Photocatalytic oxidation and subsequent adsorption characteristics of humic acids

1996 ◽  
Vol 34 (9) ◽  
pp. 65-72 ◽  
Author(s):  
Miray Bekbölet ◽  
Ferhan Çeçen ◽  
Gülhan Özkösemen
Keyword(s):  
Activated Carbon ◽  
Humic Acid ◽  
Humic Acids ◽  
Photocatalytic Oxidation ◽  
Irradiation Time ◽  
Batch Reactor ◽  
Freundlich Isotherm ◽  
Oxidation Products ◽  
Adsorption Characteristics ◽  
Significant Change

Effect of TiO2 photocatalyzed oxidation on the degradation and decolorization of humic acids was studied. The photocatalytic oxidation products were further investigated in terms of adsorptivity on activated carbon. With photocatalytic oxidation in a lab-scale batch reactor significant decolorization and a decrease in UV280 and UV254 took place. Simultaneously there was a decrease in TOC and COD. Parallel to this an evolution of BOD5 was observed. Thus the BOD5/COD ratio increased with irradiation time and more biodegradable substances have been formed. A significant change in the structure of compounds in humic acid took place only after 3-4 hours of irradiation as determined by the decrease in COD/TOC ratio. Generally there was a slight decrease of adsorptivity after irradiation as concluded from the comparison of Freundlich isotherm constants for raw and irradiated humic acid. This decrease increased as the irradiation time increased. But for irradiation times to be used in practice in photocatalytic oxidation no significant change in adsorption is expected.

scholarly journals Effect of partial oxidation by ozonation on the photocatalytic degradation of humic acids

2003 ◽  
Vol 5 (2) ◽  
pp. 75-80 ◽  
Author(s):  
Aslihan Kerc ◽  
Miray Bekbolet ◽  
Ahmet Mete Saatci
Keyword(s):  
Humic Acid ◽  
Photocatalytic Degradation ◽  
Humic Acids ◽  
Partial Oxidation ◽  
Photocatalytic Oxidation ◽  
Natural Waters ◽  
Adsorption Model ◽  
Pseudo First Order Reaction ◽  
Adsorption Characteristics ◽  
Degradation Rates

In this study humic acids, which are known to be a heterogeneous group of organic macromolecules found in natural waters, were oxidized using ozonation and photocatalysis in a sequential system. Ozonation was employed for achieving partial oxidation of humic acids prior to photocatalytic oxidation. Degradation of humic acid was explained by using pseudo first order reaction rate model based on UV-vis measurements. An improvement was achieved in the photocatalytic degradation rates with respect to the degree of pre-oxidation by ozonation. Due to the surface oriented nature of photocatalysis, adsorption characteristics of partially oxidized humic acid samples onTiO2photocatalyst were evaluated by the application of the Freundlich adsorption model. The photocatalytic degradation rates did not correlate well with the dark adsorption characteristics of the pre-ozonated as well as untreated humic acid samples.

Effects of oxidative treatment techniques on molecular size distribution of humic acids

2004 ◽  
Vol 49 (4) ◽  
pp. 7-12 ◽  
Author(s):  
A. Kerc ◽  
M. Bekbolet ◽  
A.M. Saatci
Keyword(s):  
Humic Acid ◽  
Size Distribution ◽  
Humic Acids ◽  
Photocatalytic Oxidation ◽  
Irradiation Time ◽  
Molecular Size ◽  
Treatment Techniques ◽  
Degradation Rates ◽  
Distribution Ranges ◽  
Molecular Size Distribution

In this study ultrafiltration has been used for the fractionation of humic acid samples. Humic acids were treated in a sequential oxidation system in which ozonation was followed by photocatalytic oxidation using TiO2. Evaluation of the spectroscopic characteristics of the oxidized and fractionated humic acid samples have shown that molecular size distribution ranges shift to lower molecular sizes depending on the oxidation stages. Applied ozone dosage and irradiation time during the photocatalysis stage are the factors affecting the molecular size distribution in the treated humic acid samples. Formation of lower molecular weight compounds during the ozonation stage resulted in increased degradation rates during the photocatalysis stage.

