Volume 60, Issue 3

Automatic dishwashers combine capital, energy, and water to provide a relevant household service, namely dishwashing. Consumer behaviour in using the automatic dishwasher influences to a great extend the environmental impact of such a device. But what simple and intuitive recommendation can be given to consumers to save energy and water while maintaining the cleaning performance? This task is investigated by modelling the resource consumption for automatic dishwashers in six European countries by considering the installed base of automatic dishwashers and recently surveyed consumer programme selection behavior. Using this model, a simulation is performed on how three simple recommendations on the programme selection would affect the overall consumption. As a result, more than 20% of the consumed energy can be saved by following these simple recommendations. To facilitate consumers’ actual adoption of the recommendations, this publication presents effective communication measures based on the science of consumer behaviour.

Moisture-wicking clothes are widely used in various sports or athletic activities due to their function of moisture absorption and perspiration. In this study, the washing and decontamination of moisture-wicking fabrics, especially the performance and decontamination effect of moisture-wicking fabrics after washing were investigated. The results showed that the physical morphology of moisture-wicking fabric is very different from that of an ordinary polyester fabric. The cross-section of the moisture-wicking fabric is hexagonal, and this fabric has good hydrophilicity. After the degreasing & thermosetting process, the air permeability of the moisture-wicking fabric is increased from 1013 mm/s to 2911 mm/s. However, the air permeability is decreased after one washing, but it has little effect during the subsequent washing cycles. Moreover, the degreasing & thermosetting process also improve the stains removal index. If the moisture-wicking fabric was washed before the preparation of stained fabric, the stain removal index of carbon black soil and sebum stains is increased. Although most of the aggregated particles on the surface of the fibers are removed after washing, a small amount of sebum still remains in the spaces between the fibers. These results indicate that most of the carbon black in the stained area is removed after washing, while oil components are hardly removed from the moisture-wicking fabric during home laundry. Compared to other surfactants, C 18 fatty acid methyl ester ethoxylates and nonionic surfactants with long carbon chains can effectively reduce the surface tension of water and improve the wettability of moisture-wicking fabric, so that water molecules can diffuse well between fibers and stains, the binding force between stains and fabric is weakened, and the decontamination of the fabric is improved.

The surface tension ( σ ), critical micelle concentration (CMC), surface excess (Γ), minimum area occupied by a surfactant molecule ( A min ), the viscosity and oscillatory rheological studies of aqueous solutions containing cocamidopropyl betaine (CAPB) and sodium dodecylbenzene sulfonate (SDBS) at molar fractions of 0.00, 0.25, 0.50, 0.75 and 1.00 and 25 °C were presented. CAPB and SDBS were not found to interact synergistically in water at any of the molar fractions studied. This is due to the fact that the critical micelle concentrations of these mixtures were higher than those predicted by Clint’s equation, indicating an antagonism that rarely occurs in mixed amphoteric/anionic surfactant systems. The minimum area occupied by a surfactant molecule ( A min ) was reduced in CAPB/SDBS mixtures compared to unmixed surfactants. In contrast, the viscosity of the mixed CAPB/SDBS system increased significantly from 1.0 mPa s to a maximum of 36.0 Pa s at higher CAPB mole fractions (0.5–0.8). The rheograms obtained from the oscillation measurements of the viscous CAPB/SDBS solutions are characteristic of wormlike micelles (WLMs) according to the Maxwell model. The results of this surprising binary CAPB/SDBS surfactant mixing system are presented and discussed.

A synergism is reported in the binary mixtures of cocamidopropyl betaine (CAPB) and sodium dodecyl benzene sulfonate (SDBS) at mole fractions of 0.25, 0.50, and 0.75, in dilute hydrochloric acid solutions (∼0.05 M) HCl, at 25 °C. Such synergism is confirmed by surface tension values, critical micelle concentration (CMC), and interaction parameter values according to Holland and Rubingh’s model and the satisfaction of Hua and Rosen conditions. Surface excess (Γ) at air/water interface and the minimum area occupied by surfactant molecule ( A min ) also indicated a reduction in the A min of mixed CAPB/SDBS compared to single surfactants that is due to the strong electrostatic interaction between surfactants heads. The composition of CAPB/SDBS mixed micelles, the interaction parameter ( β ) and the micellar activity coefficients ( f 1 and f 2 ) were evaluated from the regular solution model for these binary amphoteric/anionic mixed systems. It is clear the CAPB surfactants are converted to the cationic form by charging in the presence of HCl, which enhances the interaction between the oppositely charged CAPB and SDBS heads and overcomes the unfavourable packing between the tails predicted in pure water. Such strong interaction was also reflected on the phase behavior of CAPB/SDBS binary mixed system. Accordingly, a switching from antagonism to synergism is reported for CAPB/SDBS binary mixed system in the presence of dilute hydrochloric acid.

