An easily organic-inorganic hybrid optical sensor based on dithizone impregnation on mesoporous SBA-15 for simultaneous detection and removal of Pb(II) ions from water samples: Response-surface methodology

In this study, a novel organic-inorganic hybrid adsorbent for single-step detection and removal of Pb(II) ions based on dithizone (DZ) anchored on mesoporous SBA-15 was fabricated. The designed solid optical sensor revealed rapid colorimetric responses and high selectivity. Central composite design (CCD) combined with desirability function (DF) was applied to evaluate the interactive effects and optimization of important variables such as pH value, mesoporous SBA-15 dosage, contact time and initial concentration of Pb(II) ions and optimum conditions for each of the factors were obtained 6.0, 25 mg, 30 min and 20 mu g ml(-1), respectively. This adsorbent or solid optical chemo sensor exhibited a linear range of 1.0 to 100.0 mu g ml(-1) of Pb(II) ion concentration with a detection limit of 0.07 mu g ml(-1). This adsorbent was applied to determine and remove the Pb(II) in spiked samples. Various isotherm models such as Langmuir, Freundlich, Temkin and Dubinin-Radushkevich were studied for fitting the experimental equilibrium data. Langmuir model was chosen as an efficient model. Various kinetic models such as pseudo-first, second order intraparticle, diffusion models were studied for analysis of experimental adsorption data and the pseudo second order model was chosen as an efficient model.