Effect of ozonization in degradation of trifluralin residues in aqueous and food matrices

Abstract

This study investigates the oxidation of trifluralin residues during ozonation in aqueous and food matrices (tomato). Domestic ozonation equipment with average production of 23.9?mg O₃ L^?1 h^?1 was used in the tests. Modern chromatographic systems (SPME-GC-IT/MS/MS and QuEChERS-GC-IT/MS/MS) were applied for extraction and detection of trifluralin residue in fortified samples of ultrapure water, tap water, superficial water and tomato fruit. The samples were submitted to the ozonation process during 0, 5, 10 and 20?min. Treatment at 5?min was able to degrade 71.5% of herbicide trifluralin in surface water. The removal (%) in ultrapure water reached 83.4% after 20?min of ozonation. The degradation of trifluralin in fortified tomato samples (0.025–0.1?mg kg^?1) were conducted with ozonation at 20?min, and it ranged from 84.4 to 92.7%. After treatment, levels of trifluralin in tomato remained within the established MRLs to EU, USEPA and ANVISA (Brazil). The data provided evidence that ozone is effective for removing trace trifluralin from water and foods.     

Mass flows of endocrine disruptors in the Glatt River during varying weather conditions

This study focused on the occurrence and behaviour in wastewater and surface waters of several phenolic endocrine disrupting compounds (EDCs) including parabens, alkylphenolic compounds, phenylphenol (PhP) and bisphenol A (BPA). Analytical procedures using solid-phase-extraction and LC-MS/MS techniques were applied to samples of influents and effluents of wastewater treatment plants (WWTPs) discharging into the Glatt River (Switzerland) as well as to river water samples. A mass flow analysis provided insight into the main sources and the fate of these contaminants during different weather conditions. Concentrations in influents were in the low μg/L range for most analytes. Removal of parabens in the WWTPs was mostly above 99%. Nonylphenol polyethoxylates (A₉PEO) removal amounted to 98%, but in some cases nonylphenoxy acetic acid (A₉PEC) or nonylphenols (NP) were formed. In effluents, concentrations were highest for the A₉PEC, A₉PEO and NP. Concentrations in river water were in the high ng/L range for alkylphenolic compounds and in the low ng/L range for BPA, PhP and the parabens. During the sampling period, in which several rain events occurred, both water flows and mass flows varied strongly. Mass flows in WWTP effluents and in the river increased with increasing water flows for most compounds indicating that higher water flows do not lead necessarily to a proportional dilution of the pollutants. Throughout the low water flow period, mass flows predicted from the known inputs were similar to the actual mass flows at the end of the river for most analytes. For none of the EDCs, significant in-stream removal could be observed. In the periods with high water flows, mass flows in the river were much higher than can be explained by the initially defined sources. Discharge of untreated wastewater influent into the river was assessed as an additional source. Adding this source improved the mass balance for some, but not all of the analytes.     

Inter-laboratory exercise on steroid estrogens in aqueous samples

An inter-laboratory comparison exercise was organized among European laboratories, under the aegis of EU COST Action 636: “Xenobiotics in Urban Water Cycle”. The objective was to evaluate the performance of testing laboratories determining “Endocrine Disrupting Compounds” (EDC) in various aqueous matrices. As the main task three steroid estrogens: 17α-ethinylestradiol, 17β-estradiol and estrone were determined in four spiked aqueous matrices: tap water, river water and wastewater treatment plant influent and effluent using GC-MS and LC-MS/MS. Results were compared and discussed according to the analytical techniques applied, the accuracy and reproducibility of the analytical methods and the nature of the sample matrices. Overall, the results obtained in this inter-laboratory exercise reveal a high level of competence among the participating laboratories for the detection of steroid estrogens in water samples indicating that GC-MS as well as LC-MS/MS can equally be employed for the analysis of natural and synthetic hormones.     

