In a world where deforestation directly leads to biodiversity loss, disrupts the water cycle and alters rainfall, finding alternatives to recycling or paper production is more important than ever.
Scientists at Nanyang Technological University in Singapore have developed a pollen-based paper that, once printed, can be erased and reused multiple times without damaging the paper.
The process of making pollen paper is similar to traditional soap making, which is simpler and requires less energy. It begins with the use of potassium hydroxide to remove the cellular components encapsulated in the resistant sunflower pollen grains, which become flexible microgel particles.
Researchers then use deionized water to remove unwanted particles from the resulting pollen microgel, which is poured into a flat mold and air-dried into a sheet approximately 0.03 mm thick, or half the thickness of a human hair. It is then treated with acetic acid to make it insensitive to humidity.
The resulting paper is environmentally viable alternative to conventional paper made from wood pulp; it is more supple and translucent.
In tests, the team demonstrated how high-resolution color images could be printed on allergen-free pollen paper with a laser printer and then “unprinted”, completely removing the toner without damaging the paper, with an alkaline solution. .
The now-virgin paper is puffed after the deprinting process and placed in ethanol for five minutes to return the gel to its previous state, then air-dried and treated with acetic acid. Now the paper is ready to print again.
The process can be repeated up to a minimum of eight times without losing the structural integrity of the paper or the quality of the printed images. This is an advantage over previous systems that require strong solvents or intense light, which further damages the paper over time.
The new technique could also help reduce the carbon emissions and energy consumption associated with conventional paper recycling, which involves repulping, bleaching and rebuilding.
Paper made from sunflower crops could also help reduce deforestation. Sunflower pollen is readily available. In addition to sunflower, pollen grains from other plants, such as lotus and camellia, could also be used to make a paper-like material.
More information: www.ntu.edu.sg