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A novel adsorbent, based on modifying graphene oxide (GO) chemically with 2-pyridinecarboxaldehyde thiosemicarbazone (2-PTSC) as ligand, was designed by facile process for removal of Hg(II) from aqueous solution. Characterization of the adsorbent was performed using various techniques, such as FT-IR, XRD, XPS, SEM and AFM analysis. The adsorption capacity was affected by variables such as adsorbent dosage, pH solution, Hg 2+ initial concentration and sonicating time. These variables were optimized by rotatable central composite design (CCD) under response surface methodology (RSM). The predictive model for Hg(II) adsorption was constructed and applied to find the best conditions at which the responses were maximized. In this conditions, the adsorption capacity of this adsorbent for Hg 2+ ions was calculated to be 309 mg g −1 that was higher than that of GO. Appling the ultrasound power combined with adsorption method was very efficient in shortening the removal time of Hg 2+ ions by enhancing the dispersion of adsorbent and metal ions in solution and effective interactions among them. The adsorption process was well described by second-order kinetic and Langmuir isotherm model in which the maximum adsorption capacity ( Q m ) was found to be 555 mg g −1 for adsorption of Hg 2+ ions over the obtained adsorbent. The performance of adsorbent was examined on the real wastewaters and confirmed the applicability of adsorbent for practical applications. [ABSTRACT FROM AUTHOR]

TiO nanoparticles were synthesized by sol-gel method using titanium tetraisopropoxide. Sulfate ions were introduced on the titania by impregnation method using sulfuric acid as precursor of sulfate ions. Fourier transform infrared and energy-dispersive X-ray spectroscopy, X-ray fluorescence as well as X-ray diffraction, scanning electron microscopy, and BET methods were used for the characterization of the obtained nanoparticles. The esterification of isoamyl alcohol with acetic acid was investigated to prove the catalytic activity of the TiO nanoparticles under solvent-free conditions. Response surface methodology was applied to optimize the effect of some parameters such as the molar ratio of acetic acid to alcohol, catalyst loading, reaction temperature, and reaction time on the yield of the isoamyl acetate. The TiO nanoparticles were proved to be an excellent heterogeneous catalyst for isoamyl acetate synthesis under solvent-free conditions affording a high yield of 94 % under the following optimal conditions: molar ratio of acetic acid to alcohol (1:7), catalyst loading (3.2 wt% with respect to the acetic acid), the reaction temperature (130 °C), and the reaction time (300 min). Graphical abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

This work describes novel Fe 3 O 4 @SiO 2 core-shell nanoparticles functionalized with phenyl isothiocyanate and its application in the preconcentration of Cd(II) and Pb(II) ions. The parameters affecting the preconcentration procedure were optimized by a Box–Behnken design through response surface methodology. Three variables (extraction time, magnetic sorbent amount, and pH value) were selected as the main factors affecting the sorption step, while four variables (type, volume and concentration of the eluent; and elution time) were selected as effective factors of elution step in the optimization study. Following the sorption and elution, the ions were quantified by FAAS. The limits of detection were 0.05 and 0.9 ng mL − 1 for Cd(II) and Pb(II) ions, respectively. The relative standard deviations were less than 6.4%. The sorption capacity (in mg g − 1 ) of this new sorbent is 179 for Cd(II) and 156 for Pb(II). Finally, this nanocomposite was successfully applied to the rapid extraction of trace quantities of heavy metal ions from fish, sediment, soil, and water samples and satisfactory results were obtained. [ABSTRACT FROM AUTHOR]