In this study, the properties of amide Gemini surfactants (DLP-12, DLP-14 and DLP-16) were investigated. The results showed that these surfactants have good wettability and solubility, but these properties deteriorate with increasing hydrophobic chain length. The critical micelle concentrations (CMC) measured by the Wilhelmy method and by the steady-state fluorescence spectroscopy were similar and showed the same trend: The CMC values decreased with increasing hydrophobic chain length. The solubilization capacities in toluene were (6320, 6440 and 6680) mL/mol for DLP-12, DLP-14 and DLP-16, respectively, indicating an improvement in solubilization ability. Thermal stability experiments showed that the initial decomposition temperatures of the three surfactants were (301, 320 and 331) °C, respectively, indicating good thermal stability of these surfactants.

The industry is challenged to replace toxic chemical-based surfactants with environmentally friendly and biodegradable surfactants. In this study, binary mixtures of sodium lauryl sulfoacetate (SLSA) and an alkyl polyglucoside (APG 10 ) in various proportions were investigated for their effectiveness as degreasing agents. Efficacy was characterised using surface tension measurements, oil dispersion tests, emulsification, pH and cleaning efficacy in removing engine oil from a metal plate. The surface tension results for all solutions showed a critical micelle concentration of 1500 ppm. The dispersion tests (with oil:surfactant ratios of 1:2 and 1:3) showed that the oil was fully dispersed at an oil:surfactant ratio of 1:2 i.e., at a concentration of 2500 ppm SLSA and 2000 ppm of a binary solution with a volume ratio of SLSA:APG 10 of 75:25. At a ratio of 1:3, the oil was fully dispersed with 2500 ppm of a binary solution with a ratio of SLSA:APG 10 of 75:25. Overall, the solution with a volume ratio of SLSA:APG 10 of 75:25 was the most favourable. The results also showed that a solution containing only SLSA had good potential as a degreaser, as it achieved a cleaning performance of 90% in removing oil from the metal plate despite low emulsification levels (E 24 ) for both surfactants. In summary, a combination of these two green surfactants can be used effectively as a degreasing agent.

The effects of different surfactants on the morphology of 1,3,5-trinitro-1,3,5-triazinane (RDX) micro-nanoparticles prepared by solvent/non-solvent method in a microfluidic reactor were investigated. Alkyl polyglycoside (APG), sodium dodecyl sulphate (SDS) and dodecyltrimethylammonium bromide (DTAB) were selected as non-solvents. The surface tension and interfacial tension (IFT) properties of SDS, APG and DTAB were investigated. Compared to DTAB and SDS, the APG could effectively reduce the interfacial tension to 10 −2 mN/m and exhibited better surface tension. The RDX prepared with different surfactants were analysed by scanning electron microscopy (SEM), X-ray diffractometry (XRD) and Fourier transform infrared spectrometry (FTIR). The results showed that the different surfactants could significantly improve the dispersion effect of RDX and the crystal morphology was uniform and stable.

In this work, alkyl glyceryl ether sulfonates with two alkyl chain lengths were synthesised by etherification and sulfonation. The structures of these sulfonates were characterised by FTIR, 1 H NMR and MS. Their characterisations were investigated for their surface properties and thermodynamic properties by surface tension, conductivity and fluorescence methods. The critical micelle concentration (CMC) of surfactants increases with increasing temperature and decreases with increasing alkyl chain length. The micellation process of alkyl glyceryl ether sulfonates is spontaneous and driven by entropy.

In this work, using the natural product cardanol and chlorosulfonic acid as the main raw materials, the anionic surfactant cardanol sulfonate (CDS) was synthesised and investigated for its surface properties and thermodynamic properties using surface tension, conductivity and fluorescence methods. In addition, the application properties of CDS, such as foaming and cleaning ability were investigated and compared with those of sodium dodecylbenzene sulfonate (SDBS). The structure of the surfactant was characterised by FTIR, 1 H NMR and MS. The Krafft point of the surfactant was below 25 °C, indicating good water solubility. The CMC values were determined by surface tension, conductivity and micropolarity measurements. The obtained CMCs agreed well within the measuring accuracy. The CMC increased with increasing temperature. As a function of temperature, the following CMC values were obtained: 5.13 × 10 −3 mol L −1 (25 °C), 5.63 × 10 −3 mol L −1 (35 °C) and 5.77 × 10 −3 mol L −1 (45 °C). The values of surface tensions at the respective CMCs were γ CMC = 44.47 mN m −1 (25 °C), 43.53 mN m −1 (35 °C), and 42.45 mN m −1 (45 °C). The application property results showed that the foaming capacity, foam stabilisation and cleaning ability of CDS and SDBS were similar to each other, indicating that CDS can be used as a raw material for commercial detergent production.