2.3 Overview of Surfactant
Surfactant comes from short term of “Surface-active agent”, is a chemical that stabilizes the mixtures of oil and water by reducing the interfacial tension (IFT) at the interface of residual oil and water molecules. The water and oil usually not dissolved which is separated into two layers. By additional of surfactant into the mixture, it will keep it from separating into layers. Surfactant usually is an organic compound that is amphiphilic, meaning they contain both hydrophilic (head) and hydrophobic (tail) and thus semi-soluble in both organic and aqueous solvents (see figure 2.6). Surfactant is also referred to as amphiphile molecule because they contain a nonpolar ‘tail’ and a polar ‘head’ group within the same molecule (Green, D.W. and Wilhite, G.P, 1998). Amphiphiles adsorb effectively to interfaces and typically contribute to significant reduction of the interfacial energy (Pasley, R.M and Karaman, M.E., 2004).
Depending their nature hydrophilic group, surfactants can divide into four groups which is Anionics, Cationics, Nonionics and Amphoterics. In surfactant flooding, the anionic and non-ionic surfactant usually being used as it is by far cheaper and have low adsorption rate. Anionic surfactant is most commonly used in EOR because it can lower the IFT, their ability to create self-assembled structure,
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Their main function is to reduce interfacial tension between oil and water so that it can create emulsion and flow in continuous phases. The surfactant molecule will diffuse in water and reduce interfaces between oil and water as the result oil and water and oil will mix together. The insoluble hydrophobic group may be extend out from the bulk water phase and into the oil phase, while the water soluble head will remains at the water phase as show in figure 2.6. Thus this condition will change the surface properties of the water at the water/oil interface. This process will call as
Hydration of alkenes is characterized by the addition of water and an acid-catalyst to a carbon-carbon bond leading to an alcohol. Dehydration is exactly the opposite in which dehydration of an alcohol requires water to be removed from the reactant. Equilibrium is established between the two processes when the rate of the forward reaction equals the rate of the reverse reaction. The alkene that is used in this experiment is norbornene. Through hydration of norbornene, an alcohol group should be present on the final product yielded what is known as exo-norborneol. Percent yield is a numerical indication of how much of the reactant was actually reacted to yield product. The equation for percent yield is shown below:
As shown in Fig. 5, the final pH of the NaClO-NH3 solution after simultaneous removal are 5.4, 6.9, 7.2, 7.5, 8.5, 9.6, 10.7, 11.5 and 12.8 with respect to the initial pH of 5, 6, 7, 8, 9, 10, 11, 12 and 13, from which, an interesting law can be concluded as that if the initial pH is an acidic, the final pH is slightly increased; but if the initial pH is an alkaline, the final pH is declined. NaClO-NH3 is macromolecule compounds with a large inter surface area. It contains abundant functional groups such as hydroxyl (OH), carboxyl (COO), quinone, amino (–NH2), etc, which determines that NaClO-NH3 is a salt of strong base and weak acid, as well the ionization equilibrium and hydrolytic equilibrium would be complicated. When the pH of the NaClO-NH3 solution was acidic, the functional groups such as OH, COO and NH2- would react with H+ to generate the NH3 sediment, resulting in a decrease of inter surface area owing to the block and a great loss of NaClO-NH3, then the NOx removal as well as the duration time was decreased. As for the increase of the final pH in the acidic conditions, this was a result of the consumption of H+ by NaClO. The decrease of the
Phoeung T., Morfin Huber L. & Lafleur M., 2009. Cationic Detergent/Sterol Mixtures Can Form Fluid Lamellar Phase and Stable Unilamellar Vesicles. Langmuir, 10, 5778-5784.
