Surfactant addition

CMC), reverses the effect that the surfactant has on contact angle at lower concentrations, and at or above the CMC there is no further lowering of surface tension. At the higher concentrations, the surfactant loses some of its beneficial effect on dewateriag, as shown ia Figure 5. The beneficial effects of surfactants on dewateriag are most pronounced ia cakes that have been partially deslimed or ia cakes of partially hydrophobic particles (eg, flotation concentrates) that are adsorbed onto each other. Surfactants at or above CMC have Httle practical effect on extremely fine cakes, where pores are small and the cake has no further opportunity to consoHdate. A number of filter cakes do not respond to surfactant addition at any level. 

Shah RK, London AL (1978) Laminar flow forced convection in ducts. Academic, New York Sher I, Hetsroni G (2002) An analytical model for nucleate pool boiling with surfactant additives. Int J Multiphase Elow 28 699-706... 

Wu WT, Yang YM (1992) Enhanced boiling heat transfer by surfactant additives. In Pool and External Flow Boiling. ASME, New York, pp 361-366... 

Wu WT, Yang YM, Maa JR (1995) Enhancement of nucleate boiling heat transfer and depression of surface tension by surfactant additives. J Heat Transfer 117 526-529... 

Yang YM, Maa JR (2003) Boiling heat transfer enhancement by surfactant additives. In Proceedings of the 5th International Conference Boiling Heat Transfer, ICBHT, Montego Bay, Jamaica, 4-8 May 2003... 

A Box-Behnken design was employed to investigate statistically the main and interactive effects of four process variables (reaction time, enzyme to substrate ratio, surfactant addition, and substrate pretreatment) on enzymatic conversion of waste office paper to sugars. A response surface model relating sugar yield to the four variables was developed on the basis of the experimental results. The model could be successfully used to identify the most efficient combination of the four variables for maximizing the extent of sugar production. 

K. M. Cowan and L. Eoff. Surfactants Additives to improve the performance properties of cement. In Proceedings Volume, pages 317-327. SPE Oilfield Chem Int Symp (New Orleans, LA, 3/2-3Z5), 1993. 

Surface active agents (surfactants) are active (adsorb) at surfaces and reduce surface tensions. Surfactants work because they are amphiphilic they have opposing solubility tendencies in one molecule, such as a hydrocarbon chain and a polar end. Because of this disparity in solubility, they tend to form concentration gradients at dissimilar phase interfaces. Surfactant additives are classified according to the interface at which they are active. 

Zakin, et al. "Variables Affecting Drag Reduction by Nonionic Surfactant Additives," Chem. Eng. Commun.. 1983, 23, 77 88. 

Table 10.20 Effect of surfactant addition on AOX values after chlorite bleaching of synthetic fibres [224]...

The stripping of fully developed azoic dyeings can often be carried out using a hot solution of sodium hydroxide (1.5-3 g/1), sodium dithionite (3-5 g/1) and a surfactant addition of anthraquinone (0.5-1 g/1) generally increases the effectiveness of the process. Yellow azoic dyeings are resistant, however, and can only be partially stripped [30]. On the other hand, stripping of naphtholated material before it has been coupled with the diazo component can be done quite effectively in boiling alkali. 

If a p-i-n (i.e., LEC) device architecture is used, the choice of the ionic dopant and surfactant additives to the light-emitting organic ink are critical to the print uniformity and resulting device performance and stability. The ionic dopants have limited solubility and can prematurely fall out of solution during the printing process. Most of the previous works in... 

Fig. 3.14 Anodic stripping square-wave voltammetry (ASSWV) of 1 X 10- M Dependence of peak currents on the accumulation time, itacc = —0.8 V, tacc = 5 s. (1) organic carbon-free water and (2) double-distilled water contaminated by unknown surfactant. Additions of Triton X-100 to (2) inmg/1 (3) 0.1, (4) 0.3, (5) 0.5, (6) 0.8 and (7) 1. Esv/ = 30 mV, / = 100 Hz and AE = 2.4 mV (reprinted from [247] with permission)...

The VRU is designed to treat soils contaminated with organic contaminants and heavy metals. The system is flexible, and allows for changes in the process train, treatment temperature, surfactant addition, and the use of steam for stripping. 

PolyHIPE materials have also been prepared by polycondensation in high internal phase emulsions [153]. Thus, a resorcinol-formaldehyde (RF) porous copolymer was synthesised from an o/w HIPE of cyclohexane in an aqueous solution of resorcinol, formaldehyde and surfactant. Addition of an acid catalyst to the emulsion, followed by heating, resulted in copolymerisation. Other systems prepared included urea-formaldehyde, phenol-formaldehyde, melamine-formaldehyde and a polysiloxane-based elastomeric species. 

Temovskaya and Belopol skil (T9, T10), 1950 Experimental study of absorption of SOa in water film with various surfactant additives. Rate of absorption decreased rapidly then increased slowly as concentration of surfactant increased (cf. Levich, L7) this effect is shown to be due to damping of waves. 

Hikita and Nakanishi (H13), 1959 Film flow over spheres (1.42-4.12 cm. diameter) singly and in vertical groups of up to 5, spaced at 5-mm. intervals. CO2 absorbed in water films with and without surfactant additives, Nr, = 1-200. With pure water results for multiple spheres agree with assumption of complete mixing between spheres deviations with surfactants. 

Hanratty and Hershman (H2) 1961 Jeffreys theory (J4) for roll-wave transition on a liquid surface is applied to the cocurrent flow of gas and liquid at small slopes. Experimental data on the initiation and growth of waves on various liquids with and without surfactant additives. 

As with traditional surfactants, additives may inLuence the onset of micellization of polymeric surfactants and thus affect solubilization. These additives can include inorganic salts and sugars used to adjust isotonicity and even the solubilizate drug itself. In addition to micellization, these additives can inLuence the LCST or CP and even the structure of micelles formed. 

---