Despite modern society existing in a full-on digital age, paper production is still going strong. That's a problem if you're concerned about deforestation, pollution and waste. It takes 75,000 trees to print the Sunday edition of the New York Times and although many people recycle, about a quarter of America's landfill waste and a third of its municipal waste consists of paper.
Now scientists have figured out a way to make paper that can be printed with ultraviolet light, erased by heating it and then rewritten more than 80 times.
"That means you don't have to spend a lot of money on the paper and the inks," Yadong Yin, chemistry professor at the University of California, Riverside, told Seeker. And it saves trees, too.
"Before you had to cut 88 trees to make the same amount of paper that now takes one," he said.
Yin and other colleagues from Shandong University in China as well as Lawrence Berkeley National Laboratory think their rewritable paper could be used to make newspapers, notepads and price tags, which can be rewritten when the amount changes.
To make the inkless paper, the researchers found a low-cost, environmentally friendly way to coat conventional paper with a thin layer of nanoparticles that respond to light. For this experiment, they used two types of nanoparticles: those made of Prussian blue, a common, nontoxic blue pigment, and titanium dioxide, a nontoxic chemical used to, among other things, print the white M&Ms label on the candies.
Yin and his colleagues mixed these two kinds of nanoparticles in a solution and then applied it to a conventional piece of paper. The paper turned a deep blue.