Destruction/removal of polychlorinated biphenyls from non-polar media. Reaction of PCB with poly (ethylene glycol)/KOH

We have found that polychlorinated biphenyls (PCB's) and other unactivated chlorobenzenes react with poly (ethylene glycols) and potassium hydroxide under mild conditions. Complete reaction with PEG occurs at 75–120°C in under two hours, to produce aryl polyglycols, the products of nucleophilic aromatic substitution. This reaction has been applied to the destruction and removal of PCB's from non-polar media, including transformer oil.     

Background levels of polychlorinated biphenyls in British soils

The concentrations of PCBs in soil samples collected at rural and urban locations in Britain are reported. PCBs were detected in all samples analysed, within the range 2.3 to 444 μg kg⁻¹ (ppb), with a mean concentration of 22.8 μg kg⁻¹ and a median value of 7.2 μg kg⁻¹. A distinct sub-group of samples has a range of 2.3 to 19.2 μg kg⁻¹, with a mean of 7.5 μg kg⁻¹ and a median value of 6.8 μg kg⁻¹. These values are consistent with published data from other industrialised countries. Measurement was carried out using a two stage clean-up of soil extracts, with concentrated sulphuric acid and florisil, followed by gas chromatography and electron capture detection.     

Effect of metal and glycol on mechanochemical dechlorination of polychlorinated biphenyls (PCBs)

This paper assesses the potential of mechanochemical method with fine metal powder, glycol and alkali for polychlorinated biphenyls (PCBs) removal from waste insulating oil. The effects of relevant parameters, such as kinds of chemicals, rate and time of milling were examined. After each run, the total PCBs content in waste insulating oil was measured. Polyethylene glycol 200, long chain-glycol was more effective than triethylene glycol and ethylene glycol, short chain-glycol as hydrogen donor in mechanochemical dechlorination of PCBs. A maximum of 99.9% PCBs removal (below 2ppm) and 94% total chlorine removal were achieved with the mechanochemical process for 2h.     

鼠李糖脂洗脱土壤中多氯联苯影响因素的研究

研究了由铜绿假单胞菌发酵产生的代表性生物表面活性剂鼠李糖脂（RL）对土壤中PCBs解吸的影响。结果表明,RL的种类与浓度、土壤污染类型、解吸时间、洗脱次数、pH以及离子强度对土壤中PCBs的洗脱有一定的影响,而温度对PCBs的洗脱影响很小。当RL浓度低于CMC时,对PCBs的洗脱没有明显的促进作用;当RL浓度高于CMC后,对PCBs的洗脱有显著的促进作用。具有较低HLB的单鼠李糖脂R2对PCBs的洗脱效果要优于二鼠李糖脂R1。人工污染土壤中PCBs的洗脱效果要高于陈化土壤。污染土壤中TOC的含量越高,PCBs的洗脱率越低。延长解吸时间和增加洗脱次数可增加土壤中PCBs的洗脱率。碱性环境（pH＞7）或增加RL溶液中的离子强度均有利于土壤中PCBs的洗脱。     

Organochlorine pesticides and polychlorinated biphenyls in soils surrounding the Tanggu Chemical Industrial District of Tianjin, China