Hydrochloric acid is the clear colourless solutions of hydrogen chloride (HCl) in water, hydrochloric acid is also a highly corrosive substance and a strong mineral acid meaning they are formed from inorganic compounds, hydrochloric acid is a monoprotic acid meaning that it can only ionize one H+ ion. As a result hydrochloric acid can be used in a wide range of industrial practices such as removing rust from steel, ore processing, the production of corn syrup and making of PVC plastics. Hydrochloric acid is made using a very straight forward method which involves dissolving hydrogen chloride (HCl) in water, releasing the H+ cation and Cl- anion. In this aqueous form the H+ ion joins water to form a hydronium ion (H3O+)
Cations are positively charged ions, which are attracted to their negatively charged counterparts, anions. Precipitates can form when these cations and anions combine in aqueous solutions; however, precipitates only form if one of the products of the chemical reaction is not soluble in that solution. Solubility is instrumental in understanding how precipitation reactions occur. This is because solubility rules, determine whether a precipitate can form. A precipitate can form if the cation in the compound is soluble when combined with an anion. For example when the solutions silver nitrate and sodium chloride (reactants) are mixed, silver chloride and sodium nitrate (products) are formed. Following the solubility laws, silver nitrate is the precipitate, as it isn’t
They are also used in a variety of common products and processes. Sodium lauryl sulfate is a strong detergent used for removing oils and grease and is found in many household cleaning products, face and body washes and shampoos.
For serious accumulations of dirt or other materials or substances, a hose can be used to clear away the debris. Even notoriously difficult substances like oil will not stick to or stain the surfacing.
Disinfection is applied in water as well as wastewater treatment as a finishing step so as to destroy pathogens but the cause of concern regarding the disinfection process is the formation of disinfection byproducts (DBPs). Natural organic matter (NOM) in water has been considered as the predominant DBP precursors. Disinfectants are powerful oxidants that oxidize the organic matter present in water forming DBPs. Chlorine, ozone, chlorine dioxide, and chloramines are the most common disinfectants used nowadays and each produces its own suite of chemical DBPs in finished drinking water (Richardson, 2003). DBPs so formed pose a threat to human health because of their potential to cause cancer and reproductive/developmental effects. Most developed nations have regulated concentration of DBPs so as to minimize exposure to potentially harmful DBPs while maintaining adequate disinfection and control of targeted
Solubility is defined as the maximum amount of a substance that will dissolve in a given amount of another substance at constant temperature and pressure. Solubility is typically expressed in terms of maximum volume or mass of the solute that dissolve in a given volume or mass of a solvent. Traditionally the equilibrium solubility at a given pH and temperature is determined by the shake flask method. According to this method the compound is added in surplus to a certain medium and shaken at a predetermined time. The saturation is confirmed by observation of the presence of un-dissolved material. Saturation can also be reached if the solvent and excess solute is heated and then allowed to cool to the given temperature. After filtration of the
You have been asked to design an oral liquid formulation of ibuprofen for paediatric use.
...ussion: Adsorption sites for salt as well as for alcohol are polar silanol groups (Fig 1c). As discussed earlier, alcohol is not adsorbed on all silanol groups (prefers isolated silanol group) and alcohol is more preferentially adsorbed than salt. So, anchorage of salt on the silica surface must be very distinct, reducing the possibility of irreducible mixed metal support formation. Also for substantial adsorption, silica gel has to be contacted with very concentrated salt-alcohol solution. In our opinion small amount of water cause ionization of alcohol which further induce ionization at silanol surface creating anionic sites suitable for esterification of ethoxy group. On the other hand, salt is mostly “associated” if the water is around 1-2% in the solution and the adsorbed salt will act as nucleation site for salt present mainly because of physical interaction.
- The amount of times the mixture was stirred. We stirred the mixture until the Ammonium Nitrate was dissolved, so the amount of times we stirred after each teaspoon was different.
National Research Council. 1989. Using oil pollution dispersants on the sea. Washington, D.C.: National Academy Press.
This is an example of a soap molecule. The hydrocarbon end is non polar and hydrophilic (water hating) and the carboxylate end is polar and hydrophilic (water loving). This the property which allows it to clean, it acts as an emulsifying agent. The soap disperses in water to form miscelles where a negatively charged surface is formed and hydrocarbon chains are in the centre. These miscelles surround droplets of dirt or grease suspending them in the water so they can be washed away.
Water alone can’t remove dirt. Soap allows oil and to mix so the dirt can be effectively removed. Surfactants lower the tension in water and help break down the oil and grease. Detergents have hydrophobic chemical chains which are repelled by water, whereas hydrophilic chains are attracted to water. In general, hydrophobic and hydrophilic chains work together to attack oil and water and break them down faster and easier.