Engineering Commercial TiO2 Powder into Tailored Beads for Efficient Water Purification

In this study, efficient commercial photocatalyst (Degussa P25) nanoparticles were effectively dispersed and stabilized in alginate, a metal binding biopolymer. Taking advantage of alginate’s superior metal chelating properties, copper nanoparticle-decorated photocatalysts were developed after a pyrolytic or calcination-sintering procedure, yielding ceramic beads with enhanced photocatalytic and mechanical properties, excellent resistance to attrition, and optimized handling compared to powdered photocatalysts. The morphological and structural characteristics were studied using LN2 porosimetry, SEM, and XRD. The abatement of an organic pollutant (Methyl Orange, MO) was explored in the dark and under UV irradiation via batch experiments. The final properties of the photocatalytic beads were defined by both the synthesis procedure and the heat treatment conditions, allowing for their further optimization. It was found that the pyrolytic carbon residuals enabled the adhesion of the TiO2 nanoparticles, acting as binder, and increased the MO adsorption capacity, leading to increased local concentration in the photocatalyst vicinity. Well dispersed Cu nanoparticles were also found to enhance photocatalytic activity. The prepared photocatalysts exhibited increased MO adsorption capacity (up to 3.0 mg/g) and also high photocatalytic efficiency of about 50% MO removal from water solutions, reaching an overall MO rejection of about 80%, at short contact times (3 h). Finally, the prepared photocatalysts kept their efficiency for at least four successive photocatalytic cycles.

Titanate Nanotubes as Futuristic Catalyst Support Material

Titanate Nanotubes (TNT) were synthesized by aging commercial titanium dioxide (TiO2 - Degussa P25) with an alkali (KOH) solution at different time intervals. The prepared materials were investigated for their surface composition and textural behaviour by X-ray powder diffraction (XRD), Raman spectroscopy, Gas (N2 and CO2) adsorption measurements, and Transmission electron microscopy (TEM). The X-ray diffraction spectra revealed the decrease in the crystalline nature of the materials decreased by exposing them for a longer duration in the base solution. Raman spectra results showed that ageing time affected the structural properties. The specific surface area and the pore size of the newly synthesised materials were affected by the ageing process. The TEM images showed the influence of ageing during the formation of titanate nanotubes. HRTEM revealed that Pd particle sizes of <1 nm was present inside the tubes.

Titanate Nanotubes as Futuristic Catalyst Support Material

Titanate Nanotubes (TNT) were synthesized by aging commercial titanium dioxide (TiO2 - Degussa P25) with an alkali (KOH) solution at different time intervals. The prepared materials were investigated for their surface composition and textural behaviour by X-ray powder diffraction (XRD), Raman spectroscopy, Gas (N2 and CO2) adsorption measurements, and Transmission electron microscopy (TEM). The X-ray diffraction spectra revealed the decrease in the crystalline nature of the materials decreased by exposing them for a longer duration in the base solution. Raman spectra results showed that ageing time affected the structural properties. The specific surface area and the pore size of the newly synthesised materials were affected by the ageing process. The TEM images showed the influence of ageing during the formation of titanate nanotubes. HRTEM revealed that Pd particle sizes of <1 nm was present inside the tubes.

Fotocatálisis aplicada a la degradación de pesticidas (Profenofos) vertidos en el lago de Tota

Este trabajo tiene como objetivo principal evaluar la remoción de un pesticida vertido en el lago de Tota mediante degradación fotocatalítica. El contaminante seleccionado fue Profenofos, principio activo del Awake 500 EC, agroquímico usado en los cultivos de cebolla larga ubicados en la ronda del lago. En la fase experimental, se utilizaron dos métodos de degradación fotocatalítica: suspensión de catalizador TiO2 Degussa P25 e inmovilización de sol-gel de nanopartículas de titanio NTO en vidrio. La fuente de radiación utilizada en laboratorio y a nivel piloto fue una lámpara uv que simula la radiación solar. Se analizó el efecto del tiempo de radiación y la masa de fotocatalizador sobre la concentración del compuesto degradado. Para la determinación analítica de Profenofos se utilizó espectrofotometría uv-Vis y cromatografía de gases con detector n/p y de captura de electrones. El fotocatalizador soportado fue caracterizado con sem, rayos x e ir. Los resultados obtenidos muestran un alto porcentaje de remoción y reflejan el potencial que la fotocatálisis tiene en la degradación de agroquímicos presentes en aguas del lago de Tota.

Advantages of the Incorporation of Luffa-Based Activated Carbon to Titania for Improving the Removal of Methylene Blue from Aqueous Solution

This research aims to study the possible improvement of methylene blue (MB) removal from aqueous solution by hybrid adsorbent-catalysts (AdsCats) prepared through the incorporation of activated carbon derived from Luffa cylindrica fibers (LAC) to TiO2 photocatalysts. LAC with a specific surface area of 1170 m2/g was prepared by chemical activation with phosphoric acid at 500 °C. TiO2/LAC composites with 70 and 90 wt.% Degussa P25 titania content were prepared. The materials were characterized by N2 physical adsorption, XRD, FTIR, and XPS. The AdsCats displayed a very good dispersion of TiO2 over LAC, a surface area of close to 200 or 400 m2/g, depending on the composition, and high crystallinity, showing the presence of anatase and rutile phases. MB removal was studied in two different scenarios: under UV-light after reaching adsorption equilibrium, and under UV-light once the liquid effluent and the AdsCats were in contact. The MB removal by LAC has proved to be very efficient, highlighting the predominant role of adsorption over photodegradation. The prepared AdsCats have also been compared with their components. The results showed that TiLAC hybrids have superior photocatalytic performance than P25, showing TiLAC-7/3 90% MB removal with respect to the initial concentration just after 30 min of UV light irradiation for both studied scenarios.

