A comparative study of ultrasonic cavitation and Fenton's reagent for bisphenol A degradation in deionised and natural waters

Bisphenol A (BPA), a xenobiotic that exhibits endocrine disrupting action can be found in surface water. Its complete elimination can be obtained by advanced oxidation processes, notably upon the application of ultrasonic waves. In order to evaluate the feature of ultrasound relevance and the involvement of the hydroxyl radical in the BPA sonochemical degradation, ultrasound action was compared to Fenton's reaction in the cases of deionised acidic water (pH 3) and natural water (pH 7.6, main ions concentration: Ca(2+)=486mgL(-1), Na(+)=9.1mgL(-1), Cl(-)=10mg L(-1), SO(4)(2-)=1187mgL(-1), HCO(3)(-)=402mgL(-1)). Ultrasound was performed at 300kHz and 80W. Fenton's process was operated using ferrous sulphate (100micromolL(-1)) and continuous H(2)O(2) addition at the rate as it is produced when sonication is applied in water in absence of substrate. Experiments carried out in deionised water show that both processes exhibit identical BPA elimination rate and identical primary intermediates. Main chemical pathways involve reactions with OH radical. Chemical oxygen demand (COD) and total organic carbon (TOC) analyses show that the Fenton's process is slightly more efficient than ultrasonic treatment for the removal of BPA by-products in the case of deionised water. Experiments conducted in natural water evidenced the inhibition of the Fenton process while the ultrasound action was not hampered.     

Simultaneous photocatalytic reduction of Cr(VI) and oxidation of bisphenol A induced by Fe(III)-OH complexes in water

Simultaneously photocatalytic reduction of Cr(VI) and oxidation of bisphenol A (BPA) in aqueous solution in the presence of Fe(III)-OH complexes were investigated under a 250 W metal halide lamp (lambda>or=365 nm). Synergy effect of the simultaneous photocatalytic oxidation and reduction of both pollutants was achieved. The effects of initial pH value, initial concentration of BPA, Cr(VI) and Fe(III) were preliminarily investigated. The results showed that both photocatalytic reduction of Cr(VI) and degradation of BPA could occur simultaneously in the Fe(III)/Cr(VI)/BPA ternary system, and the rates of photocatalytic reduction of Cr(VI) and the oxidation of BPA were more rapid at a low pH range of 2.0-3.0. The increase of the initial concentration of Fe(III) was favorable to both photocatalytic reduction of Cr(VI) and oxidation of BPA. The reduction efficiency of Cr(VI) decreased with increasing initial concentrations of Cr(VI) and BPA, but the degradation efficiency of BPA was not changed obviously at different Cr(VI) concentrations.     

Mineralization of bisphenol A (BPA) by anodic oxidation with boron-doped diamond (BDD) electrode

Anodic oxidation of bisphenol A (BPA), a representative endocrine disrupting chemical, was carried out using boron-doped diamond (BDD) electrode at galvanostatic mode. The electro-oxidation behavior of BPA at BDD electrode was investigated by means of cyclic voltammetric technique. The extent of degradation and mineralization of BPA were monitored by HPLC and total organic carbon (TOC) value, respectively. The results obtained, indicate that the BPA removal at BDD depends on the applied current density (Iappl), initial concentration of BPA, pH of electrolyte and supporting medium. Galvanostatic electrolysis at BDD anode cause concomitant generation of hydroxyl radical that leads to the BPA destruction. The kinetics for the BPA degradation follows a pseudo-first order reaction with a higher rate constant 12.8x10(-5) s(-1) for higher Iappl value 35.7 mA cm(-2), indicating that the oxidation reaction is limited by Iappl control. Complete mineralization of BPA was achieved regardless of the variables and accordingly the mineralization current efficiency was calculated from the TOC removal measurements. Considering global oxidation process, the effect of supporting electrolytes has been discussed in terms of the electro generated inorganic oxidants. The better performance of BDD anode was proved on a comparative study with Pt and glassy carbon under similar experimental conditions. A possible reaction mechanism for BPA degradation involving three main aromatic intermediates, identified by GC-MS analysis, was proposed.     

