Adsorption and Radical Stabilization of Humic-Acid Analogues and Pb<sup>2+</sup> on Restricted Phyllomorphous Clay

Giannakopoulos, Evangelos; Stathi, Panagiota; Dimos, Konstantinos; Gournis, Dimitrios; Sanakis, Yiannis; Deligiannakis, Yiannis

doi:10.1021/la053273m

Cited by 58 publications

(72 citation statements)

References 57 publications

(174 reference statements)

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“…This procedure was continued until further montmorillonite additions did not change the pH of the solution. This pH value has been shown to be a good approximation to the PZNPC of oxide and clay surfaces (Kraepiel and Morel, 1999;Avena and De Pauli, 1998;Giannakopoulos et al, 2006;Stathi et al, 2009). …”

Section: Surface Charge Properties Of Montmorillonitementioning

confidence: 89%

“…The surface charge of montmorillonite suspensions were evaluated by two methods: potentiometric acid -base titrations (Schulthess and Sparks, 1986;Stathi et al, 2006;Giannakopoulos et al, 2006) and mass titration (Giannakopoulos et al, 2006;Bourikas et al, 2003).…”

Section: Surface Charge Properties Of Montmorillonitementioning

confidence: 99%

“…The concentrations of metals in the aqueous phase were determined as described earlier (Giannakopoulos et al, 2006) for clay suspensions at concentrations 1 g L -1 with an initial concentration of 4.5µM of metal ions. Sorption pH-edge experiments were performed to measure the effect of pH on the metal uptake, as follows: zenith clay was suspended in polypropylene tubes containing a buffer system of 10mM MES (N-morpholino-ethanesulfonic acid), 10mM HEPES (4-(2-Hydroxyethyl)piperazine-1ethanesulfonic) was used at all of the samples.…”

Section: Sorption Experimentsmentioning

confidence: 99%

“…This modelling approach was adapted from previous successful applications for adsorption of metals and organics on kaolinite, montmorillonite (Ikhsan et al, 2005;Barbier et al, 2000;Bradbury and Bayens, 1999) and Laponite (Giannakopoulos et al, 2006). Including more than one type variable charge surface sites e.g.…”

Section: Theoretical Surface Complexation Modelingmentioning

confidence: 99%

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Heavy-metal uptake by a high cation-exchange-capacity montmorillonite: the role of permanent charge sites

Stathi

Deligiannakis²

2013

Global NEST Journal

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A High Cation Exchange Capacity (HCM) montmorillonite clay has been prepared by acetate treatment of Zenith clay. The HCM has been evaluated for metal-uptake from aqueous solutions. The present data show that the cation exchange sites can play a significant role in the adsorption of metals in smectite clays. A theoretical analysis scheme has been developed which shows that permanent-charge sites can become dominant in metal-uptake by clays. In addition, it was shown that the permanent charge can influence the ionic-strength sensitivity of the Point of Zero Charge of the clay. KEYWORDS:Montmorillonite; CEC; Adsorption; Heavy metals; Surface Complexation Models; Permanent charge. ΙNTRODUCTIONUnder certain environmental conditions, heavy metals might accumulate up to toxic concentrations and cause ecological damage. Heavy metals are often introduced to the environment through modern human activities. Montmorillonites are a class of layered aluminosilicate minerals with unique combinations of swelling and ion exchange properties that make them valuable nanostructures in diverse fields. Their structures consist of an octahedral alumina layer fused between two tetrahedral silica layers. Smectite clays have a cation exhange capacity, which depends on the substitution of low-valent atoms such as Mg 2+ or Al 3+ in the octahedral sheet, and Al 3+ or Si 4+ in the tetrahedral sites. As a consequence, the layers are negatively charged (Sposito, 1989;Sposito, 2004). Soluble heavy metals can be removed from the environment, by adsorption. Clay minerals are low cost sorbents and are highly valued for their adsorptive properties. Therefore, a number of studies performed using clays for heavy metal adsorption showed effectiveness in removing heavy metals or organic molecules from aqueous solutions (Ikhsan et al., 2005;Barbier et al., 2000;Bradbury and Bayens, 1999;Bayens and Bradbury, 1997). Adsorption of ions on clay minerals is controlled by two different mechanisms: (i) pH-independent adsorption, usually attributed to cation exchange in the intrer-layer and resulting from the electrostatic interaction between the ions and the permanent charge. (ii) a pH dependent adsorption, thought to result from the surface complexation reaction similar to those on oxides. Cation exchange has been fount to be an important sorption mechanism for many clay minerals (Ikhsan et al., 2005;Kraepiel et al., 1999;Avena and De Pauli, 1998) with a number of studies suggesting that exchange sites are responsible for cation uptake at low pH. Adsorption models for clays based on surface complexation modeling (SCM) usually involving two distinct types of surface groups (1) X -groups bearing a permanent charge with account to the cation exchange part of adsorption (2) amphoteric sites of SOH groups. Recently we have shown that the cation exchange capacity (CEC) of a Zn-containing montmorillonite (code name Zenith) can be increased by selective removal of Zn atoms from the clay lattice (Stathi et al., 2009). According to this methodology treatment ...

