Volume 62, Issue 4

The energy and water consumption of dishwashers has greatly improved in recent decades, largely due to stringent regulatory requirements. However, consumers still use more resources than necessary. One widely accepted strategy for significantly reducing energy and water usage in households is to promote the use of the ‘Eco’ programme. However, despite its clear benefits, only 20 %–30 % of consumers actually follow this recommendation in practice. In this context, a recent paper published in this journal addressed how to better realise the potential of automatic dishwashing to reduce energy and water use in European households and proposed the introduction of a ‘Short Eco’ programme. Since the publication was purely conceptual, there was no evidence at the time to support its implementation. Consequently, the paper included a call for opinions and feedback. Some dishwasher manufacturers and detergent producers decided to conduct specific tests and consumer research, and some agreed to publish their results here. These results indicate that the concept of a ‘Short Eco’ programme is valid and that similar ‘Short Eco’ programmes could be implemented in all common household dishwashers. Finally, a discussion of the overall concept, a proposal for a refined concept, and the authors’ learnings will be presented.

Developing programs for automatic domestic dishwashers requires balancing energy consumption and program duration with cleaning and drying performance. For the EU-regulated ECO program, an inherent trade-off in program duration and energy consumption may contribute to a usage frequency of around 20–30 %, thus offering potential for further improvement of dishwasher real-life-efficiency (RLE). Academic research suggests that dishwasher RLE may be enhanced by modifying consumer behaviour to increase ECO program use and by employing ‘high-performance’ (HP) detergents in short programs. Here, we show that a recently proposed chemistry-aided ‘short ECO’ program cleans and dries worse while consuming more energy than a modern ECO program, if measured according to the compulsory methodology of EN/IEC 60436. Hence, HP-detergents alone do not suffice to develop a ‘short ECO’ program equipotent to the conventional ECO program. Overall, enhancing dishwasher RLE is a complex topic involving both technological and social aspects. We propose crucial questions that should be addressed in future discussions, and argue that (a) a common definition of (types of) short programs, (b) an in-depth analysis of the relevance of short programs for dishwasher consumers, and (c) the consideration of practical issues are pivotal aspects for further enhancements of the real-life-efficiency and sustainability of dishwashers.

Vicinal diol ethoxylate nonionic surfactants, characterized by their double hydrophilic head groups and Y-type molecular structure, exhibit excellent surface activity, wettability and emulsification properties. However, their use in metal cleaner formulations has not been reported so far. Here, we synthesized vicinal diol ethoxylates based on our previous research and selected C 12 vicinal diol ethoxylate (DC 12 E 3 ) for use in typical metal cleaner formulations. We systematically evaluated the various properties of the formulation. Compared to commercial surfactants such as TX-10, C 12 AEO 9 and TO-1309, DC 12 E 3 showed superior dynamic surface tension at 10 ms, with the order being DC 12 E 3 < TO-1309 < TX-10 < C 12 AEO 9 . Contact angle measurements showed the following order TO-1309 (44.07°) < DC 12 E 3 (49.54°) < C 12 AEO 9 (56.78°) < TX-10 (59.65°). The cleaning performance of a 10 % detergent solution was tested on standard soiling on duralumin surfaces, resulting in the following cleaning performance order: TX-10 < DC 12 E 3 ≈ C 12 AEO 9 < TO-1309. The corrosiveness of the detergent solution on different metals (duralumin, copper, carbon steel) was also evaluated. For carbon steel the order of corrosiveness was DC 12 E 3 < TX-10 < TO-1309 ≈ C 12 AEO 9 . These results indicate that vicinal diol ethoxylates have potential for broad application and provide valuable insights for the formulation of aqueous metal cleaners.

