Interfacial Tension of Methylbenzene–Water in the Presence of Hydrophilic and Hydrophobic Alumina Nanoparticles at Different Temperatures

Abstract

The effect of almost low concentrations of alumina hydrophilic (bare surface) and hydrophobic (modified surface with hexadecanoic acid) nanoparticles on interfacial tension of methylbenzene (toluene)–water was investigated based on experimental results from drop weight tensiometry. Nanoparticles were suspended in either aqueous or organic phases to provide a stable nanofluid and then were contacted with another phase to measure the interfacial tension. A nanoparticle mass fraction range of 1·10–5 to 5·10–4 (± 5·10–6) and a temperature range of [293.2 to 323.2 (± 0.1)] K were used. Interesting trends of interfacial tension variation were revealed with nanoparticles concentration, showing a sharp increase up to 55.7 mN·m–1 (± 0.1 mN·m–1) at 293.2 K, and a decrease to about 14.0 mN·m–1 at 323.2 K with hydrophilic and hydrophobic forms, respectively. The effect of increasing temperature was found to reduce interfacial tension within the used ranges and significantly higher with hydrophilic nanoparticles.