The spatial distribution of persistent organic pollutants (POPs) was examined in soils surrounding the Tanggu Chemical Industrial District in Tianjin, China. The concentrations of hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs), hexachlorobenzenes (HCBs), and polychlorinated biphenyls (PCBs) were determined in 70 surface soils using accelerated solvent extraction and gas chromatography with electron capture detection. The results showed that the ranges of ∑HCH, ∑DDT, ΣHCB, and ∑PCB concentrations in soils were 2.1–12,549 μg?kg^?1 (average, 965 μg?kg^?1), n.d.–2,033 μg?kg^?1 (average, 88.4 μg?kg^?1), n.d.–1,924 μg?kg^?1 (average, 349 μg?kg^?1), and n.d.–373 μg?kg^?1 (average, 46.2 μg?kg^?1), respectively. Of these, HCHs were the dominant POPs, accounting for 75 % of the total organochlorine pesticide (OCP) residues. Overall, the spatial distribution of OCP concentrations showed a decreasing trend from the center of the Tanggu District to the surrounding areas. Two major pollution sources were Tianjin Dagu Chemical Co., Ltd. in the district center and the Tianjin Chemical Plant in Hangu District. In contrast, PCB concentrations were relatively high in the Haihe estuary to the east and low to the west of the study area. Component analysis of OCPs in these soils showed that they mainly came from industrial point sources. Compared with soils in other regions, soil DDT pollution was at a medium level in the Tanggu Chemical Industrial District, but associated HCH, HCB, and PCB pollution was relatively heavy. By multivariate statistical analyses, Tianjin Dagu Chemical Co., Ltd. was recognized as the main source of POPs, and soil properties were clarified to play an important role on the distribution and composition of POPs, especially the organic carbon content.     

Persistence and fate of polychlorinated biphenyls (PCBs) in sewage sludge-amended agricultural soils

Four metal enriched sewage sludges containing different concentrations of polychlorinated biphenyls (PCBs) were applied to two field soils in the UK in 1968. Samples of the sludges, sludge-amended soils and soils from untreated control plots were stored and analysed retrospectively. Sludge concentrations ranged from 1 to 7 mg SigmaPCB kg(-1). The pattern of PCBs was similar in three of the four sludges, with congeners 14, 18, 28 and 52 present at the highest concentrations. The fourth sludge contained higher amounts of congeners 149, 153, 138 and 180. SigmaPCB concentrations in control plot soil have declined over the last 20 years, indicating a reduction in atmospheric deposition inputs of PCBs to the soil. SigmaPCB concentrations also declined on the sludge-amended plots, reaching control plot concentrations (30-60 microg SigmaPCB kg(-1)) in the late-1980s. Half-lives ranged from < 1 to 8.5 years for congeners 18, 28 and SigmaPCB. Biodegradation and/or the formation of reversibly sorbed soil PCB residues could not account for the losses observed. Volatilisation is implicated as the most important loss process on both the control and sludge-amended plots. Using the fugacity approach, congener concentrations in soils at Luddington were predicted still to have not reached equilibrium with the air. Further losses to the atmosphere are likely.     

生物与化学表面活性剂协同洗脱土壤中PCBs的研究

通过序批实验和土柱淋洗实验研究了由生物表面活性剂鼠李糖脂(RL)与非离子化学表面活性剂十二烷基醇聚氧乙烯(6)醚(POE(6))混合得到的复配试剂洗脱污染土壤中多氯联苯(PCBs)的作用效果及其作用机理。结果表明,同一土样中,从批实验得到的PCBs洗脱率略高于土柱淋洗实验。RL与POE(6)两种单一试剂对人工污染土样中的PCBs洗脱率均大于60%,而对陈化土样中的洗脱率均不到20%,且土壤中的TOC含量越高,PCBs的洗脱率越低。在质量浓度为301 mg/L(10 CMC)及1 505 mg/L(50 CMC)的RL-POE(6)复配试剂中,RL与POE(6)对人工污染土壤中PCBs的洗脱具有一定的协同作用。当复配试剂的浓度为301 mg/L时,RL与POE(6)对陈化土样中PCBs的洗脱没有协同作用;但当RL-POE(6)的浓度增加到1 505 mg/L时,RL与POE(6)对陈化土样中PCBs的洗脱具有明显的协同作用。     

The variability of polychlorinated biphenyls levels in urban soils from five European cities

The concentration of PCBs in topsoils from five European cities was assessed and the highest levels were found in Glasgow (Scotland), followed by Torino (Italy), Aveiro (Portugal), Ljubljana (Slovenia) and Uppsala (Sweden). All cities showed the presence of local sources in addition to diffuse contamination from global atmospheric transport. The association of general soil parameters with PCBs in Glasgow and with heavier congeners in Torino and Ljubljana indicates that retention of these compounds is occurring. The profiles obtained resemble Aroclor 1254 and 1260, which are important local sources. Nevertheless, differences in PCB profiles were observed among cities, due to the combined effects of the age of the contamination (which determines the time available for volatilisation and degradation), different sources of PCBs and differences in climate (which influence volatilisation and deposition).     