scholarly journals Adsorption Characteristics of Humic Acids by Granular Activated Carbon

1997 ◽  
Vol 15 (7) ◽  
pp. 507-516 ◽  
Author(s):  
S.H. Lin ◽  
C.M. Lin
Keyword(s):  
Activated Carbon ◽  
Humic Acid ◽  
Surface Diffusion ◽  
Humic Acids ◽  
Granular Activated Carbon ◽  
Model Parameters ◽  
Adsorption System ◽  
Transfer Resistance ◽  
Liquid Phase Mass Transfer ◽  
Continuous Adsorption

The adsorption of humic acids on granular activated carbon has been investigated. A commerically available humic acid and that extracted from the bottom sludge of a dam were employed in the studies. Both batch and continuous adsorption experiments were conducted. A simplified competitive adsorption model in conjunction with the Freundlich isotherm was employed to represent the batch multicomponent adsorption system and a homogeneous surface diffusion model utilized to describe the continuous adsorption system in a packed-bed column. The model parameters were obtained by best fit of the models to the experimental adsorption data. The results indicated that the liquid-phase mass-transfer resistance, surface diffusion coefficient and the amount of adsorption on the activated carbon decreased with increasing molecular weight of the humic acid. It was also found that the adsorption of humic acid on the activated carbon was primarily a surface diffusion-controlled process.

scholarly journals TiO2Photocatalyst Nanoparticle Separation: Flocculation in Different Matrices and Use of Powdered Activated Carbon as a Precoat in Low-Cost Fabric Filtration

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Carlos F. Liriano-Jorge ◽  
Ugur Sohmen ◽  
Altan Özkan ◽  
Holger Gulyas ◽  
Ralf Otterpohl
Keyword(s):  
Activated Carbon ◽  
Humic Acid ◽  
Photocatalytic Oxidation ◽  
Low Cost ◽  
Powdered Activated Carbon ◽  
Widespread Application ◽  
Fabric Filter ◽  
Nanoparticle Separation ◽  
Ph Range ◽  
The Impact

Separation of photocatalyst nanoparticles is a problem impeding widespread application of photocatalytic oxidation. As sedimentation of photocatalyst particles is facilitated by their flocculation, the influence of common constituents of biologically pretreated wastewaters (NaCl, NaHCO3, and their combination with humic acid sodium salt) on flocculation was tested by the pipet method. Results showed that the impact of these substances on TiO2nanoparticle flocculation is rather complex and strongly affected by pH. When humic acid was present, TiO2particles did not show efficient flocculation in the neutral and slightly basic pH range. As an alternative to photocatalyst separation by sedimentation, precoat vacuum filtration with powdered activated carbon (PAC) over low-cost spunbond polypropylene fabrics was tested in the presence of two PAC types in aqueous NaCl and NaHCO3solutions as well as in biologically treated greywater and in secondary municipal effluent. PAC concentrations of≥2 g/L were required in order to achieve a retention of nearly 95% of the TiO2nanoparticles on the fabric filter when TiO2concentration was 1 g/L. Composition of the aqueous matrix and PAC type had a slight impact on precoat filtration. PAC precoat filtration represents a potential pretreatment for photocatalyst removal by micro- or ultrafiltration.

scholarly journals The influence of ozonation on the activated carbon adsorption of phenol and humic acid

2007 ◽  
Vol 9 (4) ◽  
pp. 107-110 ◽  
Author(s):  
Bożena Seredyńska-Sobecka ◽  
Maria Tomaszewska
Keyword(s):  
Activated Carbon ◽  
Humic Acid ◽  
Oxygen Demand ◽  
Freundlich Isotherm ◽  
Model Solution ◽  
Activated Carbon Adsorption ◽  
Phenol Adsorption ◽  
Isotherm Equation ◽  
Carbon Adsorption

