Photocatalytic oxidation of aquatic humic substances using TiO2/UV in a rotating photoreactor

2006 ◽  
Vol 6 (2) ◽  
pp. 93-99
Author(s):  
I. Han ◽  
J.W. Shin ◽  
H.C. Kim
Keyword(s):  
Humic Substances ◽  
Uv Irradiation ◽  
Photocatalytic Oxidation ◽  
Tio2 Photocatalysts ◽  
Photocatalytic Reactor ◽  
Han River ◽  
Humic Materials ◽  
Air Blowing ◽  
Ft Ir ◽  
Uv Lamps

Applicability of a rotating reactor for photocatalytic oxidation of humic substances extracted from the Han River in Seoul, Korea (Han-HS) was investigated. Because air blowing for complete dispersion of TiO2 photocatalysts could inhibit ultraviolet (UV)-irradiation between UV lamps and photocatalysts by air bubbles, a rotating photocatalytic reactor with four baffles was used for better UV-irradiation in this study. Han-HS was extracted and treated with UV-irradiation. Because Han-HS is different from other commercial humic materials (e.g. Aldrich Humic acid and International Humic Substance Society NOM), structural spectroscopic analyses were conducted by FT-IR and 13C-NMR. Immobilized TiO2 coated on hollow beads was used to separate and recover the photocatalyst. During two hours of UV-irradiation, absorbance at 254 nm (UV254) and total organic carbon (TOC) content were monitored. Photocatalytic oxidation efficiencies of different wavelengths of UV lamps (254 nm and 352 nm) were also compared and raw and pre-chlorinated waters of the Han River were used to evaluate the applicability for water treatment.

scholarly journals Photocatalytic Oxidation of Gaseous Benzene under 185 nm UV Irradiation

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Haibao Huang ◽  
Xinguo Ye ◽  
Huiling Huang ◽  
Peng Hu ◽  
Lu Zhang ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Uv Irradiation ◽  
Photocatalytic Oxidation ◽  
Air Pollutant ◽  
Benzene Oxidation ◽  
Human Being ◽  
Benzene Removal ◽  
Uv Lamps ◽  
Gaseous Benzene ◽  
Great Harm

Benzene is a toxic air pollutant and causes great harm to human being. Photocatalytic oxidation (PCO) has been frequently studied for benzene removal, however, its PCO efficiency is still very low and the photocatalysts are easy to be deactivated. To improve the efficiency and stability of PCO, UV lamps with partial 185 nm UV irradiation were used to activate photocatalysts (denoted as 185-PCO). Cobalt modified TiO2(Co-TiO2) was developed to improve the PCO activity and eliminate ozone generated from 185 nm UV irradiation. Results show that benzene removal efficiency of PCO with 254 nm UV irradiation (denoted as 254-PCO) is only 2.1% while it was greatly increased to 51.5% in 185-PCO. 185-PCO exhibited superior capacity for benzene oxidation. In the 185-PCO process, much ozone was left in case of TiO2as photocatalysts while it can be nearly eliminated by 1% Co-TiO2.

scholarly journals Bacillus aryabhattai TFG5-mediated synthesis of humic substances from coir pith wastes

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Iniyakumar Muniraj ◽  
Syed Shameer ◽  
Priyadharshini Ramachandran ◽  
Sivakumar Uthandi
Keyword(s):  
Humic Substances ◽  
Copper Ions ◽  
Degradation Products ◽  
Terrestrial Ecosystem ◽  
Wash Water ◽  
Bacillus Aryabhattai ◽  
Coir Pith ◽  
Effective Synthesis ◽  
Ft Ir ◽  
Degree Of Condensation

Abstract Background Humic substances (HS) form the largest proportion among all the constituents of soil organic matter and are a key component of the terrestrial ecosystem. HS plays a multifunctional role in the environment by controlling the biogeochemical carbon cycle, providing nutrients and bio-stimulants for plant growth, and interacting with inorganic and organic pollutants. The rate of formation of HS in soils determines its productivity and carbon sequestration capacity. Enhancement of HS synthesis in the soil through the microbial route not only increases CO2 sequestration but also mitigates the greenhouse gas emissions in the environment. Result In this study, we attempted to understand the mechanism of formation and enhancement of HS from coir pith wastes using the tyrosinase produced by Bacillus aryabhattai TFG5. The bacterium TFG5 isolated from the termite garden produced the tyrosinase (1.34 U mL−1) and laccase (2.1 U mL−1) at 48 h and 60 h of fermentation, respectively. The extracellular tyrosinase from B. aryabhattai TFG5 was designated as TyrB. Homology modeling of TyrB revealed a structure with a predicted molecular mass of 35.23 kDa and two copper ions in the active center with its conserved residues required for the tyrosinase activity. TyrB efficiently transformed and polymerized standard phenols, such as p-cresol, p-hydroxyl benzoic acid, Levo DOPA, and 2,6 DMP, besides transforming free phenols in coir pith wash water (CWW). Additionally, UV–Vis and FT-IR spectra of the degradation products of the coir pith treated with TyrB revealed the formation of HS within 3 days of incubation. Furthermore, the E472/664 ratio of the degradation products revealed a higher degree of condensation of the aromatic carbons and the presence of more aliphatic structures in the HS. Conclusion The results confirmed the influence of TyrB for the effective synthesis of HS from coir pith wastes. The results of the present study also confirm the recently accepted theory of humification proposed by the International Humic Substances Society.

scholarly journals Modified-TiO2 Photocatalyst Supported on β-SiC Foams for the Elimination of Gaseous Diethyl Sulfide as an Analog for Chemical Warfare Agent: Towards the Development of a Photoreactor Prototype

