SPLITTING HAIRS [+]Enlarge Credit: Environ. Sci. Technol.

Adding cellulose nanofibers to paper pulp creates paper that can be recycled more than twice as many times as regular paper (Environ. Sci. Technol. 2015, DOI: 10.1021/acs.est.5b02676). Depending on how the nanofibers are produced, this should reduce paper’s environmental impact, researchers say.

Paper is a jumbled mat of micrometers-wide cellulose fibers. In the past few years, researchers have been interested in making paper with nanometers-wide cellulose fibers in addition to regular fibers. The high surface area of such nanofibers lets them form more bonds with adjacent fibers, resulting in tougher paper.

Marc Delgado-Aguilar of the University of Girona and his colleagues wanted to analyze the environmental impact of adding nanofibers to paper. They recycled standard paper several times by using either conventional mechanical recycling techniques or by adding 3% by weight of cellulose nanofibers to the paper pulp at each cycle. They tested the paper’s mechanical strength after every cycle.

Conventional recycling made the sheets unusable for writing after three cycles, whereas the nanofiber-treated paper could be recycled seven times.

The drawback of cellulose nanofibers is that they are made today by treating wood pulp with strong acids and oxidants, followed by mechanical division of cellulose fibers into their nanoscale subunits. To eliminate the need for chemical processing, the researchers used a purely mechanical method to separate the nanofibers, which costs 1/100th that of the conventional process.