Polystyrene fibers recycled waste produced by Solution Blow spinning with TiO2 incorporation

This study attempted to produce polymeric microfibers with low-cost and photocatalytic properties, making it possible to remedy two modern problems, plastic disposal and irregular effluent disposal, for which we used the solution blows pinning (SBS) technique to produce recycled polystyrene (PS) microfibers (recycled waste from transparent barrel pen), the use of the SBS also has good mobility for the benefit of fibers, allowing the fibers to be produced directly under the surface where intend to be used, through the SEM was found the ideal concentration to produce uniform microfibers. With the minor average diameter, FTIR analysis of the fibers showed peak characteristics of PS, demonstrating that most of the transparent barrel pen is composed of PS. The as-prepared fibers of recycled PS were incorporated into their polymer solution with a TiO2 Degussa P25 concentration of 10% (w/w) concerning the polymer mass. For the study of photocatalytic activity, the dye Rhodamine B was used as an indicator. Excellent photocatalytic activity, XRD pattern of PS and PS/TiO2-10% fibers showed PS and TiO2 in two phases, anatase and rutile.

Photolytic and Photocatalytic Treatment of Linear Alkylbenzene Sulfonate in Water

Treatment of linear alkylbenzene sulfonate using various photolytic and photocatalytic processes is described. Based on first order rates, it is shown that 5,000 mg/L of H²O² for degradation of a 100 mg/L solution of linear alkylbenzene sulfonate is optimum. Two different photocatalysts, Degussa P25 and Hombikat UV 100 TiO², are used to degrade LAS in slurry batch reactors. The optimum photocatalyst loading for Degussa P25 is higher than UV 100 for treatment of LAS since >20% adsorbs to the surface of the UV 100 photocatalyst. Combination of photocatalysts does not improve degradation rates in batch tests. Combination of Degussa P25 and 600 mg/L H²O² and irradiation with either UV light at 254 or 365 nm does not improve degradation rates over the photocatalytic or photolytic processes individually. Photolysis of LAS with UV light at 254 nm and 600 mg/L H²O² added at different time intervals was not successful and no improvement in the first order rate constant was observed. For optimum results, the hydrogen peroxide was added at the beginning of irradiation.

Photolytic and Photocatalytic Treatment of Linear Alkylbenzene Sulfonate in Water

Treatment of linear alkylbenzene sulfonate using various photolytic and photocatalytic processes is described. Based on first order rates, it is shown that 5,000 mg/L of H²O² for degradation of a 100 mg/L solution of linear alkylbenzene sulfonate is optimum. Two different photocatalysts, Degussa P25 and Hombikat UV 100 TiO², are used to degrade LAS in slurry batch reactors. The optimum photocatalyst loading for Degussa P25 is higher than UV 100 for treatment of LAS since >20% adsorbs to the surface of the UV 100 photocatalyst. Combination of photocatalysts does not improve degradation rates in batch tests. Combination of Degussa P25 and 600 mg/L H²O² and irradiation with either UV light at 254 or 365 nm does not improve degradation rates over the photocatalytic or photolytic processes individually. Photolysis of LAS with UV light at 254 nm and 600 mg/L H²O² added at different time intervals was not successful and no improvement in the first order rate constant was observed. For optimum results, the hydrogen peroxide was added at the beginning of irradiation.

Mesoporous titania nanoparticles as photocatalyst for degradation of 2-chlorophenol

Mesoporous titania nanoparticles (MTN) was successfully prepared by microwave-assisted menthod. The performance of MTN was compared with degussa P25 (commercial TiO2) on photocatalytic degradation of 2-chlorophenol (2-CP). Both catalysts were characterized by XRD, FTIR, UV-Vis DRS and surface area analysis. The characterization data indicated that MTN has higher surface area and lower particle size than P25. The 2-CP was successfully degraded completely under UV light irradiation despite of having a slightly higher band-gap value compared with P25. This study demonstrated that MTN shows a good potential as a photocatalyst.

Synthesis, Characterization, and Evaluation of Degussa P25/Chitosan Composites for the Photocatalytic Removal of Sertraline and Acid Red 18 from Water

Degussa P25 titanium dioxide/chitosan composites (P25/CS) were prepared using three different methods and two different chitosan materials. The obtained materials were characterized by diffuse reflectance UV–Vis, Fourier-transform infrared spectroscopies, X-ray diffraction, and scanning electron microscopy. It was observed for all prepared materials that the chitosan surface is homogeneously covered by Degussa P25, the particles are evenly dispersed on the whole chitosan matrix and do not form agglomerates. The performance of P25/CS composites were tested in water treatment by the photocatalytic reaction of sertraline and Acid Red 18. The obtained results show that the application of prepared composites is effective in the reaction of decomposition of model organic impurities in water. Moreover, chitosan presence in the photocatalytic materials considerably facilitates the separation of catalyst from the reaction mixture, which is a great advantage compared to pure Degussa P25. The preparation method did not show a major effect on the photocatalytic activity. The method using glutaraldehyde as the crosslinking agent is the simplest one; thus, it is recommended for Degussa P25/chitosan nanocomposites preparation. These nanocomposites can be successfully applied in water purification by photocatalytic degradation of organic pollutants. Graphic Abstract