Chlorine-based technology is used in the bleaching and pulping of paper to remove lignins, which impart the color, texture and antioxidant properties of wood, while leaving intact the cellulose, which give wood its strength. Hill and a consortium including the Forest Products Lab and several members of the bleaching and pulping industry have developed new catalysts that are not only less toxic than chlorine and its derivatives, but are also equally effective. The new approach uses polyoxometalates, or POMs, to remove lignin from wood without damaging the cellulose. POMs take electrons from the bonds that hold lignin together, washing it out of the wood pulp altogether. This last step reoxidizes the cluster back to its starting form and simultaneously mineralizes all the waste from the bleaching step, primarily partially oxidized lignin fragments, to carbon dioxide and water.
Some exotic woods present different problems with processing the wood into paper.
In addition, for POMs to be as cost efficient as chlorine, they must be at least 99.9 percent recyclable. Emory jointly owns patents for the procedure with other members of the consortium. In recent years, says Hill, paper companies have been under enormous pressure to get rid of the current bleaching process, and this new development may very well be the answer to their problems. POMs can be recycled for months, if not years.