Chemists have synthesized a porous polymer sorbent, which was able with the efficiency of more than 99 percent selectively to adsorb the precious metals from complex multicomponent mixtures. One gram cheap cost polymer bound more than half a gram of gold, which is ten times higher than the theoretically calculated values. The results of a study published in the journal Proceedings of the National Academy of Sciences.
Often in the creation of printed circuit boards using the gold that is recovered from used electronic devices, as the procedure of separation of precious metals from complex multicomponent mixtures of long and used reagents are toxic to humans and the environment. Scientists have previously proposed the use of adsorbents based on biomaterials, such as polysaccharide gels and gels modified tannin of persimmon. They were able to Sorb more than seven and a half millimole of gold per gram of sorbent. However, such adsorbents are usually checked in solutions with one or more metal ions, which shows their applicability for recycling or separation of precious metals from wastewater with a large number of interfering ions.
Promising sorbents of noble metals can be materials with porphyrin sites. Structure and properties of porphyrins allow them to bind ions of such metals with high selectivity. Engran Hong (Hong Yeongran) with colleagues from the Korean Institute of advanced technology has developed a stable porous polymer with porphyrin sites is able to quantitatively adsorb ions of noble metals from solutions of complex composition of PCB in the mixture of acids. Material synthesis chemistry conducted of the available reactants in two stages: first, the authors obtained the porphyrin monomer tetranitro of four molecules of pyrrole and p-nitrobenzaldehyde and sewed them together into the net with the help of para-phenylenediamine. The adsorbing properties of the material were checked as in standard solutions, which contained one of the studied element, and in solutions of printed circuit boards in a mixture of hydrochloric and nitric acids.