Papers by Keyword: Surfactant

Abstract: The inhibition of corrosion of stainless steel (SS)-410 in sulfuric acid using thiourea and three different surfactants, cetyle trimethyl ammonium bromide (CTAB), sodium dodecyl sulfate (SDS) and X-Triton was studied. Corrosion rates were determined by using corrosion coupons. The corrosion rate was found to be decreased with increase in inhibitor concentration. It was observed that the maximum corrosion inhibition occurred in the post micellar concentration of the surfactants. By optimizing the corrosion inhibition performance of different blends of surfactants and thiourea in 3 M H₂SO_4, the corrosion inhibition order was found as: Triton X-100 + thiourea > CTAB + thiourea > SDS + thiourea. The best results obtained by the addition of 200 ppm thiourea in 500 ppm of Triton X-100 in 3 M H₂SO₄ acid solution. This blend decreased the corrosion rate of SS-410 to 657.66 mpy.

Abstract: Ice crystal growth problem have attracted special attention due to in heat transfer deterioration and pump power consumption increasing, by adding very small amount of suitable additives can control the ice crystal growth. This paper investigates ice crystal growth in isothermal condition when adding four different additives, and then calculate the energy between surfactants and ice crystal to explain the effect of different additives. The results indicate that the interaction is Coulomb interaction and Van der Waals interaction for anionic and nonionic surfactant respectively. This method provides a method to explore the mechanism of controlling ice crystal growth with surfactant.

Abstract: Foaming methods to reduce the density of geopolymers were investigated as low density geopolymers are increasingly being reported in the literature to be effective in improving the insulating properties. However, there is no consistency in foaming methods and as such this study was performed to compare different foaming agents in order to better understand their effect on the properties of geopolymers. In particular, a surfactant and hydrogen peroxide were used individually and in combination to ensure a homogeneous pore distribution in the slurry. Physical and microstructural properties of the hardened low density geopolymers are presented and discussed. The behaviour under fire conditions of fibre reinforced and foamed geopolymer samples will also be presented in order to appreciate the suitability of geopolymer composite in high temperature applications.

Abstract: Barium hexaferrite is categorized as hexagonal ferrite material with ferrimagnet properties. Barium hexaferrite has high coercivity, curie temperature, anisotropy magnetic field, and chemical stability that is often used as permanent magnet. It can be synthesized by using bottom up or top down method. The bottom up method of sol-gel has potential advantages in industry application compared to the top down method because of low energy requirement, more homogeneous product, and low time consuming to achieve nanometer size. The development of sol-gel method by using tapioca and chitosan as surfactant increases the quality of the product. Tapioca is used to increase anisotropy properties of particles by changing the particles shape into rodlike shape whereas chitosan is used to stabilize them at small size. Molar ratio of Fe³⁺/Ba²⁺ is set on 12 and the ratio of tapioca/chitosan is set on 1/3, 1/2, and 1. Iron (III) nitrate is used as Fe³⁺ source whereas barium nitrate is used as Ba²⁺ source. Condensation is done by heating up the sol system in the oven at 100^OC. The product then is calcined at 1000^OC with holding time of 3 hours. The calcined product is then characterized by X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Vibrating Sample Magnetometer (VSM). XRD result shows that the hematite phase has still been formed. The occurrence of the phase indicates that the reaction between iron and barium is uncompleted. SEM images show the existence of needle and rod-shaped particles with diameter of 200nm–550nm. It explains that tapioca can be used as rodlike template. The increase of tapioca tends to enlarge the rod-shaped particle and remove the needle-shaped particle. VSM result shows that the highest value of Br is found in the sample of tapioca/chitosan with the ratio of 1/3 and the value of 24 emu/g. The fact indicates that the optimal ratio of tapioca/chitosan is 1/3.

