Scanning force microscopy of spin-coated humic acid

Mertig, Michael; Klemm, Denis; Pompe, W.; Zänker, Harald; Böttger, M. L.

doi:10.1002/(sici)1096-9918(199905/06)27:5/6<426::aid-sia516>3.0.co;2-n

Cited by 13 publications

(3 citation statements)

References 21 publications

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“…The minimum concentration of SRHA needed to completely coat the surface of a 1‐mg/L nC 60 particle suspension was estimated assuming that: C 60 and nC 60 are both rigid spherical particles with diameter of 1 nm [26] and 108 nm (number‐averaged particle diameter measured by NIBS), respectively; the hydrodynamic diameter of SRHA ranges from 1.5 to 3.5 nm [27], with a molecular weight of 5,000 Da [23]; and the adsorbed NOM forms a monolayer.…”

Section: Resultsmentioning

confidence: 99%

Effect of soil sorption and aquatic natural organic matter on the antibacterial activity of a fullerene water suspension

Liu¹,

Lyon²,

Li³

et al. 2008

Enviro Toxic and Chemistry

134

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The present study investigated the association of a C60 water suspension (nC6) with natural organic matter, present as a soil constituent or dissolved in the water column, and its effect on the antibacterial activity of nC60. Sorption of nC60 to soil reduced its bioavailability and antibacterial activity, and the sorption capacity strongly depended on the organic content of the soil. Adsorption of aquatic dissolved humic substances onto nC60 and possible subsequent reactions also were found to eliminate nC60 toxicity at humic acid concentrations as low as 0.05 mg/L. These findings indicate that natural organic matter in the environment can mitigate significantly the potential impacts of nC60 on microbial activities that are important to ecosystem health.

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Section: Resultsmentioning

confidence: 99%

Effect of soil sorption and aquatic natural organic matter on the antibacterial activity of a fullerene water suspension

Liu¹,

Lyon²,

Li³

et al. 2008

Enviro Toxic and Chemistry

134

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“…6 The study of humic substances structure is carried out through different spectroscopy techniques [7][8][9][10] as well as microscopies. 11,12 Among these techniques, the fluorescence spectroscopy 13,14 and the atomic force microscopy (AFM) [15][16][17][18] have been used to characterize and determine the humic substances structure.…”

Section: Introductionmentioning

confidence: 99%

“…15 AFM is a technique which has been employed to study the morphologies of humic and fulvic acid. 12,[16][17][18] It is a powerful tool to characterize small colloids, as well as colloid agglomeration, adsorption onto surfaces, or modification in morphologies affected by changes in the physico-chemical properties.…”

Section: Introductionmentioning

confidence: 99%

pH effect in aquatic fulvic acid from a Brazilian river

Saab¹,

Carvalho²,

Filho³

et al. 2010

J. Braz. Chem. Soc.

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Estudos do comportamento morfológico dos ácidos fúlvicos foram realizados utilizando a técnica de microscopia de força atômica aliada às técnicas de potencial zeta e espectroscopia de fluorescência. Os resultados mostraram que o ácido fúlvico (AFA) de um rio tropical mudou a sua morfologia quando variado o pH da solução aquosa dos AFA. Em pH ácido a morfologia é mais granular formando aglomerados de altura entre 10-55 nm. Em pH alcalino os valores foram de 2,5-4,0 nm, sendo que a morfologia em condições alcalinas é aberta formando estruturas não granulares. Estes resultados sugerem que para pH 3,5 as interações eletrostáticas são fracas e as ligações de hidrogênio são responsáveis pela formação de agregados, enquanto em pH 9,0 as interações eletrostáticas são fortes devido ao aumento da ionização de grupos fenólicos e ocorrem poucas ligações hidrogênio formando estruturas mais abertas. Os resultados de espectroscopia de fluorescência mostraram mudança na estrutura do AFA de rio tropical em pH alcalino em comparação com a estrutura em pH ácido, corroborando com os resultados obtidos pela AFM.Studies of the morphological behavior of fulvic acids were carried out using the Atomic Force Microscopy technique together with zeta Potential techniques and fluorescence spectroscopy. Results showed that the aquatic fulvic acid (AFA) of a Brazilian River changed its morphology when the AFA aqueous solution had its pH changed. In acid pH the morphology is granular forming 10-55 nm high agglomerates. In alkaline pH values were 2.5-4.0 nm, and the morphology forms non granular structures. These results suggest that for pH 3.0 electrostatic interactions are weak and hydrogen bonding is responsible for the aggregates formation; while at pH 9.0 electrostatic interactions are strong due to the increase in phenolic groups ionization and low hydrogen interaction forming open structures. Fluorescence spectroscopy results confirmed the AFM, that is, a change in the AFA in tropical river in alkaline pH compared to the structure in acid pH.

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Scanning force microscopy of two‐dimensional structure formation in thin humic acid films

Mertig

Klemm

Zänker

et al. 2002

Surface & Interface Analysis

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Humic acid films have been prepared by spin-coating on mica substrates and imaged by scanning force microscopy (SFM). The deposited humic acid films exhibit typical dewetting patterns formed by rupture of the spin-coated film. Two-dimensional Fourier analysis of the SFM images shows that the observed film structures can be well described by a characteristic wavelength that depends on both the concentration of the humic acid solution and the evaporation rate of the solvent. The latter can be controlled by the relative humidity during film preparation. Thus, the investigations give clear evidence that structure formation in thin humic acid films is caused by dewetting during film deposition.

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Scanning force microscopy of spin-coated humic acid

Cited by 13 publications

References 21 publications

Effect of soil sorption and aquatic natural organic matter on the antibacterial activity of a fullerene water suspension

Effect of soil sorption and aquatic natural organic matter on the antibacterial activity of a fullerene water suspension

pH effect in aquatic fulvic acid from a Brazilian river

Scanning force microscopy of two‐dimensional structure formation in thin humic acid films

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