Use of Ca–alginate as a novel support for TiO2 immobilization in methylene blue decolorisation

Abstract

This study provides a preliminary contribution to the development of an industrial process for the UV/TiO(2) water treatment by introducing a novel support for TiO(2) immobilization. For the following study, Methylene Blue (MB) was chosen as the model dye to evaluate this novel immobilization system. The results showed that TiO(2) immobilized in a Ca-alginate bead retained its photoactivity during all of the experiments and the TiO(2)-gel beads presented good stability in water for maintaining its shape after several uses. When a proportion of 10% (v/v) of these beads was used, the configuration system demonstrated an improved mass transfer and consequently enhanced degradation efficiency. Experiments were also performed using 'recycled' beads. The results showed an increase in the degradation efficiency when the beads were reused, with an eventual 'self-destructive' effect. These studies showed great promise regarding the recyclable reagents with a reduction in waste at no greater cost or reduction in efficiency. Therefore, the potential of TiO(2)-gel beads as a simple and environmentally friendly catalyst for continuous use was developed.

Study of the Effect of Titanium Dioxide Hydrosol on the Photocatalytic and Mechanical Properties of Paper Sheets

“…Despite the loss of efficiency, however, the immobilization of TiO 2 on solid support such as paper sheets is still attractive because it offers a lot of advantages in terms of long-term and environmental safe stability (avoiding leaching of TiO 2 nanoparticles in solution, for example) [52]. From an economically point of view, it is also attractive because it allows the simple recovery and reuse, eliminating the need of a postprocess filtration step to remove the photocatalyst nanoparticles from the treated water [53]. the rate of the photocatalytic reaction increased upon increasing the concentration of TiO2/sodium alginate nanocomposite to the paper pulp, reaching the better performance (42% of COD removal) for the sample loaded with 20 wt.% nanocomposite.…”

Degradação fotocatalítica de tartrazina com TiO2 imobilizado em esferas de alginato

“…12 A maior eficiência de degradação pode ser atribuída a maiores quantidades de sítios ativos, devido à maior área específica de contato entre o TiO 2 ativado e as espécies moleculares que podem formar os radicais que desencadeiam a decomposição do corante. 38,39 A presença das esferas contendo o catalisador constitui uma barreira para a passagem das ondas eletromagnéticas, 40,41 pois elas se tornam opacas após a secagem (imagem não mostrada), e também deve ser avaliada. Por último, tem sido relatado que a disponibilidade de fotocatalisador é limitada à área específica disponível, pois a reação fotoquímica se dá na superfície das esferas.…”

“…Por último, tem sido relatado que a disponibilidade de fotocatalisador é limitada à área específica disponível, pois a reação fotoquímica se dá na superfície das esferas. 38,39 Isto é compatível com as imagens das esferas após a secagem em estufa (Figuras 2A, 2B e 2C), as quais perderam os poros, revelados na metodologia B.E.T. e de acordo com outros relatos.…”

Simultaneous photocatalytic and microbial degradation of dye-containing wastewater by a novel g-C3N4-P25/photosynthetic bacteria composite

“…A 50 mL portion of the resulting mixture was injected dropwise into 150 mL of 2% CaCl2 solution using a 2.5 mL syringe to form calcium alginate-photocatalyst (CA+PC) beads, which were left in the 2% CaCl 2 solution for 24h at 4℃ to harden. Calcium alginate-photosynthetic bacteria (CA+B) beads were formed in same manner, except the photocatalyst were replaced to photosynthetic bacteria to the alginate solution, and the mixing was performed by stirring rather than sonication [35–37]. …”