Agglomeration and dissolution of zinc oxide nanoparticles: role of pH, ionic strength and fulvic acid

2013 ◽  
Vol 10 (4) ◽  
pp. 306 ◽  
Author(s):  
Rute F. Domingos ◽  
Zohreh Rafiei ◽  
Carlos E. Monteiro ◽  
Mohammad A.K. Khan ◽  
Kevin J. Wilkinson
Keyword(s):  
Organic Matter ◽  
Ionic Strength ◽  
Fulvic Acid ◽  
Natural Organic Matter ◽  
Organic Matter Content ◽  
Engineered Nanoparticles ◽  
Colloidal System ◽  
Nominal Size ◽  
Mass Ratios

Environmental context The number of nano-enabled products reaching consumers is growing exponentially, inevitably resulting in their release to the environment. The environmental fate and mobility of nanomaterials will depend on their physicochemical form(s) under natural conditions. For ZnO nanoparticles, determinations of agglomeration and dissolution under environmentally relevant conditions of pH, ionic strength and natural organic matter content will provide insight into the potential environmental risk of these novel products. Abstract The increasing use of engineered nanoparticles (ENPs) in industrial and household applications has led to their release into the environment and increasing concern about their effects. Proper assessment of the ecological risks of ENPs will require data on their bioavailability, persistence and mobility over a broad range of physicochemical conditions, including environmentally relevant pH, ionic strength and concentrations of natural organic matter (NOM). In this study, fluorescence correlation spectroscopy was used to determine the agglomeration of a ZnO ENP (nZnO) with a nominal size of 20nm. Particle dissolution was followed using scanned stripping chronopotentiometry. The effects of Suwannee River fulvic acid (SRFA, 0–60mgL–1) and the roles of pH (4–10) and ionic strength (0.005–0.1M) were carefully evaluated. Agglomeration of the bare nZnO increased for pH values near the zero point of charge, whereas the dissolution of the particles decreased. At any given pH, an increase in ionic strength generally resulted in a less stable colloidal system. The role of SRFA was highly dependent upon its concentration with increased agglomeration observed at low SRFA : nZnO mass ratios and decreased agglomeration observed at higher SRFA : nZnO mass ratios. The results indicated that in natural systems, both nZnO dispersion and dissolution will be important and highly dependent upon the precise conditions of pH and ionic strength.

Aggregation of titanium dioxide nanoparticles: role of calcium and phosphate

2010 ◽  
Vol 7 (1) ◽  
pp. 61 ◽  
Author(s):  
Rute F. Domingos ◽  
Caroline Peyrot ◽  
Kevin J. Wilkinson
Keyword(s):  
Organic Matter ◽  
Tio2 Nanoparticles ◽  
Natural Organic Matter ◽  
Organic Matter Content ◽  
Consumer Products ◽  
Correlation Spectroscopy ◽  
Health Impacts ◽  
Phosphate Adsorption ◽  
Nominal Size

Environmental context. The increasing use of nanomaterials in consumer products has led to increased concerns about their potential environmental and health impacts. TiO2 is a widely used nanoparticle found in sunscreens and electronic products. In order to understand and predict the mobility of TiO2 in the natural environment, it is essential to determine its state of aggregation under environmentally relevant conditions of pH, ionic strength, ion and natural organic matter content. Aggregation is likely to lead to both reduced mobility and bioavailability in soils and natural waters. Abstract. The physicochemical characterisation of nanomaterials is crucial to predict their environmental and health impacts. Ion adsorption is known to influence the surface properties of nano-metal oxides in natural systems. The role of calcium and phosphate adsorption on aggregation was examined in the presence and absence of natural organic matter. Fluorescence correlation spectroscopy (FCS) was performed in order to determine the diffusion coefficients of TiO2 nanoparticles having a nominal size between 3 to 5 nm. Based upon FCS and electrophoretic mobility measurements, the presence of calcium resulted in a destabilisation and aggregation of the TiO2 nanoparticles, even in presence of Suwannee River fulvic acid (SRFA). Conditions which favoured phosphate adsorption also resulted in a destabilisation of the TiO2 sample but for low SRFA concentrations only.

