Interfacial reaction between humic acid and Ca-Montmorillonite: Application in the preparation of a novel pellet binder

Zhang, Yuanbo; Lu, Manman; Su, Zijian; Wang, Jia; Tu, Yikang; Chen, Xijun; Cao, Chutian; Gu, Foquan; Liu, Shuo; Jiang, Tao

doi:10.1016/j.clay.2019.105177

Cited by 37 publications

(15 citation statements)

References 40 publications

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“…NOM only associates with the smectite surface in the MD simulations involving 16 NOM molecules and Ca 2+ ions and does so through quaternary O b –H 2 O–Ca 2+ –COO ‑ NOM complexes, suggesting that high-charge-density cations play a special role in NOM–smectite surface complexation. This finding is in excellent agreement with batch adsorption experiments using Ca-smectites. ,, As noted earlier, the ADP’s of the two NOM simulations (Figure b, d) show that the NOM clusters reside near the midplane of the mesopore along the surface normal, roughly halfway between the two smectite surfaces, and that they never approach either smectite surface. In the 16 NOM simulation with Cs + , the 6 small clusters of NOM molecules occasionally approach the surface but do not coordinate to the basal surface oxygen atoms or surface-adsorbed Cs + ions at any time, as seen in Figure b and c.…”

Section: Resultssupporting

confidence: 88%

“…This finding is in excellent agreement with batch adsorption experiments using Ca-smectites. 22,23,27 As noted earlier, the ADP's of the two NOM simulations (Figure 4b, 4d) show that the NOM clusters reside near the midplane of the mesopore along the surface normal, roughly halfway between the two smectite surfaces, and that they never approach either smectite surface. In the 16 NOM simulation with Cs + , the 6 small clusters of NOM molecules occasionally approach the surface but do not coordinate to the basal surface oxygen atoms or surface-adsorbed Cs + ions at any time, as seen in Figure 5b and 5c.…”

Section: ■ Materials and Methodssupporting

confidence: 71%

“…The interaction of organic and biomolecules with smectite (clay mineral) surfaces is central to various geochemical, industrial, and environmental processes including the biogeochemistry of soils; − the fate and transport of heavy metals, − radionuclides, and organic contaminants; − the performance assessment of filtration membranes; ,, and the global carbon balance. − Natural organic matter (NOM) is a complex mixture of compounds derived from the natural decay of plant matter and microbes, giving NOM a heterogeneous distribution of functional groups, structures, compositions, and molecular weights. As a result, NOM is ubiquitous in terrestrial and aquatic environments that support life and exhibits complex (and potentially regiospecific) interactions with minerals and suspended solids. − It has been shown that NOM molecules associate with one another in aqueous solution and that NOM readily adsorbs onto many mineral surfaces including micas (a type of phyllosilicate closely related to smectites), altering the surface properties and impacting the distribution and transport of organic and inorganic species in the environment. − …”

Section: Introductionmentioning

confidence: 99%

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A Mechanistic Exploration of Natural Organic Matter Aggregation and Surface Complexation in Smectite Mesopores

et al. 2020

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Soil minerals and organic matter play critical roles in nutrient cycling and other life-essential biogeochemical processes, yet the structural and dynamical details of natural organic matter (NOM) film formation on smectites are not fully understood on the molecular scale. XRD of Suwannee River NOM–hectorite (a smectite clay) complexes shows that the humic and fulvic components of NOM bind predominantly at the external surfaces of packets of smectite platelets rather than in the interlayer slit pores, suggesting that the key behavior governing smectite–NOM interactions takes place in mesopores between smectite particles. New molecular dynamics modeling of a ∼110 Å H2O-saturated smectite mesopore at near-neutral pH shows that model NOM molecules initially form small clusters of 2–3 NOM molecules near the center of the pore fluid. Formation of these clusters is driven by the hydrophobic mechanism, where aromatic/aliphatic regions associate with one another to minimize their interactions with H2O, and charge-balancing cations associated with the deprotonated carboxylate sites are located only at the outer surface of these clusters. Despite hydrophobicity driving the initial clustering, NOM clusters are formed more quickly when high-charge-density cations like Ca2+ are present vs low-charge-density cations like Cs+, as the former cations more effectively minimize the electrostatic repulsions between the negatively charged NOM molecules. Once the small hydrophobicity-driven NOM clusters form, the simulations show that Ca2+ promotes the aggregation of NOM clusters through tetradentate Ca2+ bridges involving carboxylate groups on two different NOM clusters. Importantly, our studies indicate that Ca2+ plays a crucial role in binding the NOM clusters to the smectite surface, which occurs through multiple quaternary complexes (Ob)–H2O–Ca2+–COO‑ NOM. In contrast, Cs+ never forms any coordination or acts like bridges between NOM molecules nor as ion bridges to the smectite surface. Additionally, we observe the formation of a metastable superaggregate involving all 16 NOM molecules several times in a Ca2+-bearing mesopore fluid. Superaggregates are never observed in the simulations involving Cs+. The modeling results are fully consistent with helium ion microscope images of NOM–hectorite complexes suggesting that NOM surface films develop when preformed NOM clusters interact with smectite surfaces. Overall, the binding of NOM clusters to the outer surfaces of smectite particles and the formation of large NOM aggregates at neutral pH occur through cation bridging, and cation bridging only occurs when high-charge-density cations like Ca2+ are present.

