Facultatea de Chimie şi Tehnologie Chimică / Faculty of Chemistry and Chemical Technology
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Item MONITORIZAREA PROCESELOR DE AUTOPURIFICARE CHIMICĂ A SISTEMELOR ACVATICE ÎN BAZA INDICATORILOR CINETICI(Editura USM, 2023) Bunduchi, Elena; Duca, Gheorghe; Gladchi, VioricaÎn lucrarea de față sunt aduse date privind conținutul și dinamica temporală a peroxidului de hidrogen [H2O2], a reducătorilor peroxidazici [Red], a stării redox cinetice (ox./inst./red.) și a constantei efective de întrerupere a lanțului radicalic în procesele de oxidare cu participarea radicalilor •OH, pentru unele ape naturale. Perioada de monitorizare a cuprins anii 2020-2022. Supravegherea a scos în evidenţă prezența unor cantităţi scăzute de H2O2 (˂ 10 μg/L), dar mai des lipsa acestui oxidant în toate apele investigate, fapt ce arată că din totalul de substanţe reducătoare prezente în ape prevalează constant substanţele care sunt oxidate preferenţial de către H2O2. Obiectele acvatice se confruntă constant cu deficit de peroxid de hidrogen. Ca rezultat starea redox cinetică a apelor a fost frecvent fie instabilă, fie reducătoare. Se menționează că apele monitorizate au fost poluate cu captori de radicali •OH. Gradul de poluare variază de la poluată ușor (≈ 2.0·105 s-1 ) până la poluată înalt (> 10.0·105 s-1). Râul Ichel și lacul Dănceni sunt obiectele acavatce în care procesele deautopurificare radicalică sunt încetinite. Datele nu relevă că apele afluenților mărescpoluarea apelor nistrene.Item REDOX SELF-PURIFICATION MECHANISM OF NATURAL WATERS WITH THE INVOLVEMENT OF THIOGLYCOLIC ACID AND THIOUREA(Pennsylvania,USA, 2023) Lis, Angela; Duca, Gheorghe; Gladchi, Viorica; Bunduchi, Elena; Blonschi, VladislavThis chapter studied the influence of TGA and TU on the self-purification processes of aquatic systems on model systems, whose composition was modeled to be as close as possible to the natural waters. As a source of irradiation was used the DRT-400 lamp and the Solar Simulator, Oriel model 9119X, the emission spectra of which overlap with the emission spectrum of the Sun. The results of the research show that on irradiation, TGA can regenerate an additional amount of OH radicals, thus contributing to the intensification of water self-purification processes. But in the presence of transition metals, such as Cu (II) and Fe (III), it has been established that the intensity of self-purification processes decreases due to the formation of the mercaptides, whose catalytic activity is low. Unlike TGA, TU leads to decreasing the intensity of the self-purification processes of aquatic systems, through the intense consumption of OH radicals, and at the same time on the interaction with transition metals, such as Cu (II) and Fe (III), form stable complexes with low catalytic activity.Item ASSESSMENT OF KINETIC PARAMETERS IN THE WATERS OF THE NISTRU COURSE IN THE SECTION NASLAVCEA – DUBASARI(2006) Bunduchi, Elena; Duca, Gheorghe; Gladchi, Viorica; Goreaceva, Nelli; Mardari, IgorThe current work represents the results of a monitoring executed on Nistru River waters between October 2003 and September 2005. The water quality was evaluated on the basis of such kinetic indicators as redox state and capacity of inhibition. The obtained results shows that Nistru River water in the segment Naslavcea village – Dubasari barrage are continuously polluted with reducing substances that diminish the H2O2 content, that actually determines the redox state of natural waters and the content of free radicalsItem THE STUDY OF REDOX CONDITIONS IN THE DNIESTER RIVER(2008) Gladchi, Viorica; Goreaceva, Nelli; Duca, Gheorghe; Bunduchi, Elena; Romanciuc, Lidia; Mardari, Igor; Borodaev, RuslanThe work presented in the paper discusses the contribution of the Novodnestrovsc water system to the formation of redox conditions in the lower Dniester. The conclusions were drawn on the basis of a long-term protocol of analyses that included the analysis of the oxygen regime, evaluation of the content of hydrogen peroxide,rH2, biological oxygen demand as well as other additional parameters.Item ESTIMATION OF THE NATURAL WATER SELF-PURIFICATION CAPACITY FROM THE KINETIC STANDPOINT(2008) Duca, Gheorghe; Bunduchi, Elena; Gladchi, Viorica; Romanciuc, Lidia; Goreaceva, NelliThe current paper contains a synthesis of the processes of chemical auto-purification that take place in natural waters; examples of mechanisms of such processes occurring with participation of dissolved organic matter, oxidants of the biogeochemical cycle of oxygen and of transition metals including copper and iron are presented. The kinetic indicators of natural water quality are presented as well.Item THE STUDY OF REDOX CONDITIONS IN THE DNIESTER RIVER(Academia de Știinițe a Moldovei, 2008) Gladchi, Viorica; Goreaceva, Nelli; Duca, Gheorghe; Bunduchi, Elena; Romanciuc, Lidia; Mardari, Igor; Borodaev, RuslanThe work presented in the paper discusses the contribution of the Novodnestrovsc water system to the formation of redox conditions in the lower Dniester. The conclusions were drawn on the basis of a long-term protocol of analyses that included the analysis of the oxygen regime, evaluation of the content of hydrogen peroxide, rH2, biological oxygen demand as well as other additional parameters.Item ESTIMATION OF THE NATURAL WATER SELF-PURIFICATION CAPACITY FROM THE KINETIC STANDPOINT(Academia de Știinițe a Moldovei, 2008) Duca, Gheorghe; Bunduchi, Elena; Gladchi, Viorica; Romanciuc, Lidia; Goreaceva, NelliThe current paper contains a synthesis of the processes of chemical auto-purification that take place in natural waters; examples of mechanisms of such processes occurring with participation of dissolved organic matter, oxidants of the biogeochemical cycle of oxygen and of transition metals including copper and iron are presented. The kinetic indicators of natural water quality are presented as well.Item ASSESSMENT OF KINETIC PARAME TERS IN THE WATERS OF THE NISTRU COURSE IN THE SECT ION NASLAVCEA – DUBASARI(Academia de Știinițe a Moldovei, 2006) Bunduchi, Elena; Duca, Gheorghe; Gladchi, Viorica; Goreaceva, Nelli; Mardari, IgorThe current work represents the results of a monitoring executed on Nistru River waters between October 2003 and September 2005. The water quality was valuated on the basis of such kinetic indicators as redox state and capacity of inhibition. The obtained results shows that Nistru River water in the segment Naslavcea village – Dubasari barrage are continuously polluted with reducing substances that diminish the H2O2 content, that actually determines the redox state of natural waters and the content of free radicals