TY  - JOUR
AU  - Jovanović, Uroš D.
AU  - Marković, Mirjana
AU  - Cupać, Svjetlana
AU  - Tomić, Zorica P.
PY  - 2013
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/5778
AB  - Humic acids (HAs), similar to other fractions of humic substances (HSs), have a large number of reactive functional groups enabling them to aggregate in solutions. Regardless of the origin of humic acid (aqueous or soil), this aggregation process is dependent on environmental conditions and strongly influences the mobility of soluble ionic and molecular pollutants. The aim of this work was to monitor the aggregation process of two humic acids isolated from different mineral soils (IHSS Elliot soil HA standard and Rendzic Leptosol HA) in the 2-11 pH range. Changes in aggregate size in HA sols were followed up using dynamic light scattering (DLS), while zeta potential (ZP) measurements in the same pH range were performed applying laser Doppler electrophoresis (LDE) technique. The effect of HA sol concentration and soil source on aggregation was examined as well. Besides, HA samples were characterized using Fourier transform infrared (FT-IR) spectroscopy. By inspecting HA-particle-size dependence on pH, it can be concluded that both HAs in corresponding sols behave as molecular aggregates or supramolecular structures, formed from small individual moieties (sizes LT 10 nm) at higher pH values. The ZP vs. pH curve for both HAs revealed the ZP minimum in the 5-7 pH range, caused most likely by dissociation of acidic functional groups prevailing at lower pH values and deaggregation predominating over dissociation at higher pH values.
T2  - Journal of Plant Nutrition and Soil Science
T1  - Soil humic acid aggregation by dynamic light scattering and laser Doppler electrophoresis
VL  - 176
IS  - 5
SP  - 674
EP  - 679
DO  - 10.1002/jpln.201200346
ER  - 

@article{
author = "Jovanović, Uroš D. and Marković, Mirjana and Cupać, Svjetlana and Tomić, Zorica P.",
year = "2013",
abstract = "Humic acids (HAs), similar to other fractions of humic substances (HSs), have a large number of reactive functional groups enabling them to aggregate in solutions. Regardless of the origin of humic acid (aqueous or soil), this aggregation process is dependent on environmental conditions and strongly influences the mobility of soluble ionic and molecular pollutants. The aim of this work was to monitor the aggregation process of two humic acids isolated from different mineral soils (IHSS Elliot soil HA standard and Rendzic Leptosol HA) in the 2-11 pH range. Changes in aggregate size in HA sols were followed up using dynamic light scattering (DLS), while zeta potential (ZP) measurements in the same pH range were performed applying laser Doppler electrophoresis (LDE) technique. The effect of HA sol concentration and soil source on aggregation was examined as well. Besides, HA samples were characterized using Fourier transform infrared (FT-IR) spectroscopy. By inspecting HA-particle-size dependence on pH, it can be concluded that both HAs in corresponding sols behave as molecular aggregates or supramolecular structures, formed from small individual moieties (sizes LT 10 nm) at higher pH values. The ZP vs. pH curve for both HAs revealed the ZP minimum in the 5-7 pH range, caused most likely by dissociation of acidic functional groups prevailing at lower pH values and deaggregation predominating over dissociation at higher pH values.",
journal = "Journal of Plant Nutrition and Soil Science",
title = "Soil humic acid aggregation by dynamic light scattering and laser Doppler electrophoresis",
volume = "176",
number = "5",
pages = "674-679",
doi = "10.1002/jpln.201200346"
}

Jovanović, U. D., Marković, M., Cupać, S.,& Tomić, Z. P.. (2013). Soil humic acid aggregation by dynamic light scattering and laser Doppler electrophoresis. in Journal of Plant Nutrition and Soil Science, 176(5), 674-679.
https://doi.org/10.1002/jpln.201200346

Jovanović UD, Marković M, Cupać S, Tomić ZP. Soil humic acid aggregation by dynamic light scattering and laser Doppler electrophoresis. in Journal of Plant Nutrition and Soil Science. 2013;176(5):674-679.
doi:10.1002/jpln.201200346 .

Jovanović, Uroš D., Marković, Mirjana, Cupać, Svjetlana, Tomić, Zorica P., "Soil humic acid aggregation by dynamic light scattering and laser Doppler electrophoresis" in Journal of Plant Nutrition and Soil Science, 176, no. 5 (2013):674-679,
https://doi.org/10.1002/jpln.201200346 . .

