The effects of nanoparticle aggregation processes on aggregate structure and metal uptake

Gilbert, Benjamin; Ono, R. K.; Ching, K. A.; Kim, Christopher S.

doi:10.1016/j.jcis.2009.07.058

Cited by 169 publications

(136 citation statements)

References 57 publications

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“…79,83,84 In addition, mineral characterization must be done on samples prepared under conditions relevant to those used in reactivity studies. This point is highlighted by the results from this study on birnessite and others on ferrihydrite, 78,85 which reveal the interconnectedness of solution chemistry, particle surface charge and structural properties (e.g., crystallite size, BET-SSA, and aggregate or agglomerate structure). Finally, the formation of open versus closed structures upon nanoparticle aggregation or agglomeration has important implications for ion sorption by nanoscale oxides and merits further investigation.…”

Section: Implications For Nanoparticle Reactivitysupporting

confidence: 51%

“…However, surface processes, including sorption, desorption, and dissolution, depend on particle size and particle aggregation, which may or may not be captured well by BET-SSA measurements. 21,[78][79][80][81][82] Evidently, precise definitions of particle size and careful characterization of the mineral structure are necessary. 79,83,84 In addition, mineral characterization must be done on samples prepared under conditions relevant to those used in reactivity studies.…”

Section: Implications For Nanoparticle Reactivitymentioning

confidence: 99%

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Crystal growth and aggregation in suspensions of δ-MnO₂nanoparticles: implications for surface reactivity

Marafatto

Lanson

Peña

2018

Environ. Sci.: Nano

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a Birnessite (layer-type Mn oxide) is a key reactive phase in soils and sediments and its sorption and oxidative properties render it attractive for use in technical applications. The most widely used synthetic analog of natural and biogenic birnessite in laboratory studies is nanocrystalline δ-MnO 2 . However, a wide range of physicochemical properties have been reported in the literature for δ-MnO 2 . In this study, we produced several batches of δ-MnO 2 and identified the mechanisms leading to significant variations in particle size, as probed by X-ray diffraction (3 to 7 nm), dynamic light scattering (85 to 501 nm) and N 2 Ĳg) BET specific surface area (SSA: 119 to 259 m 2 g −1) measurements. Both the coherent scattering domain (CSD) size in the ab plane and the wet-aggregate size decreased with increasing suspension pH and Na content, which is consistent with base-catalyzed oxidation and nucleation at high pH and growth by oriented attachment at low pH. The increase in the CSD size upon sample acidification but not basification provides further evidence for OA as a crystal growth mechanism. Finally, the sample SSA was not related to the crystallite size, but instead was inversely correlated to the suspension pH and Na : Mn content. The surface charge and counter-cation content of δ-MnO 2 control the aggregate structure, where low pH (low Na : Mn) favored high surface area structures and high pH (high Na : Mn) favored low surface area structures. The reversibility of SSA upon the acidification or basification of parent suspensions and the crystal growth only upon suspension acidification confirmed that the primary crystallite size and the aggregate/agglomerate size are highly sensitive to solution chemistry and surface charge and has direct implications for δ-MnO 2 nanoparticle reactivity towards organic and inorganic contaminants in environmental systems that can encompass a dynamic range of pH values and ionic compositions.

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Section: Implications For Nanoparticle Reactivitysupporting

confidence: 51%

Section: Implications For Nanoparticle Reactivitymentioning

confidence: 99%

Crystal growth and aggregation in suspensions of δ-MnO₂nanoparticles: implications for surface reactivity

Marafatto

Lanson

Peña

2018

Environ. Sci.: Nano

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“…However, Yu et al (2009) suggested that an increment in concentration of nanoparticles could lead to an increase in nanoparticle agglomeration. Besides, Gilbert et al (2009) suggested that ionic strength and pH of the solution also could induce agglomeration between nanoparticles. …”

Section: Figurementioning

confidence: 99%

Organic-inorganic hybrid membranes in separation processes: a 10-year review

Souza

Quadri

2013

Braz. J. Chem. Eng.

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-In relation to some inorganic membranes, polymeric membranes have relatively low separation performance. However, the processing flexibility and low cost of polymers still make them highly attractive for many industrial separation applications. Polymer-inorganic hybrid membranes constitute an emerging research field and have been recently developed to improve the separation properties of polymer membranes because they possess properties of both organic and inorganic membranes such as good hydrophilicity, selectivity, permeability, mechanical strength, and thermal and chemical stability. The structures and processing of polymer-inorganic nanocomposite hybrid membranes, as well as their use in the fields of ultrafiltration, nanofiltration, pervaporation, gas separation and separation mechanism are reviewed.

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“…Previous studies have shown that the adsorption of metals onto metal-oxide nanoparticles is pH dependent [12,29]; therefore, desorption of metals should be possible through pH adjustment. Desorption experiments at pH 8.0, pH 6.0, and pH 4.0 examined the reversibility of the adsorption reaction and determined the most efficient pH for the desorption of divalent metals from nanohematite.…”

Section: Desorption Experimentsmentioning

confidence: 99%

Adsorption and desorption of bivalent metals to hematite nanoparticles

Grover

Engates

et al. 2011

Enviro Toxic and Chemistry

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The use of commercially prepared hematite nanoparticles (37.0 nm) was studied as an adsorbent in the removal of Cd(II), Cu(II), Pb(II), and Zn(II) from aqueous solutions. Single-metal adsorption was studied as a function of metal and adsorbent concentrations, whereas binary metal competition was found to be dependent on the molar ratio between the competing metals. Competitive effects indicated that Pb had strong homogenous affinity to the nanohematite surface, and decreased adsorption of Cd, Cu, and Zn occurred when Pb was present in a binary system. Metal adsorption strength to nanohematite at pH 6.0 increased with metal electronegativity: Pb > Cu > Zn ∼ Cd. Equilibrium modeling revealed that the Langmuir-Freundlich composite isotherm adequately described the adsorption and competitive effects of metals to nanohematite, whereas desorption was best described by the Langmuir isotherm. The desorption of metals from nanohematite was found to be pH dependent, with pH 4.0 > pH 6.0 > pH 8.0, and results showed that greater than 65% desorption was achieved at pH 4.0 within three 24-h cycles for all metals.

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The effects of nanoparticle aggregation processes on aggregate structure and metal uptake

Cited by 169 publications

References 57 publications

Crystal growth and aggregation in suspensions of δ-MnO₂nanoparticles: implications for surface reactivity

Crystal growth and aggregation in suspensions of δ-MnO₂nanoparticles: implications for surface reactivity

Organic-inorganic hybrid membranes in separation processes: a 10-year review

Adsorption and desorption of bivalent metals to hematite nanoparticles

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The effects of nanoparticle aggregation processes on aggregate structure and metal uptake

Cited by 169 publications

References 57 publications

Crystal growth and aggregation in suspensions of δ-MnO2nanoparticles: implications for surface reactivity

Crystal growth and aggregation in suspensions of δ-MnO2nanoparticles: implications for surface reactivity

Organic-inorganic hybrid membranes in separation processes: a 10-year review

Adsorption and desorption of bivalent metals to hematite nanoparticles

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Crystal growth and aggregation in suspensions of δ-MnO₂nanoparticles: implications for surface reactivity

Crystal growth and aggregation in suspensions of δ-MnO₂nanoparticles: implications for surface reactivity