Volume 54, Issue 4

Energy Labels are an instrument supporting on-going market transformation towards higher energy efficiency by motivating consumers to select more energy-efficient products. Since the purchase decision can be influenced by the consumers' understanding of the Energy Label, this paper addresses the clarity of the Energy Label of washing machines from a consumer's point of view, and their expectations and wishes concerning a future Energy Label. Information on consumers' opinions/expectations regarding the Energy Label was collected by a semi representative survey in eleven European countries in 2015. The main outcome of the study is that consumers are generally familiar with the symbols on the Energy Label, but they do not know this information belongs to which programme. They believe that a washing machine with the highest Energy efficiency class available on the market can help make savings on energy and water in all its programmes. Finally, the study suggests which modifications need to be applied to the current version of the Energy Label to improve its effectiveness.

The effects of water hardness on textile detergency in aqueous linear dodecylbenzene sulfonate (LAS) solutions were examined under various washing conditions. Plain-woven and towel cotton fabrics and plain-woven polyester fabric were soiled with a mixture of carbon black/oleic acid. The soiled fabrics were shake-washed in the LAS solution together with the original unsoiled fabrics. Surface reflectance measurements revealed that the soil removal and redeposition decreased and increased, respectively, with increasing water hardness. The identity of the mineral species (calcium or magnesium ions) in the hard water had no notable effect on the detergency. The addition of significant amounts of extra LAS did not fully compensate the reduction in detergency in hard water. Addition of softening agents and an alkali builder to the hard water limited the reduction in detergency, but the detergency was still lower than that in the absence of hardness salts. Moreover, a high wash temperature and repeated rinse procedure did not prevent the reduction in detergency in hard water. Finally, a washing test was carried out in hard water under the conditions considered to be effective for improving the detergent quality in hard water, based on the experimental results. The LAS detergency toward the cotton fabrics under these conditions was still poorer than that in the absence of hardness salts. We concluded that using soft wash water is the best choice for maximizing the cleaning power of detergents.

The objective of this study was to analyze the relationship between structural changes and surface-activity of water-soluble silk fibroin prepared by treatment with calcium nitrate tetrahydrate (Ca(NO 3 ) 2 · 4 H 2 O). Ca(NO 3 ) 2 · 4 H 2 O, is a hygroscopic compound at room temperature and a suitable solvent upon melting at 100 °C, which was traditionally used as a solvent for dissolving cocoons or silk. The cocoons or silk were optimally dissolved by Ca(NO 3 ) 2 · 4 H 2 O when using a 40 % (w/w) Ca(NO 3 ) 2 solution, a 1 : 10 ratio of cocoons or silk to solvent and a dissolving time of 69 min. The results showed that the hydrophobic region of the silk fibroin was destroyed, resulting in the exposure of the hydrophobic groups. The emulsifying ability and the emulsion stability as well as the foaming ability and the foam stability, and the γ CMC and CMC of soluble silk fibroin were 92.8 %, 97.3 %, 213.3 %, 88.1 %, 65.83 mN/m and 0.42 mg/mL, respectively. The molecular conformation of silk fibroin chains was the β-sheet, as shown by the intense amide I–III bands at 3 163 cm −1 , 1 627 cm −1 , 1 518 cm −1 , and 1 231 cm −1 . The random coil/α-helix structure induced from Ca(NO 3 ) 2 convert to β-sheet conformation. Owing to the calcium nitrate's dissolution, silk fibroin can be dissolved in water by changing its structure, and shows excellent surface activity.

In petroleum industries, an emulsification process is often necessary to transfer and upgrade heavy crude oil. Saponins are the main group of biosurfactants used for this purpose and they are often extracted from plants. In this study, saponin was extracted from Glycyrrhiza glabra using a soxhlet method. The aim of present study was to optimize the effective parameters in production of saponin in order to obtain the maximum emulsification index (E 24 ) and optimum mean droplet size by Taguchi method. The evaluated parameters include extraction temperature, first solvent volume fraction, second solvent volume fraction and n -butanol volume fraction. Response parameters resulted in yield, cost and E 24 of produced saponin. The obtained results showed that temperature and n -butanol volume fraction were the most effective factors in the extraction process. Optimum operation condition including yield, cost and E 24 were (3.6 ± 0.1) g/200 g of plant material, (3.4 ± 0.14) $/g and (98 ± 5) %, respectively. The mean droplet size of water in oil (W/O) emulsion was (35 ± 6) μm using dynamic light scattering (DLS) analysis. The results of present research could reduce the cost of saponin production for the applications in oil industries.

Microbial biosurfactants consists of hydrophilic and hydrophobic moieties in its structure and are produced by microorganisms. Glycolipid class of biosurfactants has wide range of surface and interfacial properties. The emulsification activity and emulsion stability of the Glycolipids Trehalose lipids (THL), Mannosylerrythritol lipids (MEL), Sophorolipids (SL) and Rhamnolipids (RL) were investigated using liquid paraffin (hydrocarbon source) and sunflower oil (vegetable source) as hydrophobic source by UV spectroscopy. Emulsification activity and stability are in the order THL > MEL > SL > RL. The stability as a function of the temperature in the range of 20 °C – 80 °C is in order THL > SL > MEL > RL. The effect of pH was studied using buffers of acidic and basic pH. It was observed that RL and SL had excellent emulsification activity at pH 8 while the activity of trehalose lipids and mannosylerrythritol lipids was not affected by pH. Similar effect of various concentrations of salt (NaCl) was studied; THL and MEL emulsion were very resistant to concentration of salt but the stability of SL and RL emulsion decreased with increased salt concentration. Average droplet diameter of emulsion and the polydispersity index were determined by dynamic light scattering. The emulsions of THL and SL have smallest droplet diameter of 422 nm and 625 nm, while emulsions of MEL and RL have a droplet size of 1923 nm and 2245 nm respectively. Emulsions of all investigatesd glycolipid surfactants had good polydispersity index and negative zeta potential, suggesting their possible applications in pharmaceutical, cosmetics, industrial and environmental techniques.

