Removal of color substances using photocatalytic oxidation for membrane filtration processes

2001 ◽  
Vol 43 (10) ◽  
pp. 319-325 ◽  
Author(s):  
J. H. Tay ◽  
D. Chen ◽  
D. D. Sun
Keyword(s):  
Hydrogen Peroxide ◽  
Membrane Filtration ◽  
Photocatalytic Oxidation ◽  
Removal Rate ◽  
Membrane Surface ◽  
Rejection Rate ◽  
Solution Treated ◽  
Low Concentrations ◽  
Photo Catalytic Oxidation ◽  
Positive Effect

This study aims to remove the color substances, which normally cause difficulties in membrane filtration processes due to fouling using heterogeneous UV/TiO2/H2O2 reactor. It is confirmed that the technique used in this study was effective to remove TOC at 38% and color400 at 89% within 150-min irradiation. The experiment results showed that low concentrations of hydrogen peroxide dosage (less than 0.016 M) to UV/TiO2 system accelerated the TOC and Color400 removal rate from 9% to 38% and 40% to 89% respectively, while over-dosage made this positive effect decline. The humic acid solution treated by photo catalytic oxidation in UV/TiO2/H2O2 reactor did not change the zeta potential on membrane surface and membrane rejection rate.

Photocatalytic Oxidation of Shenfu Bituminous Coal and Xilinhaote Lignite with H2O2 over TiO2

2011 ◽  
Vol 233-235 ◽  
pp. 1684-1689 ◽  
Author(s):  
Heng Shen Xie ◽  
Zhi Min Zong ◽  
Qing Wei ◽  
Pei Zhi Zhao ◽  
Jian Jun Zhao ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Titanium Dioxide ◽  
Catalytic Oxidation ◽  
Photocatalytic Oxidation ◽  
Bituminous Coal ◽  
Straight Chain ◽  
Photo Catalytic Oxidation ◽  
Alkyl Side Chains ◽  
Lignite Coal ◽  
Oxidation Effect

Shenfu bituminous coal (SFBC) and Xilinhaote lignite (XL) were subject to photo-catalytic oxidation with hydrogen peroxide over titanium dioxide. The reaction mixtures were extracted with acetone exhaustively. The extracts were analyzed with FTIR and GC/MS. The results show that coals be oxidized selectively and degraded partially. Compared with the bituminite coal, the oxidation effect of the lignite coal with active hydrogens is more obvious. The alkyl side chains of the macromolecules, particularly, chains of methyl, methylene and aromatic, are the most vulnerable in relation to other compounds in coals. Moreover, the increasing of straight-chain alkanes and the decreasing of condensed nucleus in SFBC and XL through oxidation suggest that the oxidation is an effective method of coal utilization with no difficultly, also be friendly towards the environment after treated as well as in the process of the treatment.

Removal efficiency of an integrated adsorption/photocatalysis system for reducing low concentrations of nitrogen oxides in microenvironments of museums for cultural relics conservation

2016 ◽  
Vol 25 (8) ◽  
pp. 1185-1196 ◽  
Author(s):  
Dawei Wang ◽  
Danian Zhang ◽  
Yan Wu ◽  
Hua Wei ◽  
Jing Luo ◽  
...  
Keyword(s):  
Nitrogen Oxides ◽  
Removal Efficiency ◽  
Photocatalytic Oxidation ◽  
Removal Rate ◽  
Nitrogen Monoxide ◽  
Bamboo Charcoal ◽  
Low Concentrations ◽  
Integrated Device ◽  
Direct Use ◽  
Cultural Relics

Nitrogen oxides (NOx) could pose a threat to the conservation of cultural relics and could also enhance the corrosion induced by other pollutants such as sulphur dioxides and organic acids. The NOx removal rate was studied through a combination of adsorption onto bamboo charcoal and photocatalysis. The integrated NOx removal efficiency by both methods was evaluated in both lab and pilot scales. The studies have shown that the direct use of biomass can remove moderate level of NOx; while higher level of NOx removal was achieved by using bamboo charcoal carbonized at 520℃. The photocatalytic oxidation of NOx was found to be well fit with Langmuir–Hinshelwood model. The different carriers of photocatalysis combined with adsorbents were compared, and the optimised process was shown to reduce the nitrogen monoxide and nitrogen dioxide level to 2.76 and 0.68 µg/m3, respectively, in 20% relative humidity (RH). An integrated device was developed, and the results have demonstrated that the combined technologies of photocatalysis and adsorption can have great removal potential for reducing NOx and therefore in improving the air quality under different RH conditions.