Advanced oxidation of alkylphenol ethoxylates in aqueous systems

Alkylphenols and alkylphenol ethoxylates are ubiquitous wastewater contaminants. In this study the oxidation of nonylphenol ethoxylates (NPEO) and octylphenol ethoxylates (OPEO) by oxidant systems generating hydroxide radicals was evaluated. The reaction of each oxidant with a technical mixture of NPEO (Tergitol™) and OPEO (Triton X-100™) in ultrapure laboratory water and four aqueous environmental matrices was carried out in order to develop an understanding of reaction kinetics. The oxidation of APEOs was evaluated by hydroxyl radical generated by (1) hydrogen peroxide in the presence of ultraviolet light, (2) Fenton’s reagent, and (3) a photo-Fenton’s process. The second order kinetic rate constant for both NPEO and OPEO with hydroxyl radical was calculated to be 1.1 × 10¹⁰ M⁻¹ s⁻¹. The efficacy of the AOPs within an aqueous environmental matrix was dependent on the rate of formation of hydroxyl radical and the scavenging capacity of the matrix. A model based on the hydroxyl radical formation, scavenging capacity and the kinetic rate constant of target APEO was developed from the existing literature and applied to predict the concentration of APEOs in solution during advanced oxidation in different aqueous environmental matrices.     

胺化木质素对水中Cu（Ⅱ）、Cd（Ⅱ）的吸附

以胺化木质素作吸附剂对水中Cu2＋、Cd2＋的去除进行了研究,主要考察了吸附时间、溶液pH值、温度和金属离子初始浓度对吸附去除率的影响,并研究了其吸附等温线和动力学。结果表明,胺化木质素能有效去除水溶液中的Cu2＋、Cd2＋,且对Cd2＋的吸附能力大于Cu2＋吸附动力学符合准二级动力学方程,吸附等温线均可以很好地用Langmuir方程描述。     

Degradation of lidocaine,tramadol, venlafaxine and the metabolites O-desmethyltramadol and O-desmethylvenlafaxine in surface waters

The photodegradation and biotic transformation of the pharmaceuticals lidocaine (LDC), tramadol (TRA) and venlafaxine (VEN), and of the metabolites O-desmethyltramadol (ODT) and O-desmethylvenlafaxine (ODV) in the aquatic environmental have been investigated. Photodegradation experiments were carried out using a medium pressure Hg lamp (laboratory experiments) and natural sunlight (field experiments). Degradation of the target compounds followed a first-order kinetic model. Rates of direct photodegradation (light absorption by the compounds itself) at pH 6.9 were very low for all of the target analytes (?0.0059 h^?1 using a Hg lamp and ?0.0027 h^?1 using natural sunlight), while rates of indirect photodegradation (degradation of the compounds through photosensitizers) in river water at pH 7.5 were approximately 59 (LDC), 5 (TRA), 8 (VEN), 15 (ODT) and 13 times (ODV) higher than the rates obtained from the experiments in ultrapure water. The accelerated photodegradation of the target compounds in natural water is attributed mainly to the formation of hydroxyl radicals through photochemical reactions. Biotic (microbial) degradation of the target compounds in surface water has been shown to occur at very low rates (?0.00029 h^?1). The half-life times determined from the field experiments were 31 (LDC), 73 (TRA), 51 (VEN), 21 (ODT) and 18 h (ODV) considering all possible mechanisms of degradation for the target compounds in river water (direct photodegradation, indirect photodegradation and biotic degradation).     

