Solar photocatalytic disinfection using ink-jet printed composite TiO2/SiO2 thin films on flexible substrate: Applicability to drinking and marine water

Abstract

Hybrid TiO2/SiO2 thin films deposited by material printing technique on flexible substrates were prepared, characterized and tested for solar photocatalytic disinfection. Effect of surface hydrophilicity/hydrophobicity of printed coatings on photocatalytic disinfection was studied by means of i) drinking water contaminated with natural consortia of fecal bacteria (gram-negative: Escherichia coli and total coliforms; gram-positive: Enterococci), and ii) seawater containing pathogenic gramnegative bacteria (Vibrio owensii, Vibrio alfacsensis and Vibrio harveyi). Inactivation of gramnegative bacteria in drinking water with fecal contamination by solar photocatalysis was slightly more efficient than solar disinfection, while for gram-positive bacteria similar efficiency was observed.These results, in combination with observed release of titanium from coatings (detected by means of inductively coupled plasma atomic emission spectrometer), indicate that TiO2/SiO2 needs further improvements for solar photocatalytic disinfection of drinking water. Efficiency of seawater disinfection towards gram-negative Vibrio spp. (Vibrio owensii, Vibrio alfacsensis and Vibrio harveyi) was significantly enhanced when TiO2/SiO2 coatings were used under natural solar light.Moreover, hydrophobic thin films led to faster Vibrio spp. inactivation as compared to hydrophilic ones, which was attributed to higher bacteria adhesion on hydrophobic coatings. However, decrease of photocatalytic activity of hydrophobic TiO2/SiO2 coatings was observed after ten experimental cycles mainly due to deposition of salts on the surface of photocatalyst. Generally, results of this study suggest that autochthonous bacteria such as Vibrio spp. in seawater are significantly more resistant to solar disinfection in comparison with not autochthonous bacteria such as Escherichia coli, total coliforms and Enterococci in contaminated drinking water.

Removal of pharmaceutically active compounds (PhACs) and bacteria inactivation from urban wastewater effluents by UVA-LED photocatalysis with Gd3+ doped BiVO4

“…As previously commented, the cell structure of the different bacteria can have a direct relationship with caused oxidative damages. For instance, E. coli, as gram negative bacteria are known to be sensitive to UV light, especially at high intensities [39]. This high sensitivity to UVA radiation might lead to more effective bacteria inactivation in photolysis as compared to photocatalytic processes [39,56,57] as was also observed in this study (Figure 8c).…”

“…Thus, quantification of Total coliforms, Escherichia coli (E. coli), and Enterococci were carried out by standard plating on commercial media: Chromogenic Collinstant Agar (Scharlab) and Slanetz & Bartley Agar (Panreac). Likewise, TCBS Thiosulfate Citrate Bile Salts Sucrose Agar (Pronadisa, Condalab) was used as solid media for Klebsiella pneumoniae (99.6%) which was identified by the amplification and sequencing of a fragment of 16S rDNA, as explained in previous studies [39]. The plates were incubated at 30 ± 2 °C for 24 -48 h according to the specific bacteria.…”

Keratin–cinnamon essential oil biocomposite fibrous patches for skin burn care

“…On the other hand, this precedence order could be reversed, due to the extra outer membrane of Gram (À) bacteria. 67,68 This complex behavior is reflected in our results, as bacterial populations were reduced at various levels, whether the bacterium was Gram (+) or Gram (À) (Fig. 4f).…”

Photocatalytic Treatment of Different Types of High−Concentration Ammonia Wastewater by Cu/TiO2 Film and its Mechanism Study

“…However, when the ow rate decreases, the catalyst lm on the glass surface is also damaged. The reason may be that the residence time of the solution on the surface of the catalyst lm increases, and anions tend to accumulate on the surface of TiO 2 and destroy the bonding structure of TiO 2 /SiO 2 , thereby reducing the removal rate of ammonia (Levchuk et al 2019). Therefore, the ow rate 40 mL/min was selected for subsequent experiments.…”