混合洗脱剂对土壤中重金属和多氯联苯的同步高效洗脱

针对电子垃圾拆解、焚烧场地周边污染土壤中的重金属和疏水性有机物的复合污染问题,对重金属和有机物同步高效洗脱方法进行了研究。将皂素、吐温-80和柠檬酸按照不同浓度配比组合并制成混合洗脱剂,采用批量平衡振荡的方法,研究其对Cu、Pb、Cd和多氯联苯（PCBs）复合污染土壤的洗脱效果,以及浓度配比、pH和洗脱时间对洗脱效果的影响,并找出最优的洗脱条件。结果表明：在混合洗脱剂中皂素、吐温-80和柠檬酸的浓度分别为12、10和5 g·L-1,pH值为5,批量平衡振荡洗脱时间为6 h的条件下,洗脱效果最佳,对Cu、Pb、Cd和PCBs的洗脱率分别为88.32%、82.75%、94.89%和80.56%,实现了复合污染土壤中重金属和疏水性有机物的同步高效洗脱。     

Analysis of 4-nonylphenols, phthalates, and polychlorinated biphenyls in soils and biosolids

When sewage sludge is added to agricultural land, organic chemicals contaminants are also added. The fate of these chemicals, particularly those shown to have oestrogenic potential, has received much research and regulatory interest in recent years. A method was developed for the analysis of 4-nonylphenols, phthalates, and PCB congeners in soils, mesophilic anaerobially digested dewatered (MADD) sewage sludge, and MADD sludge-amended soil. After Soxhlet-extraction, the 4-nonylphenols and phthalates were separated from the PCBs on an isolute cyanopropyl SPE cartridge and analysed by GC-MS directly. The PCBs were acid treated on a Bakerbond PCB-A cartridge, then passed through a gel filtration column of Biobeads SX-3 resin, before GC-MS analysis. The method was successfully validated and then used for routine analysis, where average recoveries of the surrogate standards were 83+/-17% (4-n-heptylphenol), 96+/-11% (dimethyl-tere-phthalate), 101+/-12% (dibenzyl-phthalate), and 79+/-13% (PCBs 6, 54, 104, 155, and 198).     

Elementary reaction path on polychlorinated biphenyls formation from polychlorinated benzenes in heterogeneous phase using ab initio molecular orbital calculation

We have investigated the elementary reaction path on the 3,3',4,4',5,5'-hexachlorinated biphenyl (HxCB) formation from two 1,2,3,5-tetrachlorobenzenes (TCBz) and the catalytic role of copper on this formation using ab initio molecular orbital calculation. The elementary reaction path on the 3,3',4,4',5,5'-HxCB formation from two 1,2,3,5-TCBzs has been shown to occur as follows: Step 1--the dissociation of Cl atom substituted at 5-position in 1,2,3,5-TCBz, Step 2--the association between Cl atom substituted at 5-position in another 1,2,3,5-TCBz and the Cl radical formed in Step 1, Step 3-the elimination of Cl2 molecule from the intermediate species formed in Step 2, and Step 4--the 3,3',4,4',5,5'-HxCB formation from the direct condensation of two 1,2,3-trichlorophenyl radicals formed in Step 1 and Step 3. The geometric factor, which decides the reactivity of this formation, is the C-Cl bond strength of 1,2,3,5-TCBz. The catalytic roles of copper are to stabilize the total energy in the adsorption of 1,2,3,5-TCBz onto the copper surface and to weaken the C-Cl bond strength due to the charge transfer from the 1,2,3,5-TCBz to the copper surface. Moreover, we have achieved the prediction of the minimum energy path on the formation of non- and mono-ortho polychlorinated biphenyls congeners for which TEFs have been determined.     

