Effects of aluminum ion on particle sizes and surface charges of exopolysaccharides from Rhizobium tropici and pH effects

Larson, Steve L.; Ballard, John H.; Runge, Kauri A.; Zhang, Huimin; Breland, Benjamin; Nick, Zachary H.; Vroman, Ethan Tyler; Weiss, Charles; Han, Fengxiang X.

doi:10.1016/j.rhisph.2023.100713

Cited by 5 publications

(9 citation statements)

References 30 publications

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“…Dontsova and Bigham reported that divalent cations (Sr 2+ , Ca 2+ , and Mg 2+ ) better enhanced sorption of xanthan than monovalent cations (K, Na, and Li) on clays at the same ionic strength, indicating that cations participated in the binding of xanthan to clay surfaces. Our previous study indicated that Al ions significantly increased the particle sizes of EPS-Al composites through reducing the ζ-potential of EPS . However, as the present study indicates, EPS-Al showed less capacity in surface interaction with clay particles than EPS alone due to a strong complex of EPS and Al ions.…”

Section: Resultscontrasting

confidence: 47%

“…Our previous study indicated that Al ions significantly increased the particle sizes of EPS-Al composites through reducing the ζ-potential of EPS. 2 However, as the present study indicates, EPS-Al showed less capacity in surface interaction with clay particles than EPS alone due to a strong complex of EPS and Al ions.…”

Section: Effects Of Eps and Eps-al/ca/na Composites On The Aggregate ...mentioning

confidence: 47%

“…EPS alone significantly increased the aggregate sizes of the composites due to its strongest polymer-to-polymer associations with full functional groups. The associations between EPS and cations were remarkably decreased due to occupying of most of the functional groups in EPS by cations . Among three cations, Al showed a high binding capacity with the clay mineral surface through a cation bridge, leading to large aggregate sizes of the composites of EPS-Al-clay, compared with those with EPS-Na and EPS-Ca (Figure C,D).…”

Section: Resultsmentioning

confidence: 99%

“…The associations between EPS and cations were remarkably decreased due to occupying of most of the functional groups in EPS by cations. 2 Among three cations, Al showed a high binding capacity with the clay mineral surface through a cation bridge, leading to large aggregate sizes of the composites of EPS-Al-clay, compared with those with EPS-Na and EPS-Ca (Figure 7C,D). Larson et al 2 reported that with the continuing increase in Al-ion molar ratios, EPS-Al complexes became less negative, and a further increase in the Al content led to the positive ζpotential.…”

Section: Effects Of Eps and Eps-al/ca/na Composites On ζ-Potentials O...mentioning

confidence: 99%

“…However, the coarse silt fraction still contained significant montmorillonite and kaolinite as indicated by X-ray diffraction (XRD). The composites of montmorillonite/kaolinite-EPS/Na/Ca/ Al were formed according to the procedure of Larson et al 1,2 Stock clay suspensions were prepared at 33.1 and 31.7 g/L of montmorillonite and kaolinite, respectively. 1 mL of clay suspension for montmorillonite and kaolinite was mixed with 100 and 500 μL and 1, 2, 4, and 10 mL of EPS/Na/Ca/Al solution (3.9−4.7 g/L).…”

Section: Sources and Purification Of Eps And Claymentioning

confidence: 99%

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Modification of Surface Properties of Clay Minerals with Exopolysaccharides from Rhizobium Tropici

Walshire,

Zhang,

Nick

et al. 2024

ACS Earth Space Chem.

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Exopolysaccharides (EPS), extracellular macromolecular biopolymers produced by soil microorganisms, are important in formation of soil microaggregate structures and in maintenance of proper soil moisture and bioavailability of nutrients. The objectives of this study are to investigate the effects of exopolysaccharides from Rhizobium Tropici on surface properties of two common clays, kaolinite and montmorillonite (STX-1). The effects of EPS alone and cation-substituted EPS (Na, Ca, and Al) on the particle size distribution, ζ-potential, and surface areas of clays were examined. Results show that EPS alone significantly increased the aggregate particle sizes of montmorillonite by 50−110-fold and kaolinite by 90-fold via formation of EPS-clay composites through interparticle associations of EPS. Cation-substituted EPS (EPS-Na/Ca/ Al) remarkably weakened such interparticle association in formation of the large particle sizes (increasing the particle size by 5−40-fold). Strong correlations between the mean aggregate sizes and ζ-potentials of these EPS-clay composites were observed. The more negative charge of the EPS/Na/Ca/Al-clay composites led to stronger repelling Coulomb forces between particles, thus decreasing the overall aggregate sizes. On the other hand, EPS adsorption on two clay minerals significantly reduced their surface area, especially on montmorillonite, by 61%. Montmorillonite's surface area was initially slowly reduced, followed by rapid decreases, while kaolinite initially slightly increased, followed by a slow decrease with further increases in EPS adsorption. Thus, the current study provides a deep understanding of mechanisms of EPS interaction with clay minerals and its effects on the sizes, ζ-potentials, and surface areas of clay minerals.

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Section: Resultscontrasting

confidence: 47%

Section: Effects Of Eps and Eps-al/ca/na Composites On The Aggregate ...mentioning

confidence: 47%

Section: Resultsmentioning

confidence: 99%

Section: Effects Of Eps and Eps-al/ca/na Composites On ζ-Potentials O...mentioning

confidence: 99%

Section: Sources and Purification Of Eps And Claymentioning

confidence: 99%

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