Low-pressure membrane filtration with unconventional coagulation regimes

2005 ◽  
Vol 5 (5) ◽  
pp. 1-8 ◽  
Author(s):  
K.Y. Choi ◽  
B.A. Dempsey
Keyword(s):  
Activated Carbon ◽  
Membrane Filtration ◽  
Membrane Surface ◽  
Cross Flow ◽  
Chemical Cleaning ◽  
Sand Filters ◽  
Charge Neutralization ◽  
Floc Size ◽  
Filtration System ◽  
Pre Treatment

The objective of the research was to evaluate in-line coagulation to improve performance during ultrafiltration (UF). In-line coagulation means use of coagulants without removal of coagulated solids prior to UF. Performance was evaluated by removal of contaminants (water quality) and by resistance to filtration and recovery of flux after hydraulic or chemical cleaning (water production). We hypothesized that coagulation conditions inappropriate for conventional treatment, in particular under-dosing conditions that produce particles that neither settle nor are removed in rapid sand filters, would be effective for in-line coagulation prior to UF. A variety of pre-treatment processes for UF have been investigated including coagulation, powdered activated carbon (PAC) or granular activated carbon (GAC), adsorption on iron oxides or other pre-formed settleable solid phases, or ozonation. Coagulation pre-treatment is often used for removal of fouling substances prior to NF or RO. It has been reported that effective conventional coagulation conditions produced larger particles and this reduced fouling during membrane filtration by reducing adsorption in membrane pores, increasing cake porosity, and increasing transport of foulants away from the membrane surface. However, aggregates produced under sweep floc conditions were more compressible than for charge neutralization conditions, resulting in compaction when the membrane filtration system was pressurized. It was known that the coagulated suspension under either charge-neutralization or sweep floc condition showed similar steady-state flux under the cross-flow microfiltration mode. Another report on the concept of critical floc size suggested that flocs need to reach a certain critical size before MF, otherwise membranes can be irreversibly clogged by the coagulant solids. The authors were motivated to study the effect of various coagulation conditions on the performance of a membrane filtration system.

Coagulation/flocculation/ultrafiltration for natural organic matter removal in drinking water production

2004 ◽  
Vol 4 (5-6) ◽  
pp. 215-222 ◽  
Author(s):  
A.R. Costa ◽  
M.N. de Pinho
Keyword(s):  
Drinking Water ◽  
Organic Matter ◽  
Natural Organic Matter ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Membrane Surface ◽  
Water Production ◽  
Cellulose Acetate Membranes ◽  
Wide Range ◽  
Drinking Water Production

Membrane fouling by natural organic matter (NOM), namely by humic substances (HS), is a major problem in water treatment for drinking water production using membrane processes. Membrane fouling is dependent on membrane morphology like pore size and on water characteristics namely NOM nature. This work addresses the evaluation of the efficiency of ultrafiltration (UF) and Coagulation/Flocculation/UF performance in terms of permeation fluxes and HS removal, of the water from Tagus River (Valada). The operation of coagulation with chitosan was evaluated as a pretreatment for minimization of membrane fouling. UF experiments were carried out in flat cells of 13.2×10−4 m2 of membrane surface area and at transmembrane pressures from 1 to 4 bar. Five cellulose acetate membranes were laboratory made to cover a wide range of molecular weight cut-off (MWCO): 2,300, 11,000, 28,000, 60,000 and 75,000 Da. Severe fouling is observed for the membranes with the highest cut-off. In the permeation experiments of raw water, coagulation prior to membrane filtration led to a significant improvement of the permeation performance of the membranes with the highest MWCO due to the particles and colloidal matter removal.

