Volume 58, Issue 2

Questions and potential misperceptions have arisen about the potential contribution of liquid detergent capsules to the environmental microplastics issue. The film of these detergents is highly water soluble, also in cold water, as it must fully dissolve during every type of washing process. Water-soluble grades of polyvinyl alcohol, the most commonly used detergent capsule film material, are recognised to be biodegradable. In the current paper, adequate biodegradability is confirmed by means of ready biodegradation screening tests, across a range of polyvinyl alcohol detergent grade films. The high water solubility in itself implies that detergent capsule films are not within the microplastic scope. Furthermore, their biodegradability ensures there is no concern for persistence or accumulation in the environment.

This study investigates the effect of washing fabrics (nylon 6.6 powernet knitted fabrics with 30% spandex) treated with chitosan on their moisture management and air permeability. The knitted fabrics were treated with three different solutions of chitosan and dimethylol dihydroxyethylene urea (DMDHEU); in addition to chitosan and DMDHEU, one solution contained the complexing agent ethylenediaminetetraacetic acid (EDTA) and the other contained the nonionic surfactant and penetration agent octylphenol ethoxylate. The three solutions were compared in terms of their effect on moisture management and air permeability properties. Nylon fabrics treated and washed with these solutions were characterized by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Nylon fabrics treated with chitosan and DMDHEU showed the potential to transfer liquid moisture to the lower layer and keep the layer next to the skin dry after 20 washes.

Three formulations for bath liquids were developed, differing in the type of amphoteric surfactant applied. The formulations used Cocamidopropyl Betaine, Cocamidpropyl Hydroxide and newly synthesized sulfobetaine based on sweet almond oil (Oleicamidopropyl Sultaine). The molecular structure of the surfactant used in the manufactured formulations has a negatively charged sulfonate group and a positively charged quaternary nitrogen atom. Such molecular structures suggest that the functional properties of this substance are mild. Based on the research, it was found that the bath fluid containing the newly synthesized sulfobetaine based on sweet almond oil had the lowest zein number, the lowest pH increase of bovine albumin solution and the lowest ability to emulsify fatty dirt. This indicates a very low irritant effect of the tested bath liquid.

To prepare lyophobic magnetic nanoparticles (LMNs) with core/shell structure to be applied in silicone emulsion defoamer, magnetic nanoparticles covered with silica (MNS) were prepared in a one-step process from FeCl 3 · 6H 2 O, FeCl 2 · 4H 2 O and tetraethyl orthosilicate and then modified with poly (methylhydrosiloxane). X-ray powder diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscope (FTIR), thermogravimetric analysis (TGA), and contact angle tests were performed to characterize the nano-particles, and the droplets of the defoamer emulsion were observed with a microscope. The foam breaking and foam inhibition properties of the defoamer and the magnetic separation of the particles were observed and recorded by a camera. It was found that the silicone emulsion defoamer exhibited good foam breaking and foam inhibition properties for foaming systems with anionic, cationic and non-ionic surfactants, respectively. The solid particles in the defoamer could be easily separated from the defoamed systems by a magnet.

Invasion of fluids into porous media during drilling can lead to irreparable damage and reduced well productivity. Hence, minimizing the filtration loss of the drilling fluid into the formation is very important. The stability of colloidal suspensions plays a crucial role in controlling the interfacial forces and consequently on minimizing the filtration. The zeta potential is an indicator of the stability of colloids with respect to their electrostatic interactions. In this study, the rheological properties of bentonite suspensions are investigated with and without additives. The starch and CMC were used as additives to enhance the rheological properties of bentonite. The effects of these additives on the drilling fluid filtration were examined. Zeta-potential, viscosity, gel strength and yield point were measured to characterize the extent to which control of the filtration loss of the drilling fluids can be achieved. The zeta-potential and the amount of filtration loss of water-bentonite suspensions were correlated. Finally, the results showed that the addition of either starch or carboxymethyl cellulose (CMC) enhances the filtration properties of water-bentonite suspensions.

