Rhodamine B In Water Research Articles

Degradation of Rhodamine B by CuFe2O4 nanoparticles anchored on montmorillonite as an activator of sodium persulfate

Background: Advanced oxidation techniques based on sulfate radicals can be more effective in dealing with the threats posed by dye wastewater. Methods: In this study, a series of montmorillonite-loaded CuFe2O4 (CFO, 1-CFO/Mt, 2-CFO/Mt, 3-CFO/Mt) composites were prepared using a simple one-pot solvent method for the activation of sodium persulfate (PDS) for the removal of Rhodamine B (RhB) from water. Significant findings: The efficient catalytic activity of the composite catalyst was verified by the degradation of RhB with different systems, and the efficient adsorption of this catalyst accelerated the reaction process of pollutant degradation. The results showed that 97.7% of RhB could be removed within 25 min using 0.3 g/L of 2-CFO/Mt composite catalyst and 1 mM of PDS at the initial pH = 7.5; In addition, the composite catalyst can show good catalytic performance in a wide pH range. It still has high catalytic activity after 3 cycles. The involvement of SO4•−, •OH, 1O2, and O2•− in the degradation of RhB by the 2-CFO/Mt/PDS system was determined by radical quenching experiments as well as EPR test analysis, in which 1O2 dominated in the degradation of RhB by the 2-CFO/Mt/PDS system. Overall, 2-CFO/Mt has significant potential as a PDS activator in the treatment of RhB in water.

Fluorescence spectroscopy based characterisation method for aggregation behaviour of rhodamine B (RhB) in water, ethanol, and propanol

The aggregation behaviour of rhodamine B (RhB) dye has been studied with the change in the concentration of the RhB in water, ethanol and propanol using absorption and laser induced fluorescence spectroscopy. The dimer and monomer fluorescence emissions were observed simultaneously in all the solvents. The monomer to dimer fluorescence intensity ratio , where IM = Monomer fluorescence intensity, ID = Dimer fluorescence intensity, has been calculated and found that at a certain concentration of RhB the magnitude of the ratio is different in different solvents. The ratio becomes equivalent to one for 1.5 gm l−1, 3 gm l−1 and 4.2 gm l−1, (gm l−1: gram litre−1) concentration of RhB in water, ethanol and propanol respectively. This concentration of RhB at which the ratio become unity is proposed as ‘critical concentration’. Above this critical concentration the dimeric fluorescence dominates and below which the monomeric fluorescence dominates. The parameter ‘critical concentration’ provides a condition of equilibrium between the monomer and their aggregates. Moreover, in the solvent for which the magnitude of critical concentration is less the fluorophore molecule aggregates more easily and vice versa. The ratio and critical concentration quantify the aggregation process of the fluorophore in the solvent. Hence, the ‘critical concentration’ value of the fluorophore (RhB) could be assumed as the characteristic parameter to study the aggregation behaviour of the fluorophore in solvents. The described method has the merit of use in the study of lasing ability and the wavelength tunability of the dye laser gain media as well as in the heavy metal sensing technology in water. This method may also be extended for other fluorophores and solvents.

Degradation of Rhodamine B in water by heat/persulfate process

BackgroundThis investigation concerns the effectiveness of the heat/persulfate process in the degradation of Rhodamine B (RhB) in water. MethodsThe dependences of the efficiency and rate of degradation of RhB by the heat/persulfate process on the temperature, initial concentration of RhB, and Na2S2O8 concentration were examined. Significant findingsThe degradation of RhB by the heat/persulfate process followed pseudo-first-order kinetics. The efficiency and rate of degradation of RhB at 70 °C dramatically exceeded those at 30 °C. At 70 °C, increasing the initial concentration of RhB reduced the efficiency and rate of degradation of RhB. At 70 °C, the efficiency and rate of degradation of RhB increased with Na2S2O8 concentration. The heat/persulfate process at 70 °C with an initial concentration of RhB of 5 mg/L and an Na2S2O8 concentration of 32 mM completely degraded RhB in 7 min, revealing that the heat/persulfate process is highly effective in the degradation of RhB in water.

