New 'unprinting' method can help recycle paper

Scientists have created a new way to erase black, blue, red and green toners from printed pages -- an advance that may help recycle paper.

The method, developed by researchers at Rutgers University in the US, can work with the standard, coated paper used in home and office printers.

It uses pulses of light from a xenon lamp, and can erase black, blue, red and green toners without damaging the paper, according to a study in the Journal of Cleaner Production.

"Our method makes it possible to unprint and then reprint on the same paper at least five times, which is typically as many times paper can be reused with conventional recycling," said Rajiv Malhotra, an assistant professor at Rutgers University.

"By eliminating the steps involved in conventional recycling, our unprinting method could reduce energy costs, pollution and greenhouse gas emissions," said Malhotra.

Conventional recycling of coated paper is a major contributor to climate change emissions, chemical pollution and energy use, according to the study.

Extending the life of paper while avoiding these recycling steps would yield significant environmental benefits.

The engineers' next steps are to further refine the method by testing additional toner colours on a wider range of paper types.

Unprinting can be done with simple equipment and a wipe with a very small amount of benign alcohol, and the engineers are working to integrate unprinting with typical office and home printers.