Investigation of adsorption behavior of bisphenol A on well fabricated organic surfaces using surface plasmon resonance spectroscopy

Molecular adsorption of bisphenol A (BPA) on three types of self-assembled monolayers with different functionalities, such as -CH3, -SH, and -COOH, was examined using surface plasmon resonance (SPR) spectroscopy. BPA molecules in an aqueous solution were easily adsorbed onto a hydrophobic surface compared to a hydrophilic surface. Sorption behavior of BPA into poly(2-methoxyethyl acrylate) (PMEA) layer, which is known as a biocompatible polymer, was also investigated. Sorption and desorption dynamics of BPA into PMEA were found to be very rapid and quite reversible. The swelling of PMEA by sorption of BPA results in the change in SPR angle and allows one to quantify the BPA concentration below 100 ppm. In addition, the transport mechanism of BPA within the membrane of organ can be inferred by the experimental results.     

Modification and application of mesoporous carbon adsorbent for removal of endocrine disruptor bisphenol A in aqueous solutions

Bisphenol A (2,2-bis(4-hydroxyphenyl) propane, BPA) is a typical endocrine disruptor in aquatic environment. The removal of BPA by adsorption is a simple and effective way. Mesoporous carbon (MC) and N-modified mesoporous carbon (NMC) were synthesized by the soft template method and used for BPA adsorption. The adsorption performance of MC and NMC was investigated by the batch and dynamic system, and compared with commercial activated carbon (AC). Additionally, the kinetics and isotherms of BPA adsorption on MC and NMC were also investigated. The specific surface areas and average pore sizes of MC and NMC were 687.8 and 579.6 m²/g, 4.06 and 4 nm, respectively. The equilibrium adsorption capacity of MC and NMC was positively correlated with the initial BPA concentration, and negatively correlated with adsorbent dosages. The pH value of 3–8 was conducive to the adsorption of BPA on MC and NMC. Pseudo-second-order kinetic model and Freundlich isotherm model provided well fit for BPA adsorption on MC and NMC. Compared with AC, MC and NMC exhibited a higher adsorption capability and more stable recycling performance. In the dynamic adsorption tests, with the increase in BPA concentration and flow rate in the influent, the breakthrough time and saturation time are shortened. However, the increase in adsorption layer height extended the breakthrough time and saturation time.     

Determination of boron-containing compounds in urine and blood plasma from boron neutron capture therapy patients. The importance of using coupled techniques

The necessity of using coupled techniques to analyze samples from boron neutron capture therapy (BNCT) patients prior to element-specific detection has been demonstrated. BNCT patients were infused with p-boronophenylalanine (BPA)-fructose complex before the therapy started. Urine and blood plasma samples were collected at different times after the start of the BPA administration and were run on a porous graphitic carbon column coupled on-line to an inductively coupled plasma-atomic emission spectrometer (ICP-AES) and an ICP time-of-flight mass spectrometer (TOF-MS). In addition to BPA, a possible metabolite to BPA and some minor boron-containing compounds, eluting close to the front, were also found in the urine and plasma samples. Because only the total concentration of boron has been measured so far in earlier studies, the suspected metabolite could not be detected, and this is the first report indicating its presence in urine and plasma of BNCT patients. The abundance of 10B in urine was about the same for BPA and its possible metabolite (98-99%). The ratio between the possible metabolite and BPA was found to differ in the urine from different patients. Most of the patients had a metabolite concentration of approximately 10 mol % of the BPA content in their urine 5-11 h after the start of the BPA administration. This ratio increased to between 30 and 80% when 24 h had passed. The ratio of metabolite to BPA was found to be lower in the plasma than in the urine samples at comparable time after the start of BPA infusion. Preliminary results from micro-LC-electrospray ionization (ESI)-MS/MS measurements on four urine samples indicate that the metabolite has a higher mass than BPA.     

