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.

Removal of natural organic matter from water using a nano-structured photocatalyst coupled with filtration membrane

2004 ◽  
Vol 49 (1) ◽  
pp. 103-110 ◽  
Author(s):  
D. Sun ◽  
T.T. Meng ◽  
T.H. Loong ◽  
T.J. Hwa
Keyword(s):  
Membrane Fouling ◽  
Photocatalytic Oxidation ◽  
Experimental Results ◽  
Bet Surface Area ◽  
Catalyst Loading ◽  
Flux Rate ◽  
Permeate Flux ◽  
Illumination Time ◽  
Filtration Membrane ◽  
Nano Size

A study of the characteristics of a novel photocatalyst indicated that it consisted of 17.3 nm nano size (average) TiO2 in the anatase phase and porous Fe2O3. SEM results revealed that nano size TiO2 was uniformly deposited onto the surface of Fe2O3 to form a bulk photocatalyst, as TiO2/Fe2O3. The porous TiO2/Fe2O3 catalyst had a BET surface area of 168 m2/g, which is three times higher than that of commercial TiO2. The experimental results indicated that the suspended TiO2/Fe2O3 photocatalyst in a photocatalytic oxidation (PCO) reactor was effective in removing TOC at 61.58% and color400 at 93.25% at 180 min illumination time, under 0.4 g/l catalyst loading and pH 7. Experimental results also revealed that pH at 7 and TiO2/Fe2O3 loading at 0.4 g/l was the optimum condition for removal of humic acids using a PCO reactor. Experimental results clearly indicated that the permeate flux rate of the ultrafiltration (UF) membrane was improved and the filtration membrane fouling phenomenon was reduced with the addition of TiO2/Fe2O3 photocatalysts to the UF membrane system. It was found that increasing the filtration time from 40 min to 185 min, the improvement to the permeate flux rate was from 57 to 83 L/hr.m2.

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.

Removal of humic acid foulant from ultrafiltration membrane surface using photocatalytic oxidation process

2005 ◽  
Vol 51 (6-7) ◽  
pp. 373-380 ◽  
Author(s):  
H. Fang ◽  
D.D. Sun ◽  
M. Wu ◽  
W. Phay ◽  
J.H. Tay
Keyword(s):  
Humic Acid ◽  
Acid Solution ◽  
Calcium Ions ◽  
Photocatalytic Oxidation ◽  
Ph Value ◽  
Membrane Surface ◽  
Reaction Times ◽  
Permeate Flux ◽  
Filtration Time ◽  
Tio2 Particles

The experimental results indicated that without the TiO2 particles and PCO treatment, the permeate flux of ultrafiltration (UF) membrane declined to 40% of the initial permeate flux after 8 hours filtration. Feeding the humic acid solution with TiO2 particles dosage of 1 g/L with calcium ions into UF membrane, after the same filtration time and PCO reaction at 120 minutes, the permeate flux was increased to about 90% of the initial permeate flux. At longer PCO reaction times, a better water quality of UF permeate was observed. It has been found that with the coexistence of calcium ions in humic acid solution, the smaller molecular fragments of humic acid (HA) generated by PCO reaction may be transferred to the surface of TiO2 by means of adsorption. The humic acid adsorption by TiO2 in the presence of Ca2+ is also pH dependent. The adsorption rates were 21.0, 14.9 and 10.8 ppmTOC/gTiO2 for pH value of 4, 7 and 10 respectively. The combination of effects of PCO mineralization of humic acid into CO2 and adsorption of humic acid by TiO2 through the forming of HA-Ca2+-TiO2 aggregate particles were responsible for the removal of humic acid foulant from UF membrane surface.

scholarly journals Photocatalytic Degradation of Methylene Blue by Fe/ZnO/SiO2Nanoparticles under Visiblelight

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
R. M. Mohamed ◽  
I. A. Mkhalid ◽  
E. S. Baeissa ◽  
M. A. Al-Rayyani
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Photocatalytic Degradation ◽  
Visible Light Irradiation ◽  
Photocatalytic Oxidation ◽  
Catalyst Loading ◽  
Blue Dye ◽  
Methylene Blue Dye ◽  
Illumination Time

The photocatalytic activity of Fe/ZnO/SiO2catalysts under visible-light irradiation for the degradation of methylene blue was evaluated. The effect of pH, illumination time, amount of catalyst loaded, and initial dye concentration on the degradation efficiency of methylene blue was investigated. The results reveal that the optimum photocatalytic oxidation conditions of methylene blue are as follows:pH=4and illumination time is 30 min, the amount of catalyst loading is 0.075 g/L and 50 ppm methylene blue dye concentration. Under these conditions, the removal efficiency of methylene blue was 100%.

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.

