Interaction of exopolysaccharide with clay minerals and their effects on U(VI) adsorption

Zhang, Huimin; Larson, Steve; Ballard, John; Nie, Jing; Zhang, Qiqi; Kazery, Joseph A.; Dasari, Shaloam; Pradhan, Nihar; Dai, Qilin; Olafuyi, Olanrewaju M.; Zhu, Xianchun; Ma, Youhua; Han, Fengxiang X.

doi:10.1007/s11368-023-03589-6

Cited by 3 publications

(8 citation statements)

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“…This was in agreement with our previous studies. 1,4 With initial increases in the ζ-potential (more negative values) with EPS adsorption on the outside surface of clays, the surface areas of montmorillonite were reduced at the rate of 7.92 m 2 /g per ζ-potential (mv) (Figure 8C). Overall, EPS significantly blocked the specific surface area of montmorillonite and kaolinite as adsorption of EPS.…”

Section: Effects Of Eps On Surfacementioning

confidence: 99%

“…Furthermore, montmorillonite usually has a high surface area and rich surface functionary groups compared with kaolinite. − Clay and surface-modified clays have been applied in pharmaceuticals, remediation of heavy metals and trace elements from water and soil, and in enhancing soil structure stability for erosion control in soils. − Clay and modified clays have been extensively used in remediating contaminated soils and waters. It was reported that clay minerals, especially montmorillonite with various surface modifications, were used to move heavy metals, trace elements, and radionuclides from waters and soils, including Cd, Cr, As, U, Se, Sr, etc. ,, Various modification techniques were utilized to functionalize the clay surface, mainly including thermal treatment, acid washing, pillaring, and organic modification . It was reported that thermal treatment of montmorillonite with microwave radiation significantly enhanced the surface areas of smectites (165.8 m 2 /g) over that of the natural smectites (29.2 m 2 /g) .…”

Section: Introductionmentioning

confidence: 99%

“…It was reported that clay minerals, especially montmorillonite with various surface modifications, were used to move heavy metals, trace elements, and radionuclides from waters and soils, including Cd, Cr, As, U, Se, Sr, etc. 3,4,6 Various modification techniques were utilized to functionalize the clay surface, mainly including thermal treatment, acid washing, pillaring, and organic modification. 6 It was reported that thermal treatment of montmorillonite with microwave radiation significantly enhanced the surface areas of smectites (165.8 m 2 /g) over that of the natural smectites (29.2 m 2 /g).…”

Section: Introductionmentioning

confidence: 99%

“…1 We also reported that EPS (from R. tropici) modified montmorillonite significantly enhanced its adsorption capacity of U, Sr, and Cs from water. 3,4 The modification of clays with EPS significantly increased the adsorption capacity of other heavy metals such as Cd and Cr. 21,29 Polysaccharides occurred as a network of strands in the interparticle porosity of clay minerals, forming an organomineral network with extensive interparticle bridging.…”

Section: Introductionmentioning

confidence: 99%

“…39,40 In general, the surface area available for sorption of nutrients, heavy metals, and trace elements in soils increases with increasing clay contents with high surface areas. 3,4,40,41 However, the effects of EPS on surface areas of clay minerals and the detailed distribution of particle sizes were not clearly understood. 42−4445 Thus, the objectives of this study were to investigate the effects of exopolysaccharides from R. Tropici on surface areas, aggregate particle size distributions, and ζ-potentials of kaolinite and montmorillonite.…”

Section: Introductionmentioning

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: Effects Of Eps On Surfacementioning

confidence: 99%