Inorganic–organic Ag-rhodamine 6G hybrid nanorods: “Turn on” fluorescent sensors for highly selective detection of Pb2+ ions in aqueous solution

Abstract

Lead metal ions are of great concern and the monitoring of their concentration in the environment has become extremely important. In the present study, a new inorganic–organic hybrid assay of Ag nanorods (AgNR)-Rhodamine 6G (R6G) was developed for the sensitive and selective determination of Pb²⁺ ions in aqueous solutions. To the best of our knowledge there is almost no literature on the use of silver nanorod sensors for determination of lead ions in aqueous solutions. The sensor is developed by the coating of R6G on the surface of AgNRs. The sensing is based on the photoluminescence of R6G. The sensor was rapid as the measurements were carried out within 3 min of addition of the test solution to the AgNR-R6G hybrid. Moreover, the system showed excellent stability at tested concentration levels of Pb²⁺ ions. The naked eye detection of the colour was possible with 1 mg L⁻¹ of Pb²⁺ ions. The present method has a detection limit of 50 μg L⁻¹ of Pb²⁺ (for a signal/noise (S/N) ratio > 3). The selectivity toward Pb²⁺ ions against other metal ions was improved using chelating agents. The proposed method was validated by analysis using different techniques.