Volume 59, Issue 6

We developed a new, innovative foam-based cleaning method with which the amount of detergent can be reduced by up to 90%. In addition, foams generate physical cleaning mechanisms, namely imbibition and wiping. The combination of imbibition and wiping is so efficient that it is sufficient to simply let the foam sit on the surface for a while before removing it by vacuuming. No additional mechanical action is needed! This publication describes how we managed to clean the historic carriages of kings and emperors of past centuries in the “Marstallmuseum” in Nymphenburg Palace in cooperation with the “Bavarian Administration of State-Owned Palaces, Gardens and Lakes”.

Dow Home and Personal Care has developed a protocol using a custom imaging station and software suite to standardize data collection and automated analysis in automatic dishwashing. Previously, a panel rating based on ASTM D3556-14 was used to provide a score for filming and spotting on glassware. Progress has been made toward a standardized and semi-automated method utilizing a combination of a custom imaging station built in house, image analysis techniques, and a statistical model. The statistical model was built using a series of panel ratings from an array of glasses, giving computed ratings which agree closely with experimental scores assigned by human raters.

A thermodynamic approach was developed to predict the precipitation conditions of surfactants using the solubility product relationship between surfactant monomer concentrations, in order to calculate the monomer-precipitate equilibrium. This approach provides an explicit equation which predicts the amount of solid phase which forms in any surfactant mixture. All calculations of the total change in Gibbs energy (Δ G ) were performed for concentrations of both surfactants that were below their CMC values. The elaborated Δ G -pH diagrams offer the possibility to determine the areas of thermodynamic stability of the solid phases depending on the chemical composition and acidity of the studied system. It was shown that with increasing concentration of the surfactant and the metal ion, the range of precipitate formation, either as slightly soluble salt or as slightly soluble acid, was extended by a few pH units in all cases.

The environmentally friendly surfactant ethoxylated cardanol (EC) was investigated for dispersing copper phthalocyanine (CuPc) pigment nanoparticles into aqueous solution. The stability of the dispersion was investigated using UV-Vis spectra. The particle size was measured by optical microscopy, transmission electron microscopy and dynamic light scattering. The surface of the nanoparticles was characterised by measurements of the zeta potential and wettability. The coating application was investigated by incorporating CuPc blue pigment into resin and inorganic filler, and the colour strength of the coating film was compared. The results show that the EC can effectively wet and disperse the CuPc particles. The stabilisation of the particles is achieved by a steric mechanism in which the hydrophobic chains of the surfactant are adsorbed onto the surfaces of the CuPc nanoparticles and the ethylene oxide chains are dispersed in the aqueous phase. At EC concentrations greater than 0.1%, the CuPc nanoparticles appear to deagglomerate. The colour strength of CuPc nanoparticles present as dispersed pigment in resin can be increased in the presence of the EC surfactant.

In this work, sodium N-lauroyl glutamate (SLG) was mixed with cationic cellulose JR30 M. The rapidly occurring change in surface tension and the mass action law of the mixed (compound) system were investigated using dynamic and equilibrium surface tension methods. The behaviour of the system during phase separation was investigated by turbidimetry. The results showed that in the presence of JR30 M, the surface tension of SLG was reduced to a lower level in the given time interval due to the strong interaction compared to that of a solution with the same concentration of SLG but without JR30 M. The largest decrease was obtained with a JR30 M concentration of 0.2 g L −1 , which reduced the equilibrium surface tension of SLG from 38.4 mN m −1 to 31.7 mN m −1 . The rate of decrease in surface tension increased from 37.61 mN m −1  s −1 to 74.7 mN m −1  s −1 . An association complex formed between SLG and JR30 M, and the equilibrium surface tension curve showed a double platform. As the concentration of JR30 M increased, the first platform broadened and the CMC value increased. The phase separation behaviour of the compound system disappeared with the increase of SLG concentration, and the area became narrower with the decrease of JR30 M concentration.

Due to the amphiphilic structure of surfactants, aqueous surfactant solutions can behave like very good solvents and dissolve both polar and non-polar solutes. This study reports on the solubilisation of a direct dye (Direct Blue 86) in a micellar medium using the cationic surfactant cetyltrimethylammonium bromide (CTAB). Solubilisation of dyes is important for their subsequent removal from aqueous media. UV spectroscopy and conductometry, among others, were used to quantitatively evaluate this process. The extent of solubilisation, the interaction between the molecules and the stability of the processes were checked using the partition coefficient ( K x ), the binding constant ( K b ) and the corresponding thermodynamic parameters. From the results, it could be concluded that the solubilisation of Direct Blue 86 is a spontaneous process supported by an increase in entropy. It was also found that the micellar medium CTAB is efficient for solubilisation and binding of the dye and can be used economically.

In this study, three oligomeric cationic Gemini surfactants (Ⅲ 1 , Ⅲ 2 , and Ⅲ 3 ) were prepared from different major raw materials, including long-chain alkyl amine (dodecyl amine, tetradecyl amine or cetyl amine), formic acid, formaldehyde, diethyl amine hydrochloride and epichlorohydrin. The synthesis conditions for one of the three surfactants, bis-[2-hydroxy-3-(N,N-dimethyl-N-dodecyl)propyl]dipropylammonium chloride (Ⅲ 1 ), were optimised by orthogonal experiments. The optimum synthesis conditions were: molar ratio of intermediate Ⅱ to intermediate Ⅰ 1  = 1.0:2.2, reaction temperature = 85 °C and reaction time = 16 h. The structures of the three prepared compounds were characterised by FTIR and 1 H NMR. Their thermal properties were evaluated by thermal gravimetric analysis (TGA). The Geminisurfactants prepared exhibited better surface active properties than conventional single chain cationic surfactants. With increasing carbon chain length from C 12 to C 16 , both CMC and surface tension γ CMC decreased, while the viscosity of the thickening solution prepared with the synthesised oligomeric cationic Gemini surfactants as the main component increased. The optimum thickening formula was: 2.0 wt% Ⅲ 3  + 0.8 wt% sodium salicylate (NaSal) + 0.6 wt% KCl. The viscosity of the optimum thickening formulation was 190.4 mPa s. Gemini oligomeric cationic surfactants could be used as thickeners in the production of fracturing fluids, flooding agents and drilling fluids for oil and gas production in oil fields.

Bacillus subtilis was used as a bio-surface modifier to improve the floatability of talc mineral (Mg 3 Si 4 O 10 (OH) 2 ) in the talc ore. The surface behavior of chlorite mineral as the main associated gangue with talc mineral was studied in the presence of B. subtilis using zeta potential, scanning electron microscopy, and Fourier-transform infrared spectroscopy techniques. The floatability of both minerals was investigated as a function of pH, contact time, and concentration of B. subtilis . The results showed that the zeta potential of the talc mineral was strongly influenced by the treatment with B. subtilis . The maximum separation efficiency of talc from chlorite was achieved at pH 4. A talc concentrate with 98% quality and about 95% recovery was prepared from a binary talc-chlorite mixture containing 85% talc under optimum conditions of 8 × 10 5  cells/mL B. subtilis , pH 4, 35°C, and a contact time of 10 min.