Characterization of electrical current and liquid droplets deposition area in a capillary electrospray

Abstract

A comprehensive study was conducted to investigate the effects of applied voltage, distance between needle tip and counter electrode, liquid flow rate, pH and conductivity of water on the electrical current in a capillary electro-spray. Atomic Force Microscopy (AFM) was employed to measure the size distribution of water droplets, which presented a mean diameter of 299 ​± ​76 ​nm. Statistical analysis using three-way ANOVA and nonlinear multivariate regression model were employed to study the interactions of applied voltage, distance between needle tip and counter electrode, and liquid feed rate with electrical current, and to develop regression equations to predict the current. It was found that electrical current was significantly (p ​< ​0.05) influenced by applied voltage (0 to ±10 ​KV) and the distance (2, 3 and 4 ​cm), but not by the liquid feed rate (1–10 ​μl/min) within the range investigated in this work. A water contact indicator was employed for the first time in the electrospray system to investigate the effect of parameters mentioned above on the liquid droplets deposition area. The experimental data demonstrated that increasing the distance of the capillary needle, liquid feed rate, pH, and conductivity, resulted in increased electrosprayed area.