We use materials that are classified as toxic every day, from printing ink to batteries containing lithium. If you’re a science student, when conducting experiments, do you think about how much hazardous waste you’re producing? As standard procedure, we segregate our chemical waste bins and do not pour solvents down the drain, but where do they end up?
Contamination of land and water is a global problem. Toxic waste removal is expensive; large industrial sites often have to build special treatment facilities on site, and infrastructure for treating domestic sewage is a necessary investment for any city. The economic burden leads to improper and unsatisfactory disposal, which is particularly worrying at an industrial level.
Guidelines on the University of York’s website for laboratory waste disposal simply suggest dilution; however some chemicals are harmless even in low concentrations.
Better suggestions would include further chemical reactions to alter the biological activity of the chemical or storing it in isolation in the case of more dangerous chemicals with longer lives. As each chemical poses a different risk they must be separated and treated differently.
Green chemistry is designing products and processes that minimise use and generation of hazardous substances. However, measuring the efficiency of a chemical process is complicated, and suitable and accurate calculations are hard to define. For new technologies to be introduced, the improvement over the original methods must be quantified.
A group of York-based researchers have developed a simple ‘metrics toolkit’ to measure and evaluate how green a reaction is. They managed to create a consistent, universal measurement tool for chemical reactions, based on a range of criteria and applicable both in the laboratory and in industrial settings. In cooperation with other academics, pharmaceutical companies and private enterprises, they would use the simple excel spreadsheet to assess the sustainability of a reaction.
The spreadsheet has new calculations for a reaction’s optimum efficiency, impact of raw materials – where they come from and if they are renewable and amount of waste produced – as well as the hazard to workers and effect on the environment.
A traffic light system (red for undesirable, amber for acceptable and green for preferred) allows researchers and students to compare their reactions to existing methods. As the toolkit looks at different aspects of the procedure separately identifying where improvements could be made is easier.
The movement towards more green chemistry methods will have a huge environmental and health impact. By facilitating the invention of efficient and environmentally friendly reactions, the researchers have taken a step towards protecting a wide range of ecosystems from further disruption.