Authors:Ana C. R. Melo, Edjane F. B. Silva, Larissa C. L. F. Araujo, Mirna F. Farias, and Antonio S. Araujo
products of high molecular weight precursors in the formation of coke. When the kinetic energy of the atoms involved in a chemical bond exceeds the potential energy that binds them together, there is beginning the process of thermal degradation of
Authors:Edjane F. B. Silva, Marcílio P. Ribeiro, Luzia P. F. C. Galvão, Valter J. Fernandes, and Antonio S. Araujo
residues can be converted in valuable products through thermal or catalytic degradation [ 1 ]. Consequently, polymer degradation became an increasing and important method to convert plastic residues into chemical products such as fuel and petrochemicals [ 2
Authors:Dragica M. Minić, Maja T. Šumar-Ristović, Đenana U. Miodragović, Katarina K. Anđelković, and Dejan Poleti
the best inhibitory activity against Candida albicans .
In our previous study on thermal stability of transition metal N -Boc-gly complexes [ 17 ] it was shown that the mechanism of multi-step thermal degradation starts with a loss of water
The objective of this investigation was to verify the degradation of endrin by gamma irradiation. 60Co was used as radiation source for irradiation of 50 mg L−1 endrin with a varied dose of 1–6 kGy. High performance liquid chromatography (HPLC) coupled with diode array detector was
used as an analytical technique to monitor the degradation rate along with numbers of degradation products formed. At dose
rate of 6 kGy ≥99% of endrin was degraded. It is proposed that utilization of ionization radiations can be an effective and
efficient tool for the removal of halogenated pesticides.
Authors:Gang Xu, Tingting Bu, Minghong Wu, Jisan Zheng, Ning Liu, and Liang Wang
The degradation characteristics of clopyralid irradiated by electron beam (EB) was studied in aqueous solutions. The effects
of factors, such as initial clopyralid concentrations, addition of radicals scavenger, initial solution pH and addition of
H2O2, were investigated on clopyralid degradation efficiency and mechanism. It was found that the EB-radiolysis was an effective
way to degrade clopyralid and its degradation rate decreased with the increasing of substrate concentration. In the investigated
initial concentrations range of 100–400 mg L−1, the radiolytic degradation of clopyralid followed a pseudo-first kinetic order. The results from addition of radicals scavenger
indicated that both •OH and eaq− played significant roles in the degradation of clopyralid. Furthermore, the alkaline condition and addition of H2O2 (<10 mM) in the solution also slightly enhanced the efficiency of clopyralid degradation. The ion chromatography analysis
showed that some organic acids (formic acid, acetic acid and oxalic acid) were formed, while the completely dechlorination
of the substrate was achieved and organic nitrogen was recovered in the form of ammonium and nitrate ions during the irradiation
Authors:P. Pathak, D. Prabhu, M. Bindu, S. Tripathi, and V. Manchanda
The primary purpose of this study was to understand the alpha radiolytic degradation behavior of N,N-dihexyl octanamide (DHOA) vis a vis tributyl phosphate (TBP) solutions in n-dodecane under plutonium loading conditions. These studies were carried out as a function of dose on different Pu loaded
samples (containing 0.002-10 g/L Pu) from 4 M HNO3 medium. These Pu loaded solutions were evaluated for stripping behavior by contacting with 0.5 M NH2OH at 0.5 M HNO3 solutions. Organic phase analysis was carried out by gas chromatography (GC) and by visible spectrophotometry. These studies
clearly indicated that Pu stripping becomes difficult with increased dose in the case of TBP system. On the other hand, no
such problem was observed in DHOA system during stripping of plutonium, thereby indicating that DHOA is a promising candidate
for the reprocessing of high burn up Pu rich spent fuels.
A series of crosslinked polyurethane acrylate solids with glass transition temperatures ranging from –49 to +65 °C was prepared
by photopolymerization of specially formulated solvent-free resins. The kinetics of thermooxidative and thermal (in N2) degradation of these crosslinked acrylate networks at temperatures ranging from 100 to 400 °C was studied as a function
of crosslink density using thermogravimetry. The polyacrylate network degradation rate decreased with the increase of crosslink
density, while apparent activation energy of degradation increased. Polyacrylate thermal stability increase with crosslinking
was explained by decreased rate of oxygen and volatile products diffusion and/or slowing of depolymerization due to increased
radical recombination rate, and decreased chain segments mobility in systems with higher crosslink density.
Alachlor has been widely used in agriculture all over the world. It is suggested that it may be a carcinogen and an environmental
estrogen. The aim of this work was to verify the degradation the alachlor by gamma radiation. Gamma radiation from 60Co was used to degrade the alachlor herbicide in water and methanol solution. The alachlor in water and alcohol solution in
the concentration of 100 mgL−1 was irradiated with doses of 0.25–50 kGy, at dose rate 5–6 and 2.7 kGyh−1. High performance liquid chromatography was used as an analytical technique to determine the degradation rate of herbicide
Carotenoids are important pigments found in foods and biological samples. Among carotenoids, β-carotene is the major carotenoid present in vegetable oils. It plays an important role in the thermal stability of the vegetable oil. We established a simple, precise, specific, sensitive, repeatable, and accurate HPTLC method for the analysis of β-carotene in fortified vegetable oils and assessment of its degradation. Analysis was performed on silica gel HPTLC plates with petroleum ether-hexane-acetone 2:3:1 (
) as mobile phase and densitometric detection. The
of β-carotene was 0.91 and regression analysis showed response was a linear function quantification of amount of β-carotene in the range 100–600 ng (
= 0.99991). The limits of detection and quantification were 0.11 and 0.37 ng, respectively. The thermal degradation (1–5 h at 100°C) of β-carotene in fortified sunflower oil was studied. It was observed that this HPTLC method could be used for efficient analysis and monitoring of the degradation of β-carotene in edible oils.