While the word, RECYCLING may bring Ògreen thoughtsÓ to mind, for many of us the word, CHEMISTRY, conjures up thoughts of bad chemicals, mad scientists, and incomprehensible concepts. Even the definition of chemistry, Òthe science that deals with the composition and properties of substances and various elementary forms of matter,Ó
is enough to make most of us either yawn or not want to learn more. But, letÕs put all of our preconceived ideas about chemistry behind us and take a look at where chemistry is heading; it is in the early stages of going green. And, letÕs take one step further and see how this new green chemistry can even make recycling greener.
Although the realm of chemistry may deal with elementary forms of matter, its application goes way beyond the chemical industry; applied chemistry spans industries as diverse as pharmaceuticals, transportation, agriculture, law enforcement, materials, and electronics. In fact, the list of its applications is probably almost endless. Globally, chemistry is a $2.4 trillion industry. Although the chemical industry often parallels the growth and trends of broader industry, it was inside the chemical industry itself where the march to the green trail began. How did the chemical industry arrive at such an important crossroad?
Somewhere along the bumpy road of modern industrialization, society realized that widespread use of chemicals often came with a price- the price of toxins in the environment. In the early 1960Õs when information surfaced about the toxicity of the pesticide DDT (dichlorodiphenyltrichloroethane), footsteps toward (but yet not on) the path of green chemistry began to march. Used extensively during World War II to control insect borne diseases like malaria and typhus, DDT also soon became the major agricultural weapon for the combat of crop destroying insects. According to the EPA, in 1959 alone nearly 80 million pounds of this chemical was used in the USA. But indiscriminate use of this chemical would soon change when in 1962, the book by Rachel Carson, Silent Spring, brought to light how DDT was harmful to birds and to the food chain. In 1972, the USA EPA banned the use of DDT. So, what replaced it? Nothing too green thatÕs for sure; DDT was replaced with other harmful chemicals like TEPP (tetraethyl pyrophosphate) and parathion – an insecticide that is extremely lethal to birds and to humans. While for the past 40 years REGULATION has been the main focus in the control of harmful chemicals, the replacement of DDT with other toxic chemicals illustrates just how faulty the regulatory approach can be. To preserve the environment and safeguard public health from harmful chemicals, chemistry itself had to change. And, in the early 1990Õs two scientists began to change the direction of chemistry and called it, Green Chemistry.
Scientists Paul Anastas and John Warner looked at chemical development and application differently than anyone had ever done before. Whereas industry and government focused on how to deal with chemical waste, these green pioneers questioned why the waste should exist in the first place. Their Twelve Principles of Green Chemistry is the worldwide framework for the Òdesign of chemical products and processes that reduce or eliminate the use and generation of hazardous substancesÓ1 .
Although green chemistry has been on the science scene for twenty years, putting it into wide scale practice will take much longer. To make green chemistry useful, it must be applied to broader industry. Today, it is estimated that only about 1% of the chemical industryÕs production is based on green chemistry so we have a long way to go before its application becomes widespread. Since green chemistry strives to reduce or eliminate hazardous substances its application can be very beneficial to any industry and that includes the industry of recycling too.
To keep things simple, letÕs take a look at a few ways that chemistry is helping (or can help in the future) recyclables like plastic, paper, glass, and electronics:
For those of us who recycle, plastic recycling has become part of our everyday lives. Each year hoards of PET (Polyethylene Terephthalate) plastic containers in the form of drink bottles, condiment jars, and even microwaveable food trays find their way into our recycling bins. The highly recognized PET#1 plastic resin code is on many of the grocery items we purchase. According to NAPCOR, in 2008, over 5.4 billion pounds of PET bottles and jars were available for recycling in the USA. ThatÕs a lot of PET plastic! But, did you know that the PET soda pop or water bottle you recycle cannot be recycled into another bottle? PET plastic bottles and jars are almost always made from virgin plastic; recycled PET plastic normally leaves the food industry and ends up in textiles. Why? Because current PET recycling methods are unable to breakdown the long plastic polymer chains (chemistry logo for carbon chains) into the small molecules required to recombine and produce new bottles and other products. Most PET recycling is a mechanical process which results in lower quality plastic that cannot be used for most beverage and food containers. While the chemical recycling of PET does exist and does result in high quality recycled plastic, it is an expensive process and is not economically viable due to the low cost of virgin PET resin. If it is less expensive to make virgin bottles, industry will not use a potentially polluting, more expensive chemical method to make bottles out of recycled PET plastic. Greener chemistry (I emphasize the ÒerÓ) may soon solve that problem. Last year researchers at IBM and Stanford found that a molecule Òinspired by vitamin B1Ó called a carbene facilitated the breakdown of the PET plastic quickly and in a cost efficient manner. The resulting recycled PET has sufficient quality to be used again for the production of bottles and other food containers. As with all chemical reactions, no reaction has 100% efficiency; there are still ancillary products left over from the process. According to what I understand, in the case of this particular process, the by-products of the carbene chemical breakdown of PET are less harmful to the environment than those of traditional chemical processes. However, I would love if a true, knowledgeable chemist could comment on this. Please?! The one certain thing is that if this process becomes commercially available, the recycling rate of PET plastic will increase and the use of virgin resin will decrease. This process will allow a closed loop PET bottle system to become standard practice.