Microemulsions are self-aggregating systems that can be used as artificial models to study processes that occur in biological systems such as the transport of substances in the body and the charge transfer in neurons. Additionally, the environment of life in living organisms is mainly water, or more precisely, aqueous solutions of salts. Therefore, the study of the influence of different salt additives on the electrical percolation threshold in reverse microemulsions is topical. Our aim was to study the process of water-induced and temperature-induced electrical percolation in reverse microemulsions prepared by dissolving of the anionic surfactant sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in n -decane in the presence of additives of different salts in the water droplets or dispersion phase of the microemulsions. To reveal how differences in both ion charge density and kosmotropic-chaotropic properties of salts ions affect the inhibition of electrical percolation phenomenon in reverse microemulsions was also the purpose of the proposed research. It was found that electrical percolation in AOT reverse microemulsions occurs at a relatively higher value of water/surfactant molar ratio (W) upon the addition of aqueous solutions of salts than in the case of pure water. Water-induced electrical conductivity percolation is most suppressed by salts containing both ions with high charge density values, i.e. modification of water droplets with lithium fluoride causes complete quenching of electrical percolation. It was found that electrical percolation in microemulsions with a fixed value of W takes place at relatively higher temperatures in the presence of kosmotropic and chaotropic salt additives in the water pockets of reverse microemulsions compared to microemulsions without salt additives. In the temperature-induced percolation process, the suppression of electrical conductivity percolation or its complete quenching is mainly determined by the kosmotropic or chaotropic nature of an added ions, i.e. potassium ions in conjunction with both kosmotropic and chaotropic anions, e.g. potassium fluoride and perchlorate, strongly suppress the percolation process. In contrast, sodium ions show a suppressive effect only in conjunction with strong chaotropic anions, i.e. bromide, iodide and perchlorate ions. The results may introduce a certain contribution to the study of possible mechanisms of electrical conductivity in reverse microemulsions modified with aqueous solutions of salts.

Herein, the adsorption of nonionic surfactant on slaked lime was investigated. The slaked lime, after being converted into fine structures, were characterized by FTIR, SEM and pHPzc. The CO 3 group on the lime surface was confirmed by FTIR analysis, while its surface area was estimated to be 398 m 2  g −1 . The adsorbent/adsorbate interactions were evaluated using batch adsorption approaches. The effect of experimental conditions such as temperature, pH, and contact time was also evaluated. The maximum adsorption of the selected surfactant on the slaked lime occurred at pH 7 and equilibrium was reached in 30 min. The results of kinetic studies revealed that the data best fit a pseudo-second-order model, i.e. chemisorption (R 2 = 1). The Langmuir model best fitted the adsorption isotherm data. The thermodynamic analysis showed the process to be exothermic with an enthalpy change (ΔH°) of −25.75 kJ mol −1 , spontaneous with negative ΔG° values at all tested temperatures. A positive ΔS° value of 2.162 kJ mol −1  K −1 pointed towards the increase in disorder at the solid-solution interface. Thus, slaked lime, being a cheap material, could thus be used as an alternative to other expensive adsorbents, as indicated by the parameters studied, but further validation requires more studies to fully evaluate the potential of this adsorbent.

Increasing concerns for environmental effects promote green surfactants, derived from renewable resources. A recent development suggests that double-headed Y-shaped alkyl triazole glycosides (ATGs) are a promising alternative to alkyl polyglucosides (APGs). In order to evaluate their significant potential, a study on their toxicity was conducted. The study emphasizes on non-animal testing approaches utilizing a software guided methodology. The results indicate promising biodegradability and absence of severe health effects, reflecting mutagenic effects. However, the ATGs are expected to exhibit skin sensitizing and severe eye damage potential, thereby limiting the application potential of the surfactants.

While amino acid-based surfactants have been widely applicated in daily chemical products, their further development is constrained by limited structural diversity. In contrast, polypeptide-derived surfactants exhibit brighter potential due to their abundant natural sources, structural versatility, and multifunctional properties. In this work, potassium N-lauryl osteopeptide carboxylate (PLOC) was successfully synthesized from lauryl chloride and bovine osteopeptide via Schotten-Baumann reaction. Surface tension, isoelectric point, application performance and irritation of PLOC were studied and compared with conventional surfactants. The isoelectric point of PLOC was determined to be 5.15 by pH titration, which is lower than its amino acid counterpart, potassium lauroyl glycinate (PLG, 6.51), due to the existence of acidic amino acids such as glutamic acid. The surface tension of PLOC at pH = 7 was 30.54 mN m −1 , much lower than that of PLG (37.05 mN m −1 ). Due to the high content of non-polar amino acid, PLOC exhibited less pH sensitivity. Increasing pH to 10 slightly elevated the minimum surface tension to 38.56 mN m −1 . Under neutral conditions (pH = 7), PLOC demonstrated superior emulsification efficiency and significantly reduced dermal irritation potential compared to PLG, owing to its larger hydrophilic head group structure. These results highlight the promising application potential of PLOC in household chemical formulations.

