Development of a Sustainable Enrichment Strategy for Quantification of Mercury Ions in Complex Samples at the Sub-Parts per Billion Level

Recognition of Heavy Metals by Using Resorcin[4]arenes Soluble in Water

The complexing properties of two water-soluble resorcin[4]arenes (tetrasodium 5,11,17,23-tetrakissulfonatemethylen 2,8,14,20-tetra(butyl)resorcin[4]arene, Na₄BRA, and tetrasodium 5,11,17,23-tetrakissulfonatemethylen-2,8,14,20-tetra(2-(methylthio)ethyl)resorcin[4]arene, Na₄SRA) with polluting heavy metals such as Cu²⁺, Pb²⁺, Cd²⁺ and Hg²⁺ were studied by conductivity, and the findings were confirmed by using other techniques to try to apply this knowledge to removing them. The results indicate that Na₄BRA is able to complex Cu²⁺ in a 1:1 ratio and Pb²⁺ in a 1:2 ratio, while Na₄SRA complexes Hg²⁺ in a 1:1 ratio. On the contrary, no indications have been observed that either of the resorcin[4]arenes studied complexes the Cd²⁺ ions. The results suggest that the bonds established between the sulfur atoms located at the lower edge of the SRA^4- and the solvent hydrogens could prevent the entry of the guest into the host cavity. However, in the case of Hg²⁺ ions, the entry is favoured by the interactions between the sulfur donor atoms present on the lower edge of Na₄SRA and the Hg²⁺ ions. Therefore, it can be said that Na₄BRA is selective for Cu²⁺ and Pb²⁺ ions and Na₄SRA is selective for Hg²⁺ ions.

Engineering Spherically Super-Structured Polyamides for the Sustainable Water Remediation

Unlike metal-ornamented hybrid material and linear polymers, we invoked the growth of a biodegradable superstructured cross-linked polyamide-ester material. The material is thermally stable. The thiol-alkene photoclicked material acted as an efficient water remediator. The material efficiently monitored amphiphilic dyes like rhodamine B (RHB), methylene blue (MB), and chronic mercuric ions in water. The adsorption kinetics revealed the material could adsorb >95% dyes within 24 h. The RHB-functionalized polymer could sense mercuric ions too. The Density functional theory (DFT) calculation shows a chelated mercury complex with thioether in the polymer, Poly-Am-RhAll, to form a comparatively more stable complex.