According to the Forest & Paper Association, the USA Paper industry used about 31.3 million tons of recovered paper last year; that kept about 47% of our paper waste of out of landfills. With all that recycling, what happened to all the ink that was printed on those millions of magazines, documents, and newspapers? Well, it may have literally washed on down the river. When it comes to paper recycling, the deinking process is Òvery chemistry-intensiveÓ and requires chemicals like sodium hydroxide, hydrogen peroxide, and chelating agents like DTPA and EDTA. It is the use of the chelating agents that is of most environmental concern because these chemicals bind with heavy metal ions like copper, manganese, and iron (inherent in ink formulations) and wash them out with the waste effluent from the recycling plant. Heavy metals poison rivers. New research at North Carolina State University is exploring how sugar and protein-based surfactants (think of them as soaps) can be used effectively to remove ink during the paper recycling process and keep toxic metals out of the waste stream. This is green chemistry at its best.
Until recently, large pieces of glass like those found in our 60 inch LCD TVs always contained the heavy metal arsenic. (Arsenic is required to remove bubbles from the glass during its manufacture). To meet the environmental product design demands of its customer, Sharp (a leader in LCD TV technology), Corning chemists used green chemistry to produce large format glass without the use of heavy metals. Recycling LCD screens (at least those from Sharp) immediately became more environmentally friendly.
More and more the proliferation and handling of electronic waste is a worldwide concern. Not only are mountains of plastic and glass recovered from these devices, but their printed circuit boards and wires are often made of polluting heavy metals. While traditional metal recycling processes can be used to capture the metals, they are not effective in separating higher value metals like copper from other lesser value metals. To best capture the value out of the waste stream, green chemistry is being used to separate out individual, valuable metals. Research conducted at the Shanghai Jiao Ton University in China has developed a process that can capture all of the heavy metals and separate out valuable copper. But copper reclamation is just a start. Many scarce metals like tantalum, platinum, and hafnium are also used frequently in electronic components. Recapturing these metals is an important goal of green chemistry. Reclamation of valuable metals reduces the demand for mining and all the environmental hazards that come along with it.
These are just a few examples how green chemistry can help to make recycling greener and even improve its profitability. The small steps that are being taken now can make great environmental strides possible in the future. Governments, universities, and industries must work together to promote the development of economically viable green chemistry solutions. Since the application of chemistry cuts across a myriad of industries, it will take commitment and cooperation between industries to keep heading down this road. As with the story of DDT, government regulation of the chemical industry does not always result in a greener solution. Government can provide support to help make this great change by providing research and development incentives to businesses conducting work in green chemistry. As citizens we can do our part too by purchasing ÒgreenerÓ products. Many consumer goods like household cleaners, paint, and food packaging are now available in greener, less polluting, more recyclable formats. We canÕt afford to turn back.
Happy Green Product Shopping!
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References: www.dictionary.com, 1 ÒPOLICY INCENTIVES FOR A CLEANER SUPPLY CHAIN: THE CASE OF GREEN CHEMISTRY, Ò, Kira J.M. Mattus, Journal of International Affairs, Fall/Winter 2010, Vol. 64, No.1, pg. 121-136, ÒChemistry Goes GreenÓ, Science, Vol. 297, Aug. 2002, pg. 798-810, ACS News Service Weblog, Weblog Interview:Paul Anastas, Father of Green Chemistry,http://acsnewsservicetypepad.com/ac_news_service_weblog/2006/06/weblog_intervie.html, Twelve Principles of Green Chemistry, EPA, http://www.epa.gov/gcc/pubs/principles.html, ÒThe Global Business of Chemistry: Prospects and ChallengesÓ, Journal of Business Chemistry, T. Swift, Jan. 2006, ÒDDT Ban Takes EffectÓ, EPA press release- December 31, 1972, www.epa.gov/history, ÒDDT and BirdsÓ, Metallic Poisons: Wintering and Conservation; Conservation of Raptors, P. Ehrlich, et al, 1998 www.stanford.edu, ÒparathionÓ, Encyclopedia Britannica, www.britannica.com, Ò2008 Report on Postconsumer Pet Container Recycling ActivityÓ, NAPCOR, www.napcor.com, ÒGreen chemistry could make for easier-to-recycle plasticsÓ, March 9, 2010, www.greenbang.com, ÒThe Depolymerization of Poly(ethylene terephthalate) 9PET) Using N-Heterocyclic Carbenes from Ionic LiquidsÓ, N. Kamber, R. Pratt, et al, Journal of Chemical Education, Vol. 87, No. 5, May 2010, ÒDesign of a De-Inking Process for Recycling Mixed Waste PaperÓ, V. Venugopal, www.p2pays.org/ref/0908623.pdf, ÒPaper RecyclingÓ, http://cnr.ncsu.edu/fb/research/centerinitiatives/paperrecycling.html, ÒCorningÕs environmentally friendly LCD glass makes green solutions possible for Sharp and the LCD industryÓ, www.corning.com/possiblilities/sharp.aspx, ÒBetter Living through green chemistryÓ, New Scientist, S. Everts, March 10, 2010, Issue 2751.