The synthesis, structural analysis and properties of saturated cardanol sulfonate salt Gemini surfactant (Gemini-SCSS) were described and compared with saturated cardanol sulfonate salt (SCSS). The structure was characterized by infrared spectra and proton nuclear magnetic resonance. Gemini-SCSS reduced the surface tension of water to a minimum value of approximately 35 – 37 mN m −1 with concentrations of (0.9 − 2.0) × 10 −4 mol L −1 and displayed low foamability and high emulsification, which were better than those of SCSS. Finally, Gemini-SCSS and SCSS both demonstrated good resistance to acid, alkali, hard water.

In order to clarify the role of surface dilatational property in foam flow in a porous medium, three systems were prepared: a system with low surface dilatational modulus and high surface tension, a system with low surface dilatational modulus and low surface tension, and a system with high surface dilatational modulus and low surface tension. By measuring the lamella number and pressure drop across the porous medium, it has been found that differing from flow in a capillary tube, a system with high surface dilatational modulus could achieve a high pressure drop in a porous medium. The conclusion drawn as to the reason is that bubbles with smaller diameter resulting from a structure induced breakup and high dilatational modulus are the main reasons. Flow experiments at 40°C also demonstrate the effect of surface dilatational modulus on the pressure drop.

The implementation of nanotechnology in all industries is one of most significant research fields. Nanoparticles have shown a promising application in subsurface fields. On the other hand, various surfactants have been used in the oil industry to reduce oil/water interfacial tension and also widely used to stabilize the nano-suspensions. The primary objective of this study was to investigate the improvements of surfactants ability in term of interfacial tension (γ) reduction utilizing addition of silicon dioxide nanoparticles at different temperatures and salinity. The pendant drop technique has been used to measure γ and electrical conductivity has been used to measure the critical micelle concentration (CMC). The synergistic effects of surfactant-nanoparticles, salt-nanoparticles, and surfactant-salt-nanoparticles on γ reduction and the critical micelle concentration of the surfactants have been investigated. Extensive series of experiments for γ and CMC measurements were performed. The optimum condition for each formulation is shown. We conclude that nanoparticles-surfactant can significantly reduce γ if correctly formulated.

The interaction of cresol red (CR) with cetylpyridinium bromide (CPB), sodium dodecyl sulphate (SDS), and Triton X-100 (TX-100) was studied in aqueous solutions employing conductometric, tensiometric, and spectroscopic methods. Various micellar and interfacial parameters were calculated in absence and in presence of CR. The interactions suggest the formation of a CR-CPB adduct, an association of CR with the micelle of TX-100 while no adduct is formed between CR and SDS. Appreciably low critical micelle concentration, CMC value of TX-100 compared with those of CPB and SDS in pure water and drastic reduction of CMC of CPB (about one-twelfth of its value in pure water) than SDS and TX-100 in the presence of CR were observed. Higher negative values of Gibbs free energy of micellization, Δ G m 0 , for all the three surfactants indicate that micellization process is spontaneous. The values of maximum surface excess concentration, Γ max , and minimum area per molecule, A min , suggest that in the presence of CR, the air-solution interface is closely packed and the orientation of surfactant molecules is almost perpendicular to the surface. UV-visible spectra suggest the formation of ion-pair complex between the dye CR and the monomers of CPB in the pre-micellar region, while above the CMC a breaking up of the ion-pair complex takes place and the dye is solubilized in the micelles of CPB. In the case of SDS the absorption spectra indicate weak interaction between CR and SDS molecules formation of H-bonding, short range dispersive forces, and hydrophobic interactions between CR and TX-100 molecules in the solution.

Environment-friendly green amino acid surfactants were prepared by the reaction of glutamic acid with various fatty acids (C 2 –C 14 ). These green amino acid surfactants have been found to exhibit good surface activities i.e. surface tension, foaming, wetting power and emulsifying ability. The critical micelle concentration (CMC) increases with an increase of the alkyl chain of amino acid surfactants. After 5 days the biodegradation of these amino acid surfactants was larger than 60% and consequently, the surfactants should be regarded as readily biodegradable. Finally, the green amino acid surfactants were added to natural plant dyes to test their applicability for dyeing wool fibers. The surfactant developed in this study will contribute to green and sustainability chemistry.

In this work, six ionic surface-active alkyl ammonium halides were synthesized and evaluated as demulsifiers of W/O emulsions obtained from a Mexican heavy crude oil. A centrifugation test was employed as a fast method for following the kinetics of the demulsification process with the synthesized demulsifiers. Trioctylmethylammonium bromide showed the best performance as demulsifier.