Characterization of polychlorinated biphenyls and brominated flame retardants in surface soils from Surabaya, Indonesia

In this study, soil contamination by PCBs, PBDEs, HBCDs and two novel BFRs such as 1,2-bis-(2,4,6-tribromopenoxy) ethane (BTBPE) and decabromodiphenyl ethane (DBDPE) in various locations such as industrial, urban, rural, dumping site and agricultural areas of Surabaya, Indonesia has been characterized in order to evaluate their contamination status, profiles, potential sources, fate and behavior. Range and median concentrations of PCBs, PBDEs, HBCDs, BTBPE and DBDPE were ND - 9.6 (1.2), 0.069 - 24 (7.4), ND - 1.8 (0.48), ND - 1.7 (0.14) and ND - 7.6 (2.2) ng g⁻¹ dw, respectively. Industrial, urban and dumping areas were inventoried as the main sources of these pollutants. Decreasing gradient levels were observed for these contaminants from industrial district, urban, dumping site, rural and agricultural areas, in that order. Furthermore, organic carbon contents and proximity to the point sources were found as the major controlling factors. Contaminant profiles were characterized by the predominance of hexa-, hepta- and penta-homologues for PCBs; deca-, nona- and octa- for PBDEs and α-isomer for HBCDs. Product mixtures such as Ar1260/KC600 and Ar1254/KC500 for PCBs, deca- and octa-BDEs for PBDEs were the possible common formulations used in study area. To our knowledge, this is a first comprehensive study on characterization of soil contamination by PCBs, PBDEs and HBCDs together with two novel BFRs in a highly industrialized city located in tropical region. This study provides baseline information for establishing national monitoring programs in Indonesia.     

Kinetics on the decomposition of polychlorinated biphenyls with activated carbon-supported iron

The process of destroying polychlorinated biphenyls (PCBs) generates exhaust gases that contain low quantities of PCBs, which cannot be disposed of easily. Activated carbon (AC) can be used to adsorb residual PCBs after disposal of high-level PCBs. We examined the chemical reactivity of AC-supported iron as a catalyst to decompose PCB-153, and varied three decomposition parameters (temperature, time and iron concentration) under an atmosphere of either air or N(2). We measured the Brunauer-Emmett-Teller (BET) surface area and pore volume of AC to assess the adsorption capacity of AC before and after decomposition. At low temperatures the adsorption process was more important than the decomposition process. The decomposition process was completed within 30 and 60 min under air and N(2), respectively. The efficiency of PCB-153 decomposition at 350 degrees C for 120 min was approximately 100.0% and 97.1% under air and N(2), respectively. Analysis of inorganic chloride ions revealed that PCB-153 was effectively destroyed during decomposition. The differences between decomposition under air and N(2) reflected differences in BET surface and pore volume.     

Levels, distributions and profiles of polychlorinated biphenyls in surface soils of Dalian, China

Surface soil (0-5cm) samples from 14 sampling sites including rural and urban areas of Dalian, a coastal city in Liaoning Province, China, were collected and analyzed for 84 polychlorinated biphenyls (PCBs). Total 57 PCB congeners were identified and mean concentration of total PCBs among all the sites was 2.8mugkg(-1) dry weight (dw) with a range of 1.3 (rural site) to 4.8mugkg(-1)dw (urban site). For the urban sites, total PCB concentrations in the soil samples collected in industrial area are highest, followed by those from business/residential sites and the garden sites, but the differences are not significant. Higher percentage of lighter weighted molecular PCBs were found in the rural site than urban sites in Dalian, possibly indicating the "urban fractionation effect". Total seven dioxin-like PCBs (CB-77, 81, 105, 114, 118, 123, and 126) have been found in Dalian soils and the mean concentration (in mugkg(-1)dw) among all the sites of CB-105 (0.17) is higher than any other dioxin-like PCBs, followed by that for CB-81 (0.14) and for 118 (0.06). No significant correlation relationship between the concentrations of dioxin-like PCBs and those of total PCBs was found. The toxic equivalency (TEQ) concentrations (in ngkg(-1)dw) of these seven dioxin-like PCBs in 14 soil samples range from 0.006(7) to 4.885(7) (with a mean 1.372(7)) for humans and mammals, from 0.001(7) to 0.37(7) (with a mean 0.14(7)) for fish, and from 0.01(7) to 31.47(7) (with a mean 17.23(7)) for birds.     

