Adsorption of heavy-metal ions (Pb 2+ , Cu 2+ ) on perm-lotion-treated human hair

Removal of toxic heavy metal ions from environmental and biological systems is important, but the use of commercially available heavy metal adsorbents is complicated by the need for specific pretreatment steps. We chose to study human hair treated with perm lotion as a heavy metal adsorbent because it is readily available and contains a large number of sulfur atoms for strong coordination to heavy metal ions. The optimal pH of adsorption by perm lotion-treated human hair was 4.16, which was slightly higher than the isoelectric point (pI) of the hair. The maximum removal ratio at pH 4.16 was 88.5% for a 50 ppm Cu 2+ solution, and 96.79% for a 50 ppm Pb 2+ solution. Almost 90% of the Pb 2+ was removed from a 120 ppm Pb 2+ solution. The perm-lotion-treated human hair was a cation-selective adsorbent.