Soil contamination, often by toxic compounds, is a major environmental challenge. In this research, a luminescence biosensor was developed for the detection and toxicity assessment of Zn 2+ , Cr 6+ , Ni 2+ and Cu 2+ . Initially, the presented metals were extracted from the soil by combining two strong biosurfactants of saponin and rhamnolipid. The maximum extraction efficiency of the soil washing process was about 85 %, 68 %, 59 % and 55 % for Ni, Cr, Cu and Zn respectively at an optimum hydrophilic-lipophilic balance (HLB) value of 10.5. Immobilized Escherichia coli ( E . coli ) Luc was used as luminescent bacteria for the detection of heavy metals. The optimum aeration rate of the designed biosensor was 30 mL min −1 . The toxic effect of heavy metals on E . coli with Luc plasmid gene bacterium was determined for each heavy metal using the effective concentration (EC 50 ). When the bioluminescence intensity (BL) decreased to half, the EC 50 was determined to be (0.042, 0.125, 12 and 56) mg L −1 for Cu 2+ , Zn 2+ , Cr 6+ and Ni 2+ respectively. Therefore, the toxicity sensitivity of heavy metals is in the order of Cu 2+ > Zn 2+ > Cr 6+ > Ni 2+ . From the obtained results it seems that the washing process using biosurfactants and designed biosensor is very useful for monitoring toxic heavy metals from cost and environmental point of view.

This study presents an innovative and highly effective reverse micellar liquid-liquid extraction approach for the removal of the anionic dye Xylenol Orange (XO) from aqueous solutions. The extraction process was facilitated by the cationic surfactant cetylpyridinium chloride (CPC), which formed reverse micelles in different organic solvents – toluene, m -xylene, hexane and cyclohexane – allowing selective encapsulation and separation of the dye by gravitational settling. Among the solvents tested, toluene exhibited the highest dye removal efficiency, demonstrating its superior ability to stabilise reverse micelles. Kinetic analysis revealed that the extraction process followed pseudo-first order kinetics with a rate constant of 0.016 min −1 and a half-life of 43.3 min. In addition, increasing the pH of the solution from 7 to 12 significantly improved the extraction efficiency, which was attributed to the increased anionic character of the dye, which improved its interaction with the cationic surfactant. This study highlights the potential of reverse micellar extraction as a highly efficient, cost-effective and environmentally friendly alternative to conventional dye removal techniques. The method not only ensures high extraction efficiency with minimal sludge production, but also offers a promising strategy for industrial wastewater treatment.

The contemporary foam oil drive technology is impeded by two critical issues: the instability of the foaming agent and the corrosive impact of airborne O 2 on injection and production pipelines. These challenges significantly impact the safe and efficient operation of oil fields. Given the unique molecular structure of surfactants, this study proposes an innovative integrated formulation that combines air-foam oil displacement with a corrosion inhibitor to effectively address these limitations. The results show that the integrated air-foam oil displacer-corrosion inhibitor all-in-one formulation SSTN (0.8 % BS-12 + 0.6 % AES + 0.07 % CTAB + 500 mg L −1 N 2 H 4 –H 2 O) exhibits exceptional foaming efficiency and salt resistance. When interacting with simulated condensate, the SSTN foam shows remarkable stability, with the ability to tolerate condensate concentrations in excess of 10 %. In addition, the SSTN solution exhibits superior corrosion inhibition efficacy, as confirmed by both static pendant drop and electrochemical methods, confirming the multi-functionality of this integrated agent. At lower concentrations, SSTN can effectively reduce surface tension, achieving an oil displacement efficiency of 25.37 % in core simulation experiments. The development of this integrated air-foam oil displacement-corrosion inhibitor provides a valuable reference for related fields and has significant potential for application in enhancing oil recovery in oilfields.