chlorinated phenols
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PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0257415
Author(s):  
Luoyan Ai ◽  
Tiancheng Ren ◽  
Qin Yan ◽  
Mengdan Wan ◽  
Yajuan Peng ◽  
...  

Degradation of 2,4,6-trichlorophenol (2,4,6-TCP) by zero-valent iron (ZVI) activating three common peroxides (peroxymonosulfate (PMS), hydrogen peroxide (H2O2), and peroxydisulfate (PS)) was investigated. The effects of ZVI dosage, peroxides concentration, initial pH, and Cl- concentration were examined. The 2,4,6-TCP degradation efficiencies by Fe0/peroxides (PMS, H2O2, PS) were compared. Results showed that the order for degradation efficiency was H2O2≥PMS>PS. The degradation efficiency of 2,4,6-TCP in ZVI/peroxides systems were optimal at c(Ox) = 1 mmol•L-1; c(Fe0) = 0.1 g/L; initial pH = 3.2. Additionally, pH had a vital effect on 2,4,6-TCP degradation. At pH<3.2, ferrous play a vital role in all reaction, and accelerate the reaction rate rapidly. The existence of NaCl showed different results in the four systems. Chloride had little effect on 2,4,6-TCP degradation when chloride concentration at 5 mM, whereas the presence of 300 mM chloride significantly accelerated the degradation of 2,4,6-TCP from 72.7% to 95.2% in ZVI-PMS system. Notably, the other three systems showed opposite results. In contrast, the AOX (Absorbable Organic Halogen) values were highest in ZVI-PMS-Cl- system, due to the formation of lots of refractory chlorinated phenols as identified by GC-MS. These findings are good for choosing the most suitable technology for chlorophenol wastewater treatment.


Organics ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 142-160
Author(s):  
Keith Smith ◽  
Gamal A. El-Hiti

para-Selective processes for the chlorination of phenols using sulphuryl chloride in the presence of various sulphur-containing catalysts have been successfully developed. Several chlorinated phenols, especially those derived by para-chlorination of phenol, ortho-cresol, meta-cresol, and meta-xylenol, are of significant commercial importance, but chlorination reactions of such phenols are not always as regioselective as would be desirable. We, therefore, undertook the challenge of developing suitable catalysts that might promote greater regioselectivity under conditions that might still be applicable for the commercial manufacture of products on a large scale. In this review, we chart our progress in this endeavour from early studies involving inorganic solids as potential catalysts, through the use of simple dialkyl sulphides, which were effective but unsuitable for commercial application, and through a variety of other types of sulphur compounds, to the eventual identification of particular poly(alkylene sulphide)s as very useful catalysts. When used in conjunction with a Lewis acid such as aluminium or ferric chloride as an activator, and with sulphuryl chloride as the reagent, quantitative yields of chlorophenols can be obtained with very high regioselectivity in the presence of tiny amounts of the polymeric sulphides, usually in solvent-free conditions (unless the phenol starting material is solid at temperatures even above about 50 °C). Notably, poly(alkylene sulphide)s containing longer spacer groups are particularly para-selective in the chlorination of m-cresol and m-xylenol, while, ones with shorter spacers are particularly para-selective in the chlorination of phenol, 2-chlorophenol, and o-cresol. Such chlorination processes result in some of the highest para/ortho ratios reported for the chlorination of phenols.


2021 ◽  
Author(s):  
Tamara Apostolović ◽  
Jelena Tričković ◽  
Marijana Kragulj Isakovski ◽  
Snežana Maletić ◽  
Tijana Zeremski ◽  
...  

