Green chemistry— a Canadian perspective Green Chemistry C G Green Chemistry December 1999 G155 This journal is © The Royal Society of Chemistry 1999 anada prides itself as a clean country—full of forests, lakes and mountains. Tourism is a major industry in Canada and, because we have a small population, mostly crowded within a hundred miles of the U.S. border, our country is one of huge empty spaces where vacationers can enjoy ‘Wilderness Canada’.The reality, as with so many other idyllic views of our countries, is tempered by some unattractive realities. More than 10% of Canada’s exports are connected with mining (coal, nickel, copper, cobalt uranium, etc.). Our northern and coastal forests are exploited for both lumber and pulp. Our waters are harnessed for the production of electricity to such a degree that most Canadians call their electricity bill a hydro bill; the impacts on the ecosystem have been very significant, as evidenced by the La Grande hydroelectric generating site in northern Quebec. Because our country is resource-rich, even though we are aware that the resources are limited, green chemistry looks somewhat different through Canadian eyes.The two areas I would like to consider are the uses of green chemistry in resource industries and enhancements to green chemistry that can be achieved through the use of analytical chemistry. Here I freely admit to a bias. I am an analytical chemist. Throughout my career I have been involved with a number of environmental issues, including the Niagara River and its pollution by industries (remember Love Canal?) and a number of local pollution issues.So it is important to me that analytical chemistry be used to measure more than our failure to be stewards of the environment, but also to provide the means of C PHOTO: DIVINO MUCCIANTE, BROCK UNIVERSITYimproving that environment by following the principles that were lucidly outlined by Paul Anastas and Tracy Williamson.1 A little over a year ago, the Organization for Economic Co-operation and Development (OECD) held a workshop in Venice on ‘Sustainable Chemistry’. Problems arose from the difficulties that the delegates had trying to incorporate the perspective of the Bruntland Report2 on sustainability into the already established notion of green chemistry.The idea of sustainable chemistry creates a new set of problems.Green chemistry is, in my view, remains a better descriptor than sustainable chemistry. Extraction of non-renewable resources is, by its nature, not sustainable and so the notion of doing sustainable things with an unsustainable end sounds perverse. We no longer close down metal mines to allow the ‘veins’ of ores to regrow, as they did in the 16th Century, as our contribution to sustainability.How shall we present the case for green chemistry in resource industries? Elimination of toxic chemicals should be a goal of green chemistry in the mining industry. An example of the use of green chemistry principles was achieved in Ontario a number of years before green chemistry saw the light of day.INCO, the largest nickel producer in Canada, extracts nickel as sulfide from a huge deposit near Sudbury. In addition to the nickel sulfide, they also extract pyrrhotite, which was used as a fuel, since its oxidation is exothermic. Both these sulfides were roasted in air, generating huge amounts of SO2, which laid waste to Sudbury as a result of acidification of the entire area. An initial solution to the problem was to collect the waste gases and push them up an enormous chimney.It solved the problem for Sudbury, but it made the residents of the Ottawa River Valley upset, as the acidification reached further east and was spread over a larger area. A partial solution was achieved when INCO eliminated the pyrrhotite by flotation, increased the oxygen level of the oxidizing gas and collected the SO2 by-product, which it sold as sulfuric acid.The pyrrhotite, which, if left exposed, would be oxidized by bacteria to H2SO4 (the infamous ‘acid mine drainage’), was reburied under anoxic conditions so that the extent of acid mine drainage would be reduced. As a reduction in the release of harmful by-products, this green chemistry reduced Canada’s acid emissions by a significant percent.Consider the case of gold. Gold continues to be extracted using high concentrations of cyanide to form Au(CN)2 –. Storage of waste cyanide in ponds results in ground water infiltration, leakage from poorly constructed dams, etc. A number of other compounds form stable complexes with gold and could be used in place of cyanide, such as thiourea or thiocyanate.As the natural resources are used up in the world, chemists and biotechnologists are being asked to come up with innovative ways in which renewable resources can be used to replace non-renewable ones But there will continue to be a demand for some non-renewable resources. In my high school chemistry text, I remember clearly the figure that showed the extraction of copper from the deposits in Northern Ontario.Basically you filled a hole with copper sulfate solution, popped in a copper electrode in the solution and banged in a connector to the massive deposits of native copper and electrolyzed away until the copper boulder dissolved. What is the percentage copper in high-grade ore today? So C G G156 Green Chemistry December 1999 This journal is © The Royal Society of Chemistry 1999 1 P.T. Anastas and T. C. Williamson, Green Chemistry, American Chemical Society, Washington, D.C., 1996. 2 Our Common Future, World Commission on Environment and Development (the Bruntland Commission), Oxford University Press, Oxford, 1987.if we wish to make materials that use less resources today, we try to minimize the amount of raw material that is incorporated in the object.Analytical chemistry provides the means of ensuring that the material, be it a turbine blade or a valve for the domestic water tap, meets the purpose for which it was designed. In North America, ASTM provides standards for many types of alloys that are used by industries. As new materials are developed, new standards must be made to ensure fitness for purpose of these materials.In addition, process analytical chemistry is integral to the developments in new processes and materials. The authors of a recent paper that I read noted that a reaction, which was carried out in a melt, was subject to polymerization if a reaction proceeded seconds beyond an optimum time. Although the authors felt that timing was an issue, real time analysis for the undesirable by-product would very likely give a better and ‘greener’ process.Analytical chemistry must be involved with the development of new materials, where exquisite control is required for the production of new materials with high production values. It is central to the future of R&D in innovative technologies. At last summer’s ‘Green Chemistry and Engineering’ Conference in Washington, I raised these issues at the final plenary session. The chair suggested that the developers of new products should take their analytical chemist out for lunch. We know there is no free lunch when it comes to environmental protection. Green chemistry principles must be applied to resource industries and raw material use and by-product generation can be controlled by adherence to quality management criteria that are central to the thinking of the analytical chemist. Ian D. Brindle, Department of Chemistry, Brock University, St. Catharines, Ontario L2S 3A1, Canada November 1999 C G Green Chemistry December 1999 G157 This journal is © The Royal Society of Chemistry 1999