin, bleach must be used
* using elemental chlorine produces dioxins (highly toxic molecular compounds), so is generally replaced by ClO2
* switching to non-chlorine-based bleaches would eliminate dioxin production, however the alternative hydrogen peroxide has had limited success
* TAML, a catalyst, can make hydrogen peroxide more efficient (faster, lower temperatures)

12. ENERGY USE * paper making uses a lot of energy
* to save energy they upgrade equipment or using alternative energy sources
* they use bark and solids that are leftover and burn them for energy instead of fossil fuels

13. CONTROL OF EMISSIONS AND WASTE
* paper mills have improved significantly, but total elimination of waste is not achievable yet
* closed-loop systems do not let unwanted materials enter the environment
* scrubbers are used to capture and treat gas emissions such as hydrogen sulfide, chlorine dioxide, and sulfur dioxide
* toxic gases are covered in water and limestone to neutralize them
ex. Sulfur dioxide and calcium carbonate react to form calcium sulfite, which can then be converted into gypsum and used to drywall