Atrazine removal by ozonation processes in surface waters

Abstract

Atrazine (6‐chloro‐N‐ethyl‐N'‐isopropyl‐1,3,5‐triazinedyl‐2,4‐diamine) was treated with ozone alone and in combination with hydrogen peroxide or UV radiation in three surface waters. Experiments were carried out in two bubble reactors operated continously. Variables investigated were the ozone partial pressure, temperature, pH, mass flow ratio of oxidants fed: hydrogen peroxide and ozone and the type of oxidation including UV radiation alone. Residence time for the aqueous phase was kept at 10 min. Concentrations of some intermediates, including deethylatrazine, deisopropylatrazine and deethyldeisopropylatrazine, were also followed. The nature of water, specifically the alkalinity and pH were found to be important variables that affected atrazine (ATZ) removal. Surface waters with low alkalinity and high pH allowed the highest removal of ATZ to be reached. There was an optimum hydrogen peroxide to ozone mass flow ratio that resulted in the highest ATZ removal in each surface water treated. This optimum was above the theoretical stoichiometry of the process. Therefore, to reach the maximum removal of ATZ in a O₃/H₂O₂ process, more hydrogen peroxide was needed in the surface waters treated than in ultrapure water under similar experimental conditions. In some cases, UV radiation alone resulted in the removal of ATZ higher than ozonation alone. This was likely due to the alkalinity of the surface water. Ozonation and UV radiation processes yield different amounts of hydrogen peroxide. Combined ozonations (O₃/H₂O₂ and O₃/UV) lead to ATZ removals higher than single ozonation or UV radiation but the formation of intermediates was higher.     

Degradation of propyl paraben by activated persulfate using iron-containing magnetic carbon xerogels: investigation of water matrix and process synergy effects

An advanced oxidation process comprising an iron-containing magnetic carbon xerogel (CX/Fe) and persulfate was tested for the degradation of propyl paraben (PP), a contaminant of emerging concern, in various water matrices. Moreover, the effect of 20 kHz ultrasound or light irradiation on process performance was evaluated. The pseudo-first order degradation rate of PP was found to increase with increasing SPS concentration (25–500 mg/L) and decreasing PP concentration (1690–420 μg/L) and solution pH (9–3). Furthermore, the effect of water matrix on kinetics was detrimental depending on the complexity (i.e., wastewater, river water, bottled water) and the concentration of matrix constituents (i.e., humic acid, chloride, bicarbonate). The simultaneous use of CX/Fe and ultrasound as persulfate activators resulted in a synergistic effect, with the level of synergy (between 35 and 50%) depending on the water matrix. Conversely, coupling CX/Fe with simulated solar or UVA irradiation resulted in a cumulative effect in experiments performed in ultrapure water.     

Fenton氧化法同时脱硫脱硝的实验研究

应用Fenton液相氧化吸收法进行同时脱硫脱硝实验。首先,利用单因素实验,分别考察了H2O2浓度、Fe2+投加量、初始pH值、UV照射和温度对脱硫脱硝的影响。结果表明,SO2和NO去除率随着H2O2浓度和Fe2+投加量的增大而提高;初始pH对SO2和NO的去除有较大影响;UV能促进SO2和NO的净化;温度对脱硫效率影响不大,但对NO的去除有显著作用,适当升温可以提高脱硝效率。随后,考察了SO2对NO去除率的影响。通过单独脱硝和同时脱硫脱硝的对比实验发现,SO2的加入对NO的去除有一定的促进作用,Fenton法可同时获得起始约80%的脱硝效率和98%以上的脱硫效率。     

Competitive removal of pharmaceuticals from environmental waters by adsorption and photocatalytic degradation

This work explores the competitive removal of pharmaceuticals from synthetic and environmental waters by combined adsorption-photolysis treatment. Five drugs usually present in waterways have been used as target compounds, some are pseudo-persistent pollutants (carbamazepine, clofibric acid, and sulfamethoxazole) and others are largely consumed (diclofenac and ibuprofen). The effect of the light source on adsorption of drugs onto activated carbons followed by photolysis with TiO₂ was assessed, being UV-C light the most effective for drug removal in both deionized water and river water. Different composites prepared from titania nanoparticles and powdered activated carbons were tested in several combined adsorption-photocatalysis assays. The composites prepared by calcination at 400 °C exhibited much better performance than those synthesized at 500 °C, being the C400 composite the most effective one. Furthermore, some synthetic waters containing dissolved species and environmental waters were used to investigate the effect of the aqueous matrix on each drug removal. In general, photocatalyst deactivation was found in synthetic and environmental waters. This was particularly evident in the experiments performed with bicarbonate ions as well as with wastewater effluent. In contrast, tests conducted in seawater showed adsorption and photocatalytic degradation yields comparable to those obtained in deionized water. Considering the peculiarities of substrate competition in each aqueous matrix, the combined adsorption-photolysis treatment generally increased the overall elimination of drugs in water.     