Distribution, source and risk assessment of polychlorinated biphenyls (PCBs) in urban soils of Beijing, China

The concentration of PCBs in urban soils of Beijing across six land types including business districts (BD), cultural and educational areas (CE), classical gardens (CG), public green (PG), residential areas (RA), and roadsides (RD) was investigated. The total concentrations of PCBs ranged from below method detection limit (M.D.L.) to 37.11 × 10⁻³ mg kg⁻¹ dry weight (mean: 11.70 × 10⁻³ mg kg⁻¹; median: 13.28 × 10⁻³ mg kg⁻¹), which was at a medium level compared with other cities around the world. In general, the levels of PCBs decreased from the center of Beijing city to the suburb, suggesting the increasing PCBs concentrations with the age of the urban area. For different types of land use, the highest level of PCBs was observed in CG soils which have the oldest age, and the homologue profiles were similar, which were predominated by lowly chlorinated congeners including di-, tri- and tetra-CBs. Principal component analysis indicated that local sources such as Aroclor 1016, 1242, and 1248 were important sources in addition to long-range transport of PCBs all over the world. Although the toxic equivalency (TEQ) concentrations of dioxin-like PCBs in all soil samples of Beijing were higher than those in other urban areas of China, they met the Canadian soil quality standard.     

Synthesis of polychlorinated biphenyls (PCBs) using the Suzuki-coupling

An improved synthesis of polychlorinated biphenyls (PCBs) utilizing a palladium-catalyzed cross-coupling reaction (Suzuki-coupling) is described. The coupling of (chlorinated) aryl boronic acids 1-3 with bromochlorobenzenes 4 using the standard conditions of the Suzuki-coupling gave the desired PCB congeners 5-7 in good to excellent yields. The self-coupling product of the aryl boronic acids is the major impurity of this reaction. 3,4,5-trichlorophenyl derivatives such as 10 can be synthesized by coupling of an aryl boronic acid with the corresponding bromochloroaniline 8. The approach offers the advantage of high selectivity and good yields compared to conventional methods such as the Cadogan reaction and allows the use of less toxic starting materials.     

Sources and toxicities of phenolic polychlorinated biphenyls (OH-PCBs)

Polychlorinated biphenyls (PCBs), a group of 209 congeners that differ in the number and position of chlorines on the biphenyl ring, are anthropogenic chemicals that belong to the persistent organic pollutants (POPs). For many years, PCBs have been a topic of interest because of their biomagnification in the food chain and their environmental persistence. PCBs with fewer chlorine atoms, however, are less persistent and more susceptible to metabolic attack, giving rise to chemicals characterized by the addition of one or more hydroxyl groups to the chlorinated biphenyl skeleton, collectively known as hydroxylated PCBs (OH-PCBs). In animals and plants, this biotransformation of PCBs to OH-PCBs is primarily carried out by cytochrome P-450-dependent monooxygenases. One of the reasons for infrequent detection of lower chlorinated PCBs in serum and other biological matrices is their shorter half-lives, and their metabolic transformation, resulting in OH-PCBs or their conjugates, such as sulfates and glucuronides, or macromolecule adducts. Recent biomonitoring studies have reported the presence of OH-PCBs in human serum. The occurrence of OH-PCBs, the size of this group (there are 837 mono-hydroxyl PCBs alone), and their wide spectra of physical characteristics (pKa’s and log P’s ranging over 5 to 6 orders of magnitude) give rise to a multiplicity of biological effects. Among those are bioactivation to electrophilic metabolites that can form covalent adducts with DNA and other macromolecules, interference with hormonal signaling, inhibition of enzymes that regulate cellular concentrations of active hormones, and interference with the transport of hormones. This new information creates an urgent need for a new perspective on these often overlooked metabolites.     

