This article was downloaded by: [Temple University Libraries]On: 23 November 2014, At: 15:12Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,37-41 Mortimer Street, London W1T 3JH, UK

Journal of Dispersion Science and TechnologyPublication details, including instructions for authors and subscription information:http://www.tandfonline.com/loi/ldis20

Physicochemical Properties of the Dispersion ofTitanium Dioxide in Organic Media by Using ZetametryTechniqueTayssir Hamieh a b , Joumana Toufaily a & Haytham Alloul aa Laboratoire de Chimie Analytique, Matériaux, Surfaces et Interfaces (CHAMSI),Département de Chimie, Faculté des Sciences , Université Libanaise , Hadeth, Mont-Liban,Beyrouth, Libanb Institut de Chimie des Surfaces et Interfaces (ICSI-CNRS) , Mulhouse, FrancePublished online: 16 Jun 2010.

To cite this article: Tayssir Hamieh , Joumana Toufaily & Haytham Alloul (2008) Physicochemical Properties of the Dispersionof Titanium Dioxide in Organic Media by Using Zetametry Technique, Journal of Dispersion Science and Technology, 29:9,1181-1188, DOI: 10.1080/01932690701856626

To link to this article: http://dx.doi.org/10.1080/01932690701856626

PLEASE SCROLL DOWN FOR ARTICLE

Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) containedin the publications on our platform. However, Taylor & Francis, our agents, and our licensors make norepresentations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of theContent. Any opinions and views expressed in this publication are the opinions and views of the authors, andare not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon andshould be independently verified with primary sources of information. Taylor and Francis shall not be liable forany losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoeveror howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use ofthe Content.

This article may be used for research, teaching, and private study purposes. Any substantial or systematicreproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in anyform to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/terms-and-conditions

Physicochemical Properties of the Dispersion ofTitanium Dioxide in Organic Media by UsingZetametry Technique

Tayssir Hamieh,1,2 Joumana Toufaily,1 and Haytham Alloul11Laboratoire de Chimie Analytique, Materiaux, Surfaces et Interfaces (CHAMSI), Departement deChimie, Faculte des Sciences, Universite Libanaise, Hadeth, Mont-Liban, Beyrouth, Liban2Institut de Chimie des Surfaces et Interfaces (ICSI-CNRS), Mulhouse, France

The study of the physicochemical properties of solids dispersed in organic media, and especiallythe dispersion of titanium dioxide (TiO2) particles, is very important in many industrial processes.The aim of this study is to determine the acid-base behavior of TiO2 particles dispersed in organicmedia by measuring their zeta potential by electrophoresis technique. After normalized theelectron donor (DN0)and acceptor numbers (AN0)of organic solvents, we applied our new methodto determine the donor (DNS

0) and acceptor numbers (ANS0) of TiO2 by using a Mathematica

program. The effect of pretreatment temperature on physicochemical properties of TiO2 was alsostudied. Results obtained showed that DNS

0 values of TiO2 are comprised between 36 and 47(or 14 and 19 kcal/mol) and ANS

0 values comprised between 10 and 17.

Keywords Donor and acceptor numbers, organic molecules, titanium dioxide, zeta potential

INTRODUCTION

In many articles,[1–12] titanium dioxide (TiO2) powderswere used as a model to study the stability and rheologicalproperties of concentrated dispersion of powders inaqueous solution, especially the effects of various surfac-tants on the properties of TiO2, dispersions. Bae et al.[13]

studied the effects of the nature of various organic sol-vents relating to viscosity and dielectric constant and theelectrolyte-induced surface charge on the dispersion stabi-lity of TiO2 nanopowders fabricated by homogeneousprecipitation process at low temperatures. The factors con-tributing to the dispersion stability have also been corre-lated. Zeta potential measurements have been carried outto elucidate the solid=liquid interfacial charge processesand interactions between particulate surfaces.[13]

Many studies were devoted to the structure of the electri-cal double layer (EDL) and have focused on systems whereonly one kind of electrolyte was present in the liquidphase.[14–38] The heterogeneity of the solid phase involvedin many different interactions is very important in

aggregation processes; however, liquid phase complexitycan influence the stability of dispersed systems by changingthe EDL parameters. Such changes may result in competitiveadsorption of ions in ways different from that of simplesolutions.[39] The interaction between particles is wellknown to influence the sedimentation velocity, consolida-tion, and flow properties of particle suspensions.[40–45] Therelationship between particle interaction and sedimentation(consolidation) properties has been a subject of extensiveresearch, both by theoretical calculations[46,47] and experi-mentally by addition of fatty acids,[48] polymers,[49] polyelec-trolytes,[50] or electrolytes,[43,44,51] and as a function ofpH.[43,50–53] Many models of batch sedimentation have beenproposed in literature.[54–60] The total energy of interactionbetween particles can be calculated according to the classicalDerjaguin–Landau and Verwey–Overbeek (DLVO) theory.[61]

The study of acid-base properties of oxide and hydro-xide surfaces is of vital importance in physical chemistry,in particular in adhesion. Many methods are proposed inthe literature to understand and quantify the acid-baseinteractions at interfaces of such mineral oxides.[62] Acidityof a solid surface can be usually characterized by its point ofzero charge (PZC) that corresponds to the pH at which thesolid has no net surface charge.[63] PZC can be predicted byusing Parks’ equation[64,65] which is essentially a functionof (Z=R), where Z is the formal charge of the cation andR is the sum of the cationic radius and the oxygen diameter(2.8A).[63]