Direct and Indirect Toxic Effects of Engineered Nanoparticles on Algae: Role of Natural Organic Matter

2013 ◽  
Vol 1 (7) ◽  
pp. 686-702 ◽  
Author(s):  
Antonietta Quigg ◽  
Wei-Chun Chin ◽  
Chi-Shuo Chen ◽  
Saijin Zhang ◽  
Yuelu Jiang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Natural Organic Matter ◽  
Engineered Nanoparticles ◽  
Toxic Effects

Decolorisation of natural organic matter by Phanerochaete chrysosporium: the effect of environmental conditions

2004 ◽  
Vol 4 (4) ◽  
pp. 175-182 ◽  
Author(s):  
K. Rojek ◽  
F.A. Roddick ◽  
A. Parkinson
Keyword(s):  
Organic Matter ◽  
Ionic Strength ◽  
Natural Organic Matter ◽  
Phanerochaete Chrysosporium ◽  
Fungal Growth ◽  
Low Ph ◽  
Colour Removal ◽  
Humic Material ◽  
Carbon And Nitrogen ◽  
Carbon And Nitrogen Content

Phanerochaete chrysosporium was shown to rapidly decolorise a solution of natural organic matter (NOM). The effect of various parameters such as carbon and nitrogen content, pH, ionic strength, NOM concentration and addition of Mn2+ on the colour removal process was investigated. The rapid decolorisation was related to fungal growth and biosorption rather than biodegradation as neither carbon nor nitrogen limitation, nor Mn2+ addition, triggered the decolorisation process. Low pH (pH 3) and increased ionic strength (up to 50 g L‒1 added NaCl) led to greater specific removal (NOM/unit biomass), probably due to increased electrostatic bonding between the humic material and the biomass. Adsorption of NOM with viable and inactivated (autoclaved or by sodium azide) fungal pellets occurred within 24 hours and the colour removal depended on the viability, method of inactivation and pH. Colour removal by viable pellets was higher under the same conditions, and this, combined with desorption data, confirmed that fungal metabolic activity was important in the decolorisation process. Overall, removals of up to 40–50% NOM from solution were obtained. Of this, removal by adsorption was estimated as 60–70%, half of which was physicochemical, the other half metabolically-dependent biosorption and bioaccumulation. The remainder was considered to be removed by biodegradation, although some of this may be ascribed to bioaccumulation and metabolically-dependent biosorption.

Coating ligands mediated dynamic formation of natural organic matter (NOM) corona on engineered nanoparticles in environments

2021 ◽  
Author(s):  
Chuan-Wang Yang ◽  
Li Yuan ◽  
Hong-Zhi Zhou ◽  
Xin Zhang ◽  
Guo-Ping Sheng
Keyword(s):  
Organic Matter ◽  
Natural Organic Matter ◽  
Engineered Nanoparticles ◽  
Aquatic Systems ◽  
Solution Interface ◽  
Dynamic Formation

Natural organic matter (NOM) can adsorb onto engineered nanoparticles (ENPs) and form NOM-corona on ENPs-solution interface, thus affecting the performance and ecotoxicity of ENPs in aquatic systems. Nevertheless, the formation...

HUMUS FRACTION RATIOS AS A MEANS OF DISCRIMINATING BETWEEN HORIZON TYPES

1980 ◽  
Vol 60 (2) ◽  
pp. 219-229 ◽  
Author(s):  
L. E. LOWE
Keyword(s):  
Organic Matter ◽  
Humic Acid ◽  
Carbon Content ◽  
Fulvic Acid ◽  
Soil Classification ◽  
Acid Fraction ◽  
Humus Fraction ◽  
Wide Range ◽  
Fraction Distribution

Humus fraction distribution in a wide range of horizon samples was examined by measuring carbon content in humic acid (Ch), in fulvic acid (Cf) and in the strongly colored polyphenolic component of the fulvic acid fraction (Ca). Fraction distribution was described by the ratios Ch/Cf and Ca/Cf. It was concluded that humus fraction ratios were related to horizon types as used in the Canadian System of Soil Classification, and were effective in discriminating between certain horizon types, particularly between Luvisolic Bt and Podzolic Bf. The results also suggested that humus fraction ratios may be effective in separating distinct sub-populations within Ah horizons and Bf horizons in general, based on qualitative differences in organic matter present. Aspects of the role of humus fractions in soil genesis are discussed.