直接投菌法在城市重污染河流治理中的应用研究

在无截污和清除内源的情况下,对深圳市甘坑河采用梅花式接种法将本源微生物菌剂分两次直接接入河流水体及底泥中。结果表明,第1次接种后的4 d内各项水质指标都不稳定,4 d后,悬浮物、COD、TP和NH3-N等浓度下降,水质明显改善;但从第8天开始,COD、NH3-N和TP的去除率同时下降,本源微生物的处理效率开始降低,需进行第2次接种;第2次接种后,DO浓度提升至2.0 mg/L以上,COD、TP和NH3-N的去除率分别保持在40%、30%和40%以上。结果表明,直接投菌法在城市重污染河道治理中可以初步消除河道的黑臭现象,修复水质。     

电解法去除重污染河水中的磷

近年来,河流污染严重,严重影响了社会的发展,治理河水污染成为目前急需解决的问题。研究了石墨-铁板电极电解法对城市内河中重污染水体中磷去除的可行性;分析了静置时间、电解时长、初始磷浓度、电压、pH及极板间距对电解法除磷效果的影响,确定了电解法处理重污染水体的最佳运行参数,比较了电解法处理实际河水和模拟河水的TP去除效果。结果表明,重污染河流水体中的磷在较短时间内可以得到去除,在静置时间为3 h,电压为10 V,极板间距为1.5cm,pH保持在中性或弱酸性,电解时长在10~15 min时,TP去除率达到90%以上。同时,在最佳运行条件下,电解法处理实际河水效果较好。     

In Memoriam

ABSTRACT

A feasibility study of polychlorinated biphenyl (PCB) removal from contaminated soils using microwave-generated steam (MGS) was performed. Initial experimental results show that MGS effectively removed PCBs from contaminated soil with an overall removal efficiency of greater than 98% at a steam-to-soil mass ratio of 3:1. Removal efficiency was found to be dependent upon the amount of steam employed, expressed as a mass ratio of steam applied to soil mass. Evaporation was identified as a major mechanism in removing PCBs from the soil. Rapid expansion and evaporation of pore water by microwave dielectric heating accelerated evaporation rates of PCB molecules. Increased solubility of PCBs into the heated aqueous phase is also hypothesized. Together these effects increase mass-transfer rates, thus enhancing removal of PCBs from the soil.     

Synergistic adsorption and advanced oxidation activated by persulfate for degradation of tetracycline hydrochloride using iron-modified spent bleaching earth carbon

At present, tetracycline hydrochloride (TCH) is a widely used antibiotic, and is often detected in water, posing a serious harm to human and ecological health. In this study, spent bleaching earth (SBE) was pyrolyzed to obtain spent bleaching earth carbon (SBE@C) and the nano Fe⁰/SBE@C prepared after zero-valent iron loading was adopted to remove TCH in water for the first time. The combination of nano Fe⁰/SBE@C and PS, the strong adsorption of SBE@C coupled with the oxidation of free radicals could achieve TCH efficient removal. The effects of nano Fe⁰ load, nano Fe⁰/SBE@C dosage, solution initial pH, and PS/TCH molar ratio on TCH removal efficiency in nano Fe⁰/SBE@C?+?PS system were studied. The results indicate that the optimal reaction conditions are 5% nano Fe⁰ load, 0.2 g/L nano Fe⁰/SBE@C dosage, initial pH of 3, PS/TCH molar ratio of 100:1. Under these conditions, TCH removal efficiency could reach 91%. Meanwhile, response surface methodology (RSM) was applied to predict optimal value of reaction conditions. The removal efficiency corresponding to the predicted optimal conditions was consistent with the actual removal efficiency obtained from the experiment. Moreover, six reaction systems were tested, and TCH removal efficiency in the SBE@C?+?PS system was 22.6%. When nano Fe⁰ was loaded on SBE@C, TCH removal efficiency in Fe⁰/SBE@C?+?PS system increased to 78.2%, in which TCH was first adsorbed on the surface of nano Fe⁰/SBE@C, and then was degraded by the oxidation of SO₄^?? and ?OH. Totally, the nano Fe⁰/SBE@C?+?PS system displayed excellent TCH removal efficiency, good stability and reusability, exhibiting a promise toward TCH removal.

