Margit Varga

Biofilm controlled sorption of selected acidic drugs on river sediments characterized by different organic carbon content

The sorption process of selected non-steroidal anti-inflammatory drugs (ibuprofen, naproxen, ketoprofen, diclofenac) on biofilm covered river sediments were investigated in laboratory. In the course of the experiments, the effect of pH of aqueous phase, the effect of TOC (total organic carbon) content of biofilm on the sorption processes were studied. The determination of concentration of drugs was performed by gas chromatography mass spectrometry (GC-MS) both in liquid and solid phases. The pseudo-first-order rate constant of the sorption was found to be 83 min(-1). The effect of pH on the sorption of diclofenac was significantly lower than the obtained values in case of the other three drugs. The calculated K(d) (sorption coefficient) values increased in the sequence of ibuprofen, naproxen, ketoprofen and diclofenac and varied between 0.1-0.4; 0.2-0.7; 0.2-1.2; 0.2-1.4 kg L(-1) respectively, depending on the characteristics of the sediments. The value of K(d)×f(oc) showed a straight line as function of f(oc) (fraction of organic carbon) therefore, instead of the widely distributed normalization process (K(d)/f(oc)), an empirical equation (K(d)=A/f(oc)+B) was suggested for estimation of the K(d) values in case of different TOC content sediments.

Thorough study of bromide control in bromate oscillators, III. Simulation by the oregonator model of the behavior of reacting BZ systems perrturber by mercury (II) ions

The behavior of the bromate-maloni acid-cerium (III) oscillator in the presence of mercury (II)-a bromide-removing ion-can be simulated by the Oregonator model if the dynamics of bromocomplex-formation and dissociation reactions is taken into account.AbstractПоведение осциллятора бромат-малоновая кислота-церий (III) вписутствии ртыти(II)-иона удаляющего вромид-может быть симулирована с помощьы модели Орегонатора, если принять в расгет динамику реакций овразования и диссоциации бромных комплексов.

Iodide-promoted uncatalyzed bromate oscillators

Iodide ions—in a rather narrow concentration range—induce some of the uncatalyzed bromate oscillators to a more pronounced oscillatory activity: the number of oscillations increases considerably and the overall rate of the chemical reaction drops about an order of magnitude. Preliminary suggestion is made on the mechanism of iodide-induced oscillatory reactions.AbstractИодистые ионы—в достаточно узком интервале концентраций—индуцируют некатализированные броматные осцилляторы до более выраженной колебательной активности: число колебаний значительно увеличивается и суммарная скорость химической реакции уменьшается приблизительно на делый порядок величины. Приводятся предварительные заключения о механизме иодид-индуцированных колебательных реакциях.

A novel possibility to clarify the role of bromide in bromate oscillators

Bromocomplex forming metal ions (Tl3+, Hg2+) alter considerably the parameters of chemical oscillations in bromate oscillators. Even at 10−5 M metal ion concentration the period of the oscillation is doubled or tripled; at 10−4 M the oscillation is quenched. At high (≥10−2 M) Tl3+ concentration, high frequency, strongly damped oscillations occur although [Br−]eq is below 10−10 M. By the addition of Tl3+ we could determine the amount of Br− formed in a single autocatalytic step, which we found to be about 10−4 M.AbstractМеталлические ионы (Tl3+, Hg2+), образующие бромные комплексы, значительно изменяют параметры химических колебаний в броматных осцилляторах. Даже при концентрациях металлических ионов 10−5 M период колебания либо удвоен, либо утроен; при 10−4 M осцилляция гасится. При высоких концентраниях Tl3+ (≥10−2 M) наблюдается осцилляция высокой частоты с сильно пониженной амплитудой, хотя [Br−]eq ниже 10−10 M. Добавлением Tl3+ удалось определить количество Br−, образующегося но единственной автокаталитической ступени, которое оказалось равным 10−4 M.

Perturbation of Bromate Oscillators

Bromate oscillators have been investigated from many aspects. One of the aims has been to reveal the chemical prerequisites of the oscillatory behaviour. Some quantitative results have been already published [1]. The bromate oscillators can be perturbed, e.g. by the addition of inhibitory property halides [2,3], by the supply of O2 [3–6]; by keeping low the bromide concentration (addition of Ag+) [7]; or by γ-irradiation of the reacting system [8]. From the effect the perturbation exerts on a bromate oscillator, important information can be gained on the chemical mechanism of the oscillatory reaction.

Various dynamic behavior of Ag+-induced oscillations in uncatalyzed bromate oscillators

Silver ion induces the uncatalyzed bromate oscillators /aromatics-bromate-acid/on a variety of dynamic behavior, including high frequency and complex oscillations. The behavior of a reacting system depends on the chemical composition of the armatics, the time of addition of Ag+, and the concentration of Ag+. The chemistry underlying the phenomena is discussed.AbstractИон сера индудирует некаталитческие броматные осцилляторы (ароматики-бромат-кислота) в различных динамическнх поведениях, включая вясокие частоты и комплексные осциллирования. Поведение реагирующих систем зависит от химического состава ароматических соеднхений, времени присоединения Ag+ и концентрации Ag+. Обуждается химия этих явлений.

Study of Bromide Control in Bromate Oscillators

The control function of bromide ions in bromate oscillators has been questioned recently, and suggestions have been made to replace the Oregonator model by other ones in order to account for the occurrence of oscillations in silver ion containing BZ systems [1,2].

Iodide-Induced Oscillation in Uncatalyzed Bromate Oscillators

At least fifty of such organic compounds (mostly phenol- and analine-derivatives) are known at present which under certain concentration conditions in their reaction with acidic bromate show chemical oscillations. These systems are called uncatalyzed bromate oscillators [l, 2] and have been investigated from various aspects in many laboratories Although the skeleton mechanism suggested [3] seems to account for the behaviour of these systems properly [4], we are rather ignorant of the chemical prerequisites of the oscillation.