Effects of Fe (II) on stability of aqueous foam prepared by hydrolyzed rice protein in the presence of oil

Unveiling the organic nature of phosphogypsum foam: Insights into formation dynamics, pollution load, and contribution to marine pollution in the Southern Mediterranean Sea

The foamability of dissolved phosphogypsum from the phosphate fertilizer factories of Gabes (SE Tunisia) is a spectacular phenomenon that has not yet been thoroughly studied. The main objective of this research was to investigate the organic properties of phosphogypsum foam (PGF) to understand its formation process, determine the origin of its enhanced radiochemical contaminants load, and identify its role in pollutants dispersion in marine environment of the Southern Mediterranean Sea. This study identified PGF as an unnatural, surfactant-stabilized, and ephemeral aqueous foam. PGF-forming process comprises three main steps: (i) formation (through phosphogypsum dissolution), (ii) stabilization (facilitated by organic surfactants and gypsum crystals), and (iii) destabilization (geochemical (involving the dissolution of the PGF skeleton gypsum) and/or mechanical (influenced by wind and wave action)). The amphiphilic nature of PGF organic matter and the presence of specific organic groups are responsible for its high toxic contaminants load. PGF contributes, through its elevated pollutants content and its ability to migrate far from its source, to the marine dispersion of industrial toxic radiochemical contaminants. It is therefore recommended to mitigate the environmental and health risks associated with PGF, including banning the discharge of untreated phosphogypsum and other industrial wastes into the coastal environment of Gabes.

Comparative Study on Interfacial Properties, Foam Stability, and Firefighting Performance of C6 Fluorocarbon Surfactants with Different Hydrophilic Groups

Liquid fuel is flammable and hazardous, and a pool fire is one of the most serious disasters. Therefore, it is important to develop high-performance firefighting agents. To synthesize aqueous film-forming foam (AFFF) formulations, two C6 short-chain fluorocarbon surfactants Capstone 1157 (FC1157) and sodium perfluorohexylethyl sulfonate (SF852) with different hydrophilic groups were introduced, and three hydrocarbon surfactants sodium dodecyl sulfate (SDS), decyl glucoside (APG0810), and coco glucoside (APG0814) were chosen. The AFFF formulations based on the short-chain fluorocarbon-hydrocarbon compounding system were developed, and the firefighting performance of the formulations was assessed according to the standard pool fire extinction test. The results indicated that amphoteric FC1157 was slightly more effective than anionic SF852 in extinguishing small-scale pool fires and could reduce heat flux more effectively than SF852. Fluorocarbon surfactant FC1157 has been shown to suppress large pool fires much better than SF852, possibly due to its higher foam stability, higher foaming property, lower dynamic surface tension, and lower bubble coarsening rate. Both formulations we studied were more effective than commercial AFFF formulations. A concentration of 0.1-0.3% of FC1157 in an AFFF solution was optimal for extinguishing high-boiling-point oil fires.

Surface tension of native and modified plant seed proteins

The present review, dedicated to Prof. Zbigniew Adamczyk on the occasion of his 70th anniversary, covers the literature data on surface tension and surface compression (dilational) rheology of the adsorbed layers of 21 plant seed proteins (10 leguminous and 11 non-leguminous plants). They are typically analyzed as protein concentrates or isolates, the latter usually obtained by isoelectric precipitation or diafiltration. Despite generally lower solubility, as compared to their animal counterparts (lactoglobulins, caseins, albumins, etc.), the plant seed proteins are also capable of lowering surface tension and forming viscoelastic adsorbed layers. Many seed proteins serve mostly as amino acids reservoirs for the future seedling (storage proteins), hence their instantaneous amphiphilicity is not always sufficient to induce strong adsorption at the aqueous-air interface. They can be, however, conveniently unfolded, hydrolyzed and/or chemically/enzymatically modified to expose more hydrophilic or hydrophobic patches. As shown in numerous contributions reviewed below, the resulting shift of the hydrophilic-lipophilic balance can boost their surface activity to the level comparable to that of many animal proteins or low molecular weight surfactants. An important advantage of the plant seed proteins over the animal ones is their much lower environmental cost and abundance in many plants (e.g. ~40% in sunflower or soybean seeds).