Abstract: Surfactant-enhanced permanganate oxidation (SEPO) technology utilizes the surfactant to mobilize and/or solubilize the dense-non-aqueous-phase liquids (DNAPLs) and then exploits the high oxidation capacity of permanganate (MnO₄^-) to oxidize them. SEPO technology has been shown as an effective way to remediate the aquifers contaminated with chlorinated organic pollutants such as trichloroethylene (TCE). Experiments were carried out with a series of continuous stir batch reactor to quantify the kinetic parameters of which MnO₄^- oxidizes the aqueous TCE in the presence of surfactant. It was found that TCE followed the observed pseudo-first-order reaction with respect to MnO₄^- whether the surfactants were present or not. In the absence of surfactants, the observed pseudo-first-order rate constant (k_obs) and half-life (t_1/2) were 0.12-0.25 min^-1 and 2.5-7.1 min for MnO₄^-, respectively. For the Tween80 concentration less than its critical micelle concentration (CMC), the k_obs value was 0.14 min^-1 and the t_1/2 was 2.6 min for MnO₄^-. As the Tween80 concentration exceeded its CMC, the k_obs values increased to 0.32-0.37 min^-1 and the t_1/2 reduced to 0.44-0.46 min. The results showed that combination of permanganate with a proper type of surfactant can speed up the removal of contaminants in aquifers.

Abstract: The effect of surfactant on improving the leaching rate of uranium was studied under both batch and column experiments. Batch experiments show that surfactant DMSS can improve the leaching rate and the the surface tension is decreased about 55.29%. 70 mg/l DMSS has the highest leaching rate of uranium , which close to the micellar concentration of DMSS. In the column study, with the addition of DMSS, the leaching rate of uranium is improved 8.3%. Thus the surfactant DMSS can accelerate leaching of uranium.

Abstract: The concentration of suspended solid, oil, HPAM, surfactant, sulfide and silicate colloid was investigated by the simulation aeration and settling experiment. The major factors that influenced the content change of suspended solid were also determined in this study to provide reliable basis for the actual process.By the simulation experiment, the main influence factors that changed the concentration of suspended solid in ASP produced water were the precipitation of HPAM

Abstract: In general, water-in-diesel (W/D) emulsion reduces both particulate matter and nitrogen oxides gas emissions level in diesel engine application as compared of using conventional diesel fuel. W/D emulsion was usually produced by addition of water into the diesel fuel with a slight quantity of surfactant at high speed of propeller mixing. The studies examine the result of several aspects on emulsion stability. Investigated variables are type of surfactant, mixing speed and mixing time. Surfactant used are span 80 and many type of glycerines which have been derived from a corn oil, palm oil, soy oil, rice bran oil and sunflower oil. The results show that the type of surfactant gives a big impact on the stability period of the emulsion fuel. The higher mixing speed and less water percentage increase the stability period of W/D emulsion fuel. Optimum mixing time is 5 minutes for W/D emulsion fuel which using Span 80 as surfactant with mixing speed of 2500 rpm.

Abstract: Inhalable particles suspended in air were an important pollution of atmospheric Environment. Because of very small in size, they were different to be captured by conventional filter. Chemical active agent, surfactant and flocculate, were introduced into chamber and encouraged the agglomeration of inhalable particles. Nonionic surfactant could reduce more than 30% of particles, while ionic surfactant could lead to the decrement of 23-26%. The particle removal efficiencies were only 15-18% in the presence of polymer flocculate and slightly above that of water. The larger droplet of spray favored the agglomeration of inhalable particles. Increasing the surfactant concentration resulted in the higher removal of inhalable particle.

Abstract: Tetramethyl ammonium hydroxide (TMAH) has wide applications in semiconductor industry, including photoresist development, silica etching (especially Sigma etching), and wafer cleaning, etc. One of the critical areas of the photolithography process is the development of unexposed (negative) or exposed (positive) photoresists without pattern distortion. As a metal free, basic aqueous solution, TMAH is the most common positive photoresist developer providing no metal contaminations. The bath composition, especially the concentration of TMAH, is strictly controlled within the process specifications (~2.2 to 2.4 % (w/w)), since it greatly affects the developing rate and contrast [1]. Traditional monitoring of TMAH concentration does not suffice for the modern needs of a sub-20 nm IC fabrication process. Additional critical parameters include dissolved carbonate and proprietary surfactants.