Rhodamine 6G derivative for the selective copper detection and remediation using nanoporous diatomaceous earth-engineered functional receptor

A rhodamine-derived receptor was synthesized and comprehensively characterized for structural confirmation. The receptor was able to distinguish the copper ions (Cu(2+)) from other competing cations. The yellow color of the receptor changed to pink upon adding Cu(2+) ions, however, other competing cations ions were impotent towards any color variation. The UV–visible titration studies revealed the binding stoichiometry of a 1:1 ratio with a detection limit of 9.663 × 10(−8) M. Additionally, a novel idea of the work resides in the use of diatom for the practical application, where the receptor has been tethered on nanoporous diatomaceous earth microparticles (P2D) to remove Cu(2+) ions. The results confirmed that 50 mg receptor functionalized DE could adsorb 10 mL of 1 ppm Cu(2+) ions from water. Furthermore, a proof-of-concept device that is inexpensive, simple to operate, and continuously removes Cu(2+) ions from water has been developed. The efficiency of the device in Cu(2+) ion removal could be realized through the naked eye by observing the color change of P2D particles, which has excellent potential for application in remote locations where water contamination is a significant issue.