scholarly journals Rapid Photocatalytic Degradation of Methylene Blue under High Photon Flux UV Irradiation: Characteristics and Comparison with Routine Low Photon Flux

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Qian Zhang ◽  
Chaolin Li ◽  
Ting Li
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Degradation ◽  
Uv Irradiation ◽  
Irradiation Time ◽  
Photon Flux ◽  
Photocatalytic Process ◽  
Toc Removal ◽  
High Photon Flux ◽  
Degradation Of Dyes ◽  
Photonic Efficiency

This study examined the photocatalytic degradation efficiency under high UV photon flux (intensity normalized by photon energy) irradiation; the incident UV photon flux was einstein   made by a super high-intensity UV apparatus. A comparative study between high photon flux photocatalytic process and routine low photon flux photocatalytic process for methylene blue degradation has been made in aqueous solution. The experimental results showed that under the best conditions of high UV photocatalytic reaction 99% decolorization and 95% TOC removal of 20 mg L−1methylene blue could be achieved in 30 s and 120 s of UV irradiation time, respectively. To the best of our knowledge, photocatalytic decolorization and photocatalytic degradation of dyes in such a short time has not been reported. Aiming at the low photonic efficiency in high photon flux photocatalytic process, we found that reducing the density of excited electron-hole appropriately could improve initial apparent photonic efficiency effectively. The TOC experiments under high UV photon flux showed a faster mineralization rate and a different mineralization process compared to that under low UV photon flux.

Synthesis and Optical Properties of Sb-Doped CdS Photocatalysts and Their Use in Methylene Blue (MB) Degradation

2017 ◽  
Vol 15 (2) ◽  
Author(s):  
Irem Firtina Ertis ◽  
Ismail Boz
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Degradation ◽  
Hydrothermal Method ◽  
Irradiation Time ◽  
Chemical Precipitation ◽  
Hexagonal Structure ◽  
Mercury Lamp ◽  
Uv Visible ◽  
Cubic Structure ◽  
Visible Reflectance

Abstract Sb-CdS catalysts with good crystalline structure were prepared by chemical precipitation and hydrothermal method. The results showed that hydrothermal treatment is an effective method to prepare CdS based catalysts of hexagonal structure. Single Sb2S3 catalyst has spherical and Sb doped CdS catalysts have hexagonal structure. Sb doped CdS which is prepared by Na2S with chemical precipitation, has cubic structure. The band gap energies of Sb doped CdS photocatalysts were estimated using UV-visible reflectance spectra to be about the range of 2.35–2.57 eV. In particular, the photoluminescence (PL) spectra show enhancing emission peaks that strongly decrease with a doping Sb where the catalyst was prepared with ethylenediamine (EDA) and thioacetamide (TAA), has shown the lowest luminescence intensity. Photocatalytic degradation of methylene blue was carried out using Sb doped and Sb2S3-CdS binary catalysts under a 400 W medium-pressure mercury lamp of visible light irradiation (λ>420 nm). Higher photocatalytic degradation was achieved by adding Sb to CdS catalyst with using hydrothermal method and EDA as coordinating agent compare with the other catalysts. In this case the photocatalytic degradation of the Sb-CdS-EDA-TAA photocatalyst after 4 h irradiation time was about 84 %.

scholarly journals Influence of Ag Photodeposition Conditions over SERS Intensity of Ag/ZnO Microspheres for Nanomolar Detection of Methylene Blue

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3414
Author(s):  
Luis Zamora-Peredo ◽  
Josué Ismael García-Ramirez ◽  
Amado Carlos García-Velasco ◽  
Julián Hernández-Torres ◽  
Leandro García-González ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Raman Spectroscopy ◽  
Uv Irradiation ◽  
Irradiation Time ◽  
Molar Concentration ◽  
Sers Substrate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nanomolar Detection ◽  
Ag Deposition

Surface enhanced Raman spectroscopy (SERS) is considered a versatile and multifunctional technique with the ability to detect molecules of different species at very low molar concentration. In this work, hierarchical ZnO microspheres (ZnO MSs) and Ag/ZnO MSs were fabricated and decorated by hydrothermal and photodeposition methods, respectively. For Ag deposition, precursor molar concentration (1.9 and 9.8 mM) and UV irradiation time (5, 15, and 30 min) were evaluated by SEM, TEM, X-ray diffraction and Raman spectroscopy. X-ray diffraction showed a peak at 37.9° corresponding to the (111) plane of Ag, whose intensity increases as precursor concentration and UV irradiation time increases. SEM images confirmed the formation of ZnO MSs (from 2.5 to 4.5 µm) building by radially aligned two-dimensional ZnO nanosheets with thicknesses below 30 nm. The Raman spectra of Ag/ZnO MSs exhibited a vibration mode at 486 cm−1 which can be directly associated to Ag deposition on ZnO MSs surface. The performance of SERS substrate was evaluated using rhodamine 6G. The SERS substrate grown at 9.8 mM during 30 min showed the best SERS activity and the ability to detect methylene blue at 10−9 M.

