According to this article from the New Journal of Chemistry, Japanese researchers from Saga University were able to recover precious metals such as gold, palladium and platinum from industrial wastewater using a sorption active gel formed from chemically treating an ordinary newspaper with p-amino benzoic acid, a compound used in sunscreen.
The researchers said a high percentage recovery of the precious metal ions (85-95%) and regeneration of the gel was attained by using a mixture of 0.15 M thiourea and 1 M HCl.
“The fact that valuable high demand metals can be recovered by using waste paper looks promising for its practical future application. From an economic viewpoint, this gel raises the prospect for recovering expensive metals at low cost and, from the environmental viewpoint, this gel is quite environmentally benign and acceptable.”
For those who are interested in doing more research in this development, the scientists said they bought their thionyl chloride from US-based Sigma Aldrich, and sodium-aminobenzoate from Tokyo Chemical Industries (TCI) of Japan.
Analytical grade chloroauric acid and chloroplatinic acid (both from WAKO, Japan) were used to prepare the gold and platinum test solutions, respectively. Ion exchange resins used were acquired from the Mitsubishi Chemical Corporation, Japan. All other chemicals used for the synthesis and for the sorption tests were of analytical grade and were used without further purification.