Natural organic matter and colloidal stability: Models and measurements

Environmental contextThe fate of silver nanoparticles (AgNPs) in aqueous systems could be influenced by the hydrophobicity of natural organic matter. We observed that the aggregation and dissolution of oppositely charged AgNPs were controlled by the selectivity and dynamics of sorption processes involving the nanoparticle surface and hydrophobic groups on natural organic matter. These findings will be helpful to understand the fate and effects of coated AgNPs in natural systems. AbstractThe fate of silver nanoparticles (AgNPs) released into aquatic environments is significantly affected by natural organic matter (NOM). However, current studies are still insufficient to understand interactions between NOM and AgNPs because they do not explicitly consider the heterogeneity of NOM. We investigated how NOM components with different properties (hydrophobicity, molecular weight, aromaticity, and polarity of functional groups) interact with AgNPs coated with citrate (Cit) and branched polyethylenimine (BPEI) and influence their colloidal stability and dissolution. Pony Lake fulvic acid (PLFA) selected as a model NOM was fractionated into hydrophobic (HPO) and transphilic (TPI) fractions. Sorption of PLFA molecules with a high content of polar functional groups bound to the aromatic rings onto nanoparticles was more favourable in the case of the TPI fraction, which most likely resulted in higher aggregation for both AgNPs and stronger protection of BPEI-AgNPs against dissolution compared with the HPO fraction. Additionally, in contrast to the Cit-AgNPs, resorption of Ag+ ions released from BPEI-AgNPs and/or sorption of Ag+-PLFA complexes to the nanoparticles was most likely a dynamic process, as suggested by the time-dependent changes in the molecular weight of the PLFA fractions sorbed to the BPEI-AgNP surface. These observations suggest that the accessibility of the AgNP surface for the hydrophobicity-based fractions of NOM as well as their colloidal stability and dissolution are controlled by the type and charge of coating materials and by the molecular weight, aromaticity, and content of polar functional groups of NOM.

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Effects of natural organic matter (NOM), metal-to-sulfide ratio and Mn2+ on cadmium sulfide nanoparticle growth and colloidal stability

Environmental Science Nano ◽

10.1039/d0en00764a ◽

2020 ◽

Vol 7 (11) ◽

pp. 3385-3404

Author(s):

Kevin Hoffmann ◽

Iso Christl ◽

Ralf Kaegi ◽

Ruben Kretzschmar

Keyword(s):

Organic Matter ◽

Crystal Lattice ◽

Cadmium Sulfide ◽

Natural Organic Matter ◽

Colloidal Stability ◽

Cds Nanoparticles ◽

Nanoparticle Growth ◽

Naturally Occurring

Growth of naturally occurring CdS nanoparticles is constrained by natural organic matter (NOM), which also limits the reduction of CdS colloidal stability by Mn2+ and prevents incorporation of Mn into the CdS crystal lattice.

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Natural organic matter and colloidal stability: models and measurements

Colloids in the Aquatic Environment ◽

10.1016/b978-1-85861-038-2.50010-3 ◽

1993 ◽

pp. 89-102 ◽

Cited By ~ 1

Author(s):

Christine L. Tiller ◽

Charles R. O'Melia

Keyword(s):

Organic Matter ◽

Natural Organic Matter ◽

Colloidal Stability

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Effects of Ozone on the Colloidal Stability and Aggregation of Particles Coated with Natural Organic Matter

Environmental Science & Technology ◽

10.1021/es9500567 ◽

1996 ◽

Vol 30 (2) ◽

pp. 431-443 ◽

Cited By ~ 51

Author(s):

Mysore S. Chandrakanth ◽

Gary L. Amy

Keyword(s):

Organic Matter ◽

Natural Organic Matter ◽

Colloidal Stability

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The Removal of CuO Nanoparticles from Water by Conventional Treatment C/F/S: The Effect of pH and Natural Organic Matter

Molecules ◽

10.3390/molecules24050914 ◽

2019 ◽

Vol 24 (5) ◽

pp. 914 ◽

Cited By ~ 2

Author(s):

Rizwan Khan ◽

Muhammad Ali Inam ◽

Du Ri Park ◽

Sarfaraz Khan ◽

Muhammad Akram ◽

...

Keyword(s):

Organic Matter ◽

Natural Organic Matter ◽

Colloidal Stability ◽

Copper Oxide Nanoparticles ◽

Engineered Nanoparticles ◽

Cuo Nps ◽

Effects Of Ph ◽

Alkaline Conditions ◽

Ft Ir ◽

The Fourier Transform

The increased use of engineered nanoparticles (ENPs), such as copper oxide nanoparticles (CuO NPs), in commercial products and applications raises concern regarding their possible release into freshwater sources. Therefore, their removal from water is important to eliminate adverse environmental and human health effects. In this study, the effects of pH and natural organic matter (NOM), i.e., humic acid (HA) and salicylic acid (SA) on the removal of CuO NPs by coagulation/flocculation/sedimentation (C/F/S) were evaluated. The results indicated that pH significantly affects the coagulation efficiency, where 10–60% CuO NPs removal was achieved under extreme acidic/alkaline conditions. However, at neutral pH, removal of up to 90% was observed with a lower ferric chloride (FC) dosage (0.2 mM). The coagulation efficiency and mechanism were strongly affected by the type of Fe species present in the aqueous phase, which is mainly controlled by pH. Higher concentrations of both HA and SA decrease the CuO NPs agglomeration rate, and thereby improve the colloidal stability due to the NOM molecules adsorbed onto the NPs surface. The presence of hydrophobic HA needs a higher FC dosage of 0.5–0.8 mM than a dosage of hydrophilic SA of 0.25–0.35 mM, to obtain a similar CuO coagulation efficiency. Moreover, higher removals of dissolved organic carbon (DOC) and UV254 were observed more in hydrophobic NOM than in hydrophilic. The results of the Fourier transform infrared (FT-IR) analysis of FC composite flocs confirm that the charge neutralization and enmeshment of coagulant might be a possible removal mechanism. The findings of the current study may provide critical information in the prediction of the fate, mobility, and removal of CuO NPs during C/F/S in water treatment.

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