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Aggregation and disaggregation of ZnO nanoparticles: Influence of pH and adsorption of Suwannee River humic acid

Abdul Aziz, Hamidi
Published in Science of the Total Environment. 2014, vol. 468-469, p. 195-201
Abstract The surface charge and average size of manufactured ZnO nanoparticles (NPs) was studied as a function of pH to understand the aggregation behaviour and importance of the electrostatic interactions in solution. The interactions between ZnO and Suwannee River humic acid (SRHA) were then investigated under a range of environmentally relevant conditions with the ZnO nanoparticles pHPZC as the point of reference. The anionic charges carried by aquatic humic substances were found to play a major role in the aggregation and disaggregation of ZnO nanoparticles. At low concentrations of SRHA (<0.05 mg/L) and below the pHPZC, anionic SRHA was rapidly adsorbed onto the positively charged ZnO NPs hence promoting aggregation. With similar SHRA concentrations, at pHPZC, SRHA was able to control the suspension behavior of the ZnO and promote partial disaggregation in small volumes. This was more distinguishable when the pH was greater than pHPZC as SRHA formed a surface coating on the ZnO nanoparticles and enhanced stability via electrostatic and steric interactions. In most cases, the NP coating by SRHA induced disaggregation behavior in the ZnO nanoparticles and decreased the aggregate size in parallel to increasing SRHA concentrations. Results also suggest that environmental aquatic concentration ranges of humic acids largely modify the stability of aggregated or dispersed ZnO nanoparticles.
Keywords ZnO nanoparticlesSuwannee River humic acidZeta potentialAggregationDisaggregation
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Research groups Environmental Physical Chemistry
ISE Pôle Sciences
Projects FNS: 200021_135240
(ISO format)
MOHD OMAR, Fatehah Binti, ABDUL AZIZ, Hamidi, STOLL, Serge. Aggregation and disaggregation of ZnO nanoparticles: Influence of pH and adsorption of Suwannee River humic acid. In: Science of the Total Environment, 2014, vol. 468-469, p. 195-201. https://archive-ouverte.unige.ch/unige:32702

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Deposited on : 2013-12-23

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