Received 21 July 2007; accepted 13 August 2007.The authors gratefully acknowledge financial support from the

National Council for Scientific Research of Lebanon (NCSRL).Address correspondence to Tayssir Hamieh, Laboratoire de

Chimie Analytique, Materiaux, Surfaces et Interfaces (CHAMSI),Departement de Chimie, Faculte des Sciences, Section 1, Univer-site Libanaise, Hadeth, Mont-Liban, Beyrouth, Liban. E-mail:tayssir.hamieh@ul.edu.lb

Journal of Dispersion Science and Technology, 29:1181–1188, 2008

Copyright # Taylor & Francis Group, LLC

ISSN: 0193-2691 print=1532-2351 online

DOI: 10.1080/01932690701856626

1181

Dow

nloa

ded

by [

Tem

ple

Uni

vers

ity L

ibra

ries

] at

15:

12 2

3 N

ovem

ber

2014

This theory is basically related to the Brønsted acid-ity.[63] Recently, acid-base interactions at interfaces havebeen studied extensively in colloidal systems.[66,67] Fowkeset al.,[68,69] in particular, have studied the adsorption ofacidic and basic molecules from neutral solvents on inor-ganic powders such as iron, silicon, and titanium oxides.They found that the calorimetric heats of adsorption areactually the heats of acid base interactions, governed byDrago equation[70] and that the Drago equation constantscan be accurately determined for the surface sites of theseinorganic solids. On the other hand, it is known[71–74] thatwhen strong electron acceptor (Lewis acids) or donor(Lewis bases) entities are adsorbed on metal oxides, thecorresponding radicals are formed as a result of electrontransfer between the adsorbed molecules and the metaloxide surface. Such electron donor–acceptor interactionsat interfaces become important for elucidating the adhe-sion forces at these interfaces.[75] It was Fowkes who firstproposed in the field of adhesion to describe nondispersiveor specific interactions in terms of acid-base or electrondonor–acceptor interactions.[76,77] Fowkes then consideredthese nondispersive interactions to be identical to electondonor–acceptor or acid-base interactions.

Janardhan et a1.[78] studied the adsorption of alkyd resinon an anatase TiO2 surface by using gel permeation chro-matography and concluded that the amount adsorbeddepends on the dielectric constant of the solvent and alsoon the solvent resin interaction. They also studied[79] theadsorption of polyurethane on the surface of iron oxidein methyl ethyl ketone and in a mixture of methyl ethylketone and n-heptane. Zettlemoyer et al.[80] observed thatthe level of adsorption of polyamide resin on carbon blackand on rutile TiO2 was optimum in a 1-butanol-watermixture. This was due to a progressive change in theinteraction of pigment compared to that in 1-butanol orin a 1-butanol-decane mixture. Romo’s calculations[81]

based on the theories of Hamaker and Overbeck-Verweyled to the conclusion that the stability of TiO2 suspensionin 1-butanol and in l-butylamine was due to electrostatic

attraction. The Toronto Society studied the suspensionbehavior of pigments and classified TiO2 into alcohol andether groups, red iron oxide in ketone groups, and phtha-locyanines in ketones and ester groups on the basis of theirinteraction with organic liquids.[82]

In this article, we studied the physicochemical propertiesand acid-base behavior of the dispersion of TiO2 particlesin organic medium and the effect of pretreatment tempera-ture on these properties. We also developed a new methodallowing the determination of the electron donor andacceptor numbers of titanium dioxide, using the dataobtained by zetametry in organic medium.

PHYSICOCHEMICAL PROPERTIES OF USEDSOLVENTS AND THEIR DONOR ANDACCEPTOR NUMBERS

Gutmann[83] developed an empirical measure of the donorand the acceptor strengths of solvents. The donor effect of asolvent is given by its donor number (DN). The DN of asolvent is traditionally determined by measuring�DH forthe formation of solvent –SbCl5 complexes in dilute dichloro-ethane solutions.[83] Therefore, a high DN indicates thesolvent is a strong electron donor. Other methods formeasuring donor effect were later developed that correlatedwell with Gutmann’s donacity scale.[84–86]

For solvents with strong intermolecular interactions(e.g., water), however, the donor effects of their dilute solu-tions in another solvent and the donor effects when theyare used as bulk solvents can differ significantly.[85,86] Thenewer methods measure the donacity of bulk solvents whileGutmann’s method measures DN for dilute solutions of thesolvent. Gutmann realized that his method did not accountfor intermolecular interactions and even suggested thatthe DN measured for water represented the donacity ofgaseous water.[83] The DN for the bulk solvents are listedin Table 1 for solvents used in this study.

