scholarly journals Enhanced Solar Photocatalytic Reduction of Hexavalent Chromium in Seawater over Carbon Doped TiO2 Nanoparticles

2018 ◽  
Vol 28 (2) ◽  
pp. 17-26
Author(s):  
Yasser A. Shaban Yasser A. Shaban
Keyword(s):  
Hexavalent Chromium ◽  
Removal Rate ◽  
Reduction Rate ◽  
Pure Tio2 ◽  
Photocatalytic Reduction ◽  
Experimental Conditions ◽  
Carbon Doped ◽  
First Order Kinetics ◽  
Photocatalytic Removal ◽  
Hole Scavenger

The photocatalytic removal of hexavalent chromium Cr(VI) from polluted seawater has been successfully investigated by using carbon doped titanium oxide (CTiO2 ) nanoparticles under irradiation of natural sunlight. The photoactivity of CTiO2 was comparatively evaluated with pure TiO2 under the same experimental conditions. The effects of catalyst dose, initial Cr(VI) concentration and pH were studied and optimized. The highest removal rate was obtained at pH 3 and catalyst dose of 2.0 g L-1 . Furthermore, the existence of hole scavenger remarkably enhanced the reduction rate of Cr(VI). According to Langmuir–Hinshelwood model, the photocatalytic reduction of Cr(VI) using CTiO2 obeyed the pseudo-first-order kinetics

scholarly journals Photocatalytic Reduction of Hexavalent Chromium with Nanosized TiO2 in Presence of Formic Acid

2019 ◽  
Vol 3 (2) ◽  
pp. 33 ◽  
Author(s):  
Jahida Binte Islam ◽  
Mai Furukawa ◽  
Ikki Tateishi ◽  
Hideyuki Katsumata ◽  
Satoshi Kaneco
Keyword(s):  
Titanium Dioxide ◽  
Formic Acid ◽  
Tio2 Nanoparticles ◽  
Hexavalent Chromium ◽  
Oxidation Reaction ◽  
Photocatalytic Reduction ◽  
Nanosized Titanium Dioxide ◽  
Hole Scavenger ◽  
Nanosized Tio2 ◽  
Commercial Tio2

Nanosized titanium dioxide (TiO2) nanoparticles were used for the photocatalytic reduction of hexavalent chromium in the presence of formic acid. The photoreduction of Cr(VI) in the absence of formic acid was quite slow. When formic acid was added in the chromium solution as the hole scavenger, a rapid photocatalytic reduction of Cr(VI) was observed, owing to the consumption of hole and the acceleration of the oxidation reaction. Furthermore, three commercial TiO2 nanoparticles (AEROXIDE® P25; Ishihara Sangyo ST-01; FUJIFILM Wako Pure Chemical Corp.) were evaluated for the photoactivity of reduction of Cr(VI).

scholarly journals Impacts of Mixing Mode on Photocatalytic Reduction of Hexavalent Chromium over Titanium Dioxide Nanomaterial under Various Environmental Conditions

Water ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2291
Author(s):  
Chih-Chi Yang ◽  
Khanh-Chau Dao ◽  
Yo-Sheng Lin ◽  
Teng-Yun Cheng ◽  
Ku-Fan Chen ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Hexavalent Chromium ◽  
Species Distribution ◽  
Uv Light ◽  
Photocatalytic Reduction ◽  
Oxygen Effect ◽  
Strong Interactions ◽  
Nitrogen Gas ◽  
Key Factor ◽  
Hole Scavenger