&lt;p&gt;Amendment of alluvial sediments with carbon rich materials such as biochars can be an effective method for controlling the penetration of hazardous substances from river water into drinking water sources during river bank filtration (RBF). In this work, the transport of chlorinated phenols (CPs) during simulated RBF through Danube alluvial sediment with and without biochar amendment was studied. In order to assess the effect of the biochar amendment on CPs retention in the alluvial sediment, column experiments were carried out, with the addition of biocide to exclude the influence of biodegradation. Four CPs that differ in polarity were used as sorbates: 4-chlorophenol (4-CP), 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP) and pentachlorophenol (PCP). For the column packing, Danube alluvial sediment was used, characterized as a mesoporous sandy material with low organic carbon content (1.57 %) and small specific surface area (1.65 m&lt;sup&gt;2&lt;/sup&gt;/g). In contrast, the material used as the amendment in the column experiment is a biochar with high organic carbon content (89.8 %) and large specific surface area (341 m&lt;sup&gt;2&lt;/sup&gt;/g). The breakthrough curves obtained for the alluvial sediment column without biochar amendment showed poor retention of all investigated CPs. Retardation factors (&lt;em&gt;R&lt;/em&gt;&lt;sub&gt;d&lt;/sub&gt;) for 4-CP, 2,4-DCP and 2,4,6-TCP were 1.65, 1.98 and 1.48, respectively, whereas for PCP, &lt;em&gt;R&lt;/em&gt;&lt;sub&gt;d&lt;/sub&gt; was somewhat higher (4.28) most likely due to the fact that it&amp;#8217;s nonpolar nature greatly affects its distribution between the solid and aqueous phase. The addition of biochar into the alluvial sediment at a 0.5 % mass ratio significantly increased the retardation of all investigated CPs. The obtained &lt;em&gt;R&lt;/em&gt;&lt;sub&gt;d&lt;/sub&gt; values for 4-CP, 2,4-DCP, 2,4,6-TCP and PCP were 102, 83, 78 and 92, respectively. The general increase in retardation of all investigated CPs can be explained by the increase of organic carbon content in the alluvial sediment by the addition of biochar, which is known to be the main fraction for organic components sorption in sediments and soils. In addition, the enhanced affinity of the alluvial sediment to retain the more polar CPs after biochar amendment indicates that sorption is carried out not only through nonpolar interactions, but also by electrostatic interactions between the CPs and functional groups on the surface of the biochar. The results show that biochar amendment of alluvial sediments could have a great potential for organic contaminants retention in the RBF zone, thus decreasing the risk of groundwater and drinking water sources contamination.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Acknowledgement: &lt;/strong&gt;The authors acknowledge financial support of the Ministry of Education, Science and Technological Development of the Republic of Serbia (Grant No. &amp;#8234;451-03-68/&amp;#8234;2020-14/ 200125). The authors want to express their gratitude to Basna d.o.o. &amp;#268;a&amp;#269;ak for providing the biochar.&lt;/p&gt;


Plants ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1774
Author(s):  
Emmanuelle Demers ◽  
Margit Kõiv-Vainik ◽  
Sara Yavari ◽  
Michel Mench ◽  
Lilian Marchand ◽  
...  

Pentachlorophenol and chromated copper arsenate (CCA) have been used worldwide as wood preservatives, but these compounds can toxify ecosystems when they leach into the soil and water. This study aimed to evaluate the capacity of four treatment wetland macrophytes, Phalaris arundinacea, Typha angustifolia, and two subspecies of Phragmites australis, to tolerate and treat leachates containing wood preservatives. The experiment was conducted using 96 plant pots in 12 tanks filled with three leachate concentrations compared to uncontaminated water. Biomass production and bioaccumulation were measured after 35 and 70 days of exposure. There were no significant effects of leachate contamination concentration on plant biomass for any species. No contaminants were detected in aboveground parts of the macrophytes, precluding their use for phytoextraction within the tested contamination levels. However, all species accumulated As and chlorinated phenols in belowground parts, and this accumulation was more prevalent under a more concentrated leachate. Up to 0.5 mg pentachlorophenol/kg (from 81 µg/L in the leachate) and 50 mg As/kg (from 330 µg/L in the leachate) were accumulated in the belowground biomass. Given their high productivity and tolerance to the contaminants, the tested macrophytes showed phytostabilization potential and could enhance the degradation of phenols from leachates contaminated with wood preservatives in treatment wetlands.


2020 ◽  
Vol 98 ◽  
pp. 134-142
Author(s):  
Tamara Apostolović ◽  
Jelena Tričković ◽  
Marijana Kragulj Isakovski ◽  
Branislav Jović ◽  
Snežana Maletić ◽  
...  