     

Effects of pH,initial Pb2+ concentration,and polyculture on lead remediation by three duckweed species

Various geographical duckweed isolates have been developed for phytoremediation of lead. The Pb²⁺ removal efficiency of Lemna aequinoctialis, Landoltia punctata, and Spirodela polyrhiza was investigated in monoculture and polyculture at different levels of pH and initial Pb²⁺ concentrations. L. aequinoctialis was not sensitive to the tested pH but significantly affected by initial Pb²⁺ concentration, whereas synergistic effect of pH and initial Pb²⁺ concentration on removal efficiency of L. punctata and S. polyrhiza was found. Although the majority of polycultures showed median removal efficiency as compared to respective monocultures, some of the polycultures achieved higher Pb²⁺ removal efficiencies and can promote population to remove Pb²⁺. Besides, the three duckweed strains could be potential candidates for Pb²⁺ remediation as compared to previous reports. Conclusively, this study provides useful references for future large-scale duckweed phytoremediation.

     

化学氧化絮凝技术在强化处理受污染河水中的应用

采用化学氧化絮凝技术(COF)对东莞市某河流的受污染河水进行处理,通过烧杯搅拌试验,考察了COF技术除污效能,在此基础上进行现场试验.结果表明,COD、BOD5、TP和NH3-N的去除率分别可达到71.2%、77.4%、91.1%和68.7%,出水指标达到了国家一级排放要求,为工程设计提供了依据.     

Effect of water composition on the photocatalytic removal of pesticides with different TiO2 catalysts

The objective of this work is double—firstly to explore the photocatalytic efficiency of five different commercial TiO₂ catalysts in the photodegradation of a mixture of pesticides classified by the EU as priority pollutants and secondly to analyze the correlation between their physicochemical properties and the inhibition of the studied photocatalytic process when natural water was employed. Photocatalytic efficiencies when ultrapure water was used seem to point out that surface area was not a prerequisite for the photodegradation of the selected mixture of pesticides. On the other hand, significant differences in total organic carbon (TOC) conversions were obtained with the two studied water compositions. On one side, Evonik materials appear to be mostly inhibited when natural water was employed, whereas on the other, it should be remarked that anatase Sigma-Aldrich (SA) and, particularly, Hombikat UV100 (HBK) materials presented a very limited photo-efficiency inhibition or even a higher initial rate of TOC removal when a natural water matrix was used, probably due to their specific surface properties (PZC, S _BET). Therefore, heterogeneous photocatalysis has proved to be a promising technology for the degradation of the selected mixture of pesticides where the final photo-efficiency of the five commercial titania catalysts studied here responds to a complex balance between its surface and structural properties.     