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 403
Author(s):  
Armelle Sengele ◽  
Didier Robert ◽  
Nicolas Keller ◽  
Valérie Keller
Keyword(s):  
Photocatalytic Oxidation ◽  
Chemical Warfare Agents ◽  
Chemical Warfare Agent ◽  
Chemical Warfare ◽  
Diethyl Sulfide ◽  
Tio2 Photocatalysts ◽  
Doped Tio2 ◽  
Model Molecule ◽  
Warfare Agents ◽  
Oxidation Efficiency

In the context of the increase in chemical threat due to warfare agents, the development of efficient methods for destruction of Chemical Warfare Agents (CWAs) are of first importance both for civilian and military purposes. Amongst possible methods for destruction of CWAs, photocatalytic oxidation is an alternative one. The present paper reports on the preparation of Ta and Sn doped TiO2 photocatalysts immobilized on β-SiC foams for the elimination of diethyl sulfide (DES) used as a model molecule mimicking Yperite (Mustard Gas) in gaseous phase. Photo-oxidation efficiency of doped TiO2 catalyst has been compared with TiO2-P25. Here, we demonstrate that the Sn doped-TiO2 with a Polyethylene glycol (PEG)/TiO2 ratio of 7 exhibits the best initial activity (up to 90%) but is deactivates more quickly than Ta doped-TiO2 (40% after 800 min). The activity of the catalysts is strongly influenced by the adsorption properties of the support, as β-SiC foams adsorb DES and other sulfur compounds. This adsorption makes it possible to limit the poisoning of the catalysts and to maintain an acceptable conversion rate even after ten hours under continuous DES flow. Washing with NaOH completely regenerates the catalyst after a firs treatment and even seems to “wash” it by removing impurities initially present on the foams.

ORGANIC MATTER CHARACTERISTICS OF UNDISTURBED AND CULTIVATED CHERNOZEMIC AND SOLONETZIC A HORIZONS

1979 ◽  
Vol 59 (4) ◽  
pp. 349-356 ◽  
Author(s):  
J. F. DORMAAR
Keyword(s):  
Organic Matter ◽  
Humic Substances ◽  
Chelating Resin ◽  
Anthropogenic Pressures ◽  
Organic C ◽  
Amide Bonds ◽  
Acid Ratio ◽  
Humic Materials ◽  
Fallow System ◽  
Extractable Organic Matter

Under a wheat-fallow system of farming practised on Brown, Dark Brown, and Black Chernozemic soils, on a Black Solodized Solonetz, and on Brown and Black Solods, organic C decreased by as much as 60%; the humic acid/fulvic acid ratio decreased little for the semiarid soils but up to 38% for the Black soils; ethanol/benzene-extractable organic matter increased by as much as 330%; chelating resin-extractable C increased by 27–115%; and total acidity of the extracted humic substances increased up to 36%. The ash contents of the humic substances from the Ah horizons were all less than 12%, whereas those of the Ap horizons varied between 20 and 28%. Apparent differences between the infrared spectra of the resin-extractable humic substances of the Ah and Ap horizons existed particularly near 2920 and 1550 cm−1 suggesting less aliphatic C-H and amide bonds. Anthropogenic pressures have wrought, therefore, distinct measurable qualitative changes, i.e., the general trend with cultivation was towards humic materials with a decreased proportion of side chain components, such as C-H and NH2 groups, but increased carboxyl group content.

scholarly journals Ultrafast time-resolved quantum cascade laser diagnostic for revealing the role of surface formate species in the photocatalytic oxidation of methanol

2020 ◽  
Vol 10 (16) ◽  
pp. 5618-5627 ◽  
Author(s):  
Josefine Schnee ◽  
Marco Daturi ◽  
Mohamad El-Roz
Keyword(s):  
Ir Spectroscopy ◽  
Photocatalytic Oxidation ◽  
Time Resolved ◽  
Quantum Cascade ◽  
Oxidation Of Methanol ◽  
Laser Diagnostic ◽  
Surface Formate ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

QCL-assisted operando FT-IR spectroscopy revealed the role of surface formate species in the photocatalytic oxidation of methanol over TiO2.

Effect of Humic Substances on Americium (III) Retention onto Silica

1988 ◽  
Vol 127 ◽  
Author(s):  
Valerie Moulin ◽  
Denise Stammose
Keyword(s):  
Ionic Strength ◽  
Humic Substances ◽  
Safety Assessment ◽  
Natural Waters ◽  
Major Influence ◽  
Liquid Interfaces ◽  
Aquifer Systems ◽  
Humic Materials ◽  
Solid Liquid ◽  
Influence Of Ph

ABSTRACTThe migration/retention phenomena of radionuclides in geological systems are of great interest for the safety assessment of a nuclear disposal. Interactions at solid/liquid interfaces play a significant role in the speculation and transport of radionuclides in aquifer systems. Oxide surfaces and humic substances which occur in natural waters in large concentration ranges (from few mg/1 to several hundred mg/1) may have a major influence on radionuclides behaviour. For this purpose, studies have been carried out on a ternary system: oxide-humic substances-americium (III). The influence of pH, ionic strength and humic concentration on the adsorption of americium onto silica has been investigated. The ionic strength of the solution (0.1 and 0.01) has little effect on the americium adsorption. In the presence of humic materials, the fixation of americium is enhanced at low pH (pH<5) whereas, at higher pH (pH>5), the adsorption is lowered and dependent of humic concentration.

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