scholarly journals Photochemical Degradation of Cyanides and Thiocyanates from an Industrial Wastewater

Molecules ◽  
2019 ◽  
Vol 24 (7) ◽  
pp. 1373 ◽  
Author(s):  
Juan Jose Viña Mediavilla ◽  
Begoña Fernandez Perez ◽  
Maria C. Fernandez de Cordoba ◽  
Julia Ayala Espina ◽  
Conchi O. Ania
Keyword(s):  
Uv Light ◽  
Degradation Mechanism ◽  
Industrial Effluents ◽  
Photochemical Oxidation ◽  
Solar Light ◽  
Photochemical Degradation ◽  
Simulated Solar Light ◽  
Cyanide Detoxification ◽  
Detoxification Systems ◽  
Recombination Reactions

We have explored the simultaneous degradation of cyanides and thiocyanate present in wastewaters from a cokemaking factory using photoassisted methods under varied illumination conditions (from simulated solar light to UV light). Overall, the photochemical degradation of cyanides was more efficient than that of thiocyanates, regardless of the illumination conditions, the effect being more pronounced in the absence of a photocatalyst. This is due to their different degradation mechanism that in the case of thiocyanates is dominated by fast recombination reactions and/or charge transfer reactions to electron scavengers. In all cases, cyanate, ammonia, nitrates, and nitrites were formed at different amounts depending on the illumination conditions. The conversion yield under simulated solar light was almost complete for cyanides and quite high for thiocyanates after 6 h of illumination. Regarding toxicity, photochemical oxidation at 254 nm and under simulated solar light decreased significantly the toxicity of the pristine wastewater, showing a correlation with the intensity of the irradiation source. This indicate that simulated light can be effectively used to reduce the toxicity of industrial effluents, opening an interesting perspective for optimizing cyanide detoxification systems based on natural light.

Photocatalytic Discolouration of Solutions of Reactive Dyes in the Presence of H2O2

1995 ◽  
Vol 30 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Deng Nansheng ◽  
Tian Shizhong ◽  
Xia Mei
Keyword(s):  
Photochemical Reaction ◽  
Uv Light ◽  
Reactive Dyes ◽  
Solar Light ◽  
Rate Equations ◽  
Oh Radical ◽  
Test Results ◽  
Dye Molecules ◽  
First Order ◽  
Dye Solutions

Abstract Tests for the photocatalytic degradation of solutions of three reactive dyes, Red M-5B, Procion Blue MX-R and Procion Black H-N, in the presence of H2O2 were carried out. When the solutions of the three reactive dyes were irradiated by UV or solar light, the colour of the solutions disappeared gradually. A statistical analysis of the test results indicated a linear relation between the concentration of dyes and the time of irradiation. The discolouration reaction of the solutions was of the first order. Rate equations for the discolouration reactions of dye solutions were developed. The dark reactions or the dye solutions containing H2O2 were very slow, illustrating that the photochemical reaction played a very important role. It was demonstrated that UV light and solar light (300 to 380 nm) photolyzes the HO and that the resulting OH radical reacts with the dye molecules and destroys the chromophore.

scholarly journals TiO2-carbon microspheres as photocatalysts for effective remediation of pharmaceuticals under simulated solar light

2021 ◽  
pp. 119169
Author(s):  
Manuel Peñas-Garzón ◽  
Wael H.M. Abdelraheem ◽  
Carolina Belver ◽  
Juan J. Rodriguez ◽  
Jorge Bedia ◽  
...  
Keyword(s):  
Solar Light ◽  
Carbon Microspheres ◽  
Simulated Solar Light

scholarly journals Titanium Nitride Nanodonuts Synthesized from Natural Ilmenite Ore as a Novel and Efficient Thermoplasmonic Material

Nanomaterials ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 76
Author(s):  
Thanh-Lieu Thi Le ◽  
Lam Tan Nguyen ◽  
Hoai-Hue Nguyen ◽  
Nguyen Van Nghia ◽  
Nguyen Minh Vuong ◽  
...  
Keyword(s):  
Titanium Nitride ◽  
Low Cost ◽  
Visible Region ◽  
Resonance Absorption ◽  
Solar Light ◽  
Localized Surface Plasmon ◽  
Water Evaporation ◽  
Energy Applications ◽  
Simulated Solar Light ◽  
New Class

Nanostructures of titanium nitride (TiN) have recently been considered as a new class of plasmonic materials that have been utilized in many solar energy applications. This work presents the synthesis of a novel nanostructure of TiN that has a nanodonut shape from natural ilmenite ore using a low-cost and bulk method. The TiN nanodonuts exhibit strong and spectrally broad localized surface plasmon resonance absorption in the visible region centered at 560 nm, which is well suited for thermoplasmonic applications as a nanoscale heat source. The heat generation is investigated by water evaporation experiments under simulated solar light, demonstrating excellent solar light harvesting performance of the nanodonut structure.

scholarly journals Fabrication of AQ2S/GR composite photosensitizer for the simulated solar light-driven degradation of Sulfapyridine

2021 ◽  
pp. 100111
Author(s):  
Shuang-Yang Zhao ◽  
Cheng-Xin Chen ◽  
Jie Ding ◽  
Shan-Shan Yang ◽  
Ya-Ni Zang ◽  
...  
Keyword(s):  
Solar Light ◽  
Simulated Solar Light

Activation and β-FeOOH modification of sepiolite in one-step hydrothermal reaction and its simulated solar light catalytic reduction of Cr(VI)