This study explores the effects of initial Cr(VI) concentration, wavelength, hole-scavenger (absence and presence of salicylic acid), and oxygen conditions (aeration by air, nitrogen gas, and mechanical stir only) on photocatalytic reduction of hexavalent chromium over titanium dioxide photocatalyst and the chromic species distribution after photocatalysis. The experimental results show the existence of strong interactions between these factors. The factor of hole-scavenger was more important than the UV light wavelength condition for a reduction of 3 mg Cr(VI) L−1, whereas both factors became important when Cr(VI) concentration increased to 20 mgL−1. The higher the UV wavelength was, the less the amount of chromium retained on the TiO2 surface. The influence of oxygen-containing conditions in the solution on the reduction of 3 mgL−1 Cr(VI) was unobvious, whereas its influence became remarkable for the reduction of 20 mgL−1 Cr(VI) in the presence of SA. The interaction between oxygen-containing factor and other environmental factors, such as Cr(VI) concentration and scavenger presence (SA in this study), is a key factor about the degree of oxygen effect on Cr(VI) photo-reduction and the chromic species distribution. Simple stirring obtained better photocatalytic efficiency than aeration by air or nitrogen gas.

Biodegradation rates of aromatic contaminants in biofilm reactors

1995 ◽  
Vol 31 (1) ◽  
pp. 117-128 ◽  
Author(s):  
Jean-Pierre Arcangeli ◽  
Erik Arvin
Keyword(s):  
Aromatic Hydrocarbons ◽  
Competitive Inhibition ◽  
Removal Rate ◽  
First Order ◽  
Biofilm Reactors ◽  
First Order Kinetics ◽  
Reducing Conditions ◽  
Low Concentrations ◽  
Degradation Rates ◽  
Order Surface

This study has shown that microorganisms can adapt to degrade mixtures of aromatic pollutants at relatively high rates in the μg/l concentration range. The biodegradation rates of the following compounds were investigated in biofilm systems: aromatic hydrocarbons, phenol, methylphenols, chlorophenols, nitrophenol, chlorobenzenes and aromatic nitrogen-, sulphur- or oxygen-containing heterocyclic compounds (NSO-compounds). Furthermore, a comparison with degradation rates observed for easily degradable organics is also presented. At concentrations below 20-100 μg/l the degradation of the aromatic compounds was typically controlled by first order kinetics. The first-order surface removal rate constants were surprisingly similar, ranging from 2 to 4 m/d. It appears that NSO-compounds inhibit the degradation of aromatic hydrocarbons, even at very low concentrations of NSO-compounds. Under nitrate-reducing conditions, toluene was easily biodegraded. The xylenes and ethylbenzene were degraded cometabolically if toluene was used as a primary carbon source; their removal was influenced by competitive inhibition with toluene. These interaction phenomena are discussed in this paper and a kinetic model taking into account cometabolism and competitive inhibition is proposed.

scholarly journals The Efficient Photocatalytic Degradation of Organic Pollutants on the MnFe2O4/BGA Composite under Visible Light

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1276
Author(s):  
Qian Li ◽  
Xiaoyu Jiang ◽  
Yongfu Lian
Keyword(s):  
Rhodamine B ◽  
Synergetic Effect ◽  
Reaction Rate Constant ◽  
Experimental Conditions ◽  
First Order Kinetics ◽  
Boron Doped ◽  
Fenton Catalyst ◽  
Aerogel Composite ◽  
Doped Graphene ◽  
Apparent Reaction Rate Constant

The MnFe2O4/BGA (boron-doped graphene aerogel) composite was prepared by hydrothermal treatment of MnFe2O4 particles, boric acid, and graphene oxide. When applied as a photo-Fenton catalyst for the degradation of rhodamine B, the MnFe2O4/BGA composite yielded a degradation efficiency much higher than the sum of those of individual MnFe2O4 and BGA under identical experimental conditions, indicating a strong synergetic effect established between MnFe2O4 and BGA. The catalytic degradation of rhodamine B was proved to follow pseudo first-order kinetics, and the apparent reaction rate constant on the MnFe2O4/BGA composite was calculated to be three- and seven-fold that on BGA and MnFe2O4, respectively. Moreover, the MnFe2O4/BGA composite also demonstrated good reusability and could be reused for four cycles without obvious loss of photocatalytic activity.

scholarly journals Degradation of hydroxypropyl guar gum at wide pH range by a heterogeneous Fenton-like process using bentonite-supported Cu(0)