Donor–acceptor interactions are strong in the aceto-nitrile because of its low DN and AN. If the dielectric

TABLE 1Physicochemical properties of the organic solvents and water[88–94]

SolventRelative permittivity

er at 15�CViscosity g (mPa s)

at 15�CRefractiveindex nD

pKa at25�C

Boiling pointtbp (�C)

DN(kcal=mol) AN

Water 78.54 1.00 1.333 14.0 100.0 33 54.8Nitromethane 37.27 0.630 1.382 10.3 101.1 2.7 20.5Ethanol 24.3 1.29 1.361 18.9 78.3 20.0 37.9Nitrobenzene 35.6 1.863 1.556 3.98 210.8 4.4 14.8Acetonitrile 37.5 0.34 1.344 25 81.6 14.1 18.9Acetone 20.7 0.30 1.359 22 56.1 17.0 12.5Dimethylsulfoxide

(DMSO)4.7 2.20 1.478 31.8 189.0 28.9 19.3

1182 T. HAMIEH ET AL.

Dow

nloa

ded

by [

Tem

ple

Uni

vers

ity L

ibra

ries

] at

15:

12 2

3 N

ovem

ber

2014

constant was the only factor considered, this result wouldhave been difficult to explain. The dielectric constant foracetonitrile is higher than that of ethanol because of thestrong dipole present in acetonitrile.[83–87]

Gutmann[83] developed an empirical measure of thedonor and the acceptor strengths of solvents. The donoreffect of a solvent is given by its donor number (DN).The DN of a solvent is traditionally determined by measur-ing the absolute value of enthalpy change measured bycalorimetry during the interaction of a selected compound,a base, and a strong Lewis acid, antimony pentachloride(SbCl5), in dilute dichloroethane solutions.[83] Accordingly,the resulting DN number is given in kcal=mol units.

Therefore, a high DN indicates the solvent is a strongelectron donor. Other methods for measuring donor effectwere later developed that correlated well with Gutmann’sdonacity scale.[84–86] For solvents with strong intermolecu-lar interactions (e.g., water), however, the donor effectsof their dilute solutions in another solvent and thedonor effects when they are used as bulk solvents can differsignificantly.[85,86]

Acceptor numbers of solvents are found by comparing the31P NMR shifts of triethylphosphine oxide (Et3PO) when itis dissolved in the investigated acid.[83,84,87] Actual AN valuescan be derived with the help of an arbitrary scale on which 0is set by the chemical shift of Et3PO in n-hexane, while 100 isobtained for a dilute solution of SbCl5 in 1,2-dichloroethane.Higher AN indicates higher electron acceptor properties forthe solvent. Solvents that can act as hydrogen bond donors(e.g. water and methanol) generally have higher AN thanthose that cannot (e.g., DMSO and acetonitrile).

We used in this study 10-model organic solvents. Table 1gives some of their physicochemical properties,[88–94] moreparticularly, relative permittivity (er), viscosity (g), refrac-tive index (nD), autoprotolysis constant (pKa), boilingpoint tbp, donor number (DN), and acceptor number(AN).[90,93,94] A solvent’s autoprotolysis constant givesinformation about both accepting and donating a proton.Amphiprotic solvents possess low pKa values and are goodproton acceptor and donor, while aprotic solvents are eitherbad proton acceptor or donor. Thus, water and ethanol canbe classified as amphiprotic solvents, and nitromethane,dimethylsulfoxide (DMSO), acetonitrile, acetone, andnitrobenzene as aprotic solvents. Furthermore, acceptorand donor numbers describe the acidic and basic strengthof a solvent. A solvent with a high DN possesses a strongbasic strength. DN is a quantitative measure for a solvent’sability to donate electrons, that is, to bind a proton.[88,90,91]

NORMALIZATION ESSAY OF ACCEPTOR ANDDONOR NUMBERS

Experimental determinations of AN and DN numbers ofsolvents lead to dissimilar dimensions of their values

(Table 1). Sometimes modified parameters are proposedand used in practice. Riddle and Fowkes[95] proved that adistinct shift can be measured in the 31P NMR spectrumof Et3PO also in completely apolar liquids, such asn-hexane, which interact only by dispersion forces.They showed that the van der Waals contribution to the31P NMR chemical shifts of Et3PO are quite significant,as are also the infrared chemical shifts for the –P¼Ostretching peaks. When the 31 P NMR shifts are correctedby subtracting the van der Waals contribution, the result-ing shifts allowed to correct the AN value determined bythe technique of Gutmann,[96] the value obtained aftercorrection, AN–ANd, is also dimensionless, but now it isrelated only to the acceptor character of the givencompound. Let us put AN0 ¼AN–ANd (see Table 2), AN0

will be considered as dimensionless number.The units of AN and DN can be homogenized and

expressed in kcal=mol. The problem can be easily solvedby taking into account the enthalpy change associated withthe interaction of the two reference compounds (SbCl5 andEt3 PO) of Gutmann’s[96] theory. In this case, the correctednumber AN0 ¼AN–ANd denoted as AN00 and expressed inkcal=mol units is obtained from:

AN 00 ¼ 40ðkcal=molÞðAN � ANdÞ100

¼ 0:4ðkcal=molÞAN 0

The second possibility will be the normalization and theconversion of the donor number to a dimensionless num-ber DN’ according to the following relationship:[97,98]

DN 0 ¼ 100DNðkcal=molÞ40ðkcal=molÞ ¼ 2:5DN ð1Þ

The modified and normalized donor and acceptor num-bers determined by the different methods described aboveare listed in Table 2 for the solvents used in this article.