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Section: Surface Charge Properties Of Montmorillonitementioning

confidence: 89%

Section: Surface Charge Properties Of Montmorillonitementioning

confidence: 99%

Section: Sorption Experimentsmentioning

confidence: 99%

Section: Theoretical Surface Complexation Modelingmentioning

confidence: 99%

See 2 more Smart Citations

Heavy-metal uptake by a high cation-exchange-capacity montmorillonite: the role of permanent charge sites

Stathi

Deligiannakis²

2013

Global NEST Journal

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“…For example, gallic acid, protocatechuic acid, 4-hydroxybenzoic acid (Giannakopoulos et al, 2006),tetramer undecanoid acid (Aquino et al, 2011), and benzoic acid (Sun et al, 2013) have been applied to simulate humic acid and dissolved organic matter.…”

Section: Model Rationalementioning

confidence: 99%

Experimental and molecular dynamic simulation study of perfluorooctane sulfonate adsorption on soil and sediment components

Zhang

Yan

Jing

2015

Journal of Environmental Sciences

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Soil and sediment play a crucial role in the fate and transport of perfluorooctane sulfonate (PFOS) in the environment. However, the molecular mechanisms of major soil/sediment components on PFOS adsorption remain unclear. This study experimentally isolated three major components in soil/sediment: humin/kerogen, humic/fulvic acid (HA/FA), and inorganic component after removing organics, and explored their contributions to PFOS adsorption using batch adsorption experiments and molecular dynamic simulations. The results suggest that the humin/kerogen component dominated the PFOS adsorption due to its aliphatic features where hydrophobic effect and phase transfer are the primary adsorption mechanism.Compared with the humin/kerogen, the HA/FA component contributed less to the PFOS adsorption because of its hydrophilic and polar characteristics. The electrostatic repulsion between the polar groups of HA/FA and PFOS anions was attributable to the reduced PFOS adsorption. When the soil organic matter was extracted, the inorganic component also plays a non-negligible role because PFOS molecules might form surface complexes on SiO 2 surface.The findings obtained in this study illustrate the contribution of organic matters in soils and sediments to PFOS adsorption and provided new perspective to understanding the adsorption process of PFOS on micro-interface in the environment.

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Clay Bragg Stack Optical Sensors

2008

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Adsorption and Radical Stabilization of Humic-Acid Analogues and Pb²⁺ on Restricted Phyllomorphous Clay

Cited by 58 publications

References 57 publications

Heavy-metal uptake by a high cation-exchange-capacity montmorillonite: the role of permanent charge sites

Heavy-metal uptake by a high cation-exchange-capacity montmorillonite: the role of permanent charge sites

Experimental and molecular dynamic simulation study of perfluorooctane sulfonate adsorption on soil and sediment components

Clay Bragg Stack Optical Sensors

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Adsorption and Radical Stabilization of Humic-Acid Analogues and Pb2+ on Restricted Phyllomorphous Clay

Cited by 58 publications

References 57 publications

Heavy-metal uptake by a high cation-exchange-capacity montmorillonite: the role of permanent charge sites

Heavy-metal uptake by a high cation-exchange-capacity montmorillonite: the role of permanent charge sites

Experimental and molecular dynamic simulation study of perfluorooctane sulfonate adsorption on soil and sediment components

Clay Bragg Stack Optical Sensors

Contact Info

Product

Resources

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Adsorption and Radical Stabilization of Humic-Acid Analogues and Pb²⁺ on Restricted Phyllomorphous Clay