The removal of mercury (II) from water by Ag supported on nanomesoporous silica

• Published in: Journal of chemical biology 2016-10, Vol.9 (4), p.127-142
• Main Authors: Ganzagh, Mohammad Ali Azizi, Yousefpour, Mardali, Taherian, Zahra
• Format: Article
• Language: English
• Subjects: Adsorbents; Adsorption; Analytic hierarchy process; Biochemistry; Biological and Medical Physics; Biophysics; Cell Biology; Channel pores; Channels; Chemistry; Chemistry and Materials Science; Correlation coefficients; Evaluation; Ion adsorption; Ions; Langmuir waves; Long range order; Mathematical models; Mercury; Mercury (metal); Morphology; Nanocomposites; Nanoparticles; Organic chemistry; Original; Original Article; Pharmacology/Toxicology; Physical Chemistry; Pore size; Pore size distribution; Porosity; Scanning electron microscopy; Silica; Silicon dioxide; Silver; Size distribution; Spectrum analysis; Surface chemistry; Synthesis; Titration; Transmission electron microscopy; Wastewater; Wastewater treatment; X-ray diffraction; X-ray spectroscopy
• ISSN: 1864-6158; 1864-6166
• DOI: 10.1007/s12154-016-0157-5

In this study, the synthesis of SBA-15/Ag nanocomposite materials with different amounts of silver (2.5, 5, and 10 %) has been investigated under acidic conditions by using P123 as a template via the direct method. The nanocomposites of SBA-15 were synthesized by the same method and by the addition of silver salt. Finally, the nanocomposite materials were examined for the removal of mercury ions from wastewater as an adsorbent by the reverse titration method. Characterization was carried out through x-ray diffraction analysis (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N 2 adsorption-desorption (Brunauer–Emmett–Teller). XRD spectra confirmed the presence of silver nanoparticles within the amorphous silica matrix of SBA-15. The Barrett–Joyner–Halenda analysis showed that SBA-15 and SBA-15/Ag have a narrow pore size distribution. SEM images demonstrated that the morphology of the matrix of SBA-15 is in spherical state. Furthermore, wavelength dispersive x-ray spectroscopy identified the presence and distribution of silver nanoparticles inside the pore channels and outside of them. Typical TEM images of SBA-15 and SBA-15/Ag (5 wt.%) indicated a regular hexagonal pore structure with long-range order and long channels. In SBA-15/Ag (5 wt.%) sample, the nanoparticles of silver was found into the pores and outside of them. The removal of mercury ions from wastewater using mesoporous silica nanocomposite containing silver nanoparticles was studied by the reverse titration analysis. The best capacity of adsorption of mercury ions from wastewater was obtained for SBA-15/Ag (5 wt.%) sample, which was equal to 42.26 mg/g in 20 min at pH of 7. The Freundlich model was used to explain the adsorption characteristics for the heterogeneous surface, and K f (adsorption capacity) and n (adsorption intensity) were determined for Hg (II) ion adsorption on SBA-15/Ag nanocomposite materials with different amounts of silver (2.5, 5, and 10 %). The value of R 2 was about 0.99, 0.99, 0.98, and 0.98 and K f was about 42, 48, 58, and 58 mg/g for SBA-15/Ag, SBA-15/Ag (2.5 %), SBA-15/Ag (5 %), and SBA-15/Ag (10 %), respectively. Furthermore, the values of n >1 show a favorable adsorption process for Hg (II) ion adsorption on SBA-15/Ag nanocomposite materials. Moreover, the Langmuir isotherm model evaluation showed that the correlation coefficients for all concentrations were R 2 >0.99, indicating that Hg (II) ions were adsorbed on the surface