Volume 56, Issue 6

Automatic dishwashing is a process which takes enormous amounts of resources (energy, water, chemicals). However, most of the dishwashing programs are designed and tested to clean the worst scenario for a certain kind of load items (glass, porcelain, etc.) and do not or only partly adapt to the actual load and soiling conditions. Thus, resources are wasted which could be avoided if a better adaptation to the actual status of the dishwashing process would be possible. It is, therefore, the aim of this study to investigate the possibility of using near-infrared technology to evaluate the status of the dishwashing process by analyzing the content of soil components already dissolved in the dishwashing water. Compared to other methods, the main advantage of near-infrared measurements is the possibility to differentiate between soils or soil components (carbohydrates, fats and protein) at very low concentrations. Near-infrared spectroscopy implemented in an automatic dishwasher could observe and evaluate an automatic dishwashing processes by using online measurements of the detachment of soils from soiled dishes. Thirty-seven model emulsions containing detergent, tap water, different soils and soil concentrations were created and measured by using near-infrared spectroscopy to demonstrate its suitability for the evaluation of dishwashing processes. The spectra were the basis of developing near-infrared calibration models for each soil component using the partial least squares regression method with internal cross-validation. The coefficients of determination in internal cross-validation (R²) are 0.88 for carbohydrates, 0.92 for fats and 0.99 for proteins. Thereafter, the calibration models developed were externally validated with samples of known concentrations of these soil components. The known concentrations were determined during external validation. The results of calibration and evaluation show that it is generally possible to measure very low concentrations of soil components in dishwashing liquor. The applicability to a real dishwashing process and the usage of other soils has yet to be tested.

The aim of this questionnaire survey study is to find out if the three socio-demographic aspects gender, age and household size have any influence on washing-up behaviour and whether people's washing-up behaviour changes due to them. The data was collected via a questionnaire created and carried out by “Forum Waschen” that could be answered by German consumers either on the internet or on the day of sustainable washing created by “Forum Waschen”. In addition to the socio-demographic facts, the questionnaire involved questions about both manual and automatic dishwashing. The results of this study vary; some aspects of washing-up behaviour are correlated and some are not. Only some aspects are dependent on gender, more the manual dishwashing behaviour than the automatic. By contrast, most aspects depend on or correlate with the participant's age. The biggest difference between households of different size are the quantities of dishes used and need to be washed per day. Besides the connections to socio-demographic aspects, there are also connections between different aspects of dishwashing behaviour itself, such as the positive correlation between the frequency of changing the tea-towel and its usage.

The equilibrium surface properties and dynamic surface tension (DST) are presented for aqueous solutions of novel eco-friendly cationic saccharide surfactants (C n DGPB) at different concentrations and temperatures. The equilibrium surface tension, the DST, the effective diffusion coefficients and the activation barrier of the surfactants are calculated and analyzed. In addition, the general diffusion mechanism of the surfactants is proposed. The equilibrium surface tension results show that the γ CMC and CMC values decrease with increasing temperature. The interactions (repulsion forces) between the hydrophobic groups and water molecules decrease with increasing temperature, which results in increased HLB values. This phenomenon causes a higher A min and lower Γ max . The DST of C n DGPB below and above the CMC is tested by the maximum bubble pressure method at temperature from 25 °C to 45 °C. The adsorption activation energy of C n DGPB is between 3 kJ/mol and 20 kJ/mol. The results show that the final stages of the DST decays are consistent with the activated diffusion-controlled adsorption mechanism.

It has been well-known that the addition of electrolytes causes the ionic surfactant solution to have a lower surface tension by stimulating the surface adsorption. When the surface concentration of an ionic surfactant remains constant, the solution with supporting electrolyte in the bulk displays a lower surface tension than a solution without electrolyte. From the surface perspective we investigate the dependence of the surface tension of a solution upon the surface concentration of ionic surfactant and the influences of the supporting electrolyte therein, by means of thermodynamics and molecular dynamics simulation. The derived thermodynamic formula and simulation results predict, that at a given surface concentration the supporting electrolyte can change the orientation of the ionic surfactant, which results in a lower surface tension. The conclusions can be useful for the investigation to the surface structure of ionic surfactant solutions and the effects of supporting electrolyte.

Micellar solubilization and physicochemical behaviour of [Ni(phen) 3 ]F 2 EtOH · MeOH · 8 H 2 O complex in sodium 2-ethylhexyl sulfate and sodium bis(2-ethyl hexyl) sulfosuccinate is addressed in this paper. The interactions of surfactants in the solution of nickel complex were studied by UV-Vis spectroscopy and electrical conductivity. The extent of solubilization in terms of partitioning and binding parameters was determined by UV-Vis spectroscopy, whereas conductivity data were employed to calculate critical micellar concentration and other thermodynamic parameters of micellization. The value of critical micellar concentration increased in both surfactants due to structure breaking effect of nickel complex. The complex showed significant antioxidant radical scavenging and hemolytic activities, without any substantial cytotoxic activity against 3T3 cell line.