Transport characterizations of natural organic matter in ion-exchange membrane for water treatment

2002 ◽  
Vol 2 (5-6) ◽  
pp. 445-450 ◽  
Author(s):  
D.H. Kim ◽  
S.-H. Moon ◽  
J. Cho
Keyword(s):  
Organic Matter ◽  
Ionic Strength ◽  
Ion Exchange ◽  
Natural Organic Matter ◽  
Membrane Surface ◽  
Factors Affecting ◽  
Organic Fouling ◽  
Adsorbed Mass ◽  
Pass Through ◽  
Exchange Membrane

A series of adsorption experiments were performed to investigate the factors affecting the transport of natural organic matter (NOM) in an ion-exchange (IX) membrane. In this study, the structure of the NOM was hypothesized to be an important factor in terms of the organic fouling of IX membrane. It was found that the adsorbed mass of hydrophobic NOM constituent on the membrane surface was higher than that of either the hydrophilic or transphilic NOM constituent. NOM adsorption was seriously affected by the apparent charge of the NOM. As the apparent charge increased, NOM adsorption also significantly increased. Moreover, the molecular mass of the hydrophobic NOM acids was too high to enable them to pass through the IX membrane, and this caused an accumulated adsorption of solutes on the membrane surface, i.e. NOM fouling. In addition, both pH and ionic strength affected NOM adsorption on the surface of the IX membrane. Lower NOM adsorption resulted from a lower pH and a higher ionic strength.

Application of composite flocculants for removing organic matter and mitigating ultrafiltration membrane fouling in surface water treatment: the role of composite ratio

2019 ◽  
Vol 5 (12) ◽  
pp. 2242-2250
Author(s):  
Xue Shen ◽  
Baoyu Gao ◽  
Kangying Guo ◽  
Qinyan Yue
Keyword(s):  
Organic Matter ◽  
Water Treatment ◽  
Surface Water ◽  
Membrane Permeability ◽  
Natural Organic Matter ◽  
Membrane Fouling ◽  
Ultrafiltration Membrane ◽  
Surface Water Treatment ◽  
Ultrafiltration Membrane Fouling

Coagulation prior to the ultrafiltration (UF) process was implemented to improve natural organic matter (NOM) removal and membrane permeability.

Investigation of membrane fouling by synthetic and natural particles

2004 ◽  
Vol 50 (12) ◽  
pp. 279-285 ◽  
Author(s):  
J.H. Kweon ◽  
D.F. Lawler
Keyword(s):  
Organic Matter ◽  
Natural Organic Matter ◽  
Membrane Fouling ◽  
Membrane Surface ◽  
Research Articles ◽  
Clay Material ◽  
Dramatic Effect ◽  
Flux Decline ◽  
Scanning Electron

The biggest impediment for applying membrane processes is fouling that comes from mass flux (such as particle and organic matter) to the membrane surface and its pores. Numerous research articles have indicated that either particles or natural organic matter (NOM) has been the most detrimental foulant. Therefore, the role of particles in membrane fouling was investigated with two synthetic waters (having either particles alone or particles with simple organic matter) and a natural water. Membrane fouling was evaluated with flux decline behavior and direct images from scanning electron microscopy. The results showed that the combined fouling by kaolin and dextran (a simple organic compound selected as a surrogate for NOM) showed no difference from the fouling with only the organic matter. The similarity might stem from the fact that dextran (i.e., polysaccharide) has no ability to be adsorbed on the clay material, so that the polysaccharide behaves the same with respect to the membrane with or without clay material being present. In contrast to kaolin, the natural particles showed a dramatic effect on membrane fouling.

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