Mesoporous composite material for efficient lead(II) detection and removal from aqueous media

A novel ligand based conjugate material (CMA) was prepared for toxic lead (Pb(II)) ion monitoring and removal from aqueous solution. The organic ligand of 6-((2-(2-hydroxy-1-naphthoyl) hydrazono) methyl) benzoic acid was successfully synthesized and then anchored onto the porous silica monolith. The CMA was enhanced the color upon addition of Pb(II) ion and the results were the evident of the one-step monitoring of wide-range Pb(II) concentrations without using the highly sophisticated apparatus, and this was unique feature of the CMA. The limit of detection was 0.42 mu g/L, which was the lower than the permissible limit in drinking water. Varying factors that may affect the Pb(II) removal efficiency such as solution pH, reaction time and coexistent metal ions were systematically investigated. The data was clarified that the developed CMA was removed more than 99% of Pb(II) ion from aqueous solution under the optimum experimental protocol. The maximum adsorption capacity for CMA was 196.35 mg/g. The adsorption data were well fitted to the Langmuir isotherm model and confirmed the monolayer coverage as desired from the CMA morphology. The CMA was exhibited the high affinity to the Pb (II) in the presence of high concentration competing ion. In addition, the adsorbed Pb(II) was desorbed from the CMA with stripping agent (0.10 M HCl) and simultaneously regenerated into an initial form for the next monitoring and removal operations after washing with water. Based on the experiment results, it is concluded that the CMA is highly sensitive and selective material for efficient water treatment for supplying the pure drinking water.