TABLE 2Modified and normalized AN and DN numbers of different

solvents used in this study[95,96–98]

Solvent

DN00

(kcal=mol)¼DN (kcal=mol)

AN00 ¼ 0.4AN0AN00

(kcal=mol) DN0 AN0

Nitromethane 2.7 5.9 6.75 14.8Ethanol 20.0 14.4 50.0 35.9Nitrobenzene 4.4 2.8 11.0 7.0Acetonitrile 14.1 6.5 35.3 16.3Acetone 17.0 3.5 42.5 8.7Dimethylsulfoxide

(DMSO)28.9 4.3 72.3 10.8

DISPERSION OF TiO2 IN ORGANIC MEDIA 1183

Dow

nloa

ded

by [

Tem

ple

Uni

vers

ity L

ibra

ries

] at

15:

12 2

3 N

ovem

ber

2014

To compare the acid-base strength of different organicsolvents, we give on Table 3 the ratios DN0=AN0 of thesesolvents. Table 3 shows that the nitromethane is the moreacidic followed by ethanol, and the dimethylsulfoxide isthe more basic followed by acetone.

EXPERIMENTAL DETERMINATION OF ANS AND DNS

OF TIO2 BY ZETAMETRY IN ORGANIC SOLVENTS

Methods and Principle of Calculation

The method used in this study to determine the electronacceptor number and electron donor number of TiO2 is thatdeveloped by Siffert et al.[99,100] Assuming that electrontransfers between solid single particles and an organic liquidare responsible for the charging of the solid surface, fourdifferent interaction energies can be considered and corre-spond to liquid–liquid associations DNL�ANL, solid–liquid interactions DNL�ANS and ANL�DNS, and finallysolid–solid interactions ANS�DNS; where the subscript Ldenotes the liquid and subscript S denotes the solid.

The total donor–acceptor interaction energy DHbetween 1 mol of solid particles and organic liquidmolecules is given by the following expression:

DH ¼ ðANS �DNSÞ � ðDNL � ANSÞ � ðANL �DNSÞþ ðDNL � ANLÞ ð2Þ

and

DH ¼ ðDNS �DNLÞðANS � ANLÞ ð3Þ

On the other hand, the electrically charged particles aresubmitted, in zetametry technique, to a constant electricfield V. The particle migration depends on the value ofthe electric charge acquired by the particles, either bygiving or receiving electrons from the dispersing liquidmedium. The particle charge Q can therefore be consideredto be proportional to the donor–acceptor interactionsbetween the liquid and the solid, thus leading to a secondexpression of the total donor–acceptor interaction energy:

DH ¼ KQVNP ð4Þ

where QV is the electrical energy of one particle, NP thenumber of particles per mole of solid and K a proportion-ality constant.

The electric charge Q can be obtained from zetametry byusing the following relationship:

Q ¼ 4pe0eaf ð5Þ

where e0 is the permittivity of a vacuum, e the permittivityof the liquid, a the particle radius and f is the zeta potentialof the dispersion.

By combining equations and, we deduce:

ðDNS �DNLÞðANS � ANLÞ ¼ 4pe0KVNPeaf ð6Þ

Naming C the new proportionality constant includingthe conversion factor of energy units and putting:

C ¼ 4pe0KVNP ð7Þ

We finally obtain the following relationship:

ðDNS �DNLÞðANS � ANLÞ ¼ Ceaf ð8Þ

In this relationship, ANL, DNL and e are known quanti-ties, and a and f can be experimentally determined, butANS, DNS and C are unknown values. However, ANS,DNS and C are solutions of the system composed of nequations by using n different organic liquids.

To resolve this system of n equations with threeunknown numbers, we used the same method that wepreviously developed in other studies.[100,101]

Putting x¼ANS and y¼DNS, we obtain:

xy� ANLy�DNLx� Ceaf ¼ �ANL �DNL ð9Þ

Our resolution method consists of the transformation ofthe nonlinear system into a linear system by taking:

t ¼ xyEquation (9) becomes:

tþ aiyþ bixþ ciz ¼ dio�uu i 2 ½1; n� ð10Þ

where {t, y, x, z} is an unknown vector, {ai, bi, ci, di} aknown vector, ai¼�ANLi, bi¼�DNLi, ci¼� eiaifi,di¼�ANLi�DNLi, z¼C and i an index relative to theused organic solvent.

By choosing 6 organic solvents of known donor andacceptor numbers (Tables 1 and 2) and TiO2 as dispersedsolid phase, linear system 10 can be written in matrixform as:

½A�½X� ¼ ½B� ð11Þ

TABLE 3Ratios DN0=AN0 of the different solvents

Solvent DN0=AN0

Nitromethane 0.456081Ethanol 1.392758Nitrobenzene 1.571429Acetonitrile 2.165644Acetone 4.885057Dimethylsulfoxide (DMSO) 6.694444

1184 T. HAMIEH ET AL.

Dow

nloa

ded

by [

Tem

ple

Uni

vers

ity L

ibra

ries

] at

15:

12 2

3 N

ovem

ber

2014

The previous linear system admits a unique solution [Xi]if the extracted matrix [A’] of order 4 can be inverted and inthis case, we obtain:

½Xi� ¼ ½A0��1½B0� ð12Þ

However, the linear system 10 is composed of6 equations and four unknown numbers with a supplemen-tary nonlinear relationship t¼ xy. By choosing any fourequations from this system, we finally have to solve15 linear systems of four equations to four unknown num-bers. So that the solution [Xi] satisfies the system 9, it isnecessary to verify the test t¼ xy. The approximated solu-tion of the system 10 is obtained by taking the mean valueof all solutions that satisfy this test.

