Surface tension, adsorption, and wetting behaviors of natural surfactants on a PTFE surface

Abstract

in Wiley Online Library (wileyonlinelibrary.com) The adsorption kinetics and wetting behaviors of three plant-based natural surfactants (Reetha, Shikakai, and Acacia) on the polytetrafluoroethylene (PTFE) surface are reported in this study. Adsorption studies of these surfactants on PTFE surface show the equilibrium adsorption time is approximately 15 min, and Langmuir-type isotherm fits well for all three surfactants. The contact angle measurements show that the value achieved by Reetha and Acacia solutions are close (109 ), but that is low in the case of Shikakai (98.13 ). Although, comparing the adsorption densities of the surfactants at PTFE-water and air-water interfaces, it has been found that adsorption densities at the PTFE-water interface are low for all three surfactants than that of air-water interface. The alcohol-Shikakai mixed solutions show nonideal behavior of surface tension reduction through a strong interaction between alcohol and Shikakai molecules, which in turn, show lower surface tension and contact angle values than that of ideal.

Wettability alteration by novel betaines at polymer–aqueous solution interfaces

“…The variations of the contact angle values with the increasing concentration of 18C and 18S are presented in Figure 2 for PTFE and PMMA surfaces. Figure 2a clearly depicts that the dependency of contact angle with the logarithm of concentrations on the PTFE surface are different from other researchers' conclusions[12,18,19,31] : for 18C and 18S, the contact angle keep almost a constant value in a wide range of surfactant concentration even more than CMC of individual surfactant solution.Above 1×10 -4 mol/L, the contact angles of both 18C and 18S show rapid downward trend and the values of 18C are significantly lower than that of 18S. However, for the conventional surfactants, there is a decrease in contact angle with the increase in surfactant concentration until CMC of surfactant solution and above that it is almost constant.…”

Wetting Behavior and Maximum Retention of Aqueous Surfactant Solutions on Tea Leaves

“…To date, the wetting behavior of surfactant solutions on abiotic solid surfaces has been extensively researched [9,10,11,12,13]. In comparison to abiotic solid surfaces, the wetting behavior of plant surfaces is more complicated, as seen in wheat [14], ginkgo leaves [15], and rice [16].…”

Surface Activity of Natural Surfactants Extracted from Sapindus mukorossi and Sapindus trifoliatus Soapnuts

“…trifiliatus are 102.6 • and 73 • , respectively. Paria et al [25] found for Sp. mukorossi 109.88 • as the minimum contact angle.…”