Band 41, Heft 5

The precipitation and deposition of calcium sulfate dihydrate (gypsum) on brass heat exchanger surfaces from aqueous solutions has been studied using a highly reproducible technique. It has been found that gypsum scale formation takes place directly on the surface of the heat exchanger without any bulk or spontaneous precipitation in the reaction cell. A variety of natural and synthetic polyelctrolytes such as fulvic acid, tannic acid, poly-(acrylic acid) and acrylic acid — based copolymers containing sulfonic group(s) have been examined for their effects on the rate of scale formation. The results indicate that the amount of gypsum scale formed on heat exchanger surface is strongly affected by polyelectrolyte architecture and concentration of polyelectrolyte. Scanning electron microscopic investigations of gypsum crystals grown in the presence of polyelectrolytes (natural and synthetic) show that structures of these crystals are highly modified.

In conventional detergent compositions, synergism between alkylpolyglucosides and conventional anionic surfactants is exploited. Now improved types of binary mixture of alkylpolyglucoside with innovative alkylpolyglucoside ester based anionic surfactant have been successfully applied to wellbore cleaning for the oil and gas industry. In recent years the environmental aspects of wellbore cleaning agents has become critical in environmentally sensitive areas since in offshore operations where there can potentially be accidental contamination of the marine environment with surfactants. Binary mixtures of alkylpolyglucosides and alkylpolyglucoside-based anionic surfactants showed the cleaning performance required, combined with the advantage of outstanding environmental properties.

The high purity decyl methylnaphthalene sulfonate (DMNS) was synthesized, the purity was determined by HPLC and the structure was confirmed by IR, UV and ESI-MS. Dynamic interfacial tensions (DIT) between DMNS flooding systems and crude oil were measured and the effects of sodium carbonate concentration, surfactant concentration and sodium chloride concentration on the DIT behaviors were investigated. It's found that the surfactant concentration, alkali concentration and the salinity have obvious influences on DIT behaviors. DMNS possessed outstanding capacity and efficiency of lowering the DIT between oil and water. The minimum dynamic interfacial tension could reach 6.35×10 −6 mNm −1 at a lowconcentration for added surfactant. DMNS might be used in Enhanced Oil Recovery with lowcosts and high efficiency.

Dissipative Particle Dynamics is a mesoscopic simulation method which allows to predict the self-assembly of amphiphilic polymers and surfactants. It was possible to reproduce the phase behavior of the non-ionic surfactant C12E5 in water. The three different phases L 1 , L a and L 2 could be characterized with Dissipative Particle Dynamics.

Association of quaternary ammonium based surfactants with activated sludge from wastewater treatment plants has been studied. Adsorption isotherms on activated sludge particles and surface properties of a series of alkyl trimethyl ammonium compounds have been investigated. The effect of alkyl chain length and the water hardness in those physical-chemical properties have been evaluated. Adsorption on sludge increased with increasing the alkyl chain length in the cationic surfactant molecule. Linear relationships between critical micelle concentration (-log CMC) and efficiency of adsorption at the liquid/gas interface (pC 20 ), and the number of carbon atoms in the alkyl chain length were found for the alkyl trimethyl ammonium compounds. Water hardness decreased the CMC values of the tested alkyl trimethyl ammonium homologues and the extent of their sorption to activated sludge. Langmuir and Freundlich adsorption isotherms described satisfactorily the equilibrium adsorption of the cationic surfactants on activated sludge.

Anionic Surfactants, and Sulphonates in particular, will continue to keep their important rule in Detergents formulation for generations to come. The sulphonation Reactor is the key-tool to generate Sulphonated Molecules for Detergent application, therefore the efforts in improving the specific technology are focused on the best possible design and search for optimum operation of the same. The limits of the present technology are discussed and the peculiarity and advantages of the latest generation of Multi Tube Falling Film Reactor are valued by highlighting: Design basis Construction accuracy Operating conditions and savings Achievable products quality