Experimental

Material

The TiO2 used in this study was obtained in powderform and provided by Degussa (Germany) with high purity(> 99%). Its specific surface area was equal to 50 m2=gmeasured by nitrogen adsorption (BET method). Particlesizes of TiO2 were comprised between 150 and 700 nm.

The organic solvents (Table 1), dispersing liquids of highpurity, were provided by Prolabo (UK) and treated during10 days with 3A

`molecular sieves to remove any trace

of water.

Preparation of Suspensions and Apparatus

The oxide particles were dried in an oven between150�C and 700�C for 24 hours and were allowed to coolunder vacuum at ambient temperature just before use.For the electrokinetic measurements, a mixture of thesolid sample and the organic solvent was ultrasonicatedfor a few minutes and agitated at room temperature in

a closed vessel during about 3 days. The resulting disper-sion was kept agitated until it was fed into the electro-phoretic cell.

The microelectrophoresis was performed with a LaserZeemeter model 500, provided by Pen Kem Inc. (USA).The apparatus converts the electrophoretic mobilityto the f potential, according to Smoluchowski’s relation-ship. It is calibrated so that the (potential can be readdirectly provided that the sample (at 20�C) has a viscosityof 1 cP and a dielectric constant of 80.1. A corrected zetapotential fcor was calculated according to the followingequation:[100–102]

fcorðg; eÞ ¼ge

80:1

1:0fmeas

where, g is the viscosity (cP), e the dielectric constant of theorganic liquid and fmeas the measured potential (mV). Eachvalue of the fcor potential was the mean of at least tenmeasurements and the data were reproducible within arelative uncertainty of 6%.

The sizes of the oxide particles dispersed in the differentorganic liquids were determined by means of a Coulter sub-micron particle analyzer, model N4S. The measurementprinciples of this apparatus are those of Brownian motionand photon correlation spectroscopy.

Experimental Results and Discussion

The experimental results obtained by following thedifferent steps of the measurements and determinationsof the corrected zeta potentials and sizes of TiO2 particlesare given in Table 4 at different temperatures of thermaltreatment of TiO2 particles. As can be seen, the sizes ofthe particles correspond mainly to that of aggregates thatcan take place depending on the type of organic liquid.

TABLE 4Corrected zeta potentials and sizes of TiO2 particles for different temperatures of thermal treatment of TiO2

Temperatures of thermal treatment of TiO2 particles

150�C 200�C 300�C 400�C 500�C 700�C

Solvent fcor

(mV)2a

(nm)fcor

(mV)2a

(nm)fcor

(mV)2a

(nm)fcor

(mV)2a

(nm)fcor

(mV)2a

(nm)fcor

(mV)2a

(nm)

Nitromethane �15 510 �12 520 11 520 20 570 14 570 �10 540Ethanol 70 280 68 260 75 330 40 310 70 260 30 310Nitrobenzene 35 310 80 750 50 770 30 670 35 470 6 500Acetonitrile �10 580 �20 500 �8 690 �10 670 �7 630 �30 370Acetone �40 630 �20 440 �18 560 �16 530 �30 670 �6 700Dimethyl-sulfoxide

(DMSO)5 490 6 550 30 450 35 430 50 460 �5 540

DISPERSION OF TiO2 IN ORGANIC MEDIA 1185

Dow

nloa

ded

by [

Tem

ple

Uni

vers

ity L

ibra

ries

] at

15:

12 2

3 N

ovem

ber

2014

In fact, the mean size of the elementary TiO2 particles isabout 300 nm.

Remember that our results were obtained in the totalabsence of water. In fact, some authors[103–107] showed thatthe charging mechanism and the sign of the inorganicparticles in protic and aprotic solvents depend extensivelyon traces of moisture. We previously proved[101] an impor-tant effect of the water content on the zeta potential andsurface charge of the clay suspensions and then a realdependence of the donor and acceptor numbers of thesesolid surfaces on the presence of water traces that arepresent in the organic dispersions.

By treating the results given on Table 4 and the data onTable 2 and using Mathematica program, we were able tosolve the problem (11) and give the approximated solutionof this system. Donor and acceptor numbers of the solidwere obtained and given on Table 5 at different tempera-tures of thermal treatment of TiO2.

Plotting DNS0 and ANS

0 as a function of pretreatmenttemperature, we obtain the curves of Figure 1. Resultsobtained showed a sleight variation of donor and accep-tor numbers of titanium dioxide when the temperatureT of thermal treatment changes. Donor effect slightlydecreases when T increases until 800 K and slowlyincreases above 800 K. However, an inverse acceptoreffect is observed: a sleight increase of AN when Tincreases below 800 K and a decrease for T more than800 K. The decrease of the donor effect is certainly dueto the elimination of water molecules that can be stronglyadsorbed by TiO2 particles. This will also implies anincrease of the acceptor effect. Above 800 K, it is possibleto have some changes in the superficial groups that cancause an increase in the donocity of the solid. In fact,all of these acid-base variations in Lewis terms are veryweak. This can lead us to suppose that the effect of thepretreatment temperature on DNS