The role of oxygen in the degradation of p-chlorophenol by Fenton system

The role of oxygen in the degradation pathway of 4-CP by Fenton system was investigated in this paper. The degradation of 4-CP, changes of Fenton reagent's concentration and formation of the intermediates in Fenton/O2 system were respectively compared with those in Fenton/N2 system. The result showed that both 4-CP degradation and COD(cr) removal in Fenton/O2 system were prior to those in Fenton/N2 system. Investigation into the intermediates suggested that the presence of oxygen impeded the formation of 4-chlorocatechol and accelerated the production of organic acids such as maleic acid, fumaric acid, acetic acid and oxalic acid. Based on the changes of reaction substances and the intermediates, the degradation mechanism of 4-CP by Fenton system in the presence of O2 was suggested. The dissolved oxygen competed against hydroxyl radical to react with ortho-parachlorohydroxyphenyl radical (ClHP) producing ortho-parachlorophenolperoxyl radical (ClPP) and impeding the generation of 4-chlorocatechol. In addition, the reaction of oxygen with (Cl)PP radical increased the extent of benzene ring cleavage, producing more aliphatic organic acids. This study makes clear the mechanism of Fenton/O2 system and thus, it is helpful to establish the kinetic model and provide a good guide to the treatment of real wastewater.     

Impact assessment of bisphenol A on lignin-modifying enzymes by basidiomycete Trametes versicolor

The impact of different concentrations of bisphenol A (BPA) was evaluated on growth of the white-rot basidiomycete, Trametes versicolor, and on the expression of genes encoding lignin-modifying enzyme (LME) activities. Effective doses (EDs) were obtained from fungal growth rate to monitor LME activities and the expression levels of their encoding genes. The fungus showed mycelial growth at concentrations of up to 300 microg ml(-1) of BPA with an ED50 value of 185 microg ml(-1). The LME activities were stimulated by BPA concentrations up to 300 microg ml(-1). The lignin peroxidase (LIP) encoding gene may be sensitive to BPA stress.     

Influence of the coexisting contaminants on bisphenol A sorption and desorption in soil

The effects of different heavy metals (Cd, Pb), surfactants (cetyltrimethylammonium bromide (CTAB), cetylpyridine chloride (CPC)) and the ionic strength (Ca2+, NH4+) on breakthrough curves (BTCs) for sorption and desorption of bisphenol A (BPA) were studied using soil column experiment. Results showed that the presence of heavy metals and cationic surfactants caused a significant increase on the BPA sorption. In addition, the volume required when effluent concentration reached half of the influent concentration (VC1/2) increased due to the introduction of heavy metals and surfactants. It was also found that the larger amount of BPA was absorbed with higher ionic strength. The cationic surfactants enhanced the desorption ability of BPA from the soil. The results provided a better understanding of BPA behavior in environment and facilitated more accurate assessment of its ecological risk and identification of appropriate management strategies.     

双酚A分子印迹吸附剂制备及性能研究

为提高吸附剂对水中双酚A(BPA)的选择识别性能,采用分子印迹溶胶-凝胶技术制备了BPA分子印迹吸附剂(BPA-MIA).以未添加BPA模板分子制得的非印迹吸附剂(BPA-MNIA)作为比较对象,利用扫描电镜(SEM)、能谱(EDS)、红外光谱(FTIR)、热重分析(TG)对BPA-MIA进行表征,并对其吸附动力学、吸附等温线及选择识别性能进行研究.结果表明,BPA-MIA经过120 min达吸附平衡,吸附过程符合准二级动力学方程及Langmuir吸附等温方程,最大吸附容量为16.69 mg/g,比BPA-MNIA吸附容量提高5倍,对BPA具有较高的选择吸附性能.     

Sorption and degradation of bisphenol A by aerobic activated sludge

Laboratory-scale batch experiments were conducted to investigate the sorption and degradation of bisphenol A (BPA) at μg/L range in an aerobic activated sludge system. The sorption isotherms and thermodynamics indicated that the sorption of BPA on sludge was mainly a physical process in which partitioning played a dominating role. The values of sorption coefficient K_oc were between 621 and 736 L/kg in the temperature range of 10–30 °C. Both mixed liquor suspended solid (MLSS) and temperature influenced BPA sorption on sludge. The degradation of BPA by acclimated activated sludge could be described by first-order reaction equation with the first-order degradation rate constant of 0.80 h⁻¹ at 20 °C. The decrease of initial COD concentration and the increase of MLSS concentration and temperature enhanced BPA degradation rate. The removal of BPA in the activated sludge system was characterized by a quick sorption on the activated sludge and subsequent biodegradation.     