TY  - JOUR
AU  - Tomić, Zorica P.
AU  - Logar, Vesna P.
AU  - Babić, Biljana M.
AU  - Rogan, Jelena R.
AU  - Makreski, Petre
PY  - 2011
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/4524
AB  - Bentonite samples collected from vicinity of Petrovac and Aleksinac were treated with different sulfuric acid molarities. Acid attack dissolved the octahedral sheets by interlayer and edge attack. The effects of the H(2)SO(4) acid caused an exchange of Al(3+), Fe(3+) and Mg(2+) with H. ions leading to a modification of the smectite crystalline structure. The Mg and Fe substitution in the octahedral sheets promoted the dispersion of corresponding layers and formation of amorphous silicon. The activated bentonites, after the treatment of sulfuric acid, exhibited a lower cation-exchange capacity (CEC)and significant increase of specific surface area from 6 to 387 m(2) g(-1) (bentonite from Petrovac) and from 11 to 306 m(2) g(-1) (bentonite from Aleksinac). The acid reaction caused a splitting of particles within the octahedral sheet which led to an increase in specific surface area and decrease in CEC in both bentonites. (C) 2011 Elsevier B.V. All rights reserved.
T2  - Spectrochimica Acta. Part A: Molecular and Biomolecular Spectroscopy
T1  - Comparison of structural, textural and thermal characteristics of pure and acid treated bentonites from Aleksinac and Petrovac (Serbia)
VL  - 82
IS  - 1
SP  - 389
EP  - 395
DO  - 10.1016/j.saa.2011.07.068
ER  - 

@article{
author = "Tomić, Zorica P. and Logar, Vesna P. and Babić, Biljana M. and Rogan, Jelena R. and Makreski, Petre",
year = "2011",
abstract = "Bentonite samples collected from vicinity of Petrovac and Aleksinac were treated with different sulfuric acid molarities. Acid attack dissolved the octahedral sheets by interlayer and edge attack. The effects of the H(2)SO(4) acid caused an exchange of Al(3+), Fe(3+) and Mg(2+) with H. ions leading to a modification of the smectite crystalline structure. The Mg and Fe substitution in the octahedral sheets promoted the dispersion of corresponding layers and formation of amorphous silicon. The activated bentonites, after the treatment of sulfuric acid, exhibited a lower cation-exchange capacity (CEC)and significant increase of specific surface area from 6 to 387 m(2) g(-1) (bentonite from Petrovac) and from 11 to 306 m(2) g(-1) (bentonite from Aleksinac). The acid reaction caused a splitting of particles within the octahedral sheet which led to an increase in specific surface area and decrease in CEC in both bentonites. (C) 2011 Elsevier B.V. All rights reserved.",
journal = "Spectrochimica Acta. Part A: Molecular and Biomolecular Spectroscopy",
title = "Comparison of structural, textural and thermal characteristics of pure and acid treated bentonites from Aleksinac and Petrovac (Serbia)",
volume = "82",
number = "1",
pages = "389-395",
doi = "10.1016/j.saa.2011.07.068"
}

Tomić, Z. P., Logar, V. P., Babić, B. M., Rogan, J. R.,& Makreski, P.. (2011). Comparison of structural, textural and thermal characteristics of pure and acid treated bentonites from Aleksinac and Petrovac (Serbia). in Spectrochimica Acta. Part A: Molecular and Biomolecular Spectroscopy, 82(1), 389-395.
https://doi.org/10.1016/j.saa.2011.07.068

Tomić ZP, Logar VP, Babić BM, Rogan JR, Makreski P. Comparison of structural, textural and thermal characteristics of pure and acid treated bentonites from Aleksinac and Petrovac (Serbia). in Spectrochimica Acta. Part A: Molecular and Biomolecular Spectroscopy. 2011;82(1):389-395.
doi:10.1016/j.saa.2011.07.068 .

Tomić, Zorica P., Logar, Vesna P., Babić, Biljana M., Rogan, Jelena R., Makreski, Petre, "Comparison of structural, textural and thermal characteristics of pure and acid treated bentonites from Aleksinac and Petrovac (Serbia)" in Spectrochimica Acta. Part A: Molecular and Biomolecular Spectroscopy, 82, no. 1 (2011):389-395,
https://doi.org/10.1016/j.saa.2011.07.068 . .