热活化过硫酸盐氧化降解水体中泛影酸钠的研究

利用热活化过硫酸盐氧化降解水体中的泛影酸钠,主要研究了体系反应温度、氧化剂浓度、溶液初始pH、底物浓度及自然水体组分对降解效果的影响.结果表明,热活化过硫酸盐降解泛影酸钠符合准一级反应动力学模型及遵循阿伦尼乌斯模型,计算得到反应活化能为105.57 kJ·mol~(-1).增加过硫酸盐初始浓度或提高反应温度及降低泛影酸钠初始浓度可以增大泛影酸钠的降解速率常数k(k=0.0062×[K_2S_2O_8]_0,R~2=0.98,[K_2S_2O_8]_0=2～8 mmol·L~(-1);lnk=-12698×1/T+34.91,R~2=0.98,T=325～345 K;k=-1.54×[泛影酸钠]_0+0.064,R~2=0.98).泛影酸钠的降解速率常数k受溶液初始pH影响较小.溶液中Cl~-、HCO~-_3和HA的存在均会抑制泛影酸钠的降解.较低的TOC去除率和产物的检测表明,泛影酸钠降解过程中仅发生苯环侧链的破坏.泛影酸钠的降解途径主要有酰胺键断裂、氨基氧化和脱羧基羟基化.     

Synthesis of nitrogen-doped carbon nanotubes-FePO4 composite from phosphate residue and its application as effective Fenton-like catalyst for dye degradation

Phosphate residue is regarded as a hazardous waste, which could potentially create significant environmental and health problems if it is not properly treated and disposed of. In this study, nitrogen-doped carbon nanotubes-FePO_4(NCNTs-FePO_4) composite was successfully synthesized from phosphate residue, and its application as an effective catalyst was explored. Firstly, an effective method was developed to recover FePO_4 from phosphate residue, achieving an impressive FePO_4 mass recovery rate of 98.14%. Then, the NCNTsFePO_4 catalyst was synthesized from the recovered FePO_4 by two main reactions, including surface modification and chemical vapor deposition. Finally, the synthesized NCNTs-FePO_4 was applied to photo-degrade 15 mg/L Rhodamine B(RhB) in a Fenton-like system. The results showed that 98.9% of RhB could be degraded in 60 min, closely following the pseudofirst-order kinetics model. It was found that even after six consecutive cycles, NCNTs-FePO_4 still retained a high catalytic capacity(50%). Moreover, ·OH radicals participating in the RhB degradation process were evidenced using quenching experiments and electron paramagnetic resonance analysis, and a rational mechanism was proposed. It was demonstrated that the materials synthesized from hazardous phosphate residue can be used as an effective catalyst for dye removal.     

Rapid removal of polyacrylamide from wastewater by plasma in the gas–liquid interface

Due to the severe restrictions imposed by legislative frameworks, the removal of polyacrylamide(PAM) rapidly and effectively from produced wastewater in offshore oilfields before discharge is becoming an urgent challenge. In this study, a novel advanced oxidation process based on plasma operated in the gas–liquid interface was used to rapidly decompose PAM, and multiple methods including viscometry, flow field-flow fractionation multi-angle light scattering, UV–visible spectroscopy, and attenuated total reflectanceFourier transform infrared spectroscopy were used to characterize the changes of PAM.Under a discharge voltage of 25 kV and pH 7.0, the PAM concentration decreased from 100 to 0 mg/L within 20 min and the total organic carbon(TOC) decreased from 49.57 to1.23 mg/L within 240 min, following zero-order reaction kinetics. Even in the presence of background TOC as high as 152.2 mg/L, complete removal of PAM(100 mg/L) was also achieved within 30 min. The biodegradability of PAM improved following plasma treatment for 120 min. Active species(such as O_3 and H_2O_2) were produced in the plasma. Hydroxyl radical was demonstrated to play an important role in the degradation of PAM due to the inhibitory effect observed after the addition of an ·OH scavenger, Na_2CO_3. Meanwhile, the release of ammonia and nitrate nitrogen confirmed the cleavage of the acylamino group.The results of this study demonstrated that plasma, with its high efficiency and chemicalfree features, is a promising technology for the rapid removal of PAM.     