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Section: Resultssupporting

confidence: 88%

Section: ■ Materials and Methodssupporting

confidence: 71%

Section: Introductionmentioning

confidence: 99%

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A Mechanistic Exploration of Natural Organic Matter Aggregation and Surface Complexation in Smectite Mesopores

et al. 2020

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“…Their cation exchange capacity can indeed be significantly hindered by the presence of such organic moieties onto the surface (Y. Zhang et al, 2019). Organic saturated clay minerals therefore display different behaviors with respect to the adsorption of organic contaminants, especially due to the significant hydrophobicity of organic moieties (de Paiva et al, 2008;Guégan, 2019).…”

Section: Competition With Other Organic Compoundsmentioning

confidence: 99%

Raw and modified clays and clay minerals for the removal of pharmaceutical products from aqueous solutions: State of the art and future perspectives

Thiebault

2019

Critical Reviews in Environmental Science and Technology

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The occurrence of pharmaceutical products (PPs) within environmental compartments challenges the scientific community and water treatment operators to find suitable and practicable removal solutions. Clay minerals are among the oldest and cheapest adsorbents used for the removal of organic and inorganic pollutants. However, despite their significant adsorption properties, little is known about their potential to remove organic contaminants such as pharmaceutical products from wastewater effluents. Hence, based on the latest published articles this review aims to standardize the adsorption properties of clay minerals for the removal of PPs. Specifically, the charge state of PPs appears to play a key role in their adsorption mechanism. In order to overcome the limitations of batch experiments (i.e. idealized solutions, static conditions) and design of a field solution, the impact of external parameters on the adsorption capacities of clay minerals is reviewed. The effect of thermal treatment and acid activation of clay minerals is also assessed in order to better understand the consequences of such modifications on the adsorption properties of clay-based adsorbents. Finally, even if most authors agree on the potential of clay-based adsorbents for the removal of PPs from wastewater, there remain significant gaps in the existing literature that need to be filled, with the aim of forecasting the real potential of clay-based treatment for the removal of pharmaceutical products at industrial scale.

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“…Between SWy2 and Na-SWy2, the adsorption performance of the latter is slightly better for the removal of cationic PPs whereas the opposite pattern is displayed for neutral and anionic PPs. This can be attributed to the fact that the compensating inorganic cations of SWy2 are not only Na + , but also Ca 2+ in a significant proportion, allowing the formation of cationic bridges with negatively charged organic moieties such as anionic PPs, or organic complexes present in the effluents (Aristilde et al, 2016;Zhang et al, 2019). These results on PPs are confirmed by the elemental analyses, in which SWy2 displays the highest adsorbed amount of carbon.…”

Section: 4comparative Efficiency Of Clay Mineralsmentioning

confidence: 67%

Clay minerals for the removal of pharmaceuticals: Initial investigations of their adsorption properties in real wastewater effluents

Thiebault

Boussafir

Fougère

et al. 2019

Environmental Nanotechnology, Monitoring & Management

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The adsorption of pharmaceutical products (PPs) onto kaolinite and raw and sodium-exchanged montmorillonite was investigated in real wastewater effluents (WWE). The important role of the charge state of the PPs in controlling the adsorption extent was highlighted. Whereas cationic PPs were mostly adsorbed through cation exchange, the adsorption of neutral and anionic PPs appeared to be controlled by the nature of compensating inorganic cations and/or the simultaneous adsorption of organic moieties onto clay minerals. In raw WWE, the concentration of PPs is indeed far lower than the concentration of other organic molecules. Among the adsorbents tested, kaolinite displayed the lowest adsorption capacity of both PPs and other organic molecules, compared to raw montmorillonite which presented the highest adsorption capacity. The sodium-exchanged montmorillonite displayed intermediate adsorption properties, highlighting the key role of divalent inorganic cations in the adsorption of non-cationic PPs and other organic molecules. Hence, raw 2 montmorillonite appears to be the most promising adsorbent for further investigations aiming to test the practicability of a clay-based adsorbent for the removal of organic contaminants, such as PPs, in WWE.

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Interfacial reaction between humic acid and Ca-Montmorillonite: Application in the preparation of a novel pellet binder

Cited by 37 publications

References 40 publications

A Mechanistic Exploration of Natural Organic Matter Aggregation and Surface Complexation in Smectite Mesopores

A Mechanistic Exploration of Natural Organic Matter Aggregation and Surface Complexation in Smectite Mesopores

Raw and modified clays and clay minerals for the removal of pharmaceutical products from aqueous solutions: State of the art and future perspectives

Clay minerals for the removal of pharmaceuticals: Initial investigations of their adsorption properties in real wastewater effluents

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