CdSe QDs@ Fe-based metal organic framework composites for improved photocatalytic RhB degradation under visible light

A series of composites based on Fe-based MOF (Fe-BDC) and CdSe quantum dots (CdSe QDs) have been synthesized with CdSe QDs well-embedded into Fe-BDC particles, which are characterized by XRD, SEM, TEM, ICP-OES, FT-IR, N 2 physical sorption, UV–visible DRS, PL and electrochemical measurements. By detecting the degradation of Rhodamine B (RhB) in aqueous solution under visible light irradiation, the photocatalytic performance of CdSe@Fe-BDC nanocomposites were apparently improved by 5.8 times relative to single Fe-BDC, which can be attributed to the heterostructure formed in CdSe@Fe-BDC. Owing to the perfect interfacial contact, this promotes electron transfer from CdSe to Fe-BDC and significantly facilitates the separation of the photogenerated electron-hole pairs. The photocatalytic mechanism studied by adding sacrificial agents revealed that the predominant active species in the system is hole cation (h + ) and oxygen free radicals (•O 2 − ). A series of composites based on Fe-BDC and CdSe quantum dots have been prepared and the resultant composites show excellent photocatalytic performance in RhB degradation. • A novel CdSe@Fe-BDC nanocomposite was synthesized and characterized. • CdSe QDs were uniformly dispersed in Fe-BDC particles. • CdSe@Fe-BDC exhibited an enhanced visible-light photocatalytic degradation of RhB in water. • The mechanism for photocatalytic degradation of RhB of CdSe@Fe-BDC was proposed.

High-efficiency adsorption of Cr(VI) and RhB by hierarchical porous carbon prepared from coal gangue

Coal gangue (CG) is one of the largest industrial solid wastes in the world produced during the process of coal mining. The accumulation of CG is easy to cause ion leakage, which is harmful to the environment and human body. The recovery and utilization of CG are imminent. In the process, a hierarchical porous carbon (HPC) adsorbent with excellent adsorption property for Cr(VI) and rhodamine B (RhB), was prepared from CG by a two-step method and characterized by SEM, TEM, XRD, XPS, TPD and BET. The results revealed that the specific surface area of HPC is up to 2012.7 m2 g−1, and its adsorption capacities for Cr(VI) and RhB are reached 320.51 and 3086.42 mg g−1. The adsorption mechanism of RhB was the synergetic effect of physics and chemistry. While XPS results suggested that hierarchical porous carbons (HPCs) only have a chemisorption effect on Cr(VI). This study provided an idea for the preparation of HPCs from CG to remove inorganic and organic pollutants such as heavy metal Cr(VI) and RhB in water.

OPTIMIZATION OF PHOTODEGRADATION CONDITIONS OF RHODAMINE B IN WATER WITH DYE-SENSITIZED TITANIUM DIOXIDE

Rhodamine B (RhB) is widely employed in dyeing in textile, paper, paints and leather industry. The wastewater containing RhB dye can cause serious environmental and biological problems. Hence, the remediation of RhB treatment is necessary for the environment. In this study, the photodegradation of RhB in water under sunlight irradiation with dye-sensitized titanium dioxide (TiO2) is investigated. The influence of various conditions, such as TiO2 dosages, initial RhB concentration, temperature, pH, sunlight intensity and irradiation time on the photodegradation of RhB are also studied. About 96% of RhB is photodegraded within 20 min under the optimized conditions. Therefore, the photodegradation treatment for the wastewater including RhB under sunlight is very simple, easy and low cost technique.

Investigation of photocatalytic performance of CuS/Bi2WO6 and degradation pathway of RhB in water

Abstract A series of CuS/Bi2WO6 composites were synthesized by solvothermal synthesis, which showed enhanced photocatalytic activity. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, photoluminescence ultraviolet–visible absorption spectroscopy, transient photocurrent and EIS. The results showed that as-prepared CuS/Bi2WO6 has flower-like nano microspheres self-assembled by nanoplates and CuS nanorods are uniformly dispersed on its surface. The CuS/Bi2WO6 forms heterojunctions between CuS and Bi2WO6 and shows a wide light response range and a strong light response intensity. The CuS/Bi2WO6 exhibits a better Rhodamine B (RhB) degradation effect than pure Bi2WO6 and CuS, and it can degrade 90% RhB in 50 min and achieve complete degradation in 70 min under Xe lamp irradiation. The CuS/Bi2WO6 has photocatalytic activity in a low pH environment and good stability. The formation of a heterojunction between CuS and Bi2WO6 can effectively separate photo-generated electrons and holes, greatly improving the photocatalytic activity. In the CuS/Bi2WO6-RhB reaction system, O2− is the main active species, and it can rapidly remove the ethyl group from the amino group linked to benzene rings to achieve the N-de-ethylation reaction in the process of RhB degradation. The N-de-ethylated products are simultaneously degraded to small organic molecules and even mineralized into CO2 and H2O.

