Yield Of Degradation Products Research Articles

Enhanced phototransformation of atorvastatin by polystyrene microplastics: Critical role of aging

Reactive oxygen species (ROS) generated from light irradiation of microplastics (MPs) can potentially affect the environmental fate of organic contaminants when they coexist in the same environment. This study investigated the effect of polystyrene (PS) MPs with different aging degrees on the phototransformation of atorvastatin (ATV) under simulated sunlight. Results showed that the presence of PS MPs facilitated the phototransformation of ATV, and the degradation rate was linearly correlated with the aging degree (i.e., carbonyl index) of MPs. The enhanced effects mainly depended on the contents of oxygen-containing functional groups of PS MPs, which increased the absorption of light energy and the generation of ROS (e.g., singlet oxygen (1O2) and triplet-excited state PS (3PS*)). Quenching experiments indicated that 1O2 generated from photosensitization of PS was the major contributor to the increased phototransformation of ATV. Additionally, the role of 3PS* became more important in the photodegradation mediated by higher degree aged MPs because much more 1O2 was generated from the 3PS* . PS MPs also increased the types and yields of degradation products, especially for higher degree aged MPs, despite the low effect on leachate toxicity. The findings provide a novel insight into the critical role of MPs in the fate of organic contaminants in aquatic environments.

Pyrolysis-gas chromatography of the macromolecular fractions of oxidized Organocell lignins

Spruce Organocell lignin has been oxidized by O 2 under pressure in acetic acid and in the presence of NaBr or NH 4Br and Co(OAc) 2 as catalyst in order to obtain chelating agents. The reaction time, O 2 pressure, and the Co(OAc) 2/bromide ratios were varied and the product quality was monitored by analytical pyrolysis-gas chromatography. The main pyrolysis products were phenol, guaiacol, 4-methyl- and 4-ethylguaiacol, catechol, isoeugenol, vanillin, and vanillic acid. In the oxidized lignins the moiety of demethoxylated, demethylated and oxidized guaiacyl units was increased. Vanillin and vanillic acid were used as marker for determination of the oxidation increments. The longer the reaction time and the more bromide as promoter was used the higher oxidation increments between 2 and 9 were observed. The oxidation increments correlate with the severity of oxidation. The yield of degradation products with low molecular weight was low. Bromides promote mainly the oxidation and not the depolymerisation of lignins.

Effects of solvent and iron-compounds on the liquefaction of brown coal

Hydrogen-donor solvents such as hydrophenanthrene are the most effective aromatic solvents for the liquefaction of brown coal. The hydrogen-donating ability of the solvent is more important for brown coals than for bituminous coals, because the thermal decomposition and subsequent recombination of the structure of the brown coals occurs rapidly. Three-ring aromatic hydrocarbons are more effective solvents than two-ring aromatics, and polar compounds are less effective solvents with brown coals than with bituminous coals. The thermal treatment of brown coal, accompanied by carbon dioxide evolution at temperatures > 300°C, in the presence of hydrogen-donating solvent did not affect the subsequent liquefaction reaction. However, thermal treatment in the absence of solvent strongly suppressed the liquefaction reaction, suggesting that the carbonization reaction occurred after the decarboxylation reaction in the absence of hydrogen donor. To study the effect of various iron compounds, brown coal and its THF-soluble fraction were hydrogenated at 450°C in the presence of ferrocene or iron oxide. The conversion of coal and the yield of degradation products are increased by the addition of the iron compounds, particularly ferrocene, and the yield of carbonaceous materials is decreased.

Radiolysis of DEHPA-CCL4 solvent mixture in the presence of aqueous solutions

In order to clarify the effect of carbon tetrachloride on the radiolysis of di(2-ethylhexyl)phosphoric acid(DEHPA), DEHPA diluted with carbon tetrachloride was exposed to60Co γ-rays in the presence or absence of aqueous solution and the yields of degradation products of DEHPA and hydrogen chloride were determined. Radiolysis of DEHPA is enhanced by carbon tetrachloride, most intensively in the stirred system of DEHPA−CCl4 and an aqueous solution. Carbon tetrachloride also corroded stainless steel immersed in it during γ-irradiation owing to the formation of hydrogen chloride. Yield of hydrogen chloride increased in the presence of the aqueous solution, most effectively upon stirring, and corrosion became significant.

Aromatic constituents of humic acids released by na-amalgam reductive cleavage, koh fusion and zinc dust fusion

Abstract Eight humic acids showing different degree of humification were treated with HCI (1:1). The hydrolyzed humic acids were subjected to reductive cleavage with Na-amalgam, KOH fusion and zinc dust fusion. The yields of degradation products were determined by colorimetry gas chromatography. The perimental results Were summarized as follows: l. The amounts of ether-soluble substances obtained by reductive cleavage with Naamlagan ranged from 21.6% for Kuragari (A type) to 7.8% for Kisokoma B2 (Rp type). The yields of phenolic substances expressed in terms of vanillic acid content ranged from 3.0% for Kuragari (A type) to 1.8% for Kisokoma B2 (Rp type). Resorcinol. p.hydroxybenzoic acid, vanillic acid, protocatechuic acid and syringic acid were detected in the gas chromatograms of the ethe-soluble substances and their total yield comprised less than 0.6% of the Kisokoma F (Rp type). 2. The KOH fusion of humic acid yielded a larger amount of degradation products as compared to reductive cleavage. The amo...