Volume 60, Issue 1

Characterization of the behaviour of commercially available non-ionic surfactants has received considerable attention due to their efficacy in a variety of applications. The main challenge in the application of these types of surfactants is that the hydrophilicity of the surfactant varies with concentration and dilution due to the polydispersity of the ethylene oxide groups. The hydrophilicity of a surfactant can be quantified by the characteristic curvature (Cc) parameter of the hydrophilic–lipophilic difference (HLD) framework. In this work, a model based on natural logarithmic regression was developed to calculate the Cc value of commercial surfactants as a function of surfactant concentration by a fast and simple phase scan. The slope of the Cc curve and the measured Cc at a reference concentration were used to develop the model. The Cc values determined with the model agreed with the measured values from the phase scans. Furthermore, the linear mixing rule proved to be reliable for mixtures of polydisperse ethoxylated surfactants. Finally, the impact of the water-to-oil ratio on the Cc was evaluated and the implications were discussed.

Experimental measurements of the viscosity, density, and ultrasonic parameters of monoethanolamine (MEA) with 1-butanol, 1-pentanol, and 1-hexanol were carried out at 298.15 K. The excess molar volume ( V E ), viscosity change (Δ η ), and isentropic compressibility (Δ K s ) are calculated using the viscosity, density, and ultrasonic velocity data. A polynomial equation of the Redlich-Kister type was used to fit these values. With increasing mole fraction, the viscosity, the density and the ultrasonic velocity increase. As the concentration of MEA rises, the excess molar volume falls. All V E values for MEA and 1-hexanol are positive, meaning that V E increases. At all concentrations, isentropic compressibility and viscosity change exhibit negative values.

In this paper, the effect of N ε -lauroyl lysine (LL) on stabilizing W/O Pickering emulsions was investigated, and the effect of crystallization temperature on the particle size of LL was explored. The Pickering emulsion was prepared with LL as particle emulsifier, and the effects of homogenization rate, emulsification temperature, particle concentration, oil-water volume ratio and other factors on the preparation of emulsion were discussed. The results showed that the LL particles were the smallest for a crystallization temperature of 30 °C with a size of (1.3 ± 0.2) µm. The oil-water-LL contact angle was 142.9° ± 1.6°, and the prepared emulsion was of W/O type. The most stable emulsions were obtained under the following conditions: homogenization rate = 11,000 r min −1 , emulsification temperature = 20 °C, particle concentration = 2 wt%, oil-water volume ratio = 1:1. In addition, LL showed good tolerance to the aqueous phases with different pH values. The LL-stabilized emulsion system proved to be stable over the long term in the stand tests.

The foam drainage technique for gas production has the disadvantage of requiring a large amount of surfactant and having low resistance to salt and oil. In this study, a new surfactant mixture (composite surfactant) of lauramidopropyl betaine (LAB-35), α-olefin sulfonate (AOST), sodium alkyl sulfonate (SASE) and cetyltrimethylammonium bromide (CTAB) was tested and its foaming properties were investigated in detail. The foaming properties were determined using high-speed measurements and the Ross-Miles method. The results show that the foaming volume of the composite surfactant can reach 563 mL, indicating that the foaming behaviour of the composite surfactant is more effective than that of the individual surfactants used for the mixture. In addition, the results show that the composite surfactant has a resistance to salt, methanol and condensate oil that most foam drainage agents do not have. However, the stability of the composite surfactant gradually decreases with increasing temperature and concentration. The surface tension was measured and the critical micelle concentration of the composite surfactant is 0.023 g/L.

Dandruff is a dermatological, harmless, non-inflammatory, chronic scalp condition caused by Malassezia species and recognisable by the white flakes of dead skin in the hair. Mannosylerythritol lipids (MEL) are non-ionic glycolipid surfactants (biosurfactants) with excellent surface-active properties. Their skin compatibility, biocompatibility, biodegradability and remarkable antimicrobial properties make them a potential alternative to conventional surfactants. In the current study, an anti-dandruff shampoo was formulated with different concentrations of sodium lauryl sulphate (SLS) and MEL as surfactants. Two anti-dandruff agents, salicylic acid and benzoic acid, were used. The other ingredients used were xanthan gum, sodium EDTA, urea, Tween 80 and distilled water. The various physicochemical parameters evaluated were colour, clarity, odour, texture, pH, skin irritation, percentage of solid content, dispersibility for dirt, foam formation and foam stability, critical micelle concentration, washability, surface tension, visual stability and antimicrobial test using recommended procedures. The pH ranged from 5.15 to 6.5, the physical appearance was golden yellow, the solids content ranged from 25.1% to 28%, surface tension ranged from 30.64 mN m −1 to 38.00 mN m −1 , CMC concentration ranged from 30.14 g/L to 30.16 g/L and foam value ranged from 190 mL to 105 mL. Antimicrobial activity was determined with Staphylococcus aureus (DSM 3463) and Malassezia furfur (ATCC14521). The zone of inhibition ranged from 10 mm to 17 mm ( S. aureus ) and 14.5 mm to 24 mm ( M. furfur ), respectively. The shampoo formulated with MEL only (formulation C) showed lower foaming and anti-dandruff activity than the synthetic shampoo (formulation A). However, the anti-dandruff activity increased when MEL was used in combination with SLS (formulation B). This shows that the antimicrobial properties of MEL and SLS together with other antimicrobial agents such as salicylic acid and benzoic acid enhance the properties of the shampoo. SLS can be completely replaced by a combination with biosurfactants to reduce the use of chemical surfactants and improve the anti-dandruff properties.