Efficient photoelectrochemical oxidation of rhodamine B on metal electrodes without photocatalyst or supporting electrolyte

We designed photoelectrochemical cells to achieve efficient oxidation of rhodamine B (RhB) without the need for photocatalyst or supporting electrolyte. RhB, the metal anode/cathode, and O2 formed an energy-relay structure, enabling the efficient formation of O 2 – species under ultraviolet illumination. In a single-compartment cell (S cell) containing a titanium (Ti) anode, Ti cathode, and 10 mg·mL–1 RhB in water, the zero-order rate constant of the photoelectrochemical oxidation (kPEC) of RhB was 0.049 mg·L–1·min–1, while those of the photochemical and electrochemical oxidations of RhB were nearly zero. kPEC remained almost the same when 0.5 mol·L–1 Na2SO4 was included in the reactive solution, regardless of the increase in the photocurrent of the S cell. The kPEC of the illuminated anode compartment in the two-compartment cell, including a Ti anode, Ti cathode, and 10 mg·mL–1 RhB in water, was higher than that of the S cell. These results support a simple, eco-friendly, and energysaving method to realize the efficient degradation of RhB. Open image in new window

The different paths and potential risks of photo(-electro)-catalytic degradation for rhodamine B in water by graphene/TiO2 membrane.

The graphene (GR)/TiO2 membrane was prepared by the sol-gel method and coated on the indium tin oxide (ITO) conductive glass, which showed high and stable photo(-electro)-catalytic activities to rhodamine B (Rh-B) in water. Characterization results showed that the GR was dispersed and wrapped in the needle-like TiO2. With GR/TiO2 membrane and simulated sunlight irradiation, the removal efficiency of Rh-B (10mgl-1 and pH at 5.4) arrived at 87.6% within 300min. However, the higher removal efficiency for Rh-B reached to 97.8% by the photo-electro-catalytic degradation with the applied voltage 4v for 30min. The ·OH that generated in the photo-catalytic degradation process were responsible for Rh-B decomposition. The ·O2- played the significant role in the photo-electro-catalytic degradation of Rh-B. Furthermore, the decarboxylation was also occurred in the photo-electro-catalytic degradation for the Rh-B in water except for the deethylation and hydroxylation in the photo-catalytic degradation. In addition, the toxicities of the intermediates were calculated using the ECOSAR program and the EPIWIN software. The results indicated that the toxicities of intermediates from photo-electro-catalytic degradation for the Rh-B were higher than photo-catalytic degradation, due to the generation of decarboxylate.

A novel electrocatalytic approach for effective degradation of Rh-B in water using carbon nanotubes and agarose.

Carbon nanotubes (CNTs)/agarose (AG) membrane on the ITO (indium tin oxide) conductive glass, with high efficiency of electrocatalytic degradation for rhodamine B (Rh-B) in water, was prepared using an easy and green method. The prepared CNTs/AG membrane was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectra (EDS), infrared spectroscopy (IR), and electrochemical impedance spectroscopy (EIS). The results revealed that CNTs were dispersed in the AG membrane. Additionally, the electrocatalytic activities for Rh-B were conducted on the electrochemical workstation with a three-electrode system. Both initial pH and potential played an important role in the process of electrocatalytic degradation. At pH3 and potential reaching 4V, the removal rate of Rh-B (10mg/L) in water achieved 96% within 20min. The stability of the prepared CNTs/AG membrane was also investigated. Besides, the toxicities of the main intermediates from the electrocatalytic degradation for Rh-B were calculated using the ECOSAR program and EPIWIN software, and results indicated that the toxicities of some intermediates were higher than those of the parent pollutant (Rh-B). These findings provided a light-spot to simplify the preparation of efficient working electrode and emphasized the possible potential risks from intermediates at the same time.

