can be printed, erased and reused » The Horticulturist

Scientists from Nanyang Technological University in Singapore have developed a new type of paper made from sunflower pollen. In addition to being environmentally friendly, paper has functions that go beyond an ordinary material: it is possible to make color laser prints and then erase them, completely eliminating the toner.

During the research, the academic team showed how high-resolution color images, printed on a common laser printer, can be erased with an alkaline solution, without damaging the paper.

After dipping the litmus paper in the solution, the ink floats, so you can remove it and wait for it to dry before using it again: completely clean.

The study showed that this new process, informally called “printing and unprinting”, can be repeated up to at least eight times. That is, without losing the structural integrity of the paper or the quality of the printed images.

They create litmus paper: it can be printed, erased and reused

“This is a new approach to paper recycling – not only to make paper more sustainably, but also to extend the life of paper so that we can get the most out of every piece of paper we we produce,” says Professor Subra Suresh. . coordinating team.


litmus paper

The process of making paper from pollen is similar to making soap, the scientists explain. The technique is based on potassium hydroxide, which is used to remove the cellular components encapsulated in sunflower pollen grains and turn them into soft particles with a gel texture.

Already at this stage, the team removes the allergy-causing component of pollen, making the paper non-allergenic.

Researchers then use deionized water to remove any unwanted particles from the resulting material. Litmus paper is also treated with acetic acid to make it insensitive to moisture.

“Previous research has shown that pollen paper can bend and curl in response to humidity in the air. To stabilize our paper and make it insensitive to humidity, we decided to soak the material in acetic acid, an active component of vinegar, and the results were excellent.”

The next step is to introduce the gel into a flat, dry mold and wait for it to dry. From this process is born an alternative to paper, about 0.03 mm thick, more flexible and translucent.

They create litmus paper: it can be printed, erased and reused

Singapore scientists believe ‘pollen paper’ could be an environmentally friendly alternative to conventional paper. The latter is carried out in a multi-step process with a significant environmental impact.

Plus, it could help reduce the carbon emissions and energy consumption associated with conventional paper recycling, which involves pulping, sanding (removing toner from the printer), and rebuilding.

They create litmus paper: it can be printed, erased and reused

The team also argues that pollen grains are produced regularly and in large quantities in reproductive plants, allowing harvesting and papermaking without cutting the plants. Additionally, in addition to sunflower pollen, research shows that camellia and lotus pollen grains can also be used to produce a paper-like material.

The researchers have filed a patent application for this invention.

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