Efficient removal of organic pollutant by activation of persulfate with magnetic Co3O4/CoFe2O4 composite

In this study, magnetic spinel Co₃O₄/CoFe₂O₄ composite were synthesized by the mechanical mixing of both powdered pristine samples. Then the catalyst was characterized by TEM, SEM, XRD, BET, XPS and VSM measurement. Next, Co₃O₄/CoFe₂O₄ composite was applied to degrade rhodamine B (RhB) in water by activating persulfate. Results showed that Co₃O₄/CoFe₂O₄ composite exhibited high efficiency for removal of RhB, and 95.59% of it could be degraded in 45 min. Besides, the effects of parameters, such as initial pH, PS dosage, Co₃O₄/CoFe₂O₄ composite dosage, initial concentration of RhB and temperture were studied. Also, the effects of coexisting anions on RhB degradation were observed and explained. Furthermore, we conducted the quenching experiment and found that sulfate radical and hydroxyl radicals were the main active radicals in the degradation process. Finally, recycle experiments proved that Co₃O₄/CoFe₂O₄ had a good stability for RhB degradation. In short, Co₃O₄/CoFe₂O₄ composite is a promising catalyst for wastewater treatment.     

Combustion synthesis of mesoporous CoAl2O4 for peroxymonosulfate activation to degrade organic pollutants

A mesoporous cobalt aluminate (CoAl₂O₄) spinel is synthesized through a combustion method and adopted for the activation of peroxymonosulfate (PMS) to degrade organic pollutants. Multiple characterization procedures are conducted to investigate the morphology and physicochemical properties of the CoAl₂O₄ spinel. Due to its mesoporous structure, large surface area, and high electrical conductivity, the obtained CoAl₂O₄ exhibits remarkable catalytic activity for Rhodamine B (RhB) degradation. Its RhB degradation rate is 89.0 and 10.5 times greater than those of Co₃O₄ and CoAl₂O₄ spinel prepared by a precipitation method, respectively. Moreover, the mesoporous CoAl₂O₄ spinel demonstrates a broad operating pH range and excellent recyclability. The influence of several parameters (catalyst amount, PMS concentration, initial pH, and coexisting inorganic anions) on the oxidation of RhB is evaluated. Through quenching tests and electron paramagnetic resonance experiments, sulfate radicals are identified as the predominant reactive species in RhB degradation. This paper provides new insights for the development of efficient, stable, and reusable cobalt-based heterogeneous catalysts and promotes the application of persulfate activation technology for the treatment of refractory organic wastewater.     

Separation and preconcentration of persistent organic pollutants by cloud point extraction

Persistent organic pollutants (POPs) are recognized as a class of poisonous compounds which pose risks of causing adverse effects to human health and the environment. Thus, it is very important to detect POPs in environmental and biological samples. The identification and determination of very low levels of POPs in complex matrices is extremely difficult. Recently a promising environmentally benign extraction and preconcentration methodology based on cloud point extraction (CPE) has emerged as an efficient sample pretreatment technique for the determination of trace/ultra-trace POPs in complex matrices. The purpose of this paper is to review the past and latest use of CPE for preconcentrating POPs and its coupling to different contemporary instrumental methods of analysis. First, the comparison of various extraction techniques for POPs is described. Next, the general concept, influence factors and other methods associated with CPE technique are outlined and described. Last, the hyphenations of CPE to various instrumental methods for their determination are summarized and discussed.     

难降解有机废水的催化氧化法处理

催化氧化法可通过多种途径来加强传统的化学法处理效果，目前已成为难降解有机废水处理的一项重要新技术。本文介绍了光催化氧化法、均相氧化法、多相氧化法(包括电催化氧化法)以及超临界水氧化技术的国内外研究现状及特点，并对其在有机废水中的应用情况和发展前景作了扼要评述。     

Multi-determination of organic pollutants in water by gas chromatography coupled to triple quadrupole mass spectrometry