Development of controlled release formulations of azadirachtin-A employing poly(ethylene glycol) based amphiphilic copolymers

Controlled release (CR) formulations of azadirachtin-A, a bioactive constituent derived from the seed of Azadirachta indica A. Juss (Meliaceae), have been prepared using commercially available polyvinyl chloride, polyethylene glycol (PEG) and laboratory synthesized poly ethylene glycol–based amphiphilic copolymers. Copolymers of polyethylene glycol and various dimethyl esters, which self assemble into nano micellar aggregates in aqueous media, have been synthesized. The kinetics of azadirachtin-A, release in water from the different formulations was studied. Release from the commercial polyethylene glycol (PEG) formulation was faster than the other CR formulations. The rate of release of encapsulated azadirachtin-A from nano micellar aggregates is reduced by increasing the molecular weight of PEG. The diffusion exponent (n value) of azadirachtin-A, in water ranged from 0.47 to 1.18 in the tested formulations. The release was diffusion controlled with a half release time (t_1/2) of 3.05 to 42.80 days in water from different matrices. The results suggest that depending upon the polymer matrix used, the application rate of azadirachtin-A can be optimized to achieve insect control at the desired level and period.     

Chemical recycling of poly(ethylene terephthalate) (pet) by hydrolysis and glycolysis

In this paper we review an interesting method of PET recycling, i.e. chemical recycling; it is based on the concept of depolymerizing the condensation polymer through solvolytic chain cleavage into low molecular products which can be purified and reused as raw materials for the production of high-quality chemical products. In this work our attention is confined to the hydrolysis (neutral, acid and alkaline) and glycolysis processes of PET chemical recycling; operating conditions and mechanism of each method are reported and described. The neutral hydrolysis has an auto accelerating character; two kinetic models have been proposed: an half-order and a second order kinetic model. The acid hydrolysis could be explained by a modified shrinking core model under chemical reaction control and the alkaline hydrolysis by a first-order model with respect to hydroxide ion concentration. To describe glycolysis, two different kinetic models have been proposed where EG can act or not as internal catalyst. Further experimental and theoretical investigations are required to shed light on the promising processes of PET chemical recycling reviewed in this work.     

Detailed study on the levels of polychlorinated dibenzo-p-dioxins,polychlorinated dibenzofurans and polychlorinated biphenyls in Yusho rice oil

One bottle of Yusho rice oil was obtained from a Yusho family in 1998. The levels of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) in the causal oil were investigated with two different approaches and the individual concentrations of all the 17 2,3,7,8-substituted PCDD/F and 14 coplanar PCB (Co-PCB) congeners were elucidated for the first time. The concentrations of PCDDs and PCDFs were found to be 0.60 and 8.8 ppm, respectively. For PCBs, more than 130 PCB peaks were observed and a total concentration of 850 ppm including 170 ppm of Co-PCBs was obtained. The toxic equivalents (TEQs) of PCDDs, PCDFs, and Co-PCBs were calculated to be 17, 470, and 120 ppb, respectively. The relative contribution of these classes to the total TEQ in Yusho oil is 3%, 77%, and 20%, respectively, indicating that PCDFs play a major role in the toxicity of Yusho oil. Furthermore, it was confirmed that 2,3,4,7,8-penta-CDF contributes 58% to the total TEQ, supporting the view that this compound is the principal causal agent in Yusho poisoning. It is noteworthy that the most toxic 2,3,7,8-tetra-CDD was newly discovered, although it contributes only 0.1% to the total TEQ. Based on our data, the smallest TEQ intake during the latent period was estimated to be 0.067 mg for Yusho patients. This value is about 60% of that previously reported, suggesting a lower minimum threshold level for the development of the toxic symptoms of Yusho.