Sustainable Chemical Engineering

This special issue of Green Chemistry represents an attempt to illustrate some of the activities and work of chemical engineers in the area of green and sustainable chemical engineering. Responding to the global drive towards multidisciplinarity in industry and academia, and particularly following a recent RSC report on “Benign and Sustainable Chemical Technologies”¹ the ambition of this issue is to encourage collaboration between green chemists and chemical engineers in the area to which the two communities bring complementary skills.

Most of the papers in this issue are in the area of green chemical engineering, but some go beyond to encompass the concept of sustainability and consider not only the environmental (“green”) aspects but also the other two components of sustainable development: economic and social. This is the main difference between “green” and “sustainable” chemical engineering: the former concentrates mainly on the environment while the latter, in addition to environmental, takes into account economic and social criteria.

Sustainable development of the chemical industry is recognised as one of the key challenges for the industry.^2,3 It is now widely accepted that this can only be achieved by balancing all three dimensions of sustainability and the industry is already working actively towards this goal.⁴ However, one of the challenges for the industry in trying to become more sustainable is to be able to assess whether it is moving towards or away from sustainability. In other words, the industry (and society) must be able to tell which processes, products and activities are sustainable and which are not. Some of the papers in this issue deal with this problem by demonstrating what tools can assist the industry in becoming more sustainable and how they can be used in the design of new or the improvement of existing products and processes.

Following their EU-based study on tools and technologies for a more sustainable chemical industry, Tsoka et al.⁵ found out that potentially sustainable technologies favoured by the industry include highly selective catalysts, process intensification, supercritical separation and small-scale processing. The study also found that the industry believes that Computer-Aided Molecule Design (CAMD) as well as process design and simulation are among the tools that could help in the design of more sustainable products and processes. Hugo et al.⁶ complement these findings by demonstrating how CAMD can be used for improved economic and environmental performance. Focussing on liquid–liquid extraction operations, they use Life Cycle Assessment (LCA) and multiobjective optimisation as tools for designing solvents that are both environmentally benign and cost effective.

Hellweg et al.⁷ also use solvents as an example and in addition to LCA demonstrate the use of a further two tools for assessing the level of sustainability of chemicals: the first tool identifies potential environmental, health and safety hazards associated with the production process and the second helps determine the environmental persistence and exposure to chemicals in the environment. The differences between the three methods and the results are illustrated on 13 organic solvents. For example, one of the results obtained consistently by all three tools is that the use of chlorinated solvents is unsustainable.

Romero-Hernandez⁸ uses a combination of process optimisation, LCA and risk assessment to assess the level of sustainability of a clean-up technology. Concentrating on the case study of organic pollution in waste water, he concludes that on a life cycle basis it does not make much sense to treat the water because the environmental impact of operating the water treatment plant is higher than that of the untreated water. However, from the social point of view, the treatment is necessary because of the adverse impact that the organic pollution in the waste water would have on human health.

These are just some examples of the many sustainability tools and methods that chemical engineers use in practice.⁹ We hope that, in addition to the other papers published in this issue, they demonstrate that green chemists and chemical engineers have the skills and knowledge necessary for meeting the challenge of sustainable development by designing chemical products and processes that provide the required effects at a price the market can bear, while not threatening human health or the environment.¹

 

Adisa Azapagic

Professor of Sustainable Engineering

School of Engineering

University of Surrey

Guildford, England

References

1. Benign and Sustainable Chemical Technologies, ed. C. Web and A. Palermo, Royal Society of Chemistry, London, 2003.
2. CEFIC, Horizon 2015: Perspectives for the European Chemical Industry, CEFIC, March 2004, http://www.cefic.org.
3. Technology Vision 2020, The US Chemical Industry, The American Chemistry Society, American Institute of Chemical Engineers, The Chemical Manufacturers Association, The Council for Chemical Research, and The Synthetic Organic Chemical Manufacturers Association, December 1996, Washington, DC, http://www.acs.org.
4. A. Azapagic, Sustainability: Lip Service or a Genuine Commitment?, IChemE Trans. B, 2004, 82, B4, 267–268.
5. C. Tsoka, W. R. Johns, P. Linke and A. Kokossis, Green Chem., 2004, 6 10.1039/b402799j , this issue.
6. A. Hugo, Ć. Ciumei, A. Buxton and E. W. Pistikopoulos, Green Chem., 2004, 6 10.1039/b401868k , this issue.
7. S. Hellweg, U. Fischer, M. Scheringer and K. Hungerbühler, Green Chem., 2004, 6 10.1039/b402807b , this issue.
8. O. Romero-Hernandez, Green Chem., 2004, 6 10.1039/b401871k , this issue.
9. Theory and Practice of Sustainable Development: Case Studies for Engineers and Scientists., ed. A. Azapagic, S. Perdan and R. Clift, John Wiley & Sons, Chichester, UK, 2004, pp. 437.

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