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Experimental Investigation of the Effective Parameters on the Removal of the Heavy Metal Ions from Salty Water by Using the Magnetic Nanoparticles Supported on Activated Carbons

Fatehi , Mohammad Hossein | 2018

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 51396 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Shayegan, Jalaloddin; Goodarznia, Iraj; Zabihi, Mohammad
  7. Abstract:
  8. In the present thesis, the adsorption ability of the functionalized magnetic nano-particles supported on the walnut and almond based activated carbons was evaluated to prepare the efficient and low cost adsorbents for removal of Pb(II), Cr(VI) and Hg(II) ions aqueous solutions in the presence of salinity. The activated carbons were derived from almond and walnut shell by the physical activation method. The functionalized nano-magnetic activated carbons were synthesized by co-precipitation consisting of AC(almond)@Fe3O4@SiO2-NH2-COOH and AC(walnut)@Fe3O4-NH2-COOH which were modified by the oxygen containing functional groups to enhance the adsorption capacity. The prepared carbonaceous adsorbents were characterized by applying the various tests including XRD, TGA, BET, Boehm, TEM, FT-IR, DLS, XRF, XPS and VSM.The Characterization study indicated that the well dispersed magnetic nanoparticles (Fe3O4) were formed with measured size less of 17 nm over the almond based activated carbon which was confirmed by the results of XRD, TEM and DLS.The XPS analysis was carried out for the fresh and used sample (AC(almond)@Fe3O4@SiO2-NH2-COOH) which illustrated that the Pb(II) and Cr(VI) were adsorbed over the magnetic adsorbent. The experimental investigation was conducted by adsorption of Pb(II) and Cr(VI) over AC(almond)@Fe3O4@SiO2-NH2-COOH separately, which demonstrated that the removal efficiencies were calculated to be 84.3% and 70%, respectively. The presence of Cr(VI) ions had a negligible effect on the adsorption of Pb(II) ions in the binary solutions. However, the removal efficiency of metal ions was reduced which were measured to be 80% and 53% for Pb(II) and Cr(VI), respectively. The obtained results also showed that the effect of salinity on the adsorption of metal ions at pH > 7 was negligible.
    Furthermore, the effective novel functionalized supported magnetic nanoparticles on the walnut based activated carbon was prepared by co-precipitation method for removal of mercury ions from saline solutions. The well dispersed magnetite nano-particles were detected over the substrate with the size less of 30 nm. The maximum adsorption capacity was achieved to be 80 mg/g by employing Langmuir isotherm while the salinity and pH parameters were kept constant at 25000 ppm and 7, respectively.A three-layer Artificial Neural Network (ANN) code was developed to predict the adsorption of Hg (II) ions by using AC (walnut) @Fe3O4-NH2-COOH. The three-layer back-propagation (BP) is configured of tangent sigmoid transfer function (tansig) at the hidden layer with 8 neurons and linear transfer function (purelin) at the output layer. According to the obtained MSEs, Levenberg–Marquardt algorithm (LMA) was the best training algorithm among the other training algorithms. The linear regressions between the predicted and experimental outputs were proven to be a good agreement with a correlation coefficient (0.9984) for five model variables. The kinetic study was also performed for the adsorption of mercury ions which indicated that the pseudo-second-order kinetic can justify the experimental data
  9. Keywords:
  10. Adsorption ; Activated Carbon ; Neural Network ; Chromium ; Mercury ; Lead ; Magnetic Nanodot

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