Novel surfactants with double hydrophilic groups (cocopropane and tallowpropane bis-guanidinium acetates), were synthesized and tested to evaluate both the basic surfactant properties and the unique application performance. Surface tension, conductivity and contact angle measurements were used to study the self-aggregation behavior in aqueous solution. Aggregation parameters were calculated such as adsorption efficiency and effectiveness (pC 20 and CAC/C 20 ), the maximum surface excess concentration (Г max ) and minimum surface area permolecule (A min ). The thermodynamic parameters of aggregation based conductivity measurements revealed that the aggregation process was spontaneous and entropy-driven. Compared to DTAC and CTAC, the alkyl bis-guanidinium acetates showed a higher emulsification capacity with both liquid kerosene and soybean oil. The evaluation of antimicrobial activity showed that the alkyl bisguanidinium acetates exhibited strong antibacterial activity against the tested strains at a concentration of 50 ppm.

Perfluorooctane sulfonate (PFOS) and its derivatives had been banned due to their potential environmental hazards, although they possessed excellent surface activity. An effective method to solve this problem was to shorten the fluorocarbon chain of these surfactants from C ° H 17 to C 4 F 9 . As previous studies had shown, zwitterionic surfactants possess higher surface activity but have lower toxicity compared to other types of surfactants. In view of this, a class of novel zwitterionic fluorocarbon surfactants (n-CFNA-Br) with perfluorobutyl moiety was synthesized in this work. Their structures were characterized by FTIR, 1 H NMR, 13 C NMR, 19 F NMR and MS. The results showed that all synthesized n-CFNA-Br had almost the same minimum surface tension, but their critical micelle concentration (CMC) decreased with increasing length of hydrophobic carbon chain. In pure water, the surface tension at the CMC (γ CMC ) of the four n-CFNA-Br were about 20 mN/m, and the CMC values were 7.73 mmol/L for 1-CFNA-Br, 4.70 mmol/L for 2-CFNA-Br, 4.13 mmol/L for 3-CFNA-Br, and 3.36 mmol/L for 4-CFNA-Br, indicating high efficiency and effectiveness. In 0.1 mol/L NaCl, the CMC values reduced to less than half of the CMC values measured in the pure aqueous surfactant solution, while the surface tensions γ CMC remained almost unchanged, indicating good salinity tolerance of the synthesized surfactants. The acidic surfactant solutions exhibited similar CMC values to the saline solutions, but the surface tension γ CMC increased slightly to 25 mN/m. However, further investigation showed that the n-CFNA-Br surfactants exhibited poor surface activity in alkaline solution (0.1 mol/L NaOH). In the pH range of 6.6 to 10.4, white precipitates appeared in the surfactant solutions after some time, indicating that the n-CFNA-Br are not suitable for use in alkaline systems with pH greater than 6.6.

Amphiphilic molecules reduce the surface tension of the aqueous medium and are widely used in industrial and domestic applications due to this property. Nowadays, amphiphilic molecules on a natural basis are in great demand to replace synthetic surfactants and thus contribute to the reduction of environmental problems. Approximately 60% of the material based on surfactants end up in seawater, which is dangerous for aquatic life. We are proposing a new type of material, which is a surfactant on a natural basis, biodegradable and an environmentally friendly alternative. Here we focus on tea saponin and study its properties such as surface tension, foaming, skin mildness, cleanability. Tea is naturally acidic, reduces the surface tension to 31.4 mN/m, has a greater foaming power, is ultra-mild to skin, and has excellent cleaning properties. The results show that tea has excellent surface activity, which is why tea can be used as a green substitute for synthetic surfactants.

In this paper, hydroxymethyl cetyltrimethyl ammonium chloride (HM-CTAC) was prepared from cetyltrimethyl ammonium chloride (CTAC) and formaldehyde with different molar ratios (1:1 to 1: 4). The effects of reaction conditions (molar ratio) on surface properties were studied, including surface tension, foaming ability, high temperature resistance, methanol resistance and salt resistance. The results show that the minimum surface tension of HM-CTAC is lower than that of CTAC, and HM-CTAC (1:1) has the lowest surface tension of 31.89 mN · m –1 . The foam volume of HM-CTAC with different molar ratios is higher than that of CTAC, and HM-CTAC (1:4) has a high foam volume of 435 mL. Compared to CTAC, the HM-CTAC under different reaction conditions has higher temperature resistance. At the methanol content of 10 wt.%, the initial foam volume of HM-CTAC is higher than that of CTAC, and the initial foam volume of HM-CTAC (1:2) is the highest with a volume of 21.5 mL. Among all the surfactants prepared under different reaction conditions, HM-CTAC (1:3) has the highest salt resistance with a relatively stable change in foam volume under different salt contents.