Improved photocatalytic activity of δ-FeOOH by using H2O2 as an electron acceptor

Abstract In this work, δ-FeOOH nanoparticles were synthesized by a simple co-precipitation method and used as a photocatalyst in the presence of H 2 O 2 for the oxidation of Rhodamine B (RhB) dye under artificial light. The δ-FeOOH was characterized by powder X-ray diffraction, 57 Fe Mossbauer spectroscopy, N 2 adsorption/desorption and UV–vis diffuse reflectance measurements. The δ-FeOOH nanoparticles have high specific surface area (101 m 2 g −1 ) and optical bandgap energy of 2.02 eV. Under artificial light, only 59% of RhB (100 mL; 20 mg L −1 ) was photocatalytically degraded by δ-FeOOH in 60 min reaction. However, after adding H 2 O 2 , the photocatalytic activity of δ-FeOOH was significantly improved, reaching 87% of dye removal. Tests using scavengers of reactive species and EPR analysis revealed that h + and OH are the main species in this system. Based on the experimental results, the mechanism of RhB photodegradation in the presence of δ-FeOOH and H 2 O 2 was proposed. By this mechanism, the OH can be formed by direct water oxidation or by H 2 O 2 reduction, as the electron transfer from the conduction band of δ-FeOOH to H 2 O 2 is thermodynamically favorable. Moreover, the H 2 O 2 retards the electron-hole recombination in δ-FeOOH, thus increasing its photocatalytic activity. Given its high efficiency for degrading RhB in water, δ-FeOOH revealed to be a promising photocatalyst to be tested in the oxidation of emerging pollutants for the environmental decontamination.

CoFe/SBA-15 catalyst coupled with peroxymonosulfate for heterogeneous catalytic degradation of rhodamine B in water

CoFe/SBA-15 catalysts were prepared by simultaneous incipient wetness impregnation using Co(NO3)2·6H2O and Fe(NO3)3·9H2O as the precursors and SBA-15 as the support. The catalysts were used to activate generation of sulfate radicals from peroxymonosulfate (PMS) for rhodamine B (RhB) dye degradation in aqueous solutions. The catalyst was characterized using X-ray diffraction, N2 adsorption-desorption, scanning electron microscopy and energy-dispersive X-ray spectroscopy, transmission electron microscopy, and vibrating sample magnetometry. The effects of the Co and Fe loadings and calcination temperature on the catalytic performance, catalyst reusability, and kinetics and mechanism of catalytic oxidative degradation of RhB in the presence of CoFe/SBA-15 and PMS were investigated. The results show that the predominant Co-Fe oxide loaded on the support was the composite CoFe2O4, which provided the active catalytic sites, and was present in the SBA-15 matrix. The surface area, pore volume, and mean pore diameter of 10Co9.5Fe/SBA-15-700 were 506.1 m2/g, 0.669 cm3/g, and 7.4 nm, respectively, lower than those of SBA-15. 10Co9.5Fe/SBA-15-700 consisted of rod-like aggregates with diameters greater than 0.25 μm. It had a magnetic intensity of 8.3 emu/g; therefore, magnetic separation was feasible. 10Co9.5Fe/SBA-15-700 showed good catalytic activity and stability, with a RhB degradation rate higher than 96% and Co leaching lower than 32.4 μg/L. The catalytic oxidative degradation of RhB in the presence of FeCo/SBA-15 and PMS obeyed first-order kinetics, and the degradation rate increased with increasing CoFe/SBA-15 and PMS dosages and with decreasing initial reactant concentrations. Quenching tests showed that sulfate radicals played a dominant role in RhB catalysis. CoFe/SBA-15 maintained high catalytic activity and good stability during 10 recycling runs, with a RhB degradation rate greater than 84%, Co and Fe leaching for each run lower than 72.1 and 35 μg/L, respectively. CoFe/SBA-15 is an efficient catalyst for PMS oxidation, and has potential applications in the removal of refractory organics such as RhB in water.

Optimized core–shell Au@Ag nanoparticles for label-free Raman determination of trace Rhodamine B with cancer risk in food product

A simple and reliable method based on surface-enhanced Raman scattering (SERS) with a portable Raman system is described for sensitive determination of trace levels of Rhodamine B (RB) in hot sauce samples. The sodium salt of phytic acid (IP6) stabilized Au@Ag core–shell bimetallic nanoparticles are constructed and used as SERS substrate, yielding high Raman enhancement of RB. The limit of detection for RB in water is 5nM (2ppb), which is below China Exit and Entry Inspection and Quarantine Bureau’s tolerance level of 5ppb. Also, the proposed easy assay of IP6–Au@Ag NPs combining with portable Raman system could be applied for on-site monitoring RB in hot sauce.