2017 ◽  
Vol 135 ◽  
pp. 547-553 ◽  
Author(s):  
Zhihui Xu ◽  
Hongmei Jiang ◽  
Yaqun Yu ◽  
Jiangyan Xu ◽  
Jianru Liang ◽  
...  
Keyword(s):  
Hydrothermal Reaction ◽  
Catalytic Reduction ◽  
Solar Light ◽  
Simulated Solar Light ◽  
One Step

scholarly journals Investigation of the β-pinene photooxidation by OH in the atmosphere simulation chamber SAPHIR

2016 ◽  
Author(s):  
Martin Kaminski ◽  
Hendrik Fuchs ◽  
Ismail-Hakki Acir ◽  
Birger Bohn ◽  
Theo Brauers ◽  
...  
Keyword(s):  
Degradation Mechanism ◽  
Degradation Process ◽  
Product Distribution ◽  
High Reactivity ◽  
Oxidation Products ◽  
Chemical Mechanism ◽  
Emission Rates ◽  
Photochemical Degradation ◽  
Atmosphere Simulation Chamber ◽  
Simulation Chamber

Abstract. Beside isoprene, monoterpenes are the non-methane volatile organic compounds (VOC) with the highest global emission rates. Due to their high reactivity towards OH, monoterpenes can dominate the radical chemistry of the atmosphere in forested areas. In the present study the photochemical degradation mechanism of β-pinene was investigated in the Jülich atmosphere simulation chamber SAPHIR. The focus of this study is on the OH budget in the degradation process. Therefore the SAPHIR chamber was equipped with instrumentation to measure radicals (OH, HO2, RO2), the total OH reactivity, important OH precursors (O3, HONO, HCHO), the parent VOC beta-pinene, its main oxidation products, acetone and nopinone, and photolysis frequencies. All experiments were carried out under low NOx conditions (≤ 2 ppb) and at atmospheric beta-pinene concentrations (≤ 5 ppb) with and without addition of ozone. For the investigation of the OH budget, the OH production and destruction rates were calculated from measured quantities. Within the limits of accuracy of the instruments, the OH budget was balanced in all β-pinene oxidation experiments. However, even though the OH budget was closed, simulation results from the Master Chemical Mechanism 3.2 showed that the OH production and destruction rates were underestimated by the model. The measured OH and HO2 concentrations were underestimated by up to a factor of two whereas the total OH reactivity was slightly overestimated because of the poor reproduction of the measured nopinone by the model by up to a factor of three. A new, theory-derived first-generation product distribution by Vereecken and Peeters was able to reproduce the measured nopinone time series and the total OH reactivity. Nevertheless the measured OH and HO2 concentrations remained underestimated by the numerical simulations. These observations together with the fact that the measured OH budget was closed suggest the existence of unaccounted sources of HO2.

Charge separation and ROS generation on tubular sodium titanates exposed to simulated solar light

2019 ◽  
Vol 470 ◽  
pp. 1053-1063 ◽  
Author(s):  
Silviu Preda ◽  
Crina Anastasescu ◽  
Ioan Balint ◽  
Polona Umek ◽  
Melita Sluban ◽  
...  
Keyword(s):  
Charge Separation ◽  
Solar Light ◽  
Ros Generation ◽  
Simulated Solar Light

scholarly journals One-step synthesis of OH-TiO 2 /TiOF 2 nanohybrids and their enhanced solar light photocatalytic performance

2018 ◽  
Vol 5 (6) ◽  
pp. 172005 ◽  
Author(s):  
Chentao Hou ◽  
Wenli Liu
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Performance ◽  
Performance Enhancement ◽  
Hydrothermal Process ◽  
Emission Spectra ◽  
Solar Light ◽  
Dominant Factor ◽  
Simulated Solar Light ◽  
Transmission Electron ◽  
Naoh Treatment

TiO 2 /TiOF 2 nanohybrids were quickly synthesized through a hydrothermal process using titanium n-butoxide (TBOT), ethanol (C 2 H 5 OH) and hydrofluoric acid as precursors. The prepared nanohybrids underwent additional NaOH treatment (OH-TiO 2 /TiOF 2 ) to enhance their photocatalytic performance. In this paper, the mechanism of NaOH affecting the pathway of transformation from TBOT (Ti precursor) to TiO 2 nanosheets was discussed. The synthesized TiO 2 /TiOF 2 and OH-TiO 2 /TiOF 2 were characterized by field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction pattern (XRD), Fourier infrared spectroscopic analysis (FT-IR), Photoluminescence (PL) emission spectra and UV–visible diffuse reflection spectra (UV–vis DRS). The photocatalytic activity and stability of synthesized samples were evaluated by degradation of methylene blue (MB) under the simulated solar light. The results showed that a larger ratio of TiO 2 to TiOF 2 in TiO 2 /TiOF 2 and OH-TiO 2 /TiOF 2 nanohybrids could allow for even higher MB conversion compared with only TiO 2 nanosheets. NaOH treatment can wash off the F ions from TiOF 2 and induce this larger ratio. The highest efficiency of MB removal was just above 90% in 1 h. Lower electron–hole pairs recombination rate is the dominant factor that induces the photocatalytic performance enhancement of TiO 2 /TiOF 2 nanohybrids. The synthesized OH-TiO 2 /TiOF 2 nanohybrids exhibit great potential in the abatement of organic pollutants.

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