Volume 59, Issue 4

Chitosan and its modifiers have been widely studied for their good biocompatibility and excellent adsorption properties for heavy metal ions. The synthesis and application of modified chitosan, the effects of process variables (such as pH, amount of adsorbent, temperature, contact time, etc.), adsorption kinetics, thermodynamics and the adsorption mechanism on the removal of heavy metal ions are reviewed. The purpose is to provide the latest information about chitosan as adsorbent and to promote the synthesis of modified chitosan and its application in the removal of heavy metals.

The surface activity of dicationic ionic liquids is described in this paper. The basic interfacial parameters including critical micelle concentration (CMC), surface tension at the CMC ( γ CMC ), the adsorption efficiency (pC 20 ), surface excess (Γ max ), the minimum surface occupied by a single molecule ( A min ), and Gibbs energy (Δ G 0 ads ) were investigated and compared. Basically, we wanted to extend our previous study on dicationic ionic liquids with bis-ammonium cation. Knowing that, the compounds obtained are effective in limiting the feeding of adult and larvae confused flour beetle ( T. confusum ), it was decided to correlate the deterrent activity with the surface properties of analyzed dicationic ionic liquids. Accordingly, it was found that the deterrent activity of the studied compounds increases with increasing wetting ability.

In the present study, the interaction behaviour of 12–2–12 Gemini surfactant in aqueous saccharide solutions (lactose and maltodextrin solutions) is investigated using density, sound velocity and viscosity measurements. The density and sound velocity data were used to determine the volume and compressibility parameters. The effects of temperature and concentration/strength of the solutions on the interaction behaviour were analysed by conductivity studies over a wide temperature (293.15–313.15) K and concentration range of the saccharides as well as of the surfactant. It was found that predominantly hydrophobic interactions together with ionic/hydrophilic interactions between 12–2–12 Gemini surfactant and the saccharides maltodextrin and lactose play a role. In addition, the structural changes in the 12–2–12 Gemini solutions induced by lactose and maltodextrin were investigated by viscosity measurements. The results confirm the observations from the volume and compressibility studies. The study of the different hydrophobic/hydrophilic interactions in the Gemini surfactant-sacharide-water mixtures are very helpful to understand the structural behaviour of Gemini surfactants in the view of their biological significance.

In this study we used glutamic acid as a linking group and glucose, propylene glycol, and fatty alcohols as raw materials to prepare glutamic acid-glucose Gemini surfactants. Fourier transform infrared spectroscopy was used to verify the structures of the surfactants. We investigated their surface properties (surface tension, contact angles), and their effect on the fluorescence of pyrene. To test their potential application, we prepared emulsions with the surfactants and olive oil, and evaluated the emulsion stability with a particle size analyzer. We also investigated the ability to dye polyester fabrics in the presence of the glutamic acid-glucose-gemini surfactants. Among our synthesized materials, those with shorter alkyl chains exhibited better surface activities and emulsification properties, resulting in excellent dye uptake and leveling.

In this study, the influence of polyols, emulsifiers and oils on the formation and stability of polyol-in-oil (P/O) emulsions was investigated. The interfacial tension in P/O systems is much lower than that of water-oil systems, so polyols and oils showed a greater affinity, which was not conducive to the stability of the emulsion system. High compatibility of the emulsifier and the inner and outer phases was the key to the formation of stable emulsions. Using polyethylene glycol 400 (PEG) as polyol phase, mineral oil or squalane as oil phase and cetyl PEG/PPG-10/1 dimethicone (EM 90) as emulsifier, long-term stable P/O emulsions with homogeneous droplets were successfully prepared.

Due to climate change and declining water resources, some farmers are turning to wastewater. One of water pollutants is household detergent. To examine this, a study was conducted to determine the effect of water contaminated with hand washing liquid on the germination characteristics of wheat, flax, and lentil in a completely randomized design with three replications in 2020. Experimental treatments included water contaminated with different concentrations of hand washing liquid ((0, 0.01, 0.1, 1, and 10)%) of hand washing liquid in water). The results showed that with increasing concentration of the contaminant in the water, the germination percentage, the caulicle length, and the radicle length of wheat, flax and lentil decreased. It was observed that wheat had a higher resistance to hand washing liquid than lentil and flax so that at a concentration of 0.01% and 0.1%, the wheat radicle was still growing. It is recommended to avoid irrigating plants with contaminated water with high amounts of hand washing liquid.

Saponin was extracted from the Anabasis setifera plant and used to stabilize an oil-in-water (O/W) emulsion based on date palm kernel oil. Different amounts of the extracted saponin were used with a constant oil concentration (1.5% w/w). The droplet size distribution, emulsion droplet size value ( d -ave), polydispersity index (PDI) and zeta potential of the emulsions were determined using dynamic light scattering (DLS). These parameters were measured and compared after seven days of emulsion preparation. The best results ( d -ave = 41.7 nm, PDI = 0.1 and zeta potential = −29.8 mV) were obtained for the CMC of saponin. Both the oil and the surfactant were specifically extracted and used from the nature of Saravan in the Baluchestan region of Iran. This research presents a green and cost-effective aspect for potential formulations of nano-emulsions that can be used in the food and cosmetic industries.

Low-molecular flow improvers for crude oil are becoming increasingly important chemical agents for crude oil production in oil fields. In this work, three alkyl benzene sulfonates were synthesized and evaluated as flow improvers for crude oil. The results show that the three flow improvers have an effect on L8401 crude oil (heavy oil). Among them, aluminium dodecylbenzene sulfonate (AlDBS) has the best effect as it reduces the viscosity rate by more than 80%. After adding 900 mg/L AlDBS, the freezing point is lowered by 15 °C. The crude oil flow improvement was proven with microphotographs. The co-crystallization behavior after addition of the agent interacts with the saturated hydrocarbons in the crude oil, which is the reason for lowering the freezing point of crude oil. Moreover, infrared spectroscopy and differential scanning calorimetry analysis (DSC) were used to illustrate the interaction mechanism between low-molecular flow improvers for crude oil and the components in crude oil.