Detoxification of photo-catalytically treated 2-chlorophenol: optimization through response surface methodology

2017 ◽  
Vol 76 (2) ◽  
pp. 323-336 ◽  
Author(s):  
Muhammad Z. Ahamd ◽  
S. Ehtisham-ul-Haque ◽  
Numrah Nisar ◽  
Khizar Qureshi ◽  
Abdul Ghaffar ◽  
...  
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Uv Irradiation ◽  
Irradiation Time ◽  
Oxygen Demand ◽  
Quadratic Model ◽  
Coefficient Of Determination ◽  
Process Variables ◽  
Treatment Efficiency ◽  
Toc Removal

The present study was conducted to degrade and detoxify 2-chlorophenol (2-CP) under UV irradiation in the presence of titanium dioxide (TiO2) and hydrogen peroxide (H2O2). The treatment efficiency was evaluated on the basis of degradation and cytotoxicity reduction as well as biochemical oxygen demand (BOD), chemical oxygen demand (COD) and total organic carbon (TOC) removal. The process variables such as TiO2, pH, UV irradiation time and H2O2 were optimized. Central composite design in combination with response surface methodology was employed to optimize the process variables. A quadratic model was proposed to predict the treatment efficiency and analysis of variance was used to determine the significance of the variables. The correlation between the experimental and predicted degradation was confirmed by the F and P values (<0.05). The coefficient of determination (R2 = 0.99) were high enough to support the validity of developed model. At optimized conditions, up to 92% degradation of 2-CP was achieved with 3.5 × 10−4 s−1 rate constant. Significant reductions in BOD, COD and TOC values were also achieved. Cytotoxicity was evaluated using bioassays and it was observed that UV/TiO2/H2O2 reduced the cytotoxicity considerably. It is concluded that UV/TiO2/H2O2 could possibly be used to detoxify 2-CP in industrial wastewater.

Photocatalytic degradation of dyes on a magnetically separated photocatalyst under visible and UV irradiation

Chemosphere ◽  
2001 ◽  
Vol 44 (5) ◽  
pp. 1159-1168 ◽  
Author(s):  
Feng Chen ◽  
Yinde Xie ◽  
Jincai Zhao ◽  
Gongxuan Lu
Keyword(s):  
Photocatalytic Degradation ◽  
Uv Irradiation ◽  
Degradation Of Dyes

scholarly journals Immobilised rGO/TiO2 Nanocomposite for Multi-Cycle Removal of Methylene Blue Dye from an Aqueous Medium

2021 ◽  
Vol 12 (1) ◽  
pp. 385
Author(s):  
Martina Kocijan ◽  
Lidija Ćurković ◽  
Igor Bdikin ◽  
Gonzalo Otero-Irurueta ◽  
María J. Hortigüela ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Degradation ◽  
Aqueous Medium ◽  
High Efficiency ◽  
Irradiation Time ◽  
Titanium Isopropoxide ◽  
Solar Irradiation ◽  
Blue Dye ◽  
Tio2 Nps ◽  
Coating Method

This work presents the immobilisation of titanium dioxide (TiO2) nanoparticles (NPs) and reduced graphene oxide (rGO)-TiO2 nanocomposite on glass sheets for photocatalytic degradation of methylene blue (MB) under different radiation sources such as ultraviolet and simulated solar radiation. The TiO2 NPs and rGO-TiO2 nanocomposite were synthesised through a simple hydrothermal method of titanium isopropoxide precursor followed by calcination treatment. Deposition of prepared photocatalysts was performed by spin-coating method. Additionally, ethylene glycol was mixed with the prepared TiO2 NPs and rGO-TiO2 nanocomposite to enhance film adhesion on the glass surface. The photocatalytic activity under ultraviolet and simulated solar irradiation was examined. Further, the influence of different water matrices (milli-Q, river, lake, and seawater) and reactive species (h+, •OH, and e−) on the photocatalytic efficiency of the immobilised rGO/TiO2 nanocomposite was careful assessed. MB dye photocatalytic degradation was found to increase with increasing irradiation time for both irradiation sources. The immobilisation of prepared photocatalysts is very convenient for environment applications, due to easy separation and reusability, and the investigated rGO/TiO2-coated glass sheets demonstrated high efficiency in removing MB dye from an aqueous medium during five consecutive cycles.

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