0 and ANS0 values of

TiO2 is so slight. Then the mean values of DNS0 and ANS

0

of titanium dioxide are the following:

DN 0S ¼ 42:5 or DNS0 ¼ 17 kcal=mol and ANS

0 ¼ 15 or

ANS0 ¼ 6 kcal=mol:

CONCLUSION

This study proposed a new protocol to determine theacid-base behavior of the dispersion of TiO2 particles inorganic medium, in Lewis terms. We developed a newmethod to calculate the donor and acceptor numbersof titanium dioxide, using a Mathematica program.Results obtained showed that DNS

0 values are comprisedbetween 36 and 47 (or 14 and 19 kcal=mol) and ANS

0

values comprised between 10 and 17. A sleight effect ofthe temperature of the thermal treatment on zeta poten-tial and the donor and acceptor numbers of TiO2 wasobserved.

REFERENCES

[1] Barr, T., Oliver, J., and Stubbings, W.V. (1948) J. Soc.Chem. Ind. London, 67: 45–55.

[2] Ottewill, R.H., and Shaw, J.N. (1972) J. Electroanal. Chem.,37: 133–142.

[3] Wiersema, P.H., Loeb, A.L., and Overbeek, J.Th.G. (1966)J. Colloid Interf. Sci., 22: 78–99.

[4] Casson, N. (1959) In Rheology of Disperse Systems, editedby C.C. Mill, Pergamon Ress, London.

[5] Tadros, Th.F. (1987) In Solid-Liquid Dispersions, edited byTh.F. Tadros, Academic Press, London: pp. 309–320.

[6] Parfitt, G.D. (1981) In Dispersions of Powders in Liquids,3rd ed., edited by G.D. Parfitt; Applied Science Publisher,London: pp. 1–50.

TABLE 5Values of DNS

0 and ANS0 of TiO2 particles

at different pretreatment temperatures

T (�C) DNS0 ANS

0

150 46 11200 44 14300 40 16.6400 37.7 17500 38.4 16700 46.3 10

FIG. 1. Evolution of DNS0 and ANS

0 of TiO2 particles as a function of

pretreatment temperature.

1186 T. HAMIEH ET AL.

Dow

nloa

ded

by [

Tem

ple

Uni

vers

ity L

ibra

ries

] at

15:

12 2

3 N

ovem

ber

2014

[7] Boehm, H.P. (1971) Discuss. Faraday Soc., 52:

264–275.[8] Gaudin, A.M., and Fuerstenau, D.W. (1955) Trans. AIME,

202: 958–962.

[9] Chander, P., Somasundaran, P., and Turro, N.J. (1987) J.Colloid Interf, Sci., 117: 31–46.

[10] Fukushima, S., and Kumagai, S. (1973) J. Colloid Interf.Sci., 42: 539–544.

[11] Parfitt, G.D. (1976) In Progress in Surface and MembraneScience, edited by D.A. Cadenhend and J.F. Danielli;Academic Press, New York: vol. 11, pp. 181–196.

[12] Chen, X., Cheng, H., and Ma, J. (1998) Powder Technology,99: 171–176.

[13] Bae, H.S., Lee, M.K., Kim, W.W., and Rhee, C.K. (2003)Colloids Surf. A, 220: 169–177.

[14] Ferrauto, R.J., Heck, R.M., and Speronello, B.K. (1992)Chem. Eng. News, 7: 34–44.

[15] Parfitt, G.D. and Rochester, C.H. eds., (1983) Adsorptionfrom Solution at the Solid=Liquid Interface, Academic Press,London: p. 246.

[16] Rhodes, W.H. (1981) J. Am. Ceram. Soc., 64: 19–22.[17] Edirisinghe, M.J., and Evans, J.R.G. (1987) Br. Ceram.

Trans. J., 86: 18–22.[18] Evanko, C.R., Dzombak, D.A., and Novak, Jr., J.W. (1996)

Colloids Surf. A, 110: 219–233.[19] Sato, T., and Kohnosu, S. (1992) J. Colloid Interf. Sci., 152:

543–547.

[20] Wiese, G.R., James, R.O., Yates, D.E., and Healy, T.W.(1976) In Electro-Chemistry of Colloid–Water Interface,edited by J. O’M Bockris, Butterworths, London.

[21] Yates, D.E., Levine, S., and Healy, T.W. (1974) J. Chem.Soc. Faraday. Trans. 1, 70: 1807–1818.

[22] James, R.O., and Parks, G.A. (1982) In Surface and ColloidScience, edited by E. Matijevic; Wiley Interscience,

New York: vol. 12, p. 119.[23] James, R.O. (1981) In Adsorption of Inorganic at

Solid=Liquid Interfaces, edited by M.A. Anderson and

A.J. Rubin; Ann Arbor Science, Ann Arbor, MI: p. 219.[24] Davis, J.A., James, R.O., and Leckie, J.O. (1978) J. Colloid

Interface Sci., 63: 480–499.[25] James, R.O., Davis J.A., and Leckie, J.O. (1978) J. Colloid

Interface Sci., 65: 331–344.[26] Davis, J.A. and Leckie, J.O. (1978) J. Colloid Interface Sci.,

67: 90–107.[27] Westall, J. and Hohl, H. (1980) Adv. Colloid Interface Sci.,

12: 265–294.[28] Sprycha, R. (1983) J. Colloid Interface Sci., 96: 551–554.[29] Sprycha, R. (1984) J. Colloid Interface Sci., 102: 173–185.[30] Sprycha, R., and Szczypa, J. (1984) J. Colloid Interface Sci.,

102: 288–291.

