Spatially Confined Radical Addition Reaction for Electrochemical Synthesis of Carboxylated Graphene and its Applications in Water Desalination and Splitting.

Due to the chemical stability of graphene, synthesis of carboxylated graphene still remains challenging during the electrochemical exfoliation of graphite. In this work, a spatially confined radical addition reaction which occurs in the sub-nanometer scaled interlayers of the expanded graphene sheets for the electrochemical synthesis of highly stable carboxylated graphene is reported. Here, formate anions act as both intercalation ions and co-reactant acid for the confinement of electro-generated carboxylic radical (●COOH) in the sub-nanometer scaled interlayers, which facilitates the radical addition reaction on graphene sheets. The controllable carboxylation of graphene is realized by tuning the concentration of formate anions in the electrolyte solution. The high crystallinity of the obtained product indicates the occurrence of spatially confined ●COOH addition reaction between the sub-nanometer interlayers of expanded graphite. In addition, the carboxylated graphene have been used for water desalination and hydrogen/oxygen reduction reaction. Therefore, this work provides a new method for the in situ preparation of functionalized graphene through the electrolysis and its applications in water desalination and hydrogen/oxygen reduction reactions.

The metal release and transformation mechanisms of V-Ti magnetite tailings: Role of the alternate flooding and drying cycles and organic acids.

V-Ti magnetite tailings (VTMTs) contain various heavy metals, such as Fe, Mn, V, Co, and Ni. The groundwater pollution caused by the tailing metal release has become a local environmental concern. Although studies have demonstrated the influence of alternate flooding and drying cycles (FDCs) on metal form and mobility in minerals, little was known about whether FDCs affect the metal release of VTMTs and the transformation of released metals. This study investigated the metal release kinetics of VTMTs and the metal transformation under FDCs in the absence and presence of acid rain (sulfuric and nitric acids) and bio-secreted organic acids (acetic, oxalic, and citric acids). The results showed that FDCs promoted metal release whether or not acids were present. The maximum released concentrations of V, Mn, Fe, Co, and Ni were as high as 78.63 mg L-1,1.47 mg L-1, 67.96 µg L-1, 1.34 mg L-1, and 0.80 mg L-1, respectively, under FDCs and citric acids. FDCs enhanced the tailing metal release by increasing the metal labile fraction proportion. However, the concentrations of released Fe, Mn, V, Co, and Ni all gradually decreased due to their (co-)precipitation. These precipitates conversely inhibited the subsequent mineral dissolution by covering the tailing surface. FDCs also enhanced the tailings' porosities by 2.94%-9.94%. The mineral dissolution, expansion and shrinkage, and changes in tension destroyed the tailing microstructure during FDCs. This study demonstrated the low metal pollution risk of VTMTs under FDCs, either in acid rain or bio-secreted organic acids. However, the increase in tailing porosity should be seriously considered as it would affect the tailing pond safety.

Interaction mechanisms of edible film ingredients and their effects on food quality.

Traditional food packaging has problems such as nondegradable and poor food safety. Edible films play an important role in food packaging, transportation and storage, having become a focus of research due to their low cost, renewable, degradable, safe and non-toxic characteristics. According to the different materials of edible films substrate, edible films are usually categorized into proteins, polysaccharides and composite edible films. Functional properties of edible films prepared from different substrate materials also vary, single substrate edible films are defective in some aspects. Functional ingredients such as proteins, polysaccharides, essential oils, natural products, nanomaterials, emulsifiers, and so on are commonly added to edible films to improve their functional properties, extend the shelf life of foods, improve the preservation of sensory properties of foods, and make them widely used in the field of food preservation. This paper introduced the classification, characteristics, and modification methods of common edible films, discussed the interactions among the substrate ingredients of composite edible films, the influence of functional ingredients on the properties of edible films, and the effects of modified edible films on the quality of food, aiming to provide new research ideas for the wide application and further study of edible films.

Divalent metal ions under low concentration environment improved the thermal gel properties of egg yolk.

To improve the thermal gel properties of egg yolk, the effect of several valence metal ions (K+, Ca2+, Mg2+ and Fe3+) with different concentrations (0-0.72%) on the rheological, gel, and structural properties of egg yolk were investigated. Results showed that monovalent and divalent ions were beneficial to the formation of uniform and dense gel network, especially with the addition of 0.72% magnesium ion, which further improved gel hardness, water holding capacity (WHC) and viscoelastic properties, the properties of egg yolk gel increased with the increase of the concentration of mono-bivalent metal ions. Adding ferric ion remarkably increased the average particle size (d4,3) and apparent viscosity of egg yolk, destroying the disulfide bonds and the hydrophobic interactions in gel. Fourier transform infrared spectroscopy (FT-IR) and fluorescence spectra analysis revealed that metal ions promoted the hydrophobic aggregation among egg yolk proteins and induced the transition of protein secondary structure from ordered to disordered. This work will provide a theoretical reference for the development of low salt and nutrient fortified egg yolk products.

Study on the Mechanism of Modified Cellulose Improve the Properties of Egg Yolk gel.

Natural fiber is not suitable for modifying yolk gel as a modifier because of its large size and high compactness. In this study, two kinds of modified cellulose were selected to improve the thermal gel properties of yolk. The results showed that the two kinds of cellulose promoted the formation of ordered structure in yolk gel. The ordered gel network not only improved the texture properties and rheological properties, but also improved the water retention of yolk gel significantly. CMC and CNFC at the same concentration, the modification effect of CMC on yolk gel was better than CNFC because of its excellent dispersion. However, high concentration of CNFC (1.20-1.60%) disrupted the cross-linking and ordered structure formation of yolk protein, and the quality of gel was significantly reduced.