Wastewater treatment with ionizing radiation

In water treatment by ionizing radiation ^·OH is suggested to initiate the degradation of organics. In these reactions mostly carbon centred radicals form. Here we show that other inorganic radicals also highly contribute to the initiation of degradation. Cl^? and HCO₃ ^? in the treated water reacting with ^·OH transform to Cl ₂ ^·? and CO ₃ ^·? . In their reactions C-centred radicals form, too. The reactions of e _aq ^? and H^· water radiolysis intermediates may also produce carbon centred radicals. The C-centred radicals react readily with dissolved O₂, this is the starting step of the gradual oxidation.     

DSC for evaluating the encapsulation efficiency of lidocaine-loaded liposomes compared to the ultracentrifugation method

Journal of Thermal Analysis and Calorimetry - This study reports the investigation of liposomal formulations of lidocaine in the form of a free base (LID). LID was encapsulated into large...     

Contact angle determination of nanoparticles: film balance and scanning angle reflectometry studies

St?ber silica nanoparticles of diameter about 45, 60 and 100 nm and different hydrophobicity are used to produce monolayers at a water-air interface. Both the surface pressure-area isotherms and the reflectivity angle of incidence curves of the layers have been measured in a Wilhelmy film balance. The contact angle of the as-prepared particles have been determined from the isotherms by two different evaluation methods, and compared to those obtained from in situ scanning angle reflectometry (SAR) measurements. SAR is proved to be an effective tool for the estimation of contact angles on nanoparticles of different wettability, using a modified version of the previously published gradient layer model (E. Hild, T. Seszták, D. V?lgyes and Z. Hórv?lgyi, Prog. Colloid Polym. Sci., 2004, 125, 61, ref. 1) for evaluation. The results are in fairly good agreement with those determined from the non-dissipative part of the isotherms of the as prepared particles, assuming a weakly cohesive film model (S. Bordács, A. Agod and Z. Hórv?lgyi, Langmuir, 2006, 22, 6944, ref. 2). It seems that the traditional way to calculate the contact angle from the film balance experiments (J.H. Clint and N. Quirke, Colloids Surf., A, 1993, 78, 277, ref. 3) results in unreasonably high contact angles for the investigated systems and the homogeneous layer optical model gives unrealistic film thickness values in the case of hydrophobic particles.     

Quasi-Hereditary Extension Algebras

The paper is a continuation of the authors' study of quasi-hereditary algebras whose Yoneda extension algebras (homological duals) are quasi-hereditary. The so-called standard Koszul quasi-hereditary algebras, presented in this paper, have the property that their extension algebras are always quasi-hereditary. In the natural setting of graded Koszul algebras, the converse also holds: if the extension algebra of a graded Koszul quasi-hereditary algebra is quasi-hereditary, then the algebra must be standard Koszul. This implies that the class of graded standard Koszul quasi-hereditary algebras is closed with respect to homological duality. Another immediate consequence is the fact that all algebras corresponding to the blocks of the category O are standard Koszul.     

Radiation induced degradation of pharmaceutical residues in water: Chloramphenicol

The γ-radiolytic degradation of chloramphenicol (CPL) was investigated in 0.1–1 mmol dm^?3 aqueous solutions at various radiation conditions. The destruction of CPL was monitored by UV–vis spectrophotometric method through the decrease in the intensity of the absorbance band at 276 nm. LC-MS/MS was used to identify the degradation products. Results indicate that ^?OH can add onto the CPL aromatic ring or can abstract H-atom from the side chain. The reductive dechlorination of CPL was also studied based on the reaction of e_aq^? with CPL. In 0.1 mmol dm^?3 solution above 2.5 kGy dose complete CPL degradation was achieved. In the presence of dissolved oxygen at relatively low dose, various oxidation products were observed. In the presence of tertiary butanol radical scavenger tertiary butanol group containing products were also detected. The toxicity increased as a function of dose to 1.0 kGy. At doses higher than 1.0 kGy the toxicity decreased continuously due to further degradation. It was also demonstrated that the O₂^??/HO₂^? pair has low reactivity in CPL solution.     

Radiation induced degradation of ketoprofen in dilute aqueous solution

The intermediates and final products of ketoprofen degradation were investigated in 0.4 mmol dm^?3 solution by pulse radiolysis and gamma radiolysis. For observation of final products UV?vis spectrophotometry and HPLC separation with diode array detection were used, and for identification MS was used. The reactions of ^?OH lead to hydroxycyclohexadienyl type radical intermediates, in their further reactions hydroxylated derivatives of ketoprofen form as final products. The hydrated electron is scavenged by the carbonyl oxygen and the electron adduct protonates to ketyl radical ^?OH is more effective in decomposing ketoprofen than hydrated electron. Chemical oxygen demand and total organic carbon content measurements on irradiated aerated solutions showed that using irradiation technology ketoprofen can be mineralised. The initial toxicity of the solution monitored by the Daphnia magna test steadily decreases with irradiation. Using 5 kGy dose no toxicity of the solution was detected with this test.     

Mineralization of aqueous phenolate solutions: A combination of irradiation treatment and wet oxidation

Wet oxidation (high-temperature, high-pressure oxidation of organic wastes in aqueous solution) and radiation technology were combined in γ-ray and electron beam induced oxidation of 4×10^?4–1×10^?2 mol dm^?3 Na-phenolate solutions in a wide O₂ concentration (1–20 bar pressure) and absorbed dose (0–50 kGy) range. Most experiments were made in stainless steel high pressure autoclave equipped with magnetic stirrer. The rate of oxidation was followed by chemical oxygen demand and total organic carbon content measurements. The rate was similar in γ-ray and pulsed electron beam irradiation and increased with O₂ concentration in the liquid.     

Ionizing radiation induced reactions of 2,6-dichloroaniline in dilute aqueous solution

In pulse radiolysis investigations the hydroxyl radical formed in water radiolysis reacts with 2,6-dichloroaniline in radical addition to the ring forming hydroxy-cyclohexadienyl radical and also in hydrogen atom abstraction from the amino group resulting in anilino radical. The hydroxy-cyclohexadienyl radical in the absence of dissolved O₂ partly transforms to anilino radical, when dissolved oxygen is present the radical transforms to peroxy radical. According to chemical oxygen demand measurements the reaction of one OH radical induces the incorporation of 0.6 O₂ into the products. It is a typical value for chlorine atom substituted aromatic molecules, and smaller than found for molecules without chlorine atom (1.0–2.0).     

Thermal stability of organoclays with mono- and di-alkyl cationic surfactants

In this study, mono- and di-alkyl cationic surfactants were used to prepare organoclays through ion exchange and the prepared organoclays were characterised by X-ray diffraction (XRD) and thermogravimetric analysis (TG). Larger basal spacings were observed in the interlayer of the organoclays intercalated with DDDMA than organoclays intercalated with DDTMA. The DTG curves identify the thermal stability of organoclays intercalated with two different types of surfactants (DDTMA and DDDMA) and the different arrangements of the surfactant molecules intercalated in the montmorillonite. Both organoclays intercalated with organic surfactant molecules proved to be thermally stable at high temperature. This study provides an understanding of the structure and properties of organoclays, which will enhance the potential applications of organoclays in environmental remediation.     

Constructions of Stratified Algebras

In this article, a construction to build recursively all basic finite dimensional standardly stratified algebras is given. In comparison to the construction described by Dlab and Ringel for the quasi-hereditary case ([15 Dlab , V. , Ringel , C. M. ( 1989 ). A construction for quasi-hereditary algebras . Compositio Math. 70 : 155 – 175 . [Google Scholar]]) some new features appear here.