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Calcium alginate beads with entrapped iron oxide magnetic nanoparticles functionalized with methionine—a versatile adsorbent for arsenic removal
Publication . Lilhare, Surbhi; Mathew, Sunitha B.; Singh, Ajaya K.; Carabineiro, Sónia A. C.; LAQV@REQUIMTE; DQ - Departamento de Química; MDPI AG
A novel beads adsorbent, consisting of calcium alginate entrapped on magnetic nanoparti-cles functionalized with methionine (MFMNABs), was developed for effective elimination of arsenic from water. The material was characterized by FT-IR (Fourier Transform Infrared Spectroscopy), SEM (Scanning Electron Microscopic), XRD (X-ray Diffraction) and TEM (Transmission Electron Microscopy). The arsenic removal capacity of the material was studied by altering variables such as pH of the solution, contact time, adsorbent dose and adsorbate concentration. The maximal removal of As(III) was 99.56% under optimal conditions with an equilibrium time of 110 min and pH 7.0–7.5. The adsorption followed a second order kinetics and data best fitted the Langmuir isotherm with a correlation coefficient of R2 = 0.9890 and adsorption capacity (qm ) of 6.6533 mg/g. The thermodynamic study showed entropy change (∆S) and enthalpy change (∆H) to be 34.32 J mol−1 K and 5.25 kJ mol−1, respectively. This study proved that it was feasible to treat an As(III) solution with MFMNABs. The synthesized adsorbent was cost-effective, environmentally friendly and versatile, compared to other adsorbents. The adsorption study was carried by low cost spectrophotometric method using N-bromosuccinimide and rhodamine-B developed in our laboratory.
Effect of the metal deposition order on structural, electronic and catalytic properties of tio2-supported bimetallic au-ag catalysts in 1-octanol selective oxidation
Publication . Kotolevich, Yulia; Pakrieva, Ekaterina; Kolobova, Ekaterina; Farías, Mario H.; Bogdanchikova, Nina; Cortés Corberán, Vicente; Pichugina, Daria; Nikitina, Nadezhda; Carabineiro, Sónia A. C.; Pestryakov, Alexey; LAQV@REQUIMTE; DQ - Departamento de Química; MDPI - Multidisciplinary Digital Publishing Institute
Au and Ag were deposited on TiO2 modified with Ce, La, Fe or Mg in order to obtain bimetallic catalysts to be used for liquid-phase oxidation of 1-octanol. The effects of the deposition order of gold and silver, and the nature of the support modifying additives and redox pretreatments on the catalytic properties of the bimetallic Au-Ag catalysts were studied. Catalysts were characterized by low-temperature nitrogen adsorption–desorption, energy dispersive spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy and ultraviolet-visible diffuse reflectance spectroscopy. It was found that pretreatments with hydrogen and oxygen at 300◦C significantly decreased the activity of AuAg catalysts (silver was deposited first) and had little effect on the catalytic properties of AgAu samples (gold was deposited first). The density functional theory method demonstrated that the adsorption energy of 1-octanol increased for all positively charged AuxAgyq (x + y = 10, with a charge of q = 0 or +1) clusters compared with the neutral counterparts. Lanthanum oxide was a very effective promoter for both monometallic and bimetallic gold and silver catalysts in the studied process.
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Fundação para a Ciência e a Tecnologia
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CEEC INST 2018
Número da atribuição
6885