Page - 135 - in Advanced Chemical Kinetics
Image of the Page - 135 -
Text of the Page - 135 -
Δμo¼ ΖþΖ�e 2
4πεoε
rþþr�ð Þ (2)
whereεo represents thepermittivity invacuumandε isdielectric constantofagivensolution.
r+ and r�present the radii of ions charged. Based on Eqs. (1) and (2), Chen andChang [12]
proposed thebelowequation:
2γ
rkTρ ¼ lnCþ ΖþΖ�e 2
4πεoεKT rþþr�ð Þ (3)
wherem is the weight of the solute molecule; γ is the interfacial energy in J/m2, the term
interfacial energy canalsobewritten asnm�1; r is theparticle size of a spherical particle and
C is the solute concentration. The author linearized Eq. (3) in terms of particle size r(Y) and
dielectric constant ε(X). It was assumed that only dielectric constant is significant and other
properties are insignificant.However, according to Israelachvili [11],Coulombic interaction is
muchweakened inwater. So, it canbepostulated that, for homologousmixtureofwater and
alcohol, theCoulombic interactionwill beveryweak.Hence, it canalsobehypothesised that
thesurface tensionof solventwilldirectlyaffect thenucleationandgrowthofparticles.
2.Experimental
2.1.Materialsandmethod
Analytical-gradeFeCl3�6H2OandNH4OH(B&MScientific,CapeTown,R.S.A)wereusedas
theyarewithoutanyfurtherpurification.Deionisedwaterandalcohol (methanol, ethanoland
propanol) weremixed together with different ratios to vary the surface tension of solvent.
Ammoniumhydroxide,NH4OH,wasaddeddropwiseuntil themixturepHreachedavalue
of 10.Acertain amountofFeCl3�6H2Owasadded to the solution tomakeup0.05Msolution
(unlessstatedotherwise),andthesolutionwasstirreduntil the ironsaltwasdissolved.ThepH
of the final solution (prior toheating)wasrecorded.ThepHwasalwayskeptconstantat~2 to
isolate the effect of pH on the particle growth in each case. The solutionwas replaced in a
teflon-linedpressureautoclave.Thetemperaturewas100�C.Areactiontimeof2hwasusedto
synthesise theparticles.
3.Resultsanddiscussion
3.1.Correlationbetweenparticle sizeandalcohol surface tension
Three different alcohols (methanol, ethanol and propanol) were used to tune the surface
tension of the solvent. If the hypothesis conceived earlier is true, then therewill be a qualita-
tive relationship between particle size,De, and surface tension of solvent, γ. The particles
synthesised in this studywere rod-shapedparticles. The length anddiameter of theparticles
were measured from TEM images. A minimum number of 250 particles was counted for
Hydrothermal Precipitation of β-FeOOH Nanoparticles in Mixed Water/Alcohol Solvent
http://dx.doi.org/10.5772/intechopen.70503 135
back to the
book Advanced Chemical Kinetics"
Advanced Chemical Kinetics
- Title
- Advanced Chemical Kinetics
- Author
- Muhammad Akhyar Farrukh
- Editor
- InTech
- Location
- Rijeka
- Date
- 2018
- Language
- English
- License
- CC BY 4.0
- ISBN
- 978-953-51-3816-7
- Size
- 18.0 x 26.0 cm
- Pages
- 226
- Keywords
- Engineering and Technology, Chemistry, Physical Chemistry, Chemical Kinetics
- Categories
- Naturwissenschaften Chemie