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Highlight► The catalysts composite TiO 2 /MgZnAl-5, was more efficient than TiO 2 P25.► The effects of different molar ratios zinc on the photocatalysts were investigated.► Synergistic effect between constituents of TiO 2 /MgZnAl-5 increases the photocatalysis.► TiO 2 /MgZnAl-5 exhibited the adsorption of light displacing the greater wavelength.► The catalyst composite TiO 2 /MgZnAl-5 can be reused for five consecutive cycles. AbstractPage 2 of 34 A c c e p t e d M a n u s c r i p t 2 A series of TiO 2 /MgZnAl photocatalysts, were successfully synthesized from ternary (Mg, Zn and Al) layered double hydroxides impregnated with TiO 2 nanoparticles by the co-precipitation method at variable pH with different Zn 2+ /Mg 2+ molar ratios . The composite photocatalysts were calcined at 500 °C resulting in the incorporation of oxide zinc, in the calcined MgZnAl LDH structure. Synergistic effect between ZnO and TiO 2 lead to significant enhancement of TiO 2 /MgZnAl photocatalytic activity. Composite photocatalysts were characterized by ICP-MS, N 2 adsorption/desorption, XRD, SEM, EDS, IR and UV-Vis DRS. Phenol in aqueous solution (50 mg/L) was used as a model compound for evoluation of UV-Vis (filter cutoff for λ > 300 nm) photocatalytic activity . The most efficient phocatalyst composite was obtained at a 5% Zn 2+ /Mg 2+ molar ratio , in the catalyst identified as TiO 2 /MgZnAl-5. This composite catalyst had high photocatalytic activity, completely destroying phenol and removing 80% of total organic carbon in solution after 360 min.The TiO 2 /MgZnAl-5 catalyst remained relatively stable, presenting a 15% decrease in phenol degradation efficiency after five consecutive photocatalytic cycles.

The new magnetic photocatalysts HT/TiO2/Fe and HT-DS/TiO2/Fe, modified with the anionic surfactant sodium dodecylsulfate (DS) were successfully synthesized in this work. Titanium dioxide (anatase) followed by iron oxide were deposited on the hydrotalcite support. Several catalyst samples were prepared with different amounts of titanium and iron. The photocatalysts were characterized by infrared and Raman spectroscopy, X-ray diffraction, scanning electron microscopy. Photocatalytic performance was analyzed by UV-visible radiation (filter cutoff, λ > 300 nm) of an aqueous solution (24 mg/L) of methylene blue (MB). The most efficient catalyst was obtained at an iron oxide:TiO2 molar ratio of 2:3. This catalyst showed high photocatalytic activity, removing 96% of the color and 61% of total organic carbon from the MB solution after 120 min. It was easily removed from solution after use because of its magnetic properties. The reuse of the HT-DS/TiO2/Fe23 catalyst was viable and the catalyst was structurally stable for at least four consecutive photocatalytic cycles.

O adsorvente quitosana-Fe(III)-reticulado (Ch-FeCL) foi desenvolvido usando Fe(III) imobilizado em esferas de quitosana. Após o processo de secagem, as esferas apresentam um diâmetro de cerca de 1 mm e são estáveis ao ar. O comportamento de adsorção do As(III) e As(V) na Ch-FeCL foi avaliado em pH 7 por estudos realizados em batelada e em coluna. As máximas capacidades de adsorção estimadas pelo modelo de adsorção de Langmuir foram 21,24 e 27,59 mg g -1 para As(III) e As(V), respectivamente. A cinética de adsorção é descrita pela equação cinética de pseudo-segunda ordem. Os resultados de adsorção em coluna indicaram que o arsênio não foi encontrado na solução efluente até cerca de 60 e 759 volumes de leito para As(III) e As(V), respectivamente. Os resultados foram satisfatórios quando se empregou o adsorvente na remoção de As(III) e As(V) de amostras de águas subterrâneas, torneira e rio.The crosslinked chitosan-Fe(III) (Ch-FeCL) adsorbent was developed using Fe(III) immobilized on chitosan beads. After drying, the beads presented a diameter of approximately 1 mm and are stable in air. The adsorption behavior of As(III) and As(V) on the Ch-FeCL was evaluated at pH 7 by studies conducted in batch and in columns. Maximum adsorption capacities estimated by the Langmuir adsorption model were 21.24 and 27.59 mg g -1 for As(III) and As(V), respectively. Adsorption kinetics is described by the pseudo second order kinetic equation. The results of column adsorption indicated that arsenic was not found in the effluent solution from roughly 60 and 759 bed volumes for As(III) and As(V), respectively. Results were satisfactory when employing the adsorbent for removal of As(III) and As(V) from groundwater, tap water and river water samples.