[31] Schindler, P.W., and Gamsjager, H. (1972) Kolloid Z.Z.Polymere, 250: 759–763.

[32] Westall, J. (1986) In Geochemical Processes at Mineral Sur-faces, edited by J.A. Davis and K.F. Hayes; ACS Symp.Ser., Washington, DC: vol. 323, p. 54.

[33] Parfitt, G.D. (1976) In Progress in Surface and MembraneScience, edited by D.A. Candehead and J.F. Danielli;Academic Press, New York: vol. 11, p. 181.

[34] Janusz, W., Kobal, I., Sworska, A., and Szczypa, J. (1997)J. Colloid. Interf. Sci., 187: 381–387.

[35] Janusz, W., Sworska, A., and Szczypa, J. (1999) ColloidsSurf. A, 152: 223–233.

[36] Regazzoni, A.E., Blesa, M.A., and Maramoto, A.J.G.(1983) J. Colloid Interface Sci., 91: 560–570.

[37] Koopal, L.K., Van Riemsdijk, W.H., and Roffey, M.G.(1987) J. Colloid Interface Sci., 118: 117–136.

[38] Janusz, W. (1988) J. Radioanal. Nuclear Chem., 125:393–401.

[39] Janusz, W., Kobal, I., Sworska, A., and Szczypa, J. (1997)J. Colloid Interface Sci., 187: 381–387.

[40] Michaels, A.S., and Bolger, J.C. (1962) Ind. Eng. Chem.Fundam., 1: 24–33.

[41] Michaels, A.S., and Bolger, J.C. (1962) Ind. Eng. Chem.Fundam., 1: 153–162.

[42] Buscall, R., and McGowan, I.J. (1983) Faraday Discuss.Chem. Soc., 76: 277–290.

[43] Mange, F., Couchot, P., Foissy, A., and Pierre, A. (1993)J. Colloid Interface Sci., 159: 58–67.

[44] Guo, J.J., and Lewis, J.A. (2000) J. Am. Ceram. Soc., 83:266–272.

[45] Wang, H., and Wen, C.S. (1998) AIChE J., 44: 2520–2525.

[46] Chih, M.-H., Lee, E., Chu, J.-W., and Hsu, J.-P. (2000)Langmuir, 16: 1650–1654.

[47] Bergstrom, L. (1992) Chem Soc Faraday Trans, 88:

3201–3211.[48] Goodwin, J.W., Hughes, R.W., Kwaambwa, H.M., and

Reynolds, P.A. (2000) Colloids Surf. A, 161: 339–359.

[49] Beattie, J.K., and Djerdjev, A. (2000) J. Am. Ceram. Soc.,83: 2360–2364.

[50] Melton, I.E., and Rand, B. (1977) J. Colloid Interface Sci.,60: 331–336.

[51] Velamakanni, B.V., and Lange, F.F. (1991) J. Am. Ceram.Soc., 74: 166–172.

[52] Font, R., Garcıa, P., and Rodrigues, M. (1999) ColloidsSurf. A, 157: 73–84.

[53] Gustafsson, J., Nordenswan, E., and Rosenholm, J.B.(2003) Colloids Surf. A, 212: 235–247.

[54] Kynch, G.J. (1952) Trans. Faraday Soc., 48: 166–176.[55] Tiller, F.M. (1981) AIChE J., 27: 823–829.[56] Fitch, B. (1983) AIChE J., 29: 940–947.[57] Tiller, F.M., and Khatib, Z. (1984) J. Colloid Interface Sci.,

100: 55–67.[58] Buscall, R., and White, L.R. (1987) J. Chem. Soc. Faraday

Trans. I, 83: 873–891.[59] Landman, K.A., White, L.R., and Buscall, R. (1988) AIChE

J., 34: 239–252.[60] Font, R. (1988) AIChE J., 34: 229–238.[61] Israelachvili, J.N. (1992) Intermolecular and Surface Forces,

2nd ed., Academic Press, London.[62] Carre, A., Roger, F., and Varinot, C. (1992) J. Colloid

Interface Sci., 154: 174–183.[63] Yoon, R.H., Salman T., and Donnay, G. (1979) J. Colloid

Interface Sci., 70: 483–493.[64] Parks, G.A. (1965) Chem. Rev., 65: 177–198.[65] Parks, G.A. (1967) Adv. Chem. Ser., 67: 121–160.

DISPERSION OF TiO2 IN ORGANIC MEDIA 1187

Dow

nloa

ded

by [

Tem

ple

Uni

vers

ity L

ibra

ries

] at

15:

12 2

3 N

ovem

ber

2014

[66] Jensen, W.B. (1980) The Lewis Acid-Base Concepts, Wiley,

New York.[67] Sorensen, P. (1975) J. Paint Technol., 47: 31–39.[68] Joslin, S.T., and Fowkes, F.M. (1985) Ind. Eng. Chem.