Synthesis of monodisperse Fe3O4 nanoparticles by optimized sonochemical method using mono(ethylene glycol) (MEG)

In this study, we successfully synthesized monodisperse magnetite nanoparticles (NPs) (Fe3O4) by sonochemical method using mono (ethylene glycol) (MEG) as a modifier of the reaction environment and found that MEG could be a good candidate to prevent oxidation and toxicity in sonochemical synthesis. The microstructure and size distribution of the Fe3O4 NPs were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) respectively. It revealed that the NPs prepared by MEG assisted sonochemical method show a smaller average size and better monodispersity compared to conventional sonochemical method. Due the the reduced average size and uniform size distribution nature of the NPs, it also showed good superparamagnetic properties with very low coercivity less than 0.5 Oe.     

重复使用下聚碳酸酯饮水桶中双酚A的迁移规律

目的研究重复使用条件下聚碳酸酯(PC)饮水桶中双酚A(BPA)的迁移规律及主要影响因素,为日常生活中PC饮水桶的正确使用提供参考。方法采用高效液相色谱方法,研究了重复使用时间、温度和换水间隔对收集的5只饮水桶中BPA迁移行为的影响,同时分析新桶与使用1年的旧桶的区别。结果 PC饮水桶中BPA的迁移主要受重复使用时间和温度的影响,并且随使用时间的延长和温度的升高而增加;间隔换水时间对BPA迁移影响较小;已使用过的PC旧桶中BPA迁移量显著高于新桶。结论在PC桶的日常使用中,应注意在常温下短期使用,避免高温长期使用,使用一段时间的PC桶应注意废弃回收。     

Preparation of polyethersulfone-organophilic montmorillonite hybrid particles for the removal of bisphenol A

Polyethersulfone (PES)-organophilic montmorillonite (OMMT) hybrid particles, with various proportions of OMMT, were prepared by using a liquid-liquid phase separation technique, and then were used for the removal of bisphenol A (BPA) from aqueous solution. The adsorbed BPA amounts increased significantly when the OMMT were embedded into the particles. The structure of the particle was characterized by using scanning electron microscopy (SEM); and these particles hardly release small molecules below 250 degrees C which was testified by using thermogravimetric analysis (TGA). The experimental data of BPA adsorption were adequately fitted with Langmuir equations. Three simplified kinetics model including the pseudo-first-order (Lagergren equation), the pseudo-second-order, and the intraparticle diffusion model were used to describe the adsorption process. Kinetic studies showed that the adsorbed BPA amount reached an equilibrium value after 300 min, and the experimental data could be expressed by the intraparticular mass transfer diffusion model. Furthermore, the adsorbed BPA could be effectively removed by ethanol, which indicated that the hybrid particles could be reused. These results showed that the PES-OMMT hybrid particles have the potential to be used in the environmental application.     

用碘释放法研究低频超声的声化学产额

本文用碘释放法研究了２８ｋＨｚ超声的声化学产额随扬强和辐照时间的变化。表明声化学产额随声强呈非线性变化，而随辐照时间近似呈线性变化。进而研究了由２８ｋＨｚ与１．０６ＭＨｚ组成的正交辐照系统的声化学产额。     

Comparison of various advanced oxidation processes for the degradation of 4-chloro-2 nitrophenol