The influence of ozonation on the activated carbon adsorption of phenol and humic acid To study the influence of ozonation on the activated carbon adsorption, a model solution containing approximately 8 mg/dm3 of humic acid and approximately 1 mg/dm3 of phenol has been ozonated, and then adsorption kintetics and adsorption isotherm experiments have been performed. The applied ozone doses ranged from 1 to 3 mg O3/dm3, and a contact time was 1 min. In the adsorption experiments, the commercial activated carbon CWZ-30 (Gryfskand Sp. z o.o., Hajnówka, Poland) has been used. Phenol adsorption under equilibrium conditions was determined by the Freundlich isotherm equation, and the modified Freudlich isotherm equation has been employed for the determination of humic acid equilibrium adsorption. The applied oxidation conditions resulted in color, chemical oxygen demand (COD), total organic carbon (TOC) and UV254 absorbance removal, by 4 - 13%, 3 - 6%, 3 - 7%, respectively. After ozonation, phenol concentration decreased by 6 - 23%. These changes in the model solution did not affect the humic acid adsorption, however, they deteriorated phenol adsorption.

scholarly journals COMPARATIVE CHARACTERISTICS OF SORPTION ACTIVITY OF SAMPLES OF NATIVE HUMIC ACID AND SOME ENTEROSORBENTS

2021 ◽  
pp. 45-55
Author(s):  
Татьяна Александровна Корельская ◽  
Екатерина Александровна Журавлева ◽  
Елена Анатольевна Айвазова ◽  
Наталья Алнксандровна Онохина
Keyword(s):  
Activated Carbon ◽  
Humic Acid ◽  
Humic Acids ◽  
Binding Activity ◽  
Lead Ions ◽  
Lead Ion ◽  
Sorption Activity ◽  
Rate Of Absorption ◽  
Functional Features ◽  
High Lead

В работе приведен сравнительный анализ сорбционных свойств гуминовых кислот, выделенных из верхового торфа Архангельской области и некоторых энтеросорбентов (активированный уголь, полисорб и фильтрум-СТИ) по отношению к ионам Pb и Zn. Структурно-функциональные особенности гуминовых кислот определяют их высокую связывающую активность и прочность связывания Pb, а также достаточно высокую селективность к Zn. На основании полученных результатов, делается вывод о перспективности разработки и применения препаратов на основе гуминовых кислот в качестве энтеросорбентов. The paper presents a comparative analysis of the sorption properties of humic acids isolated from the top peat of the Arkhangelsk region and some enterosorbents (activated carbon, polysorb, and filtrum) with respect to Pbions. The structural and functional features of humic acids determine their high lead-binding activity and the binding strength of the lead ion, which is indicated by the maximum values of the calculated constants Г∞ and K. It is shown that the degree of affinity of the Filtrum preparation to lead ions is higher than that for humic acids and other sorbents. The highest rate of absorption of lead ions was found for activated carbon and humic acids. Based on the results obtained, it is concluded that the development and use of humic acid-based drugs as enterosorbents used in acute lead poisoning is promising.

Photocatalytic Oxidation of Glycerol over ZnO: Systematic Evaluation of Reaction Parameters

2015 ◽  
Vol 18 (2) ◽  
Author(s):  
Natanael A. Hermes ◽  
André R. Corsetti ◽  
Amise S. Pacheco ◽  
Marla A. Lansarin
Keyword(s):  
Photocatalytic Oxidation ◽  
Batch Reactor ◽  
Oxidation Products ◽  
Biodiesel Production ◽  
Systematic Evaluation ◽  
Main Reaction ◽  
Significant Variable ◽  
Reaction Parameters ◽  
Glycerol Conversion ◽  
Optimum Result

