Extent Of Photocatalytic Degradation Research Articles

Photocatalytic Degradation of Allura Red (AR) with TiO<sub>2</sub> Immobilized on Solution Blow Spinning (SBS) - Spun TIPP/PVP Membranes

Titanium dioxide (TiO2) nanoparticles were immobilized on the surface of 14% TIPP/PVP membranes by (1) dip coating the membrane in the powdered nanoparticles and (2) dip coating the membranes in PAN/DMF solution containing the nanoparticles. The composite membranes were then used for the photocatalytic degradation of Allura Red (AR) dye. The effect of the presence of PAN/DMF, the initial dye concentration, and irradiation time was investigated. The extent of photocatalytic degradation was observed by measuring the absorbance of the solution using a UV-Vis spectrophotometer. The presence of PAN/DMF allowed more TiO2 nanoparticles to adhere to the surface of the membrane. The membrane with PAN/DMF/TiO2 has greater degradation efficiency across all concentrations used than the membrane without PAN/DMF. In the same membrane, the degradation efficiency increased as the initial dye concentration increased from 0.0008 mg/g AR to 0.004 mg/g AR. However, a further increase to 0.008 mg/g decreased the degradation efficiency. On the other hand, the membrane without PAN/DMF decreased its degradation efficiency as the concentration increased. The degradation efficiency increases with irradiation time but reaches equilibrium after 120 minutes. The experimental data for the membrane with PAN/DMF/TiO2 followed the Langmuir-Hinshelwood (L-H) rate form with a rate constant of 0.0253 min-1. The membrane can be reused up to 10 times at 0.0008 mg/g dye concentrations but with reduced degradation efficiency values on the extent of membrane photocatalyst reusability.

Study on Photocatalytic Cement Concrete for the Degradation of Textile Dyes

This process is developed in the way that low level usage of chemical such as Titanium-di-oxide and urea along with the cement concrete structure for the photocatalytic activity under sunlight. When the cement concrete structure is introduced the sustainability of the process is increased so the efficient use of the reactant is achieved. From this study we obtained that the photocatalytic way of separation of waste ions can increase the purification process. The feed water is the waste from the common effluent plant with high in BOD and COD content. Two crystalline forms of TiO 2 , viz. anatase and rutile were tested for their photocatalytic activity. The extent of photocatalytic degradation was found to increase with increasing TiO 2 concentration up to 2 g/L TiO 2 , 5 g/L urea above which degradation remained practically constant. Textile waste degradation was enhanced at acidic conditions and in the addition of hydrogen peroxide. For the assessment of catalyst activity on repeated use, experiments were performed; after thrice successive uses, TiO 2 had sufficiently retained its photocatalytic activity and to perform the kinetic studies.

Degradation kinetics of sodium alginate via sono-Fenton, photo-Fenton and sono-photo-Fenton methods in the presence of TiO2 nanoparticles

Sono-photo-Fenton, sono-Fenton and photo-Fenton methods combined with heterogeneous TiO2 nanoparticles are adopted to investigate the degradation of sodium alginate (NaAlg), and the kinetics mechanism is also explored. Experimental results suggest that the reaction order of NaAlg degradation (n) is 0.51 and the extent of photocatalytic degradation can increase with the loading of TiO2 nanoparticles. Meanwhile, as the catalyst concentration increases from 0.05 to 0.5 gL−1, the degradation rate constant (k) is decreased. In addition, the structure of degraded NaAlg is characterized by Fourier transform infrared (FT-IR), 1H NMR spectroscopy, and X-ray diffraction analyses. The FT-IR and 1H NMR spectra results indicate that the C2-C3 bond in the structure of NaAlg is broken and intra-molecular esters are formed during the degradation process due to the strong oxidization of the Fenton system. In general, the sono-photo-Fenton process with TiO2 nanoparticles could provide an efficient way to degrade the NaAlg to low-molecular-weight.

Photocatalytic activity of TiO2-coated glass raschig rings on the degradation of phenolic derivatives under simulated solar light irradiation

Glass raschig rings were coated with different types of TiO2, namely Evonik P25 (EP), anatase TiO2 from Sigma–Aldrich (SA), and TiO2 obtained from a sol–gel procedure. The efficiency of the coating was tested on the degradation of phenol using simulated solar light irradiation. Regardless the material tested, phenol degradation gradually increases with the number of TiO2 layers. SA-coated glass rings show the highest efficiency for phenol degradation (90% conversion), but do lose activity when reused (78% conversion after 2 cycles) due to particle disaggregation from the support. Rings coated with EP are the most stable with an average 72% conversion over 3 cycles.Raschig rings coated with 3 layers of EP were used for the treatment of a synthetic effluent consisting of a solution with a mixture of seven phenolic derivatives namely phenol, 4-hydroxybenzoic acid, 4-methoxyphenol, 4-phenylethyl alcohol, benzoic acid, protocatechuic acid and gallic acid. Photocatalytic degradation efficiency depended on the organic compound, the most easily degraded molecule being gallic acid (85% removal after 8h of irradiation) contrasting with 4-hydroxybenzoic acid which was the most refractory compound (3% removal). A relationship between the extent of photocatalytic degradation and the activating/deactivating nature of the aromatic ring substituents is proposed.

Photocatalytic Degradation of Textile Dye and Wastewater

In this study, the photocatalytic degradation of commercial azo dye (Remazol Red 133) in the presence of titanium dioxide (TiO2) suspensions as photocatalyst was investigated. The effect of various operational parameters, such as pH of dye solution and catalyst concentration on the photocatalytic degradation process, was examined. The mineralization of dye was also evaluated by measuring the chemical oxygen demand of the dye solutions. The extent of photocatalytic degradation was found to increase with increasing TiO2 concentration. For the Remazol Red dye solutions, a 120-min treatment resulted in 97.9% decolorization and 87.6% degradation at catalyst loading of 3 g/L. Experiments using real textile wastewater were also carried out. Textile wastewater degradation was enhanced at acidic conditions. The decolorization and degradation efficiencies for textile wastewater were 97.8% and 84.9% at pH 3.0, catalyst loading of 3 g/L, and treatment time of 120 min.

Treatment of textile dyehouse wastewater by TiO 2 photocatalysis

The oxidative degradation of an actual textile dyehouse wastewater was investigated by means of photocatalysis in the presence of TiO 2. The UV-A-induced photocatalytic oxidation over TiO 2 suspensions was capable of decolorizing the effluent completely, as well as reducing chemical oxygen demand (COD) sufficiently (COD reduction generally varied between about 40% and 90% depending on the operating conditions) after 4 h of treatment. Two crystalline forms of TiO 2, viz. anatase and rutile, were tested for their photocatalytic activity and anatase was found to be more active than rutile. The extent of photocatalytic degradation was found to increase with increasing TiO 2 concentration up to 0.5 g/L TiO 2, above which degradation remained practically constant, reaching a plateau. Furthermore, textile effluent degradation was enhanced at acidic conditions (i.e. pH=3) and in the presence of hydrogen peroxide. To assess catalyst activity on repeated use, experiments were performed where the catalyst was recovered and reused; after three successive uses, TiO 2 had sufficiently retained its photocatalytic activity. Finally, the luminescent marine bacteria Vibrio fischeri was used to assess the acute ecotoxicity of samples prior to and after the photocatalytic treatment and it was found that ecotoxicity was fully eliminated following photocatalytic oxidation.