Arsenic removal by MF membrane with chemical sludge adsorption and NF membrane equipped with vibratory shear enhanced process

2003 ◽  
Vol 3 (5-6) ◽  
pp. 303-310 ◽  
Author(s):  
S.-H. Yi ◽  
S. Ahmed ◽  
Y. Watanabe ◽  
K. Watari
Keyword(s):  
Arsenic Removal ◽  
Membrane Surface ◽  
Membrane Process ◽  
Low Concentrations ◽  
Strong Shear ◽  
Low Levels ◽  
Removal Processes ◽  
Removal Of Arsenic ◽  
Concentration Polarization Layer ◽  
Chemical Sludge

Conventional arsenic removal processes have difficulty removing low concentrations of arsenic ion from water. Therefore, it is very hard to comply with stringent low levels of arsenic, such as below 10 μg/L. So, we have developed two arsenic removal processes which are able to comply with more stringent arsenic regulations. They are the MF membrane process combined with chemical sludge adsorption and NF membrane process equipped with the vibratory shear enhanced process (VSEP). In this paper, we examine the performance of these new processes for the removal of arsenic ion of a low concentration from water. We found that chemical sludge produced in the conventional rapid sand filtration plants can effectively remove As (V) ions of H2AsO4- and HAsO42- through anion exchange reaction. The removal efficiency of MF membrane process combined with chemical sludge adsorption increased to about 36%, compared to MF membrane alone. The strong shear force on the NF membrane surface produced by vibration on the VSEP causes the concentration polarization layer to thin through increased back transport velocity of particles. So, it can remove even dissolved constituents effectively. Therefore, As (V) ions such as H2AsO4- and HAsO42- can be removed. The concentration of As (V) ions decreased from 50 μg/L to below 10 μg/L and condensation factor in recirculating water increased up to 7 times by using NF membrane equipped with VSEP.

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.

Heterogeneous Fenton Catalytic Removal of Organic Pollutant in Aqueous Solution by using Coal Gangue as a Catalyst

2019 ◽  
Vol 12 (4) ◽  
pp. 312-325
Author(s):  
Jiwei Zhang ◽  
Jingjing Xu ◽  
Shuaixia Liu ◽  
Baoxiang Gu ◽  
Feng Chen ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Hydroxyl Radical ◽  
Removal Rate ◽  
Organic Pollutant ◽  
Coal Gangue ◽  
Ion Leakage ◽  
Heterogeneous Fenton ◽  
Solution Ph ◽  
X Ray

Background: Coal gangue was used as a catalyst in heterogeneous Fenton process for the degradation of azo dye and phenol. The influencing factors, such as solution pH gangue concentration and hydrogen peroxide dosage were investigated, and the reaction mechanism between coal gangue and hydrogen peroxide was also discussed. Methods: Experimental results showed that coal gangue has the ability to activate hydrogen peroxide to degrade environmental pollutants in aqueous solution. Under optimal conditions, after 60 minutes of treatment, more than 90.57% of reactive red dye was removed, and the removal efficiency of Chemical Oxygen Demand (COD) up to 72.83%. Results: Both hydroxyl radical and superoxide radical anion participated in the degradation of organic pollutant but hydroxyl radical predominated. Stability tests for coal gangue were also carried out via the continuous degradation experiment and ion leakage analysis. After five times continuous degradation, dye removal rate decreased slightly and the leached Fe was still at very low level (2.24-3.02 mg L-1). The results of Scanning Electron Microscope (SEM), energy dispersive X-Ray Spectrometer (EDS) and X-Ray Powder Diffraction (XRD) indicated that coal gangue catalyst is stable after five times continuous reuse. Conclusion: The progress in this research suggested that coal gangue is a potential nature catalyst for the efficient degradation of organic pollutant in water and wastewater via the Fenton reaction.