AbstractPhotocatalytic oxidation of glycerol emerges as a potential alternative to contribute to the utilization of surplus glycerol from biodiesel production. In this work, we studied the main reaction parameters for ZnO, i.e. catalyst concentration (Ccat), initial pH and temperature (T), evaluating their influence on the conversion, selectivity and yield of the main C3 products (glyceraldehyde - GAD and dihydroxyacetone - DHA). The tests were carried out in a batch reactor (slurry) under UV radiation. The oxidation products were analysed by HPLC. When the parameters were varied individually, glycerol conversion and C3 yield increased with the increase in Ccat, pH and T, but C3 selectivity remained practically unchanged. When the parameters were varied simultaneously in a design of experiments, again the conversion increased as the parameters increased, whereby pH was the most significant variable for conversion and T for the selectivity of both GAD and DHA. The optimum result for conversion after 1h was 65%, achieved at Ccat = 4 g L

Photocatalytic oxidation technology for humic acid removal using a nano-structured TiO2/Fe2O3 catalyst

2003 ◽  
Vol 47 (1) ◽  
pp. 211-217 ◽  
Author(s):  
S. Qiao ◽  
D.D. Sun ◽  
J.H. Tay ◽  
C. Easton
Keyword(s):  
Humic Acid ◽  
Acid Concentration ◽  
Humic Acids ◽  
Photocatalytic Oxidation ◽  
Ph Value ◽  
Bet Surface Area ◽  
Catalyst Loading ◽  
Temperature Sensitive ◽  
Illumination Time ◽  
Nano Size

A novel TiO2 coated haematite photocatalyst was prepared and used for removal of colored humic acids from wastewater in an UV bubble photocatalytic reactor. XRD analysis confirmed that nano-size anatase crystals of TiO2 were formed after calcination at 480°C. SEM results revealed that nano-size particles of TiO2 were uniformly coated on the surface of Fe2O3 to form a bulk of nano-structured photocatalyst Fe2O3/TiO2. The porous catalyst had a BET surface area of 168 m2/g. Both the color and total organic carbon (TOC) conversion versus the residence time were measured at various conditions. The effects of pH value, catalyst loaded, initial humic acid concentration and reaction temperature on conversion were monitored. The experimental results proved that the photocatalytic oxidation process was not temperature sensitive and the optimum catalyst loading was found to be 0.4 g/l. Degradation and decolorization of humic acids have higher efficiency in acidic medium and at low initial humic acid concentration. The new catalyst was effective in removing TOC at 61.58% and color400 at 93.25% at 180 minutes illumination time and for 20 mg/l neutral humic acid aqueous solution. The kinetic analysis showed that the rate of photocatalytic degradation of humic acids obeyed the first order reaction kinetics.

scholarly journals EXTRACTION OF HUMIC ACID BY ALKALI AND CHELATING RESIN

1972 ◽  
Vol 52 (3) ◽  
pp. 365-374 ◽  
Author(s):  
MARIA ORTIZ DE SERRA ◽  
M. SCHNITZER
Keyword(s):  
Humic Acid ◽  
Humic Acids ◽  
Structural Changes ◽  
Functional Group ◽  
Group Analysis ◽  
Chestnut Soil ◽  
Oxidation Products ◽  
Chelating Resin ◽  
Spectroscopic Methods ◽  
Permanganate Oxidation

Humic acid was extracted from the A1 horizon of a Dark Chestnut soil (pH = 6.9) with 0.5 N NaOH after decalcification and with Na-Dowex A-1 resin without decalcification. The two humic acids were characterized by chemical and spectroscopic methods and by permanganate oxidation after methylation. Whereas ultimate, functional group, and infrared analyses showed the two humic acids to be very similar, permanganate oxidation indicated a number of differences between the two preparations. The yield of oxidation products from the resin-extracted humic acid was twice as high as that from the alkali-extracted material. In addition, the resin-extracted humic acid produced appreciably larger amounts of high-molecular weight phenolic and benzenecarboxylic acids than did the alkali-extracted humic acid. These findings, in conjunction with E4/E6 ratios, indicated that the chelating resin-extracted humic acid was more condensed or less degraded than that removed by alkali. Permanganate oxidation of methylated humic substances appears to be a more sensitive technique for uncovering structural changes in such materials than are functional group analysis and spectroscopic methods.

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