Seite - 134 - in Advanced Chemical Kinetics

canbe found in the literature. SubmicrometerZrO2nanomaterialwas synthesisedbyHuand Chen [6] using alcohol/water mixture. Fang and Chen [7] used a mixed solvent of water/ n-propanol to synthesise titania powders. ZrO2(Y2O3) nanoparticles were synthesised by Li andGao [8] using ethanol/watermixture. So far, the effect ofmixed solvent properties on the growth of 1D β-FeOOHnanorodswere not evaluated despite of its numerical industrial and scientific applications. In our previouswork,wehavedemonstrated that alcohol played an important role in controlling nucleation rate and particle size of 1D β-FeOOH nano- particles [9, 10]. Previously reportedwork in the literature considered thedielectric constant, ε, properties of thewater/alcoholmixture to be of significance in controllingparticle growth, discarding the effect of surface tension,γ.However, it is interesting tonote that theCoulomb interaction is veryweak in water and solvent with high ε [11] and Coulomb interaction is directly related toεof the solvent.This simplephenomenonmakes theapplicationof theεof solventonly to relate toparticlegrowthsasdescribed in the literature susceptible. The application ofmixed solvent is a newapproach in the synthesis andprocessing ofmate- rials [12].However, the roleof surface tension isneglectedwhenrelatingparticlegrowthwith solvent properties. Tuning the surface tension of the water/alcohol can affect the colloidal interactionbetweensolidparticles.Mostof the literature reportedon theuseof alcohol/water mixture on the precipitation of submicro meter-sized TiO2, ZrO2, SiO2 and CeO2 particles. Published literatureprovides evidence that the formationof nanoparticles strongly related to the solution pH, precursor salt concentration, time and temperature, etc.However, very few attempts have been made in the literature to describe the interaction between the process parameters from statistically designed experiments. Moreover, only one work was done to describe theeffectofprocessvariablesonparticle size [13].However, theempirical correlation reported can only predict spherical shape particles and the experiments were not designed statistically toevaluate theactual relationshipbetweenprocessvariables. Development ofmathematical relationship that combines fundamental properties andempir- ical quantitiesderived fromstatistical analysis canbeveryuseful inunderstanding theactual effect of process interactions on the particle growth. In a previous work [9], mathematical relationbetweensolventsurface tensionandparticlegrowthwasreported.However, theeffect ofvariousprocessparameterson theparticlegrowthwasnotaccounted in thatmodel.Hence, in this chapter,anevaluationof the fundamental relationshipbetweensolvent surface tension, precursor concentration, time and β-FeOOH nanorod growth is presented via statistically designedexperiments. According to classical electrostaticmodel, the chemical potential of twophases are equal in equilibriumandcanbewrittenas [11, 12]: μo S þKT lnCS¼μoLþKT lnCL (1) whereμo is thestandardchemicalpotential,C is theconcentrationof solute (SandL represent solid and liquid phases, respectively), T is the temperature expressed in Kelvin and K is Boltzmann constant. Eq. (2) also known asCoulombs interaction can be used to express the energyrequired toseparate thecharged ions fromthesolidstate [11, 12]: Advanced Chemical Kinetics134