Characterization of Tio2 - water nanofluid droplet evaporation

Abstract

Nano Science and Technology has become an emerging and impactful technology for more efficient and well-versed products in every fields. Evaporation of a droplet is common phenomena in our everyday life, it offers intriguing effects through interplay of capillary and viscous forces. Different parameters like dynamics of three phase contact line, transition of phase, generation of deposited particles patterns affects the evaporation rate. One facet of illustration of the formation of different types of patterns meets the academic quest, while the other side offers numerous applications in practical field. Investigation of post-evaporation patterns of nanoparticles suspended in a liquid droplet is increasing day by day in medical diagnosis and printing or coating technology. Nanofluids were new class of fluid made by homogeneously suspending nanometre size particles in the host liquids like water, ethylene glycol, etc. After complete evaporation of nanofluids droplet these nanometre size particles deposit on the substrate on which the droplet has been placed. Types of formation of patterns depend on many variables like types of nanoparticles, the host fluids, particles volume fraction, nature of surfactant, stabilizing time etc. In this current experiment, TiO2 has been chosen to synthesize nanofluids in deionized water as the base fluid. Droplets of stable suspensions of nanofluids were deposited gently on smooth, hydrophilic surfaces (cleaned glass slides). Coffee ring was created from the evaporation of TiO2-water nanofluids droplets at volume fraction Φ = 0.1% and Φ = 0.5%, when the parent nanofluid suspension was sonicated using bath sonicator. On the contrary, uniform patterns for Φ = 1.0%. Also, formation of coffee ring from TiO2-water nanofluids droplet was impacted when surfactant Acetic acid (AA) and Cetyl Trimethyl Ammonium Bromide (CTAB) were added to this sample. Two types of patterns were formed by the evaporation of TiO2-water-AA nanofluids droplet at two different volume fractions, viz., Φ = 0.1% and Φ = 0.5%. Results, clearly indicates that deposited patterns depend on particles volume fraction. For runs where ring formation in Φ = 0.1%, Large peaks of deposited particles were noticed. There were slight high peaks in the centre part of the ring for Φ = 0.5%, indicating more concentration of nanoparticles present there. For Φ = 1.0%, peaks in intensity graph were more or less same for every area of the pattern. Average Gray value for Φ = 0.1% was 210, for Φ = 0.5% it was 190, for Φ = 1.0% it was 185 as per the image analysis.