Going Nuts

Scientists in China have have used walnut shells to purify water. Walnut shells, a byproduct of processing for food and oil, promise an inexpensive, environmentally friendly alternative to chemical purification.

The locally obtained shells absorbed up to 97% of chromium from water. Chromium is a common heavy metal contaminant of water supplies, largely arising from the textile, leather and wood production industries.

Water supplies are often contaminated with chromium, a heavy metal used in a range of industries. Chemical-based cleaning methods are expensive and often toxic.

The scientists, at the Huaihai Institute of Technology in Lianyungang1, dried and ground up the walnut shells, and tested their efficacy as adsorbents of chromium VI. The best results were obtained at high temperatures and in acidic conditions, although performance was lower in high salt solutions. However, the nutshells do outperform other natural materials such as wool and coal, and should prove a viable alternative to chemical purification systems.

Reference
WANG, X., LI, Z., TAO, S. (2008). Removal of chromium (VI) from aqueous solution using walnut hull. Journal of Environmental Management DOI: 10.1016/j.jenvman.2008.01.011

http://water.sigmaxi.org/index.php/going-nuts/#more-58