This paper presents the improvement of the hydrophilicity of nylon fabrics on different knit designs using the Hydrowick NA process with a combination of antimicrobial silver application and characterization of the treated fabrics by FTIR, SEM, XPS and antimicrobial activity tests using the AATCC 100 test method and moisture regain test. Antibacterial nylon fabrics have been developed by incorporating antibacterial agents into the structure of the fibres, for longer durability and effect, rather than just depositing them on the surface. Hydrophilic processes have an impact on the antimicrobial activity, resistance to repeated washing and moisture regain of the nylon fabrics. The nylon fabrics showed higher antimicrobial activity against Staphylococcus aureus after the hydrophilic finishing process. It can be seen that there is a correlation between a decrease in bacterial growth and an increase in the concentration of the hydrophilic agent. The results showed that the weft-knitted nylon using the Hydrowick NA process had higher moisture regain at the same surface weight per unit of textile. Analysis of variance with p  < 0.05 showed that the results were statistically significant. The 1 × 1 rib double jersey weft-knitted nylon fabrics showed the highest antimicrobial performance. It was also observed that the surface area of the fabric was also decisive for the antimicrobial activity.

Polyester fibers tend to generate and accumulate electrical charges under friction and induction. This significantly affects the production and use process and even poses the risk of electric shocks and fire. Quaternary ammonium salt surfactants with a positive charge can be adsorbed on negatively charged polyester fibers and have excellent antistatic properties. Therefore, we have synthesised a cationic antistatic surfactant functionalised with hydroxyl and ether groups: N-hexadecyl-N,N-dimethyl-N-butanoxy glycerol ether ammonium chloride (HDBGA). The structure was characterized by 1 H NMR, FTIR and ESI/MS. The excellent properties of HDBGA in aqueous solution were investigated by measuring the Krafft point (T K ), surface tension, conductivity, and steady-state fluorescence. Also antistatic tests were carried out. The results show that the T K of HDBGA is below 0 °C indicating that it can still be applied in cold water. The new quaternary ammonium compound could effectively decrease the surface tension of aqueous solution to 31.28 mN m −1 , where the critical micelle concentration (CMC) at 298.15 K was 3.83 × 10 −4  mol L −1 . In addition, the static electricity and static half-life values of the polyester cloths treated with the HDBGA solutions were also measured, as well as the effects on the fabric properties. The product exhibited excellent antistatic properties and satisfactory wash resistance, and the fabric fibers were not damaged.

In the stone industry, about 73% of the total production is generated as solid waste. In the processing phase, only 20% is produced as harmful ultra-fine sawdust sludge. In the Turah area, Cairo, Egypt, an estimated 448,000 tons are produced annually. About 60% of the total production of dimension stones is carbonate stones. The objective of this study is to properly dispose of the ultrafine pollutants and produce value-added products. The ultrafine marble waste was characterized by different methods such as XRD, XRF, FTIR, particle size analysis and zeta potential. Calcite and dolomite minerals were the main constituents of this waste (91%). The average particle size was 6.656 µm. The fine fraction with a particle size of less than 25 µm contains 97.6% calcite with 81% weight. Sodium N-lauroyl sarcosinate (SNLS) was used as a selective flotation collector for calcite as a calcium mineral. A flotation concentrate with a purity of 99.6% and an overall yield of 80% was obtained at a pH of 9. The bleached product meets ASTM standard specifications for paint and paper applications.

Saponins are natural surfactants that are readily biodegradable, generally non-toxic to humans and environmentally friendly. In this work, the surface properties, coffee ring effect and characterisation of the extract of Albizia procera pod were studied. It showed good washing power and good soil or dirt dispersion and cleaned effectively at low surface tension. The extract is equivalent to commercial detergents, making it a viable biosurfactant. In addition to the critical micelle concentration, there is a lower concentration at which the surface tension curves flatten out. We have named this concentration “Minor Critical Micelle Concentration”. The surfactant also reduces the coffee ring effect of a drying droplet and provides a reasonably uniform distribution of suspended particles. This effect can be used to estimate the critical micelle concentration. The Fourier transform infrared spectrum of the extract shows the presence of the functional groups –OH, C–H, C=C and C–O–C, which are also found in saponins.