Adsorption of various surfactants at the gas liquid interface is studied with equilibrium and dynamic surface tension measurements. The Wilhelmey plate method and maximum bubble pressure method are used for this study. Dynamic surface tension of solutions of different surfactants, sodium lauryl sulfate (SLS), polyoxyethylene glycol 4-tert-octyl phenyl ether (Triton X 100), poly-oxyethylene(20) cetyl ether (Brij 58), and tetraethylene glycol mono-n-dodecyl ether (Brij 30), is measured at different concentrations. Adsorption of different surfactants is compared on the basis of equilibrium and dynamic behavior. Effectiveness and efficiency of different surfactants is found from equilibrium surface tension measurement. A new parameter is defined to quantify the dynamic behavior of adsorption, which gives the concentration of surfactant needed to reduce surface tension to half of its maximum reduction within a defined time available for adsorption. The dynamics of surfactant solution is quantified by using this parameter.Keywords Dynamic surface tension, interface, micelle, maximum bubble pressure method INTRODUCTIONThe dynamics of interfacial layers, especially the characterization of interfacial dynamics, has attracted large interest among interfacial researchers. Dynamics becomes increasingly important as modern technologies require more and more quantitative relationships between dynamic interfacial properties and technological parameters. In most technological applications where the interface is created rapidly, such as foam formation, quickness of interfacial adsorption (dynamics) becomes important. [1,2] The importance of dynamic surfactant adsorption in colloid systems is well recognized. Surfactant adsorption is a timedependent process, markedly varying with the mechanism of dynamic adsorption. The extent of this process is generally quantified by the variation of surface tension. However, the change in surface tension as a function of time is, in most cases, substantially slower than the one expected from diffusion-controlled adsorption. For example, a 3 mol . m 23 solution of SLS attains a reduction of 20 mN/m in surface tension of an air-liquid interface in a period of 20 s. However, a higher concentration of SLS solution achieves the same drop in less than 1 s. Some surfactants, such as polyoxyethylene(20) cetyl ether (Brij 58), adsorb more, reducing surface tension of the interface

Effect of organic additives on the dynamic behavior of surfactant in solution was studied using the maximum bubble pressure method. Dynamic surface tension of solution of sodium lauryl sulphate (SLS) was measured at different concentrations with various additives. Additives such as lauric acid diethanol amide (LDEA), cocoamidopropyl betaine (CAPB), lauryl amido propyl betaine (LAPB), and lauryl amido propyl amine oxide (LAPAO) were employed for this study. The concentration of surfactant mixture needed to reduce surface tension to the defined quantity within the time available for adsorption is compared.