A new type of catanionic surfactant phosphonium benzene sulfonate was synthesized by quaternization of triphenyl phosphine with dimethyl carbonate and followed by anion exchange with alkyl benzene sulfonic acid. The molecular structure was characterized by FT-IR, 1 H-NMR, and 31 P-NMR. The thermal stability of phosphonium benzene sulfonate was evaluated by thermogravimetric analysis (TGA). Its surface properties were studied systematically through equilibrium surface tension, electrical conductivity, and dynamic surface tension measurements. The wettability, foam properties, and emulsification of phosphonium benzene sulfonate were estimated in this paper. TGA results revealed that it has an excellent thermostability and could be used below 350 °C. Equilibrium surface tension results indicated that it has a low critical micelle concentration (CMC, about 0.10 mmol/L), lower than that of ammonium benzene sulfonate and sodium dodecyl benzene sulfonate. Furthermore, the micellization of phosphonium benzene sulfonate in aqueous solution is an entropy-driven spontaneous process. The adsorption process of phosphonium benzenesulfonate at the air-liquid interface is controlled by hybrid kinetic adsorption. Moreover, it has excellent wetting and emulsifying properties and low foam properties.

A simple, fast and interference free spectrofluorimetric method was developed for the quantification of ciprofloxacin in its pure form, pharmaceutical preparations and in human plasma. The method is based on the enhancement of the weak fluorescence signal of drugs by the addition of sodium dodecyl sulphate (SDS) surfactant micelles in citrate buffer at pH 5.5. Different experimental parameters like buffers, surfactant type and concentration were investigated. The fluorescence intensity of ciprofloxacin was measured at 446 nm (emission) and at 328 nm (excitation). A linear relationship between concentration of ciprofloxacin and fluorescence intensity was found in the range of 0.04 μg/mL–6.0 μg/mL with a correlation coefficient of 0.9946. The limit of detection (LOD) and limit of quantification (LOQ) were calculated and found to be 3.87 × 10 −5 and 1.29 × 10 −4  μg/mL respectively. The effect of common excipients and co-administered drugs were also investigated and the method was found free of interferences. The method was successfully applied for the determination of ciprofloxacin in pharmaceutical preparations and human plasma with percentage recoveries of 97.08 % to 99.32 % and 95.00 % to 101.25 % respectively.

The current requirement for science and research concerns the absolute sustainable development of a chemistry that is inherently safer, smarter and more environmentally friendly. The oxidation reaction is a very fundamental transformation reaction in organic synthesis and likely plays a significant role in the production of various value-added chemicals from biomass and others precursors. In the focus of making kinetic experiments greener several modified methodologies and safe chemicals have been employed. Surfactants are such suitable alternate that go with the requirments. Surfactant aggregates i. e. micelles are nano-sized supra molecules, able to act as catalysts. They can be used to catalyze the organic functional group transformation reactions mediated with transition metals and promoted with various aromatic bases. This allowed water to be used as a solvent, where the reactions became more sustainable. The recyclability of used surfactants, enhancement of reaction kinetics and speed of reaction with no consumption of energy has added more value to this type of catalytic oxidation. This article aims to contribute to the discussion of the mechanistic aspects of various types of surfactant-catalyzed oxidation of organic functional groups.

The amino acid surfactants were synthesized by using natural fatty acid esters (FAE) as raw materials, but FAE with a high iodine value has thermal and oxidative instabilities in chemical reactions. The oxidation of FAE by peroxyacetic acid generated was studied under various conditions, then the oxidized FAE and different amino acids (glycine, glutamic acid and aspartic acid) were used to form sodium N-acyl amino acids in glycerol. By the surface tension method, the relationship between temperature and critical micelle concentration (CMC) has been researched. The CMC value, the surface tension at the CMC (γ CMC ), and the maximum surface excess concentration Γ max were calculated, respectively. For different amino acids surfactants, the surface tension of the solution was greatly reduced at the low CMC value, and the γ CMC constantly decreases with rising temperature.

Magnetic carbon nanocomposite (MCNC) was prepared from peanut shells and then characterized by FTIR, SEM, TGA/DTA and BET surface area. The removal of cetyltrimethyl ammonium bromide (CTAB) surfactant from aqueous solution was carried out by MCNC and membrane. The effect of contact time, initial concentration of CTAB and the temperature on the adsorption of CTAB was also investigated. Initially, the adsorption of CTAB on MCNC was rapid up to 20 min and then gradually slowed down. Different kinetic models i. e. 2 nd pseudo order kinetics, power function and intraparticle diffusion were applied to determine different kinetic parameters. Intraparticle diffusion model showed that the adsorption of CTAB is a diffusion controlled process. Thermodynamic parameters i. e. ΔH° (–33.74 kJ/mol), ΔS° (0.98 J/mol K) and ΔG° (–62.91 kJ/mol, −64.37 kJ/mol and −66.33 kJ/mol) were calculated and the process was found to be exothermic and spontaneous in nature. The prepared adsorbent (MCNC) was used for controlling fouling of ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) membranes caused by CTAB. Improved permeate fluxes and percent retention of CTAB were observed for MCNC crossbreed membrane. About 100 % retention with no effect on permeate flux was observed with RO membrane when MCNC pretreatment was applied.