Mihaela Mureseanu

Modified SBA-15 mesoporous silica for heavy metal ions remediation

N-Propylsalicylaldimino-functionalized SBA-15 mesoporous silica was prepared, characterized and used as an adsorbent for heavy metal ions. The organic-inorganic hybrid material was obtained using successive grafting procedures of SBA-15 silica with 3-aminopropyl-triethoxysilane and salicylaldehyde, respectively. For comparison an amorphous silica gel was functionalized using the same procedure. The structure and physicochemical properties of the materials were characterized by means of elemental analysis, X-ray diffraction (XRD), nitrogen adsorption-desorption, thermogravimetric analysis and FTIR spectroscopy. The organic functional groups were successfully grafted on the SBA-15 surfaces and the ordering of the support was not affected by the chemical modification. The behavior of the grafted solids for the adsorption of heavy metals ions from aqueous solutions was investigated. The hybrid materials showed high adsorption capacity and high selectivity for copper ions. Other ions, such as nickel, zinc, and cobalt were adsorbed by the modified SBA-15 material. The adsorbent can be regenerated by acid treatment without altering its properties.

Mesoporous silica functionalized with 1-furoyl thiourea urea for Hg(II) adsorption from aqueous media.

New organic-inorganic hybrid materials were prepared by covalently anchoring 1-furoyl thiourea on mesoporous silica (SBA-15). By means of various characterization techniques (X-ray diffraction, nitrogen adsorption-desorption, thermogravimetric analysis, and FTIR spectroscopy) it has been established that the organic groups were successfully anchored on the SBA-15 surfaces and the ordering of the inorganic support was preserved during the chemical modifications. The hybrid sorbents exhibited good ability to remove Hg(II) from aqueous solution. Thus, at pH 6, the adsorption capacity of mercury ions reached 0.61 mmol g(-1).

Adsorptive Removal of Cadmium and Copper from Water by Mesoporous Silica Functionalized with N-(Aminothioxomethyl)-2-Thiophen Carboxamide

AbstractCopper and cadmium ions were removed from aqueous solutions by adsorption onto a new organic-inorganic hybrid material. N-(aminothioxomethyl)-2-thiophen carboxamide (TAC) was covalently anchored on SBA-15 mesoporous silica. Various characterization techniques [X-ray diffraction, nitrogen adsorption-desorption, thermogravimetric analysis, Si29, C13 nuclear magnetic resonance (NMR), and Fourier-transform infrared (FTIR) spectroscopy] have proved that the organic ligand was successfully anchored and the ordering of the inorganic support was preserved during the chemical modifications. Metal cations in aqueous solution were adsorbed onto this material with multichelating atoms by a complexation mechanism. Adsorption capacity for the divalent copper and cadmium cations were 0.74 and 0.21  mmol g−1, respectively. Cu(II) was selectively eliminated from contaminated water with Cu(II) and Cd(II). TAC-functionalized silica sorbent presented a good regeneration capacity without significantly losing its adsor...

A family of solar light responsive photocatalysts obtained using Zn2+ Me3+ (Me = Al/Ga) LDHs doped with Ga2O3 and In2O3 and their derived mixed oxides: a case study of phenol/4-nitrophenol decomposition

Photocatalytic decomposition of dangerous organic contaminants using irradiation with sunlight is of great importance for environmental remediation and human health. In this paper Zn2+Me3+ (Me = Al/Ga) layered double hydroxides (LDHs) doped with gallium oxide (Ga2O3) and indium oxide (In2O3) and their derived mixtures of mixed oxides (MMOs) as novel solar light driven photocatalysts for degrading a mixture of phenol/4-nitrophenol (Ph–4NPh) are presented. The Ga2O3/ZnMeLDHs and In2O3/ZnMeLDHs were fabricated by exploiting the LDH capability to rebuild its structure, after being destroyed by calcination at 550 °C, in aqueous solutions of gallium sulfate [Ga2(SO4)3] and indium acetate [In(C2H3O2)3], respectively, while the corresponding MMOs were obtained after the calcination at 750 °C. The effects on the structure, surface characteristics and photo-absorption properties of the catalysts were assessed using X-ray diffraction, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy and ultraviolet-visible analyses. The findings demonstrate that both Ph and 4NPh are degraded by both the reconstructed LDHs and their derived MMOs in such a way that an increased efficiency is obtained for In/Zn3Ga_750 and Ga/Zn3Ga_750 which degraded almost 90% of the 4NPh. In comparison, for In/Zn3Ga and Ga/Zn3Ga catalysts, the degradation efficiency reached only 69% and 47%, respectively. Furthermore, in the family of ZnAlLDH derived catalysts, In/Zn3Al_750 is able to decompose 98% of 4-NPh and 77% of Ph, after 240 min of irradiation, whereas the efficiency of Ga/Zn3Al_750 reached only 57% for 4-NPh and 39% for Ph. The as-prepared LDHs, Zn3Al and Zn3Ga, are almost inactive for degradation of a Ph–4NPh mixture under solar light.

CuII(Sal-Ala)/CuAlLDH Hybrid as Novel Efficient Catalyst for Artificial Superoxide Dismutase (SOD) and Cyclohexene Oxidation by H2O2

This work presents CuII(Sal-Ala) complex immobilized on the CuAlLDH as a novel efficient catalyst for artificial superoxide dismutase (SOD) enzyme activity and cyclohexene oxidation. The physico-chemical properties of CuII(SalAla)/CuAlLDH were investigated by XRD, XPS, FTIR, DRUV and TGA techniques. The correlation between the catalytic performances, structure and composition of the hybrid catalyst is also discussed.Graphical Abstract