Zeolitic Imidazole Framework-67 (ZIF-67) as a heterogeneous catalyst to activate peroxymonosulfate for degradation of Rhodamine B in water

Metal organic frameworks (MOFs) can exhibit chemical, photo and biomimetic catalytic activities. While MOFs have been intensively investigated as photo-catalysts to degrade pollutants in water, studies of wet chemical oxidation catalyzed by MOFs are still quite limited. Particularly, the activation of peroxymonosulfate (PMS) represents a widely-used chemical oxidation reaction for chemical synthesis and environmental remediation. Yet little effort has been made to evaluate MOFs as a catalyst for the PMS activation. In this study, it is proposed to use a cobalt-based MOF, ZIF-67, as a heterogeneous catalyst to activate PMS to degrade Rhodamine B (RB) dye. Through the RB degradation, ZIF-67 as the PMS activation catalyst was evaluated and its underlying mechanism was proposed. Additionally, factors affecting the PMS activation were also examined, including ZIF-67 loading, temperature, pH, UV irradiation and ultrasonication. A ratio of 1/3/1 (RB/PMS/ZIF-67) is the most effective ratio to degrade RB in water. The higher temperature, UV irradiation and ultrasonication also enhanced the RB degradation using PMS activated by ZIF-67. The recyclability test revealed that ZIF-67 can be used continuously with stable and effective catalytic activity. These features reveal that ZIF-67 can be an interesting and promising heterogeneous catalyst to activate PMS for the degradation of organic pollutants in water.

Heterogeneous activation of oxone with CoMg/SBA-15 for the degradation of dye Rhodamine B in aqueous solution

A novel heterogeneous Co catalyst CoMg/SBA-15 was prepared through a two-step incipient wetness impregnation of Mg and Co into mesoporous silica SBA-15 and used for the activation of oxone to generate sulphate radicals for degrading Rhodamine B (RhB) in aqueous solution. The CoMg/SBA-15 was characterized by several techniques such as XRD, N2 adsorption–desorption, CO2-TPD, TEM and SEM. It was found that the CoMg/SBA-15 existed as agglomerates with the particle size more than 0.3μm, and Co and Mg occurred mainly both inside and outside the support pores in the form of cubic spinel Co3O4 and Mg oxide crystallites, respectively. Loading Mg into the support increased the dispersion of Co3O4 on the support and generated the remarkable basicity of the catalyst surface promoting the formation of surface Co–OH complex. The CoMg/SBA-15 still displayed the long-range ordered arrangement of the channels in structure with the reduced pore diameter and surface area compared with the SBA-15. The Co/SBA-15–oxone–RhB system, as a test control, was demonstrated to be efficient for the activation of oxone producing sulphate radicals for the degradation of RhB in solution. And the increase of Co/SBA-15 and oxone dosages had the positive effect on the degradation efficiency and rate, with the almost complete RhB degradation in 60min and the Co leaching concentration less than 43μg/L and the leaching percent less than 0.40% at appropriate Co/SBA-15 and oxone dosages. In addition, the degradation followed the first-order kinetics. The CoMg/SBA-15 exhibited much higher activity than Co/SBA-15 and Co/MgO with the same Co loading in degrading RhB by sulphate radicals from oxone, with nearly 100% degradation in 5min, the Co leaching concentration of 80μg/L and the leaching percent of 0.96%, and almost 100% TOC removal under appropriate conditions achieved. The CoMg/SBA-15 also displayed stable performance during 25 runs of reuse. Based on the UV–vis spectra and TOC measurement, the degradation mechanism of RhB in the presence of CoMg/SBA-15 and oxone was proposed. It is believed that CoMg/SBA-15 can be widely applied in the catalytic oxidation with oxone for the degradation of the refractory organic pollutants such as dye RhB in water.

Enhancement of Visible-Light Photocatalytic Activity of Mesoporous Au-TiO2Nanocomposites by Surface Plasmon Resonance

Mesoporous Au-TiO2nanocomposite plasmonic photocatalyst with visible-light photoactivity was prepared by a simple spray hydrolytic method using photoreduction technique at90∘C. The prepared samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and N2adsorption-desorption isotherms. The formation of hydroxyl radicals (•OH) on the surface of visible-light illuminated Au-TiO2nanocomposites was detected by the luminescence technique using terephthalic acid as probe molecules. The photocatalytic activity was evaluated by photocatalytic decolorization of Rhodamine-B (RhB) aqueous solution under visible-light irradiation (λ > 420 nm). The results revealed that the TiO2could be crystallizedviaspray hydrolysis method, and the photoreduction technique was facilitated to prepare Au nanoparticles in the mesoporous TiO2at90∘C. The light absorption, the formation rate of hydroxyl radicals, and photocatalytic decolorization of Rhodamine-B aqueous solution were significantly enhanced by those embedded Au nanoparticles in the Au-TiO2nanocomposites. The prepared Au-TiO2nanocomposites exhibit a highly visible-light photocatalytic activity for photocatalytic degradation of RhB in water, and their photocatalytic activity is higher than that of the pristine TiO2nanoparticles due to the surface plasmon resonance.

