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As(III) Removal from Aqueous Solution by Calcium Titanate Nanoparticles Prepared by the Sol Gel Method

1
LabMAM, Depto. de Ingeniería Química Biotecnología y Materiales, FCFM, Universidad de Chile, Av. Beauchef 851, Santiago 8370456, Chile
2
Grupo de Química de Materiais Híbridos e Hinorgânicos, Instituto de Química de Sao Carlos, Universidade de São Paulo, 13563-120 Sa͂o Carlos, SP, Brazil
3
Laboratorio de Superficies, Depto. de Física, FCFM, Universidad de Chile, Av. Blanco Encalada 2008, Santiago 8370449, Chile
4
Laboratorio de Nanomateriales, Facultad de Ingeniería, Universidad Nacional Jorge Basadre Grohmann, Av. Miraflores s/n, Tacna 23003, Peru
*
Author to whom correspondence should be addressed.
Nanomaterials 2019, 9(5), 733; https://doi.org/10.3390/nano9050733
Received: 17 April 2019 / Revised: 7 May 2019 / Accepted: 8 May 2019 / Published: 13 May 2019
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Abstract

Arsenic (As) contamination of water is a serious problem in developing countries. In water streams, arsenic can be as As(V) and As(III), the latter being the most toxic species. In this work, an innovative adsorbent based on CaTiO3 nanoparticles (CTO) was prepared by the sol-gel technique for the removal of As(III) from aqueous solution. X-ray diffraction of the CTO nanoparticles powders confirmed the CTO phase. Transmission electron microscopy observations indicated an average particle size of 27 nm, while energy dispersive X-ray spectroscopy analysis showed the presence of Ca, Ti, and O in the expected stoichiometric amounts. The surface specific area measured by Brunauer, Emmett, and Teller (BET) isotherm was 43.9 m2/g, whereas the isoelectric point determined by Zeta Potential measurements was at pH 3.5. Batch adsorption experiments were used to study the effect of pH on the equilibrium adsorption of As(III), using an arsenite solution with 15 mg/L as initial concentration. The highest removal was achieved at pH 3, reaching an efficiency of up to 73%, determined by X-ray fluorescence from the residual As(III) in the solution. Time dependent adsorption experiments at different pHs exhibited a pseudo-second order kinetics with an equilibrium adsorption capacity of 11.12 mg/g at pH 3. Moreover, CTO nanoparticles were regenerated and evaluated for four cycles, decreasing their arsenic removal efficiency by 10% without affecting their chemical structure. X-ray photoelectron spectroscopy analysis of the CTO surface after removal experiments, showed that arsenic was present as As(III) and partially oxidized to As(V). View Full-Text
Keywords: arsenic adsorption; sol-gel technique; calcium titanate; nanoparticles; adsorption kinetic arsenic adsorption; sol-gel technique; calcium titanate; nanoparticles; adsorption kinetic
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
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Tamayo, R.; Espinoza-González, R.; Gracia, F.; Rodrigues-Filho, U.P.; Flores, M.; Sacari, E. As(III) Removal from Aqueous Solution by Calcium Titanate Nanoparticles Prepared by the Sol Gel Method. Nanomaterials 2019, 9, 733.

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