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.

The effect of photocatalytic oxidation on molecular size distribution profiles of humic acid

2015 ◽  
Vol 14 (3) ◽  
pp. 576-582 ◽  
Author(s):  
M. Bekbolet ◽  
S. Sen-Kavurmaci
Keyword(s):  
Humic Acid ◽  
Size Distribution ◽  
Photocatalytic Oxidation ◽  
Molecular Size ◽  
Drastic Change ◽  
Size Fractions ◽  
Excitation Emission Matrix ◽  
Molecular Size Distribution ◽  
Eem Fluorescence

Photocatalytic oxidation leads to a drastic change in excitation emission matrix (EEM) fluorescence features of humic acid molecular size fractions.

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.

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.

Determination of the Size Distribution of Dissolved Organics in Effluents

1973 ◽  
Vol 8 (1) ◽  
pp. 1-15 ◽  
Author(s):  
L.A. Addie ◽  
K.L. Murphy ◽  
J.L. Robertson
Keyword(s):  
Size Distribution ◽  
Biological Treatment ◽  
Oxygen Demand ◽  
Molecular Size ◽  
Monitoring Systems ◽  
Clean Surface ◽  
Sephadex Column ◽  
Dissolved Organics ◽  
Molecular Size Distribution

Abstract The importance of removing the small amounts of residual organics is increasing as the sources of clean surface water decrease. Knowledge of the nature of these soluble residual organics will be needed in order to assess the type of treatment required for their removal. Residual organics in three different biological treatment plants were analyzed and compared. An attempt was made to characterize these organics by a molecular size distribution on a Sephadex column monitored by differential ultraviolet and refractive index detectors. The organic carbon and chemical oxygen demand of the fractions collected from the column was also determined. An investigation of some of the problems inherent in the monitoring systems was conducted.

Molecular Size Distribution of Lignin in Wood

Nature ◽  
1967 ◽  
Vol 214 (5086) ◽  
pp. 410-411 ◽  
Author(s):  
W. BROWN ◽  
S. I. FALKEHAG ◽  
E. B. COWLING
Keyword(s):  
Size Distribution ◽  
Molecular Size ◽  
Molecular Size Distribution

A Study of the Malpighian Tubules of the Pill Millipede, Glomeris marginata (Villers)

1974 ◽  
Vol 60 (1) ◽  
pp. 41-51
Author(s):  
PATRICIA ANNE FARQUHARSON
Keyword(s):  
Size Distribution ◽  
Fluid Transport ◽  
Molecular Size ◽  
Malpighian Tubules ◽  
Inverse Relation ◽  
Fluid Production ◽  
Molecular Size Distribution ◽  
Molecular Sieving ◽  
Tubule Fluid ◽  
Tubule Wall

1. Tubule fluid:medium ratios (TF/M) have been measured for inulin, glucose, LMWD and HMWD. These TF/M ratios were surprisingly high. 2. The tubule appears to act as a molecular filter; that is to say, molecules move through the tubule wall in inverse relation to their size. This is best illustrated using polyvinyl pyrrolidone as a tracer. The molecular size distribution of PVP fractions present in tubule fluid differs markedly from the molecular size distribution of PVP in the bathing Ringer. 3. No correlation can be made between the inulin and glucose TF/M and the rate of fluid production. However, the inverse relationship between TF/M and rate of fluid production for dextrans indicates a molecular sieving effect. 4. The significance of these results is discussed with reference to models of fluid transport.

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