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Dissolving the Plastics Problem
Conard Holton Abstract
 Plastics pose a sticky problem in terms of disposal. When incinerated, they can release toxic emissions like hydrogen chloride and dioxin. When landfilled, they are chemically inert–perhaps too inert, for they are essentially nondegradable, consuming a disproportionate amount of landfill space. And historically, recycling has been an expensive proposition in part because, to do so, the plastics must be hand-sorted into four different types. However, a new technology that may make it more feasible to recycle plastics.
The Rensselaer Polytechnic Institute has developed a technology that eliminates sorting altogether by capitalizing on the fact that different plastics dissolve at different temperatures. In this process, unsorted plastics are first shredded and washed. Next, various solvents are added to the mixture of plastics while it is heated. As the mixture heats up and different solvents are added, each plastic type melts into a polymer solution and is drained off. Once drained off, each solution is separated back out into its components: the solvents are reused, any impurities are collected for use as fuel, and the pure plastic polymer is molded into pellets and packaged for resale.
This new process is especially useful for recycling plastics that were previously difficult to recover, such as car parts.
Unfortunately for the new technology, there is no dearth of cheap virgin plastics on the U.S. market, so competition is fierce. However, the Rensselaer technology is energy-efficient and cost-effective, and its product is even cheaper than virgin plastics. Says Ferdinand Rodriguez, a Cornell University professor of chemical engineering, "Rensselaer's technology is probably one of the most advanced and realistic [recycling technologies]. But you need to do it on a large scale because economics are a big issue. Recycling is a matter of scale and of educating the public to its importance."
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