Amount Of Acetylacetone Research Articles

EFFECT OF ACETYL ACETONE ON RADICAL POLYMERIZATION OF VINYL MONOMERS INITIATED BY BENZOYL PEROXIDE

The radical polymerization of styrene and methyl methacrylate (MMA) initiated by benzoyl peroxide (BР) with the addition of 10, 20, 50, and 80% of acetylacetone (AA) mixed with a monomer was studied. It was found that the rate of the polymerization process increases in the presence of a certain amount of AA in the system (³ 50% of the monomer). This is due to the fact that AA accelerates the decomposition of BP, while removing it from the system in the form of non-radical products, and the initiating function is performed by acetylacetonate radicals, which are formed upon interaction with BP. The incorporation of acac fragments into the polymer chain has been proved by IR and 1H NMR spectroscopy. It was found that these groups in the composition of the polymer interact with the p-system of benzene rings of polystyrene. The second reason for the accelerating action is the formation of complexes between the monomer and AA, in which the additive has an acceptor effect, leading to the facilitation of the breaking of double bonds in the monomer. It was shown that MMA has a stronger effect on AA polymerization, because forms stronger complexes with the enol form of AA, which requires a longer time for the radical to leave the complex. In this regard, during its polymerization, induction periods are observed, the duration of which is directly proportional to the concentration of AA in a mixture with MMA. It was revealed that another feature of the effect of AA on radical polymerization is its participation in chain transfer reactions, which does not decrease the rate of the process, but only leads to a decrease in the molecular weight of the products. This makes it an effective regulator of polymer molecular weights. The paper proposes a scheme for the polymerization of vinyl monomers, initiated by BP with the addition of AA.

Ligand effects on nitrate reduction by zero-valent iron: Role of surface complexation

Surface passivation is a key limiting factor in the application of zero-valent iron (ZVI) for water remediation. Addition of ligands is a useful approach to overcome this issue. In this work, a small amount of acetylacetone (AA) (0.5 mM) was found highly efficient to enhance the reduction of nitrate by ZVI at near neutral conditions (pH 6.0) with the formation of considerable black coating on ZVI. At an initial nitrate concentration of 20 mg N/L, the pseudo first-order reduction rate constant of nitrate in the ZVI-AA-NO3− system was 0.0991 h−1, which was 52 times higher than that in the ZVI-NO3− system. Under otherwise identical conditions, the other five ligands, including EDTA, formate, acetate, oxalate, and phosphate, had negligible effects. Based on the pKa values of these ligands and the final species of iron, the ligand effects on nitrate reduction by ZVI were summarized from three aspects: (1) the ability to offer potentially dissociable protons from the ligands; (2) the complexation ability to eliminate iron (hydr)oxide precipitates from the surface of ZVI; and (3) the ability to lower down the redox potentials of iron species. The good performance of AA in these three aspects makes it advantage over the other ligands. A cycle test up to six runs demonstrates that AA could continuously take effect in the ZVI system. The results here point out the potential of AA as an effective ligand in ZVI system for enhanced contaminant transformation.

Enhancement and optimization of ATO nano-crystalline films properties by the addition of acetylacetone as modifier in the sol-gel process

Sb-doped SnO2 (ATO) thin films have been prepared using the spin coating method by selecting the proper amount of acetylacetone as solution modifier. All ATO powders and films exhibited the cassiterite rutile-like structure in a crystal size below 10 nm under all the experimental conditions and a nonpreviously reported crystal structure was observed at high acetylacetone loads. The acetylacetone molar ratio influenced notably the optical and electrical properties of ATO films. When prepared at an acetylacetone molar ratio of 4, ATO films exhibited optical transparencies above 90% in the visible region and above 40% in the UV region for thicknesses of 100 and 300 nm. Films in a thickness of 100 nm and at an annealing temperature of 650 °C accounted for a high transparency of 97% in the visible wavelength. Films prepared at an acetylacetone molar ratio of 4 exhibited an electric resistivity of 1.33×10-3 Ω·cm at an annealing temperature of 650 °C. The optimal Sb content for ATO films was found to be 8 at%. The relationships among the properties of starting solutions, the experimental parameters, and properties of ATO films are discussed.

Development of a 68Ge/68Ga Generator to Avail 68Ga in Organic Medium for Industrial Radiotracer Applications

A chromatographic 68Ge/68Ga generator using nano zirconia as the sorbent matrix was developed to avail 68Ga in an organic medium for industrial radiotracer applications. Acetylacetone was used as the eluent for the extractive desorption of 68Ga ions from the sorbent phase. The effect of varying the amount of acetylacetone on 68Ga yield and achieving ideal experimental conditions were studied. The major advantage of this generator is its ability to deliver ready to use “industrial 68Ga tracer” with > 90% yield and high radionuclidic and radiochemical purity. The performance of the generator remained consistent on repeated elutions over a period of 1 year.

Early stages of crystallization in gel derived ZrO2 precursors

Three different precursor materials giving rise to contrasted nanostructures, xerogels, aerogels and precipitates, are prepared by a sol gel route in the Zrn -propoxide—acetylacetone—water—n-propanol system. Clear homogeneous gels are made by using a proper amount of acetylacetone and water. The gels are dried either by conventional processing (xerogels) or by supercritical evacuation of alcoholic solvent (aerogels). The complexation ratio (R = [acetylacetone]/[Zr(OR)4]) is the main parameter controlling the size of ZrO2 primary particles. WhenR = 0 , precipitates are obtained.