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.

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.

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.

Role of Divalent Cations on Deposition ofCryptosporidium parvumOocysts on Natural Organic Matter Surfaces

2010 ◽  
Vol 44 (12) ◽  
pp. 4519-4524 ◽  
Author(s):  
Dao Janjaroen ◽  
Yuanyuan Liu ◽  
Mark S. Kuhlenschmidt ◽  
Theresa B. Kuhlenschmidt ◽  
Thanh H. Nguyen
Keyword(s):  
Organic Matter ◽  
Natural Organic Matter ◽  
Divalent Cations

Role of natural organic matter (NOM), colloidal particles, and solution chemistry on ultrafiltration performance

2011 ◽  
Vol 78 (2) ◽  
pp. 189-200 ◽  
Author(s):  
A.W. Zularisam ◽  
Anwar Ahmad ◽  
Mimi Sakinah ◽  
A.F. Ismail ◽  
T. Matsuura
Keyword(s):  
Organic Matter ◽  
Natural Organic Matter ◽  
Colloidal Particles ◽  
Solution Chemistry

Role of tertiary amines in enhancing trihalomethane and haloacetic acid formation during chlorination of aromatic compounds and a natural organic matter extract

2018 ◽  
Vol 4 (5) ◽  
pp. 663-679 ◽  
Author(s):  
Kun Huang ◽  
Amisha D. Shah
Keyword(s):  
Organic Matter ◽  
Organic Compound ◽  
Natural Organic Matter ◽  
Aromatic Compounds ◽  
Acid Formation ◽  
Tertiary Amines ◽  
Haloacetic Acid ◽  
Anthropogenic Inputs

Tertiary amines are prevalent in waters due to anthropogenic inputs and are known to enhance organic compound degradation while increasing disinfection by-product (DBP) formation, via the strong chlorinating agent, R3N–Cl+.

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