scholarly journals Research Progress on Photocatalytic/Photoelectrocatalytic Oxidation of Nitrogen Oxides

2021 ◽  
Author(s):  
Shuangjun Li ◽  
Linglong Chen ◽  
Zhong Ma ◽  
Guisheng Li ◽  
Dieqing Zhang
Keyword(s):  
Nitrogen Oxides ◽  
Photocatalytic Oxidation ◽  
Research Progress ◽  
Future Directions ◽  
Inorganic Semiconductors ◽  
Photoelectrocatalytic Oxidation ◽  
Low Concentrations ◽  
Photocatalytic System ◽  
Metal Organic ◽  
Oxidation Of No

AbstractThe emission of nitrogen oxides (NOx) increases year by year, causing serious problems to our livelihoods. The photocatalytic oxidation of NOx has attracted more attention recently because of its efficient removal of NOx, especially for low concentrations of NOx. In this review, the mechanism of the photocatalytic oxidation of NOx is described. Then, the recent progress on the development of photocatalysts is reviewed according to the categories of inorganic semiconductors, bismuth-based compounds, nitrogen carbide polymer, and metal organic frameworks (MOFs). In addition, the photoelectrocatalytic oxidation of NOx, a method involving the application of an external voltage on the photocatalytic system to further increase the removal efficiency of NOx, and its progress are summarized. Finally, we outline the remaining challenges and provide our perspectives on the future directions for the photocatalytic oxidation of NOx.

Evaluation of the effectiveness of skin preparation methods for the reduction of Cutibacterium acnes (formerly Propionibacterium acnes) in shoulder surgery: a systematic review

2021 ◽  
pp. 175857322110325
Author(s):  
Maria Sagkrioti ◽  
Stephen Glass ◽  
Georgios Arealis
Keyword(s):  
Systematic Review ◽  
Hydrogen Peroxide ◽  
Side Effects ◽  
Cost Effective ◽  
Shoulder Surgery ◽  
Skin Preparation ◽  
Preparation Methods ◽  
Cutibacterium Acnes ◽  
Surgery Outcomes ◽  
Positive Effect

Background Cutibacterium acnes ( C. acnes) is the most common pathogen responsible for post-operative shoulder infections. The purpose of this study was to evaluate the effectiveness of skin preparation methods against C. acnes in shoulder surgery. Methods A systematic review was conducted evaluating the effectiveness of skin preparation methods in the reduction of C. acnes in patients undergoing shoulder surgery. Outcomes were assessed based on the effectiveness of the method used; side effects and cost were also analysed. Results Of the 19 included studies, 9 evaluated pre-surgical home treatments: 8 assessed benzoyl peroxide (BPO) and 6 concluded it is effective in reducing C. acnes. Nine studies assessed surgical skin preparation and concluded that Chlorhexidine gluconate (CHG) was not effective; in contrast hydrogen peroxide reduced C. acnes. Finally, one study evaluated an aseptic protocol using CHG and concluded that it was not effective. Conclusions It was demonstrated that BPO as home treatment is effective in reducing C. acnes load on skin ; it rarely causes side effects and is also cost-effective. This study highlights non-effectiveness of CHG. There was some evidence that the addition of hydrogen peroxide could have a positive effect in the reduction of C. acnes skin load; however, more studies are required.

scholarly journals Monitoring the heme iron state in horseradish peroxidase to detect ultratrace amounts of hydrogen peroxide in alcohols

RSC Advances ◽  
2021 ◽  
Vol 11 (17) ◽  
pp. 9901-9910
Author(s):  
Raheleh Ravanfar ◽  
Alireza Abbaspourrad
Keyword(s):  
Hydrogen Peroxide ◽  
Horseradish Peroxidase ◽  
Oxidative Damage ◽  
Heme Iron ◽  
Aqueous Systems ◽  
Iron State ◽  
Low Concentrations

Despite the importance of hydrogen peroxide (H2O2) in initiating oxidative damage and its connection to various diseases, the detection of low concentrations of H2O2 (<10 μM) is still limited using current methods, particularly in non-aqueous systems.

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