Pentachlorophenol (PCP) is a persistent pollutant which has been widely used as a pesticide and a wood preservative. As PCP is toxic and is present in significant quantities in the environment, there is considerable interest in elimination of PCP from waters. One of the promising methods is the application of ferrate. Ferrate is an oxidant and coagulant. It can be applied as a multi-purpose chemical for water and wastewater treatment as it degrades a wide range of environmental pollutants. Moreover, ferrate is considered a green oxidant and disinfectant. This study focuses on the kinetics of PCP degradation by ferrate under different pH conditions. The formation of degradation products is also considered. The second-order rate constants of the PCP reaction with ferrate increased from 23 M(-1) s(-1) to 4,948 M(-1) s(-1) with a decrease in pH from 9 to 6. At neutral pH the degradation was fast, indicating that ferrate could be used for rapid removal of PCP. The total degradation of PCP was confirmed by comparing the initial PCP molarity with the molarity of chloride ions released. We conclude no harmful products are formed during ferrate treatment as all PCP chlorine was released as chloride. Specifically, no polychlorinated dibenzo-p-dioxins and dibenzofurans were detected.
The production and use of chlorophenolic compounds in industry has led to the introduction of many xenobiotics, among them chlorophenols (CPs), into the environment. Five CPs are listed in the priority pollutant list of the U.S. EPA, with pentachlorophenol (PCP) even being proposed for listing under the Stockholm Convention as a persistent organic pollutant (POP). A green procedure for degrading such pollutants is greatly needed. The use of ferrate could be such a process. This paper studies the degradation of CPs (with an emphasis on PCP) in the presence of ferrate both in a spiked demineralized water system as well as in real contaminated groundwater. Results proved that ferrate was able to completely remove PCP from both water systems. Investigation of the effect of ferrate purity showed that even less pure and thus much cheaper ferrate was applicable. However, with decreasing ferrate purity, the degradability of CPs may be lower.
Regarding environmental pollution, the greatest public and scientific concern is aimed at the pollutants listed under the Stockholm Convention. These pollutants are not only persistent but also highly toxic with a high bioaccumulation potential. One of these pollutants, γ-hexachlorocyclohexane (γ-HCH), has been widely used in agriculture, which has resulted in wide dispersion in the environment. Remediation of this persistent and hazardous pollutant is difficult and remains unresolved. Of the many different approaches tested, to date, none has used ferrates. This is unexpected as ferrates are generally believed to be an ideal chemical reagent for water treatment due to their strong oxidation potential and the absence of harmful by-products. In this paper, the degradation/transformation of HCHs by ferrates under laboratory conditions was studied. HCH was degraded during this reaction, producing trichlorobenzenes and pentachlorocyclohexenes as by-products. A detailed investigation of pH conditions during Fe(VI) application identified pH as the main factor affecting degradation. We conclude that ferrate itself is unreactive with HCH and that high pH values, produced by K₂O impurity and the reaction of ferrate with water, are responsible for HCH transformation. Finally, a comparison of Fe(VI) with Fe(0) is provided in order to suggest their environmental applicability for HCH degradation.
Cílem práce bylo porovnat profil a časovou stabilitu jednotlivých parametrů kognitivních funkcí v průběhu jednoho roku od počátku schizofrenie v závislosti na průběhu onemocnění. Do studie bylo zařazeno 27 pacientů s první epizodou schizofrenie. Kritéria remise při hodnocení klinického stavu po roce od první epizody schizofrenie splnilo 22 pacientů (81 %), zbývajících 5 pacientů (19 %) tato kritéria nesplňovalo (tzv. "neremitéři"). Z našich výsledků vyplývá, že remitéři mají potenciál ke zlepšování kognitivního deficitu minimálně v průběhu jednoho roku po prodělání první epizody onemocnění, a to zejména v oblastech exekutivních a paměťových funkcí. U skupiny neremitérů nebylo naopak pozorováno zlepšování kognitivních funkcí v průběhu roku. Během první epizody schizofrenie se úroveň kognitivních funkcí nelišila mezi pozdějšími remitéry a neremitéry. Po roce od první epizody schizofrenie měli neremitéři delší auditivní reakční čas, jinak statisticky významné rozdíly mezi remitéry a neremitéry nebyly nalezeny. Lze shrnout, že kognitivní deficit v průběhu jednoho roku od první epizody schizofrenie má tendenci ke zmírňování, a to s větší mírou u remitérů. Rozdíly v kognitivním výkonu mezi remitéry a neremitéry nejsou však v časném období schizofrenie výrazné.
The goal of the study was to compare the profile and stability over time of individual parameters of cognitive functions during the period of one year from the onset of schizophrenia depending on the course of the illness. The study included 27 patients with the first episode of schizophrenia. The criteria for remission were met by 22 patients (81%) when their clinical status was assessed one year after the first episode of schizophrenia; the remaining 5 patients were evaluated as non-remitters (19%). Our results show that remitters have a potential for cognitive deficit improvement for at least one year after their first episode of the illness, especially as to executive and memory functions. On the other hand, the group of non-remitters was not found to improve in terms of cognitive function during the year. The level of cognitive functions during the first episode of schizophrenia did not differ between later remitters and non-remitters. One year after the first episode of schizophrenia non-remitters had worse auditory reaction times; no other significant differences between remitters and non-remitters were found. It may be summed up that cognitive deficit showed a trend to improvement for one year after the first episode of schizophrenia, the tendency being more prominent in remitters. The differences between cognitive performance between remitters and non-remitters are, however, not very prominent in the early stage of schizophrenia.
- MeSH
- antipsychotika aplikace a dávkování terapeutické užití MeSH
- finanční podpora výzkumu jako téma MeSH
- interpretace statistických dat MeSH
- kognitivní poruchy diagnóza klasifikace MeSH
- lidé MeSH
- risperidon terapeutické užití MeSH
- schizofrenie komplikace MeSH
- spontánní remise MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- srovnávací studie MeSH
- MeSH
- depresivní poruchy terapie MeSH
- elektromagnetická pole MeSH
- finanční podpora výzkumu jako téma MeSH
- kognitivně behaviorální terapie metody přístrojové vybavení trendy MeSH
- kognitivní poruchy psychologie terapie MeSH
- lidé MeSH
- neuropsychologické testy statistika a číselné údaje MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