Photodegradation of Rhodamine B in Water by ETS-10 Prepared through a Novel Titanium Source

Well-crystallized ETS-10 was prepared using TiO2 prepared by industrial propane/air turbulent flame CVD process as a novel titanium source. The synthesis parameters have been studied in detail The photodegradation of a dye solution, rhodamine B (RhB), assisted by ETS-10 was studied. The result showed that the well-crystallized titanosilicate ETS-10 induced complete degradation of RhB in water after 2h illumination under a 300W high-pressure mercury lamp.

Degradation of Rhodamine B in Aqueous Solution by Fenton’s Reagent

The degradation of rhodamine B (RB) in aqueous solution by Fenton’s reagent was studied. After 30 min, the 96.2% removal of RB in water (pH = 3.0, T = 25 °C) was achieved when the initial concentrations of Fe2+, H2O2 and RB were 0.5 mM, 5 mM and 10 mg/L, respectively. A higher initial concentration of Fe2+ and H2O2 resulted in a higher efficiency in RB discolorization. The removal of RB was dependent strongly on the pH value of solution. Increasing the reaction temperature was beneficial for the RB degradation. Based on the Arrhenius equation, the activation energy (Ea) was calculated to be 16.78 kJ/mol from rate constants at different temperatures. The degradation of RB by Fenton’s reagent was inhibited by the presence of oxalic acid.

Microwave‐Hydrothermal Preparation and Visible‐Light Photoactivity of Plasmonic Photocatalyst Ag‐TiO2 Nanocomposite Hollow Spheres

Visible-light-driven plasmonic photocatalyst Ag-TiO(2) nanocomposite hollow spheres are prepared by a template-free chemically-induced self-transformation strategy under microwave-hydrothermal conditions, followed by a photochemical reduction process under xenon lamp irradiation. The prepared samples are characterized by using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, N(2) adsorption-desorption isotherms, X-ray photoelectron spectroscopy, UV/Vis and Raman spectroscopy. Production of .OH radicals on the surface of visible-light illuminated TiO(2) was detected by using a photoluminescence method with terephthalic acid as the probe molecule. The photocatalytic activity of as-prepared samples was evaluated by photocatalytic decolorization of Rhodamine B (RhB) aqueous solution at ambient temperature under visible-light irradiation. The results show that the surface plasmon absorption band of the silver nanoparticles supported on the TiO(2) hollow spheres was red shifted, and a strong surface enhanced Raman scattering effect for the Ag-TiO(2) nanocomposite sample was observed. The prepared nanocomposite hollow spheres exhibits a highly visible-light photocatalytic activity for photocatalytic degradation of RhB in water, and their photocatalytic activity is higher than that of pure TiO(2) and commercial Degussa P25 (P25) powders. Especially, the as-prepared Ag-TiO(2) nanocomposite hollow spheres at the nominal atomic ratio of silver to titanium (R) of 2 showed the highest photocatalytic activity, which exceeds that of P25 by a factor of more than 2.

Photodegradation of rhodamine B in water assisted by titania films prepared through a novel procedure

Well-crystallized anatase thin films were prepared through direct oxidation of metallic titanium with 30 mass% hydrogen peroxide solution at 80 °C for 5 h, followed by soaking in distilled water at 80 °C for 3 days. The photodegradation of a dye solution, rhodamine B (RB), assisted by such deposited anatase films was studied. It was found that the well-crystallized anatase thin films induced complete degradation of RB in water with an initial concentration of less than 0.02 mM after 4–5 h of illumination under a 450 W high-pressure mercury lamp. The RB decayed directly to colorless end products of water and mineral acids. However, when the photocatalytic activity of the anatase films decreased after several repeated uses, an N-de-ethylation process producing rhodamine as an intermediate was evident during the photocatalytic degradation of RB.