Tunable wettability and adsorption activity of candle soot coated steel mesh

Abstract

In the present study, electrowetting on candle soot coated on a copper substrate was performed. The effect of temperature and voltage on the contact angle was studied. Initially, at room temperature (25 °C) the contact angle was 147°, which ultimately dropped down to 134° at 60 °C. Similarly, in unbiased condition, the contact angle between candle soot coating and water was 147°. The contact angle decreased with applied voltage. However, the contact angle leveled off and did not fall further beyond an applied voltage of 63 V. The reversibility of contact angle was studied at different voltages at 18, 36, 45, 54 and 63 V. The process was found reversible except for the first cycle for each voltage cycle. Further, candle soot was coated on a steel mesh and electrowetting was performed. The maximum drop in contact angle was found at 63 V, contact angle dropped down to 30° from 140° (at unbiased condition). Candle soot coated steel mesh (CS-mesh) also successfully adsorbs organic pollutants like rhodamine B (dye) and detergent from water. Almost 98% of dye (RB) was removed from a solution of concentration 15 μM in 15 min.