A multi-determination method has been developed for the determination and confirmation of 68 organic pollutants in water samples by gas chromatography coupled to triple quadrupole mass spectrometry (GC-MS/MS). The following chemical families were determined in a chromatographic run of less than 26?min: polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenylethers (PBDEs), and pesticides (organochlorine, organophosphorus, triazine and others). The sample preparation involved a liquid-liquid extraction (LLE) procedure, obtaining recoveries ranging from 70 to 130% when dichloromethane was used as the extracting solvent. The detection limits of the proposed method were between 0.75 and 19.8?ng?L^?1. Samples from the Maipo River in central Chile were taken from 29 different points. Seven pesticides and two PAHs were detected in field collected samples with concentrations ranging from 10 to 95?ngL^?1. Concentrations of benzo[a]pyrene in environmental samples ranged from 25 to 33?ngL^?1 and were near the maximum levels established by the European Union Directives (50?ng?L^?1).     

Direct analysis of bottom sediments by a microcoulometric titration method for determination of total organic halide pollutants

Up to now the content of the organic halides in sediments was measured as extractable organic halides compounds by different methods including microcoulometric titration one. We describe a procedure for microcoulometric determination of total organic halide pollutants by using a direct combustion of the sediments into the microcoulometric system furnace. An accelerated removal of the inorganic chlorides by reaction with potassium nitrate using ultrasonic radiation was attained. The procedure was validated for analysis of bottom sediments from natural and anthropogenic sources. The repeatability RSD = 8.5%, the expanded relative uncertainty U (n = 7, P = 95%, k = 2) = 6.4%, the reproducibility RSD was within the range 10.0–7.3%, the average recovery R = 97.6% and method LOD = 11 mg kg⁻¹ Cl. Correspondence: Zara V. Aneva, Analytical Department, University “Prof. Dr. Assen Zlatarov”, Nr. 1 Prof. Yakimov street, 8010 Bourgas, Bulgaria     

Simultaneous determination of low-molecular-weight organic acids and chlorinated acid herbicides in environmental water by a portable CE system with contactless conductivity detection

This report describes a method to simultaneously determine 11 low-molecular-weight (LMW) organic acids and 16 chlorinated acid herbicides within a single run by a portable CE system with contactless conductivity detection (CCD) in a poly(vinyl alcohol) (PVA)-coated capillary. Under the optimized condition, the LODs of CE-CCD ranged from 0.056 to 0.270 ppm, which were better than for indirect UV (IUV) detection of the 11 LMW organic acids or UV detection of the 16 chlorinated acid herbicides. Combined with an on-line field-amplified sample stacking (FASS) procedure, sensitivity enhancement of 632- to 1078-fold was achieved, with satisfactory reproducibility (RSDs of migration times less than 2.2%, and RSDs of peak areas less than 5.1%). The FASS-CE-CCD method was successfully applied to determine the two groups of acidic pollutants in two kinds of environmental water samples. The portable CE-CCD system shows advantages such as simplicity, cost effectiveness, and miniaturization. Therefore, the method presented in this report has great potential for onsite analysis of various pollutants at the trace level.     

Analysis of 51 persistent organic pollutants in soil by means of ultrasonic solvent extraction and stir bar sorptive extraction GC-MS

A novel method based on ultrasonic solvent extraction and stir bar sorptive extraction (SBSE) for the analysis of 51 persistent organic pollutants including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and polybrominated diphenylethers (PBDEs) in soil samples was developed. The different parameters that affect both the extraction of analytes from the soil samples, such as solvent selection, solvent volume, mass of soil, and extraction time, and the partitioning from the solvent/water mixture to the PDMS were studied. The final selected conditions consisted of the extraction of 1 g of soil with 15 mL methanol by sonication for 30 min. The methanol extract was mixed with 85 mL of Milli-Q water and extracted by means of SBSE for 14 h at 900 rpm. The stir bars were analyzed by thermal desorption-GC-mass spectometry (TD-GC-MS). The effects of the matrix on the recovery of the various pollutants under the developed method were studied using two soils with very different physicochemical properties. Method sensitivity, linearity, repeatability, and reproducibility were also studied. Validation and accuracy of the method were conducted by analyzing two commercial certified reference materials (CRMs). The main advantage of this method resides in the fact that a small amount of a nontoxic solvent (methanol) is needed for the extraction of only 1 g of solid sample allowing LODs ranging from 0.01 to 2.0 microg/kg. Repeatability and reproducibility variations were lower than 20% for all investigated compounds. Results of the CRMs verify the high accuracy of this method.     

