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

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).

Agro-Waste Derived Biomass Impregnated with TiO2 as a Potential Adsorbent for Removal of As(III) from Water

“…Thus, XPS results revealed that As(III) is adsorbed onto PP@TiO 2 and is partially oxidized to As(V). Similar behavior was reported by Tamayo et al [19] for As(III) removal from aqueous solution on calcium titanate nanoparticles. The partial oxidation of As(III) to As(V) could be due to the presence of physio-sorbed oxygen and surface hydroxyl groups.…”

Nanoengineering TiO2 for evaluating performance in dye sensitized solar cells with natural dyes

“…Some NPs are large and spherical while others are small in size with different shapes. 36 Further Fig. 3B shows selected area electron diffraction (SAED) pattern which is in accordance to the crystal plane structure of the nanostructures (Si–TiO 2 NPs) ( Fig.…”

Nanoparticles of the Perovskite-Structure CaTiO3 System: The Synthesis, Characterization, and Evaluation of Its Photocatalytic Capacity to Degrade Emerging Pollutants

“…These events were related to different thermal peaks that were observed in the calorimetry curve (DSC Figure 2, blue line). Thus, at a temperature of 90 • C, an endothermic peak occurred, associated with a weight loss of 6.31% up to 200 • C; this physicochemical event is related to the removal of water adsorbed on the surface of the powdered material [49,50]. Between 400 and 750 • C, three exothermic peaks were observed at ~481, 564, and 619 • C, which could be attributed to the oxidation of the organic phase present in the system, initially favoring the formation of oxy-carbonates and finally that of the oxide [49][50][51].…”