Despite more global awareness about environmentalism and recycling, people still consume paper at alarming rates. We go through 300 million tons of paper a year globally, and the United States accounts for a whopping 30% of that use. And though 38% of the world’s fiber supply is recycled, most paper is still made from virgin pulp. Chemists at University of California, Riverdale, are trying to solve the problem of paper waste by creating a new material that could be recycled by special printers. Using redox dyes, the kind of chemicals used to test for pH among other things, the scientists have created a viable prototype:
The “paper,” which can be made of glass or plastic film, comes in three colors, blue, red, and green, and can be “erased” simply by heating. So say a company wants to print out copies of a meeting’s agenda. They would use a special chemical printer to bleach the paper except for the parts where text is written. These copies could be used for up to three days, then erased by the heat of the same printer that’s used to print the next document.
“The printed letters remain legible with high resolution at ambient conditions for more than three days–long enough for practical applications such as reading newspapers,” said Yadong Yin, the lead researcher. “Better still, our rewritable paper is simple to make, has low production cost, low toxicity and low energy consumption.” Heating the paper shouldn’t be a problem either. “Even for this kind of paper, heating to 115 C poses no problem,” Yin says. “In conventional laser printers, paper is already heated to 200 C in order to get toner particles to bond to the paper surface.”
Printing is achieved by using ultraviolet light to photobleach the dye, except the portions that constitute the text on the paper. The new rewritable paper can be erased and written on more than 20 times with no significant loss in contrast or resolution.
Ultimately, Yin and his team would like to create paper that can be recycled up to 100 times without losing clarity, and increase the variety of colors and resolution, but they are hopeful for this prototype. “This rewritable paper does not require additional inks for printing [as the “ink” is contained in the “paper” itself], making it both economically and environmentally viable,” Yin said. “It represents an attractive alternative to regular paper in meeting the increasing global needs for sustainability and environmental conservation.”