Porous porphyrin polymer for precious metal capture

Abstract

Precious metals indicate the coinage group of silver and gold and the platinum group of ruthenium, rhodium, palladium, osmium, iridium, and platinum. These metals are important raw materials in various industries due to their extraordinary chemical and physical properties such as high stability, electrical conductivity, ductility, luster and catalytic properties. However, precious metals exist in nature in very small amounts and thus these metals are highly valuable. Because precious metals are limited resources, the mining of these metals should be broadened from natural ores to secondary sources such as industrial wastewater or natural water. Hospital effluents also can be a good source for precious metals because platinum based anticancer drugs like cisplatin can be contained. The current technologies for precious metal recovery from the secondary sources are applied in electronic wastes. There are several methods to recover precious metals from electronic wastes such as pyrometallurgy, hydrometallurgy, and biometallurgy but these processes require high energy costs and use hazardous organic solvents or strong acids. The research on precious metal recovery from water sources is very deficient. Therefore, the adsorbents for selectively capturing and recovering precious metals should be developed. In this study, the adsorbent, COP180, was synthesized from the porphyrin units. The structure of the prepared polymer was characterized by several analytical methods. The high selectivity toward precious metals of the polymer was confirmed by conducting the selectivity tests using ICP-MS standard solutions. The synthesized polymer shows high selectivity and uptake efficiency toward precious metals. It is considered that the porphyrin ring can interact with precious metals strongly and the detailed mechanisms will be illuminated in the future works. This study firstly uses porphyrin for metal capture application and it is expected that this study will lead further following studies and open the porphyrin metal capture field.