In the present study an attempt is made efficiently to degrade USEPA listed 4-chloro-2-nitrophenol (4C-2-NP), widely available in bulk drug and pesticide wastes using various advanced oxidation processes (AOPs). A comparative assessment using various AOPs (UV, H(2)O(2,) UV/H(2)O(2), Fenton, UV/Fenton and UV/TiO(2)) was attempted after initial optimization studies, viz., varying pH, peroxide concentration, iron concentration, and TiO(2) loading. The degradation of the study compound was estimated using chemical oxygen demand (COD) reduction and compound reduction using spectrophotometric methods and further validated with high performance liquid chromatography (HPLC). The degradation trends followed the order: UV/Fenton > UV/TiO(2) > UV/H(2)O(2) > Fenton > H(2)O(2) > UV(.) It can be inferred from the studies that UV/Fenton was the most effective in partial mineralization of 4C-2-NP. However, lower costs were obtained with H(2)O(2). Kinetic constants were evaluated using first order equations to determine the rate constant K.     

C2用于声化学研究的大功率超声系统的研制

根据声化学反应的特殊要求，我们研制了用于声化学研究的大功率超声系统，由参数可调节的超声发生器配合不同频率的换能器工作，并用它组合成杯式变幅杆结构声化学反应器。解决了有关声化学设备的一些技术问题，为声化学技术从实验室规模向工业应用过渡做了必要的准备     

C2 用于声化学研究的大功率超声系统的研制

根据声化学反应的特殊要求，我们研制了上前用于声化学研究的大功率超声系统，由参数可调节的超声发生器配合不同频率的换能器工作，并用它组合成杯式幅杆结构声化学反应器，解决了有关声化学设备的一些技术问题。为声化学技术从实验室规模向工业应用过渡做了必要的准备。     

Degradation of bisphenol A by combining ozone with UV and H<Subscript>2</Subscript>O<Subscript>2</Subscript> in aqueous solutions: mechanism and optimization

A laboratory-scale study on the abatement of bisphenol A (BPA) was performed by combining O₃ with H₂O₂ and UV (O₃/H₂O₂/UV), an ozone-based advanced oxidation processes technique (AOP). This work aimed to (1) evaluate the removal of BPA with O₃/H₂O₂/UV, and to compare the degradation efficiency with other ozone-based AOPs (such as O₃ alone, O₃/H₂O₂, and O₃/UV), (2) structurally optimize BPA abatement by using a central composite design (CCD) for experimental design purposes and/or a response surface methodology to find the optimum, and (3) identify the degradation pathways, and main intermediate products, formed during BPA abatement with O₃/H₂O₂/UV. The degradation pathways of BPA degradation were revealed by O₃/H₂O₂/UV on the basis of evidences of intermediate generation. The effect of initial pH, ozone, and H₂O₂ dose during BPA abatement was studied in detail. By increasing each of these three parameters, an enhancement of the BPA degradation efficiency is mostly observed. BPA can be degraded completely when a sufficiently high ozone dose is applied. However, excess H₂O₂, as a scavenger of HO·, has a negative effect on BPA abatement, resulting in a decrease in the BPA’s degradation efficiency. For example, the removal decreased from 64 to 58% by enhancing the H₂O₂ initial dose from 0.5 to 0.75 mmol/L (at an initial pH and ozone dose of, respectively, 7 and 0.1 mg/L). The results confirmed that combining ozone with H₂O₂ and UV was a more efficient method than the other three ozone-based AOPs on the removal of BPA. Therefore, this method could be further applied for the treatment of real wastewaters containing BPA and other micropollutants.     

Interaction of bisphenol A with bovine hemoglobin using spectroscopic and molecular modeling methods

The interaction of bisphenol A with bovine hemoglobin (BHb) under physiological conditions was investigated by using fluorescence, ultraviolet-visible (UV-Vis) absorption, circular dichroism (CD), and molecular modeling. The experimental results showed that BPA can bind with BHb to form a complex. The binding constant Ka and the number of binding sites n were calculated to be 1.49 × 10(5) L mol(-1) and 1, respectively. Molecular modeling study revealed that BPA bound into BHb central cavity, and the binding mode of BPA-BHb complex could be hydrogen bonding. The UV-Vis absorption and CD spectra indicated that the secondary structure of BHb was altered, which may affect physiological functions of hemoglobin. This work is helpful for clarifying the molecular toxic mechanism of BPA in vivo.