Reusable floating polymer nanocomposite photocatalyst for the efficient treatment of dye wastewaters under scaled‐up conditions in batch and recirculation modes

Abstract

BACKGROUND: In the last decade, research on floating photocatalysts has increased rapidly with polymer substrates being a popular choice. However, most of the published work is on very small volumes and there is very little work on scale-up of such systems. RESULTS:Polystyrene-titanium dioxide nanocomposite floating films were prepared using a facile solvent casting method and tested for the photocatalytic degradation of four different dyes under UV irradiation. The prepared film was characterised by Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma optical emission spectrometry (ICP-OES) and profilometry. Scale-up studies were done in batch mode under optimised conditions, and for the larger reactor volume, the effect of recirculation was studied. Complete decolourisation of the model dye (Remazol Turquoise Blue) was observed within 80 min in the scaled-up batch process. In the recirculation mode, for a much larger volume of the dye solution, around 75% decolourisation in 6 h was observed. The reusability of the photocatalytic film was tested, and the results promise a minimum decolourisation efficiency of around 70%. Finally, total organic carbon (TOC) and liquid chromatography mass spectrometry (LC-MS) analysis were used to assess the degradation of the dye. The maximum TOC reduction observed was around 25% possibly due to the complex nature of the dye used in this study. The intermediate products of degradation were identified, and a tentative mechanism is suggested. CONCLUSION: This work demonstrates the recirculation aspects of the photocatalytic reactor under the scaled-up conditions for a complex dye. The prepared film showed excellent stability with satisfactory wastewater decontamination under UV irradiation even after repeated use. Figure 5. Effect of catalyst loading and pH. Conditions: 200 mL of 10 ppm Remazol Turquoise Blue (RTB) solution, catalyst loading: 12 wt%.wileyonlinelibrary.com/jctb

Photocatalytic degradation of ciprofloxacin from water with waste polystyrene and TiO2 composites

“…The characteristic peaks in Fig. 1 a are also seen here, confirming the presence of crystalline TiO 2 in C50 [ 20 , 23 ].

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“…Again, the white dots appearing in the same SEM images can be interpreted as the residual solvent (chloroform) thought to be trapped in the polymeric materials [ 24 ]. SEM images of C80, C50 and C20 show that TiO 2 is evenly distributed in the polymeric matrix [ 20 ].

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“…The decrease in the amount of PS, that is, the increase in the amount of TiO 2 , causes an increase in the production rate of the electron/hole pair and accordingly the hydroxyl radicals. This increase contributes to the improvement of photocatalytic degradation performance [ 20 ].…”

“…This mixture was homogenized in a sonication water bath for 1 h. It was then stirred at 120 °C for 2 h. The resulting solution was poured into a glass Petri dish and kept in a fume hood for 24 h for solvent evaporation. The resulting product was washed several times with distilled water in order to remove any impurities that may be on the product, and it was dried in an oven at 50 °C for 24 h [ 20 ]. This procedure was applied for all PS-TiO 2 products (Cx) containing different ratios of polystyrene.…”

Upcycling of waste EPS beads to immobilized codoped TiO2 photocatalysts for ciprofloxacin degradation and E. coli disinfection under sunlight

“…Polystyrene/expanded polystyrene (EPS) beads are widely used as packaging materials (in food, electronic goods, and other fragile products), thus creating an enormous amount of waste polymers that need to be reused in a circular economy. These waste polymers can be upcycled for the development of floating photocatalysts, thus solving a major environmental problem—‘white pollution’ 43 – 45 . The challenge of lesser accessibility to photons by catalysts in the immobilized form can be overcome through the development of floating photocatalysts which use lightweight material as an inert support for immobilization.…”