A study of the reaction of ferrate with pentachlorophenol - kinetics and degradation products.

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.

Degradability of hexachlorocyclohexanes in water using ferrate (VI).

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.

[The new blood test bio-marker SEPT9 and colorectal carcinoma screening]. / Nový krevní test bio-markeru SEPT9 a screening kolorektálního karcinomu.

Due to its high incidence and mortality rates, the colorectal carcinoma represents a crucial medical issue. However, when it is detected in early stage there is high rate of successful treatment. Thats why, early stage cancer screening programmes were introduced into the clinical practice. They focus on the finding of hidden bleeding, using various laboratory techniques, sigmoidoscopy, and, primarily, colonoscopy. However, screening programmes have not yet reached the effect required. New techniques are therefore being developed, such as the detection of blood bio-markers. This group includes also methylated SEPT9 (mSEPT9) detection in blood. We applied this test on 57 patients; we divided the group into two parts. There were 33 asymptomatic individuals in the first group. In this group, we were got only one positive mSEPT9 result. The consequent colonoscopies were negative. The other group had 24 proven carcinomas. Of them, two had negative mSEPT9 results. The remaining in all 22 patients was tested mSEPT9 positive. After its efficiency is tested by further studies, this test may be used especially for patients with low compliance, as it only requires routine blood drawing.

[Endoscopic cytoscopy in examination of the digestive tract]. / Význam endoskopické cytoskopie u vysetrení trávicího traktu.

A number of new endoscopic methods have been developed recently, which aim to allow the most accurate possible viewing of the mucosa of the digestive tract. These procedures include endoscopic cytoscopy, which together with confocal endoscopy is a technique of so-called endoscopic microscopy. By means of enodcytoscopy it is possible to view "in vivo" the morphological details of the surface of the mucosa of the digestive tract. The mucosa must, however, be thoroughly cleaned and stained with methylene blue. The paper presents our own initial experience of this method, which may lead to faster and more accurate diagnosis of pre-tumorous or tumourous inflammation processes in the mucosa of the digestive tract.

Degradability of chlorophenols using ferrate(VI) in contaminated groundwater.

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.

Simple spectrophotometric determination of monopersulfate.

A simple, sensitive and accurate spectrophotometric method has been developed and validated for the determination of monopersulfate (MPS) which is an active part of potassium monopersulfate triple salt that has the commercial name - Oxone. This work proposes a spectrophotometric determination of monopersulfate based on modification of the iodometric titration method. The analysis of absorption spectra was made for the concentration range from 1.35 to 13.01 ppm of MPS (with a detection and quantification limit of 0.41 and 1.35 ppm, respectively) and different pH values. The influence of several anions on the measurement was also investigated. Furthermore, the absorbance of iron and cobalt (often used as free radical initiators) proved to have no effect on the measurement of MPS concentrations. On the basis of the conducted studies, we propose 395 nm as an optimal wavelength for the determination of MPS concentrations.