Enhanced removal of pentachlorophenol by a novel composite: nanoscale zero valent iron immobilized on organobentonite

Nanoscale zero valent iron (NZVI) was immobilized on the organobentonite (CTMA-bent), so as to enhance the reactivity of NZVI and prevent its aggregation. This novel composite (NZVI/CTMA-Bent) was characterized by transmission electron microscope and X-ray diffraction. Good dispersion of NZVI particles on the bentonite was observed. Its performance on removing pentachlorophenol (PCP) was investigated by batch experiments. Results showed NZVI/CTMA-Bent could rapidly and completely dechlorinate PCP to phenol with an efficiency of 96.2%. It was higher than the sum (54.5%) of reduction by NZVI (31.5%) and adsorption by CTMA-Bent (23.0%) separately. The kinetic studies indicated the removal rate of PCP was positively related to the adsorption. We proposed that the adsorption of PCP by CTMA-Bent enhanced the mass transfer of PCP from aqueous to iron surface. Besides, NZVI/CTMA-Bent exhibited good stability and reusability, and CTMA-Bent could also reduce the amount of iron ions released into the solution.     

高压电晕放电对五氯酚的降解研究

研究了放电电压、溶液pH等因素对高压电晕放电降解PCP效果的影响,并对高压电晕放电处理PCP的动力学进行了初步探讨,同时对高压电晕放电降解PCP的COD和TOC的变化进行了分析。结果表明:放电电压和溶液pH值对PCP降解性能影响很大,放电电压和溶液pH值越高,PCP的降解速度越快。当溶液pH值为11.2、PCP初始质量浓度40 mg/L、电晕放电电压为25 kV时,经30 min电晕放电,PCP的降解率达90%以上,电晕放电降解PCP的反应符合一级反应动力学。在氧化过程中PCP可能转化为苯醌等中间产物,TOC几乎无变化,PCP分解成的小分子有机物使COD升高,可生化性提高。     

环境中五氯酚监测研究进展

本文概述了五氯酚(PCP)的环境污染、人群暴露水平及目前有关监测方法研究进展。环境污染主要来源于本品的生产及工农业中的应用。在我国主要广泛用于杀灭血吸虫的中间宿主——钉螺。人体通过污染的空气、水体及食品可摄入PCP造成生物蓄积,危害健康。监测方法有化学法、紫外分光光度法、色谱法、极谱法、电化学检测法等,其中,色谱法简单、灵敏,易于普及使用。     

Mechanochemical removal of organo-chlorinated compounds by inorganic components of soil

The purpose of this work is to evaluate the catalytic efficiency of two metal oxides, ferrihydrite and birnessite and of a ferruginous smectite, towards organic molecules such as 4-chloroaniline (4-CA), pentachlorophenol (PCP), and five polychlorinated biphenyls (PCBs) characterised by different number and position of chlorine atoms. Mechanochemical dry contacts with light grinding between catalytic surfaces and pollutants have been carried out.

The efficiency of the mechanochemical removal was compared with batch experiments for the soluble compounds (PCP and 4-CA). The removal of 4-CA and PCP by the mechanochemical procedure resulted more effective than by batch contact in the presence of birnessite and ferrihydrite, particularly at higher pH (100% removal of 4-CA by birnessite in 30 min at pH 8.6 after the mechanochemical contact compared to 20% removal using the batch interaction at the same pH).

The mechanochemical contact of PCBs and birnessite produced a removal of pollutant that was a function of the number of chlorine atoms (complete removal of 2,2^′-dichlorobiphenyl in 10 days and a removal of 30% and 20% of 2^′,3,4-trichlorobiphenyl and 3,3^′,4,4^′-tetrachlorobiphenyl, respectively in 90 days) and of the position of chlorine atoms about the biphenyl rings (100% of 2,2^′-dichlorobiphenyl in 10 days, 84% of 3,3^′-dichlorobiphenyl in 15 days and 40% of 4,4^′-dichlorobiphenyl in 27 days).     

Enhanced cytotoxicity of pentachlorophenol by perfluorooctane sulfonate or perfluorooctanoic acid in HepG2 cells

Chlorinated phenols and perfluoroalkyl acids (PFAAs) are two kinds of pollutants which are widely present in the environment. Considering liver is the primary toxic target organ for these two groups of chemicals, it is interesting to evaluate the possible joint effects of them on liver. In this work, the combined toxicity of pentachlorophenol (PCP) and perfluorooctane sulfonate (PFOS) or perfluorooctanoic acid (PFOA) were investigated using HepG2 cells. The results indicated that PFOS and PFOA could strengthen PCP’s hepatotoxicity. Further studies showed that rather than intensify the oxidative stress or promote the biotransformation of PCP, PFOS (or PFOA) might lead to strengthening of the oxidative phosphorylation uncoupling of PCP. By measuring the intracellular PCP concentration and the cell membrane properties, it was suggested that PFOS and PFOA could disrupt the plasma membrane and increase the membrane permeability. Thus, more cellular accessibility of PCP was induced when they were co-exposed to PCP and PFOS (or PFOA), leading to increased cytotoxicity. Further research is warranted to better understand the combined toxicity of PFAAs and other environmental pollutants.     

Release of pentachlorophenol from black carbon-inclusive sediments under different environmental conditions

To investigate the feasibility of using black carbon (BC) in the control of hydrophobic organic contaminants (HOCs) in sediment, we added BCs from various sources (rice straw charcoal (RC), fly ash (FC) and soot (SC)) to sediment to create different BC-inclusive sediments and studied the release of pentachlorophenol (PCP) in the sediments under different condition. Different pH values had no obvious effect on the release of PCP in BC-inclusive sediment, but solid/liquid ratio, temperature, salinity and dissolved organic matter (DOM) content had significant influences on the release of PCP in all sediments except the RC-inclusive sediment. Adding 2% RC to sediment resulted in a 90% decrease in PCP release, which was a greater decrease than observed with FC- and SC-inclusive sediments. Therefore, from the standpoint of HOC release, the application of RC is feasible for organic pollution control in the water environment.     

Preparations and properties of transformation products of pentachlorophenol (PCP)

The present paper describes preparations and properties of pentachlorophenol derivatives.     

γ辐照和H2O2联合作用下五氯酚(PCP)的降解

研究了水溶液中的五氯酚(PCP)在γ辐照和过氧化氢(H2O2)联合作用下的降解.PCP的初始浓度为27.7 mg·L-1,外加H2O2的初始浓度为0、50和100 mg·L-1.结果表明,PCP在不同条件下的辐照降解符合准一级动力学方程.当外加H2O2的初始浓度在0～100 mg·L-1时,PCP的去除率、矿化率和脱氯...     

Immobilization of pentachlorophenol in soil using carbonaceous material amendments

In this study, three pentachlorophenol (PCP) laboratory-spiked and one field-contaminated soil were amended with 2.0% char, humic acid (HA) and peat, respectively. The amended soils were aged for either 7 or 250 days. After amendment, CaCl₂ extractability of PCP was significantly decreased. Desorption kinetics indicated that the proposed amendment could lead to a strong binding and slow desorption of PCP in soils. Amendment with char reduced the bioaccumulation factor (BAF) of PCP most significantly for earthworms (Eisenia fetida) in all soils studied. The results of both physicochemical and biological tests suggested that amendment reduced PCP bioavailability quickly and enduringly, implying that carbonaceous material amendment, especially char amendment, was a potentially attractive in situ remediation method for sequestration of PCP in contaminated soil.