Different Approaches to investigate the interfacial interactions between Natural Organic Matter and Metal Oxide

Handle URI:
http://hdl.handle.net/10754/626332
Title:
Different Approaches to investigate the interfacial interactions between Natural Organic Matter and Metal Oxide
Authors:
Zaouri, Noor A. ( 0000-0003-2759-2934 )
Abstract:
A variety of approaches were conducted to obtain a comprehensive understanding of the adsorption of Natural Organic Matter (NOM) isolates on metal oxides (MeO). Adsorption experiments with a series of small molecular weight (MW), oxygenated, aromatic organic acids were performed with Aluminum oxide (Al2O3), Titanium oxide (TiO2), and Zirconium oxide (ZrO2) surface. The experiments were conducted in batch mode at pH 4.2 and 7.6. The adsorption of simple organic acids was described by Langmuir model, and exhibited strong dependence on the relative abundance of carboxyl group, aliphaticity/aromaticity, length of alkyl chain, and the presence of hydroxyl group. The adsorption of the model compounds was high at low pH and decreased with increasing the pH. Isolated NOM fraction of strong humic character, i.e., hydrophobic (HPO) (high in MW, aromaticity, and acidity), i.e., Suwannee River fulvic acid (SRW HPO), showed strong adsorption on all MeO. However, fractions with similar acidic character, and lower MW exerted weak adsorption. NOM fraction that incorporated polysaccharides and proteins like structures (i.e., biopolymers) was not significantly adsorbed compared to HPO fractions. Interestingly, biopolymer adsorption on Heated Aluminum oxide particles (HAOP) was higher than that on Al2O3, TiO2, and ZrO2. These different adsorption profiles were related to their physicochemical characteristics of NOM and MeO, and thus, showed different interacting mechanisms and were studied by Atomic Force Microscopy (AFM). Hydrogen bonding was suggested as the main mechanism between NOM of strong hydrophilic character (i.e., biopolymers) and Al2O3, TiO2 and ZrO2 coated wafers. The strength of the hydrogen bonding was influenced by the hydrophilicity degree of MeO surface, ionic strength, and cation type. NOM fractions with strong humic character showed repulsive forces that are electrostatic in nature with MeO of high negative charge density. Hydrogen bonding and ligand exchange mechanisms are proposed to control the adsorption mechanism at high ionic strength with less negatively-charged MeO surface. Strong interactions forces was recorded between NOM molecules with different properties, more specifically with high MW humic and non humic fractions. These forces are controlled by cation type, and NOM chemical structure.
Advisors:
Wang, Peng ( 0000-0003-0856-0865 ) ; Croue, Jean Philippe
Committee Member:
Saikaly, Pascal ( 0000-0001-7678-3986 ) ; Benedetti, Marc F.; Lubineau, Gilles ( 0000-0002-7370-6093 )
KAUST Department:
Biological and Environmental Sciences and Engineering (BESE) Division
Program:
Environmental Science and Engineering
Issue Date:
Dec-2017
Type:
Dissertation
Appears in Collections:
Dissertations

Full metadata record

DC FieldValue Language
dc.contributor.advisorWang, Pengen
dc.contributor.advisorCroue, Jean Philippeen
dc.contributor.authorZaouri, Noor A.en
dc.date.accessioned2017-12-10T06:48:05Z-
dc.date.available2017-12-10T06:48:05Z-
dc.date.issued2017-12-
dc.identifier.urihttp://hdl.handle.net/10754/626332-
dc.description.abstractA variety of approaches were conducted to obtain a comprehensive understanding of the adsorption of Natural Organic Matter (NOM) isolates on metal oxides (MeO). Adsorption experiments with a series of small molecular weight (MW), oxygenated, aromatic organic acids were performed with Aluminum oxide (Al2O3), Titanium oxide (TiO2), and Zirconium oxide (ZrO2) surface. The experiments were conducted in batch mode at pH 4.2 and 7.6. The adsorption of simple organic acids was described by Langmuir model, and exhibited strong dependence on the relative abundance of carboxyl group, aliphaticity/aromaticity, length of alkyl chain, and the presence of hydroxyl group. The adsorption of the model compounds was high at low pH and decreased with increasing the pH. Isolated NOM fraction of strong humic character, i.e., hydrophobic (HPO) (high in MW, aromaticity, and acidity), i.e., Suwannee River fulvic acid (SRW HPO), showed strong adsorption on all MeO. However, fractions with similar acidic character, and lower MW exerted weak adsorption. NOM fraction that incorporated polysaccharides and proteins like structures (i.e., biopolymers) was not significantly adsorbed compared to HPO fractions. Interestingly, biopolymer adsorption on Heated Aluminum oxide particles (HAOP) was higher than that on Al2O3, TiO2, and ZrO2. These different adsorption profiles were related to their physicochemical characteristics of NOM and MeO, and thus, showed different interacting mechanisms and were studied by Atomic Force Microscopy (AFM). Hydrogen bonding was suggested as the main mechanism between NOM of strong hydrophilic character (i.e., biopolymers) and Al2O3, TiO2 and ZrO2 coated wafers. The strength of the hydrogen bonding was influenced by the hydrophilicity degree of MeO surface, ionic strength, and cation type. NOM fractions with strong humic character showed repulsive forces that are electrostatic in nature with MeO of high negative charge density. Hydrogen bonding and ligand exchange mechanisms are proposed to control the adsorption mechanism at high ionic strength with less negatively-charged MeO surface. Strong interactions forces was recorded between NOM molecules with different properties, more specifically with high MW humic and non humic fractions. These forces are controlled by cation type, and NOM chemical structure.en
dc.language.isoenen
dc.subjectMetal oxideen
dc.subjectAFMen
dc.subjectNatural Organic Matteren
dc.subjectNOMen
dc.subjectDLSen
dc.titleDifferent Approaches to investigate the interfacial interactions between Natural Organic Matter and Metal Oxideen
dc.typeDissertationen
dc.contributor.departmentBiological and Environmental Sciences and Engineering (BESE) Divisionen
thesis.degree.grantorKing Abdullah University of Science and Technologyen
dc.contributor.committeememberSaikaly, Pascalen
dc.contributor.committeememberBenedetti, Marc F.en
dc.contributor.committeememberLubineau, Gillesen
thesis.degree.disciplineEnvironmental Science and Engineeringen
thesis.degree.nameDoctor of Philosophyen
dc.person.id117647en
All Items in KAUST are protected by copyright, with all rights reserved, unless otherwise indicated.