高效液相色谱-串联质谱法同时测定水中13种有机污染物

以地表水环境质量标准严格控制的特定项目为依据,建立了直接进样-高效液相色谱-串联质谱同时测定水中13种化学性质差异较大的有机污染物的分析方法,这13种有机污染物为乐果、敌敌畏、敌百虫、对硫磷、甲基对硫磷、马拉硫磷、内吸磷、丙烯酰胺、苯胺、联苯胺、甲萘威、微囊藻毒素-LR、阿特拉津。水样经0.22 μm尼龙66滤膜过滤后,采用Kromasil 100-5 C18柱(150 mm×2.1 mm, 5 μm)分离,以甲醇-0.01%甲酸水溶液为流动相进行梯度洗脱,流速0.5 mL/min,柱温40 ℃,电喷雾正离子模式(ESI⁺)电离,多反应监测模式(MRM)进行检测,外标法定量。13种化合物的浓度与其峰面积在一定浓度范围内均呈现良好的线性关系(r≥0.9995),方法检出限为0.02~0.1 μg/L。测定低、中、高浓度的加标样品,13种化合物的相对标准偏差为0.5%~5.0%(n=6),实际样品加标平均回收率为81.2%~112%。此方法灵敏度高、干扰小、分析速度快,可适用于地表水、地下水中这13种有机污染物的同时分析。     

One stone two birds: Degradation of persistent organic pollutants to a valuable industrial chemical production of pentafluoropropionyl fluoride from HFPO oligomers catalyzed by cesium fluoride in tetraglyme

Hexafluoropropylene oxide (HFPO) oligomers are toxic, bioaccumulative, and persistent organic pollutants (POPs). Consuming the harmful chemicals to prevent them from releasing to nature is of serious significance as far as both natural environments and human health are concerned. In this study, investigation on degradation of HFPO oligomers to pentafluoropropionyl fluoride (PPF), a valuable industrial chemical, is reported. Different combinations of alkali metal fluoride in either diglyme or tetraglyme under both flask and batch autoclave conditions were examined. Under the optimal reaction conditions, HFPO oligomers (n = 2-10) were completely degraded to PPF in over 90% yield. Reactions on 200 g scale were tested and no deduction of efficiency was observed, which indicates the potential for practical industrial application of this chemistry.     

保留时间两点校正反相高效液相色谱法测定持久性有机污染物的正辛醇-水分配系数

采用改进的反相高效液相色谱法(RP-HPLC)测定了持久性有机污染物(POPs)包括多环芳烃(PAHs)、多氯二苯并二恶英(PCDDs)、多氯二苯并呋喃(PCDFs)和十溴二苯乙烷(DBDPE)等的正辛醇-水分配系数(logKow)。采用保留时间双点校正法(DP-RTC)校正因色谱柱老化等引起的保留时间漂移。以37种有可靠logKow实验值的苯系物、PAHs、PCDD/Fs类似物为模型化合物,建立了logKow和外推至纯水相的保留因子logkw的定量结构-色谱保留关系(QSRR)模型,回归方程为logKow=(1.18±0.02)logkw+(0.36±0.11),其相关系数(R2)为0.985,交叉验证相关系数(R2cv)为0.983,标准偏差(SD)为0.16。进而,用4个已有可靠logKow实验值的验证化合物(联苯、芴、PCDD 1和PCDF 114)对模型进行了外部验证,表明RP-HPLC测得的logKow值与摇瓶法/慢搅法结果有很好的一致性,尤其是对疏水性强的化合物。采用该模型测定了29种特别受关注的POPs的logKow值,这些化合物的logKow实验值均未见报道。所建立的DP-RTC-HPLC是测定强疏水性POPs的logKow值的一种值得推荐的方法。