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 Complexation of Copper(II) with Humic Acids Studied by Ultrasound Spectrometry

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Martina Klučáková
Keyword(s):  
Humic Acid ◽  
Humic Acids ◽  
Conformational Changes ◽  
Ph Value ◽  
Biologically Active ◽  
Copper Binding ◽  
Binding Ability ◽  
Initial Ph ◽  
The Individual ◽  
Concentrated Systems

Copper biogeochemistry is controlled by bonding to natural organic matter. The soluble forms of bonded copper can be more biologically active due to the higher migration in environmental systems and instability of some copper-humic complexes. In this work, the interactions of copper(II) ions with humic acids are studied by means of high-resolution ultrasound spectrometry. It was found that the stoichiometry of the formed complexes is strongly influenced by the organization of humic acid in solution and by the final pH value in equilibrium. Although the ratio between the added copper and humic acids in all used concentrations was constant and the initial pH value was neutral, we observed significant differences between the individual systems. The highest binding ability was determined for a humic content of 0.5 g·dm−3. More diluted and more concentrated systems were able to bind lower amounts of copper. The implemented method is very sensitive and can be utilized not only for monitoring copper binding but also as an indicator of conformational changes of humic acid in solutions with varying concentration.

Changes in the Humic Acid–Metal Complexation Characteristics Depending on Humification Degree / Humīnskābju – Metālu Kompleksveidošanās Rakstura Izmaiņas Atkarībā No Humifikācijas Pakāpes

2012 ◽  
Vol 51 (3) ◽  
pp. 228-237
Author(s):  
D. Dudare ◽  
M. Klavins
Keyword(s):  
Humic Acid ◽  
Stability Constants ◽  
Humic Acids ◽  
Complex Stability ◽  
Peat Layer ◽  
Raised Bog ◽  
Complexing Capacity ◽  
Humification Degree ◽  
Complexation Process ◽  
Complex Stability Constants

The aim of this study is to determine the Cu(II) complexing capacity and stability constants of Cu(II) complexes of humic acids isolated from two well-characterized raised bog peat profiles in respect to the basic properties and humification characteristics of the studied peats and their humic acids. The complex stability constants significantly change within the studied bog profiles and are well correlated with the age and decomposition degree of the peat layer from which the humic acids have been isolated. Among factors that influence this complexation process, molecular mass and ability to form micellar structures (supramolecules) of humic substances are of key importance.

EFFECT OF IRRIGATION AND GRASSING TO CHANGE SOME OF THE BIOLOGICAL PROPERTIES OF THE MINING OF BROWN CALCAREOUS SOILS

2019 ◽  
Vol 1 (1) ◽  
pp. 29-32
Author(s):  
Ruzimurod B. Boimurodov ◽  
Zebinisso Q. Bobokhonova
Keyword(s):  
Folic Acid ◽  
Humic Acid ◽  
Humic Acids ◽  
Rapid Growth ◽  
Growth And Development ◽  
Sharp Increase ◽  
Humus Content ◽  
Calcareous Soils ◽  
Biological Properties ◽  
Humus Accumulation

In this article is showing, that the irrigation mountain brown carbonate soils prone methods of irrigation and grassing comes the rapid growth and development of natural vegetation, which leads to intensive humus accumulation. Humus content in the upper layer is increased by 0.98% and a significantly smaller severely eroded. Increasing the amount of humus promotes accumulation mainly humic acids, that conducts to expansion of relations the content of humic acid: The content of folic acid. When grassing of soil traced sharp increase in the number associated with the related and R2 O3 humic acid.

Kinetic Adsorption of Humic Acids Mixture Obtained from Microalgae on Exfoliated Graphite Nanoplatelets

2018 ◽  
Vol 69 (1) ◽  
pp. 191-195
Author(s):  
Elena Radu ◽  
Elena Emilia Oprescu ◽  
Cristina Emanuela Enascuta ◽  
Catalina Calin ◽  
Rusandica Stoica ◽  
...  
Keyword(s):  
Humic Acid ◽  
Humic Acids ◽  
Alkali Treatment ◽  
Exfoliated Graphite ◽  
Acid Mixture ◽  
Acidic Ph ◽  
Graphite Nanoplatelets ◽  
Mixture Concentration ◽  
Ft Ir ◽  
Exfoliated Graphite Nanoplatelets

The dehydration of polysaccharides fraction in the presence of acid catalysts, is a chemical process in which results as secondary product humic matter. In our work, the humic acid mixture was for the first time based on our knowledge extracted from defatted microalgae biomass rich in polysaccharides by standard alkali treatment, followed by precipitation at acidic pH. The dried humic acid mixture has been characterized using infrared spectroscopic measurements (FT-IR). Exfoliated graphite nanoplatelets (xGnP) were used as new adsorbents for this type of humic acids mixture, their adsorption being investigated. The effect of several parameters such as: contact time, concentration of humic acid mixture, concentration of xGnP, temperature and pH of the solutions were studied. The process of adsorption took place with good results, in the following conditions: at a concentration of humic acid mixture of 18.6 mg L-1, an xGnP amount of 0.01 mg in 25 mL of solution, at a temperature of 25 �� and at acidic pH values, in aqueous solution.

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