Decontamination of a municipal landfill leachate from endocrine disruptors using a combined sorption/bioremoval approach

Sorption and biodegradation are the main mechanisms for the removal of endocrine disruptor compounds (EDs) from both solid and liquid matrices. There are recent evidences about the capacity of white-rot fungi to decontaminate water systems from phenolic EDs by means of their ligninolytic enzymes. Most of the available studies report the removal of EDs by biodegradation or adsorption separately. This study assessed the simultaneous removal of five EDs—the xenoestrogens bisphenol A (BPA), ethynilestradiol (EE2), and 4-n-nonylphenol (NP), and the herbicide linuron and the insecticide dimethoate—from a municipal landfill leachate (MLL) using a combined sorption/bioremoval approach. The adsorption matrices used were potato dextrose agar alone or added with each of the following adsorbent materials: ground almond shells, a coffee compost, a coconut fiber, and a river sediment. These matrices were either not inoculated or inoculated with the fungus Pleurotus ostreatus and superimposed on the MLL. The residual amount of each ED in the MLL was quantified after 4, 7, 12, and 20 days by HPLC analysis and UV detection. Preliminary experiments showed that (1) all EDs did not degrade significantly in the untreated MLL for at least 28 days, (2) the mycelial growth of P. ostreatus was largely stimulated by components of the MLL, and (3) the enrichment of potato dextrose agar with any adsorbent material favored the fungal growth for 8 days after inoculation. A prompt relevant disappearance of EDs in the MLL occurred both without and, especially, with fungal activity, with the only exception of the very water soluble dimethoate that was poorly adsorbed and possibly degraded only during the first few days of experiments. An almost complete removal of phenolic EDs, especially EE2 and NP, occurred after 20 days or much earlier and was generally enhanced by the adsorbent materials used. Data obtained indicated that both adsorption and biodegradation mechanisms contribute significantly to MLL decontamination from the EDs studied and that the efficacy of the methodology adopted is directly related to the hydrophobicity of the contaminant.     

Photolytic and photocatalytic degradation of quinclorac in ultrapure and paddy field water: identification of transformation products and pathways

Quinclorac (QNC) is an effective but rather persistent herbicide commonly used in rice production. This herbicide presents a mean persistence in the environment so its residues are considered of environmental relevance. However, few studies have been conducted to investigate its environmental behavior and degradation. In the present work, direct photolysis and TiO₂ photocatalysis of the target compound in ultrapure and paddy field water were investigated. After 10 h photolysis in ultrapure water, the concentration of QNC declined 26% and 54% at 250 and 700 W m⁻², respectively. However, the amount of quinclorac in paddy field water remained almost constant under the same irradiation conditions. QNC dissipated completely after 40 min of TiO₂ photocatalysis in ultrapure water, whereas 130 min were necessary to degrade 98% of the initial concentration in paddy field water.Possible QNC photolytic and photocatalytic degradation pathways are proposed after structure elucidation of the main transformation products, through liquid chromatography-electrospray ionization-quadrupole time-of-flight mass spectrometry and exact mass measurements. Pyridine ring hydroxylation at C-9 followed by ring opening and/or oxidative dechlorination were the key steps of QNC degradation.     

Application of response surface methodology to the removal of the antibiotic tetracycline by electrochemical process using carbon-felt cathode and DSA (Ti/RuO2-IrO2) anode

The removal of antibiotic tetracycline (TC) from water by electrochemical advanced oxidation process (EAOP) was performed using a carbon-felt cathode and a DSA (Ti/RuO(2)-IrO(2)) anode. The influence of applied current, initial pH and initial TC concentration on TC removal efficiency was investigated. Response surface methodology (RSM) based on Box-Behnken statistical experiment design (BBD) was applied to analyze the experimental variables. The positive and negative effects of variables and the interaction between variables on TC removal efficiency were determined. The applied current showed positive effect, while the initial pH value and initial tetracycline concentration gave negative effect on TC removal. The interaction between applied current and initial pH value was significant, while the interactions of initial TC concentration with applied current or initial pH were not pronounced. The results of adequacy check confirmed that the proposed models were accurate and reliable to analyze the variables of EAOP. The reaction intermediates were identified by high-performance liquid chromatography-mass spectrometry (LC-MS) technique and a plausible degradation pathway for tetracycline degradation was proposed. The acute toxicity experiments illustrated that the Daphnia magna immobilization rate reached the maximum after 240 min of electrolysis and then decreased with the progress of the reaction.