عنوان المقالة:تاثير حمض الهيومك على امتصاص جزئيات التتانيوم النانونية Effect of humic acid source on humic acid adsorption onto titanium dioxide nanoparticles

محمد ارحيم عمر ارحيم | Mohamed Erhayem | 9993

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Publication Type

Journal

Arabic Authors

محمد ارحيم وماري سون

English Authors

M Erhayem, M Sohn

Abstract

In many studies, different humic acid (HA) sources are used interchangeably to evaluate the effect of organic matter on geochemical processes in the environment. This research looks more specifically at the effect of HA source on HA adsorption onto nano-TiO2 and how HA adsorption affects the fate and transport of nano-TiO2. In this study, six humic acids (HAs) were studied which were derived from soils (SLHA), or from sediments (SDHA) all originating from the state of Florida. Humic acid adsorption onto titanium dioxide nanoparticles (nano-TiO2) and the sedimentation of HA-coated and uncoated nano-TiO2were monitored by Ultraviolet–visible (UV–vis) spectroscopy. Synchronous scan fluorescence (SSF) spectroscopywas used to complement the study of HAadsorption onto nano-TiO2. Phosphate bufferwas found to reduce the amount ofHA adsorbed onto nano-TiO2 relative to solutions ofNaCl of the samepH and ionic strength. Adsorption constant values (Kads) for HAs varied in the order SLHA N FSDHA (freshwater sedimentary HA) N ESDHA (estuarine sedimentary HA). SSF results suggested that the more highly conjugated fractions of HA, which are more prevalent in SLHAs versus SDHAs, were preferentially adsorbed. In order to better understand the relationship between adsorption and aggregation, sedimentation studies were conducted and it was found that the percentage of nano-TiO2 sedimentation was preferentially enhanced in the order of the presence of SLHA N FSDHA N ESDHA. The extent of nano-TiO2 sedimentation was decreased with increasing HA concentration. TEM imaging of nano-TiO2 confirmed that nano-TiO2 was aggregated in the presence of HAs. The findings in this study suggest that HAs from different sources influence the fate and transport of nano-TiO2 in the environment differently. © 2013 Elsevier

Abstract

In many studies, different humic acid (HA) sources are used interchangeably to evaluate the effect of organic matter on geochemical processes in the environment. This research looks more specifically at the effect of HA source on HA adsorption onto nano-TiO2 and how HA adsorption affects the fate and transport of nano-TiO2. In this study, six humic acids (HAs) were studied which were derived from soils (SLHA), or from sediments (SDHA) all originating from the state of Florida. Humic acid adsorption onto titanium dioxide nanoparticles (nano-TiO2) and the sedimentation of HA-coated and uncoated nano-TiO2were monitored by Ultraviolet–visible (UV–vis) spectroscopy. Synchronous scan fluorescence (SSF) spectroscopywas used to complement the study of HAadsorption onto nano-TiO2. Phosphate bufferwas found to reduce the amount ofHA adsorbed onto nano-TiO2 relative to solutions ofNaCl of the samepH and ionic strength. Adsorption constant values (Kads) for HAs varied in the order SLHA N FSDHA (freshwater sedimentary HA) N ESDHA (estuarine sedimentary HA). SSF results suggested that the more highly conjugated fractions of HA, which are more prevalent in SLHAs versus SDHAs, were preferentially adsorbed. In order to better understand the relationship between adsorption and aggregation, sedimentation studies were conducted and it was found that the percentage of nano-TiO2 sedimentation was preferentially enhanced in the order of the presence of SLHA N FSDHA N ESDHA. The extent of nano-TiO2 sedimentation was decreased with increasing HA concentration. TEM imaging of nano-TiO2 confirmed that nano-TiO2 was aggregated in the presence of HAs. The findings in this study suggest that HAs from different sources influence the fate and transport of nano-TiO2 in the environment differently. © 2013 Elsevier

Publication Date

9/11/2013

Publisher

Science of the Total Environment

Volume No

470

Issue No

DOI

http://dx.doi.org/10.1016/j.scitotenv.2013.09.063

Pages

92-98

Keywords

Soil and sedimentary humic acid Titanium dioxide nanoparticles Adsorption constants Sedimentation