The elimination of hazardous oxyanions NO 3 − , NO 2 − , and BrO 3 − from synthetic and real water samples using novel PdCu/10ZrCe (10 wt % ZrO 2 on CeO 2 ) structured catalysts supported on cordierite monoliths was studied in order to avoid loss of the catalytic material during water treatment. The monoliths were coated with different suspensions of the 10ZrCe support. Particle sizes, suspension concentration of 10ZrCe, and pH effects were evaluated. The structured catalyst was tested in a fixed-bed reactor at different flow rates for the elimination of the selected anions. Good results in terms of activity and selectivity to the products of interest (S N 2 : 0.99 and S Br − :1) were obtained in synthetic water. The structured catalyst was reused three times, maintaining its activity and selectivity. It was evaluated in a real water sample but the activity was lower probably due to competition for active sites by different ions present in the sample. The structured catalyst prepared is promising for the development of a system for water remediation, based on PdCu/ZrO 2 −CeO 2 materials.
It is known that the excess of oxyanions such as NO3- and BrO3- in drinking water affects its quality. In this work, three adsorbents (montmorillonite (Mt), silica (Si), and diatomaceous earth) loaded with hexadecyl- (H) and octadecyl-trimethylammonium (O) were used to remove these oxyanions from aqueous solutions by adsorption. In batch systems, the highest NO3- removal was obtained with Mt modified with H and O (Mt-H and Mt-O), attaining 33 and 50%, respectively, while for BrO3- removal Si modified with H and O, Si-H and Si-O samples, reached 38 and 42%, respectively. A direct relationship between the adsorption capacity of NO3- and BrO3- and the mass of the adsorbent was found in column filtration tests with Mt-O and Mt-H samples in standard solution and real groundwater samples. The adsorption capacity of the column, in the groundwater sample, remained constant after two reuses.The results obtained are promising for the development of a continuous oxyanion removal system containing the low-cost clay Mt modified with either H or O.
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