Prod. Res. Dev., 24: 369–378.[69] Fowkes, F.M. (1985) In Surface and Interfacial Aspects of

Biomedical Polymers, edited by J.D. Andrade; Plenum

Press, New York: vol. 1, pp. 337–372.[70] Drago, R.S., Parr, L.B., and Chamberlain, C.S. (1977)

J. Am. Chem. Soc., 99: 3203–3209.[71] Rooney, J.J., and Pink, R.C. (1962) Trans. Faraday Soc.,

58: 1632–1641.[72] Flockhart, B.D., Scott, J.A.N., and Pink, R.C. (1966)

Trans. Faraday Soc., 62: 730–740.[73] Tench, A.J., and Nelson, R.L. (1967) Trans. Faraday Soc.,

63: 2254–2263.[74] Hosaka, H., Fujiwara T., and Meguro, K. (1971) Bull.

Chem. Soc. Jpn., 44: 2616–2619.[75] Meguro, K., and Esumi, K. (1990) J. Adhesion Sci. Technol.,

4: 393–410.

[76] Fowkes, F.M. (1964) Attractive forces at interfaces, Ind.Eng. Chem., 56: 40–52.

[77] Fowkes, F.M. (1968) J. Colloid Interface Sci., 28: 493–505.[78] Janardhan, R., Gedam, P.H., Sampathkumaran, P.S.,

Narasimha, R., and Husain, S. (1988) J. Appl. Polym.Sci., 36: 1781–1797.

[79] Janardhan, R., Gedam, P.H., and Sampathkumaran, P.S.(1989) Langmuir, 5: 1031–1034.

[80] Zettlemoyer, A.C., Buckingham, J.S., and Schaeffer, W.(1963) J. Colloid Sci., 18: 104–106.

[81] Romo, L. (1963) J. Phys. Chem., 67: 382–385.[82] Raju, K.V.S.N. and Yaseen, M. (1992) Langmuir, 8: 43–47.[83] Gutmann, V. (1976) Electrochim. Acta., 21: 661–670.[84] Burger, K. (1983) Solvation, Ionic and Complex Formation

Reactions in Non-Aqueous Solvents: Experimental Methodsfor Their Investigation, Elsevier, New York.

[85] Marcus, Y. (1984) J. Solut. Chem., 13: 599–624.[86] Walbroehl, Y., and Jorgenson, J.W. (1986) Anal. Chem., 58:

479–481.[87] Mayer, U. (1979) Pure Appl. Chem., 51: 1697–1712.

[88] Babay, P.A., Gettar, R.T., Silva, M.F., Thiele, B., andBatistoni, D.A. (2006) Journal of Chromatography A,1116: 277–285.

[89] Riekkola, M.-L., Jussila, M., Porras, S.P., and Valk�oo, I.E.(2000) Non-aqueous capillary electrophoresis, J. Chroma-togr. A, 892: 155–170.

[90] Bowser, M.T., Kranack, A.R., and Chen, D.D.Y. (1998)Trends Anal. Chem., 17: 424–434.

[91] Okada, T. (1998) J. Chromatogr. A, 804: 17–28.[92] Lide, D.R. (1994) CRC Handbook of Chemistry and Physics,

75th ed., CRC Press, Boca Raton, FL.

[93] Gutmann, V. (1976) Electrochim. Acta., 21: 661–670.[94] Geiser, L., Mirgaldi, M., and Veuthey, J.-L. (2005) J. Chro-

matogr. A, 1068, 75–81.

[95] Riddle, F.L., and Fowkes, F.M. (1990) J. Am. Chem. Soc.,112: 3259–3264.

[96] Gutmann, V. (1978) The Donor-Acceptor Approach toMolecular Interactions, Plenum Press, New York.

[97] Hamieh, T., Rageul-Lescouet, M., Nardin, M., and Schultz, J.(1996) J. Chim. Phys., 93: 1332–1363.

[98] Hamieh, T., Nardin, M., Rageul-Lescouet, M., Haidara,H., and Schultz, J. (1997) Colloids Surf. A, 125: 155–161.

[99] Papirer, E., Kuczynski, J., and Siffert, B. (1987) Chromato-graphia, 23: 401–406.

[100] Hamieh, T. and Schultz, J. (1996) C.R. Acad. Sci. Paris Ser.II B, 322: 691–698.

[101] Siffert, B., Lemousy, F., Papirer, E., and Hamieh, T. (1996)C.R. Acad. Sci. Paris Ser. II B, 323: 221–228.

[102] Siffert, B., Eleli-Letsango, J., Jada, A., and Papirer, E.(1994) Coll. Surf. A, 92: 107–111.

[103] Williams, R.J. (1982) J. Cottoid Interface Sci., 88: 530–543.[104] Labib, M.E. and Williams, R. (1984) J. Colloid Int. Sci., 97:

356–366.

[105] Labib, M.E. and Williams, R. (1986) Colloid Polym. Sci.,264: 533–541.

[106] Labib, M.E. and Williams, R. (1987) J. Colloid Int. Sci.,115: 330–338.

[107] Goodwin, J.W., McDonald, F., and Reynolds, P.A. (1988)Colloids Surf., 33: 1–9.

1188 T. HAMIEH ET AL.

Dow

nloa

ded

by [

Tem

ple

Uni

vers

ity L

ibra

ries

] at

15:

12 2

3 N

ovem

ber

2014