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1349
Author(s):  
Uwe Strotmann ◽  
Daniel Pastor Flores ◽  
Odorico Konrad ◽  
Cornelia Gendig

The activated sludge respiration inhibition test and the luminescent bacteria test with Vibrio fischeri are important bacterial test systems for evaluation of the toxicity of chemical compounds. These test systems were further optimized to result in better handling, reliability and sensitivity. Concerning the Vibrio fischeri test, media components such as yeast extract and bivalent cation concentrations like Ca2+ and Mg2+ were optimized. The cultivation, storage conditions and reactivation process of the stored bacteria were also improved, which enabled simpler handling and led to good reproducibility. Additionally, the respiration inhibition test with a prolonged incubation time was further analyzed using different chlorinated phenols as reference compounds. It could be stated that a longer incubation period significantly improved the sensitivity of the test system.


Catalysts ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 906 ◽  
Author(s):  
Bassem Jamoussi ◽  
Radhouane Chakroun ◽  
Abdelmajid Timoumi ◽  
Khaled Essalah

In this study, a series of new metal phthalocyanines with imidazole function MPc(Imz) (M: Cd, Hg, Zn and Pd) were synthesized to improve the photocatalyst performances. All physical properties such as total energy, HOMO, LUMO energies of MPc(Imz), as well as their vibrational frequencies have been determined by DFT method using B3LYP theory level at 6-311G (d, p) and sdd basis set. The gap of energy level between work function (WF) of ITO and LUMO of PdPc(Imdz) was 1.53 eV and represents the highest barrier beneficial to electron injection compared to WF of ZnPc(Imz), HgPc(Imz), and CdPc(Imz). Furthermore, the PdPc(Imdz) thin films on indium tin oxide (ITO) glass were prepared by spin coating and vacuum evaporation technique, and were characterized by X-ray diffraction (XRD), surface electron morphology (SEM), atomic force microscopy (AFM), and UV–Vis spectroscopy. The photocatalytic activity of the ITO/glass supported thin films and degradation rates of chlorinated phenols in synthetic seawater, under visible light irradiation were optimized to achieve conversions of 80–90%. Experiments on synthetic seawater samples showed that the chloride-specific increase in photodegradation could be attributed to photochemically generated chloride radicals rather than other photoproduced reactive intermediates [e.g., excited-state triplet PdPc(Imz) (3PdPc(Imz)*), reactive oxygen species]. The major 2,3,4,5-Tetrachlorophenol degradation intermediates identified by gas chromatography-mass spectrometry (GC/MS) were 2,3,5-Trichlorophenol, 3,5-dichlorophenol, dichlorodihydroxy-benzene and 3,4,5-trichlorocatechol.


2020 ◽  
Vol 66 (2) ◽  
pp. 180-197
Author(s):  
E. S. Kolpakova ◽  
A. V. Velyamidova

The article presents the results of studies of the environmental properties of organochlorines which differ in properties and origin, in the lake ecosystems of the Bolshezemelskaya tundra (Nenets Autonomous Okrug, Russia). The purpose of this study was to evaluate and assess the levels, distribution characteristics and composition of organochlorines in the bottom sediments of small lakes located in the Adzva river basin in Pymvashor natural boundary (the northernmost location of the exit of thermal-mineral springs of the continental Europe) and in the adjacent area, outside this unique subarctic hydrothermal zone.In order to meet this goal, multi-method (hydrochemical, geochemical, etc.) research was carried out using standard generally approved laboratory practices with their adaptation to the study goals. The quantitative content and composition of the target individual organochlorines were determined by gas chromatographic method with electron-capture detection.The presence of chlorophenol compounds and polychlorinated benzenes (including persistent organic pollutants) was shown in the lakes sediments. The influence of specific microclimatic conditions of subarctic hydrothermal system on the composition and distribution of chlorophenol compounds in lake sediments was considered. In the small lake sediment core in Pymvashor natural boundary a reducing trend in the levels of organochlorines with depth has been recorded (conditioned among other things by the lithological features of bottom sediments). The chlorophenol compounds were found at highest concentrations (619.3–765.5 ng/g) in the sediment upper layers, rich in organic matter; chlorophenol composition was represented mainly by chlorinated phenols, most likely of biotic origin. A lower concentration (185.0 ng/g) of chlorophenol compounds of predominantly abiogenic origin was determined in the lake sediments outside hydrothermal system. The presence and levels of persistent organochlorine pollutants (pentachlorophenol 0.1–2.4 ng/g; hexa- and pentachlorobenzenes 0.4–3.6 ng/g) in the lake sediments were associated with long-range atmospheric transport from various origin sources in nearby regions and low-latitude territories.


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