Abstract
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•Preconcentration and detection of Hg(II) ions over mesoporous TiO2 was explored.•The Hg(II)-DZ complex was formed onto the TiO2 with optical colour signal changing.•A good linearity is obtained Hg(II)-DZ complex with low detection ∼2.3 × 10−9 molL-1.•The regeneration of TiO2 is considered an advantageous after five times using UV.•The Hg(II) adsorption capacity ∼0.00103 mmol/g matched the Langmuir isotherm model.
A Facile and cost-effective chemical, optical sensor based mesoporous TiO2 nanoparticles (NPs) have been evaluated for the preconcentration, removal and detection of Hg(II) ions at ultra-trace levels from an aqueous solution for the first time within 30 sec. The formation Hg(II)-Dithazone (DZ) complex in the solution was successfully anchored onto the surface of mesoporous TiO2 NPs with optical colour signal changing from beige to reddish-brown, and the intensity of the colour was found to be directly corresponding to the Hg(II) ions concentration. A good linearity is obtained between DZ and Hg(II) concentration, exhibiting a limit of detection as low as 2.3 × 10−9 molL-1. The effect of foreign ions revealed that Hg(II) ions could be detected distinctly with high selectivity regarding the Hg(II) ions. The regeneration of mesoporous TiO2 NPs is considered advantageous by UV illumination for self-cleaning TiO2, with an insignificant reduction in its efficiency even after five times. The adsorption efficiency of Hg(II) ions well matched the model of Langmuir isotherm with maximum adsorption capacity ∼0.00103 mmol/g within 30 sec over mesoporous TiO2 NPs. Moreover, the key parameters for visualized detection selective and fast adsorption of Hg(II) ions were optimized and evaluated. Interestingly, the mesoporous TiO2 NPs based optical sensor indicated remarkable selectivity, sensitivity, recyclability, and fast kinetic quantification and detection of diverse detrimental toxic metal ions in our circumference.