Supercritical carbon dioxide dewaxing of old corrugated containers

Wax-coated old corrugated containers (OCC) are not part of the paper recycling stream because a process to remove the wax coating is not presently available. Residual waxes influence fiber-fiber bonding, reducing the paper properties of recycled OCC as well as the paper machine operating efficiency. A procedure to dewax OCC is a major objective of the paper industry. Here we describe a novel process to quantitatively dewax OCC by using supercritical carbon dioxide to remove the wax. The results obtained for the extraction of both saturated and curtain-coated waxed containers are reported and compared with Soxhlet extraction with hexane. Quantitative removal of the waxes was obtained under a variety of operating conditions. Gas chromatographic analysis of the extracted paraffin wax shows that supercritical fluid extraction does not chemically alter the paraffin wax, indicating the recovered wax may be recycled. (C) 2001 John Wiley & Sons, Inc.