2020 ◽  
Vol 82 (8) ◽  
pp. 1635-1642
Author(s):  
Ling Zhou ◽  
Zhongying Xu ◽  
Jie Zhang ◽  
Zhifang Zhang ◽  
Ying Tang
Keyword(s):  
Active Sites ◽  
Guar Gum ◽  
Heterogeneous Reaction ◽  
Removal Rate ◽  
Catalytic Performance ◽  
High Dispersion ◽  
Application Process ◽  
Experimental Conditions ◽  
Hydroxypropyl Guar ◽  
Hydroxypropyl Guar Gum

Abstract To seek for efficient Fenton-like oxidation processing for treatment of waste fracturing fluid containing hydroxypropyl guar gum (HPGG), in heterogeneous reaction, five bentonite-supported zero-valent metal catalysts were prepared by liquid-phase reduction. The results showed that the bentonite-supported zero-valent copper exhibited best catalytic performance, attributed to the high dispersion of active sites of zero-valent copper. The effects of the most relevant operating factors (H2O2 concentration, catalyst dosage, temperature and pH) were evaluated in detail. Moreover, the chemical oxygen demand removal rate of HPGG can achieve 76% when the reaction time was selected at 45 min under optimal experimental conditions. The stability evaluation showed that the catalytic performance was almost unaffected after the catalyst was recycled and used once more showing the good stability of the bentonite-supported zero-valent copper in the application process.

Zr-Based MOFs as new photocatalysts for the rapid reduction of Cr(vi) in water

2020 ◽  
Vol 44 (17) ◽  
pp. 7218-7225 ◽  
Author(s):  
Haimei Xie ◽  
Duomou Ma ◽  
Wanyan Liu ◽  
Qian Chen ◽  
Yong Zhang ◽  
...  
Keyword(s):  
Hexavalent Chromium ◽  
Photocatalytic Reduction ◽  
Rapid Reduction

The hydroxyl modified Zr-based MOFs is used for photocatalytic reduction of hexavalent chromium existing in wastewater.

Photocatalytic reduction behavior of hexavalent chromium on hydroxyl modified titanium dioxide

2017 ◽  
Vol 206 ◽  
pp. 293-299 ◽  
Author(s):  
Yali Li ◽  
Yingying Bian ◽  
Hongxia Qin ◽  
Yaxi Zhang ◽  
Zhenfeng Bian
Keyword(s):  
Titanium Dioxide ◽  
Hexavalent Chromium ◽  
Photocatalytic Reduction ◽  
Reduction Behavior

scholarly journals Study on the effect of electrocatalytic oxidation treatment of 2,4,6-Trinitrophenol wastewater

2018 ◽  
Vol 238 ◽  
pp. 03003
Author(s):  
Yaling Li ◽  
Wenqiang Jiang ◽  
Ruyu Li
Keyword(s):  
Current Density ◽  
Electrocatalytic Oxidation ◽  
Electrolyte Concentration ◽  
Removal Rate ◽  
Pharmaceutical Chemical ◽  
Oxidation Treatment ◽  
Titanium Electrode ◽  
First Order Kinetics ◽  
Oxidation Technology ◽  
Aromatic Nitro

2,4,6-Trinitrophenol is a toxic aromatic nitro-compounds that widely used in pharmaceutical, chemical and pesticide production. Due to its stable structure and poor biodegradability, advanced electrocatalytic oxidation technology was selected to treat simulated wastewater. The goal of the present work is to optimize the electrolysis conditions such as current density, electrolysis pH, and electrolyte concentration. A Pt modified TiO2 electrode was chosen as the anode accompanied with a titanium electrode of the same size as the cathode The results showed that the removal efficiency of 2,4,6-Trinitrophenol was the highest when the current density was 20mA/cm2, electrolyte pH=5, electrolyte concentration was 2 g/L. Under the optimal condition, the removal rate of 2,4,6-Trinitrophenol reached 99.76% after 120 minutes electrolysis. The decay of TNP could also be described by the pseudo-first-order kinetics formula with respect to TNP concentration. Therefore, electrocatalytic oxidation technology might provide an effective method for the degradation of nitroaromatic organic compounds.

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