Potential factors and mechanism of particulate matters explosive increase induced by free radicals oxidation

Atmospheric particulate pollution in China has attracted much public attention. Occasionally, the particle number concentration increases sharply in a short time period, which is defined as a “particulate matter explosive increase”. Heavy particulate matter pollution not only reduces visibility but also has an adverse effect on human health. Hence, there is an urgent need to discover the causes of particulate matter explosive increase. During this campaign, the particle number concentration and free radicals were measured at a tall building on the campus of Lanzhou University of Technology. Additionally, we examined a series of chemicals to reproduce the observed particulate matter explosive increase in a smog chamber to determine its potential factors. Then, we analyzed the mechanism of particulate matter explosive increase in the presence of free radicals. We found that, among the potential inorganic and organic sources analyzed, a mixture of organic and SO₂ in the research region had a major effect on particulate matter explosive increase. Moreover, free radical oxidation has a large effect, especially in the formation of organic particulates.     

磁性氮掺杂碳材料活化过硫酸盐降解酸性橙7

采用一步水热碳化法制备出微米级磁性氮掺杂碳材料（Magnetic N-doped Carbonaceous Materials,MNC）作为过硫酸盐（Persulfate,PDS）活化剂,以生成的活性氧化物质降解偶氮类染料酸性橙7（Acid Orange 7,AO7）.同时,利用扫描电镜（SEM）、比表面积与孔径测定仪（BET）、振动样品磁强计（VSM）等对MNC进行表征,考察了MNC投加量、PDS浓度、初始p H值和无机阴离子对活化PDS降解AO7的影响,并采用紫外-可见光谱分析、淬灭实验和电子顺磁性共振（Electron Paramagnetic Resonance,EPR）初步探讨了AO7的降解机理.结果表明,MNC呈微米级球状,表面富含含氧基团和氨基等活性点位;饱和磁化强度为12.7 emu·g^-1,能在外加磁场条件下实现固液分离.AO7去除率随MNC投加量、PDS浓度的增加而增加,但初始p H对AO7降解的影响呈相反规律,随p H升高而降低.3种无机阴离子对AO7降解抑制程度大小顺序为HCO₃^->SO     

Anthraquinone acted as a catalyst for the removal of triphenylmethane dye containing tertiary amino group: Characteristics and mechanism

Herein, we found that anthraquinone (AQ) acted as a catalyst for the rapid and effective removal of triphenylmethane dye containing tertiary amino group (TDAG). Results showed that AQ had an enhanced catalytic reactivity towards the removal of TDAG compared to hydro-quinone, which was further proved and explained using density functional theory (DFT) calculations. AQs could achieve a TDAG removal efficiency and rate of approximately 100% and 0.3583 min⁻¹, respectively, within 20 min. Quenching experiments and electron paramagnetic resonance (EPR) tests indicated that the superoxide radical (O₂^•−) generated through the catalytic reduction of an oxygen molecule (O₂) by AQ contributed to the effective removal of the TDAG. In addition, it was found that the electrophilic attack of the O₂^•− radical on the TDAG was the driving force for the dye degradation process. Decreasing the pH led to protonation of the substituted group of AG, which resulted in formation of an electron deficient center in the TDAG molecule (TDAG-EDC⁺) through delocalization of the π electron. Therefore, the possibility of the electrophilic attack for the dye by the negative O₂^•- radical was significantly enhanced. This study revealed that the H⁺ and the O₂^•− generated by the catalytic reduction of O₂ have synergistic effects that led to a significant increase in the dye removal rate and efficiency, which were higher than those obtained through persulfate oxidation.     

FeS-Fe0纳米复合材料活化过硫酸盐降解双酚S的研究

双酚S(BPS)是一种新兴的内分泌干扰物,在环境中广泛存在,并对自然环境和人体健康有严重危害。制备了FeS-Fe⁰纳米复合材料作为催化剂,明确了FeS-Fe⁰纳米复合材料活化PS体系(FeS-Fe⁰/PS体系)的反应条件对去除BPS的影响,包括材料中FeS与Fe⁰摩尔比、材料投加量、PS浓度、溶液初始pH值等,并应用X射线衍射分析、X射线光电子能谱分析等技术表征该复合材料,通过反应体系对比实验、Fe离子溶出实验、PS的消耗实验、猝灭实验、电子顺磁共振波谱检测,探究了FeS-Fe⁰纳米复合材料的活化机理。实验结果表明:FeS-Fe⁰/PS体系降解BPS的最优条件为溶液初始pH=3、FeS与Fe⁰摩尔比1∶25、材料投加量0.10 g/L、PS浓度1.0 mM;FeS-Fe⁰/PS体系中产生的硫酸根自由基(SO₄^·-)和羟基自由基(HO·)可降解BPS,且HO·占主导作用;FeS-Fe⁰纳米复合材料表面的FeS促进了铁离子的溶出和循环,因此其活化能力优于纳米零价铁。     

不同浓度铵态氮对苦草的生理影响

研究了苦草在不同浓度(0.02,0.05,0.10,0.30,0.60,1.00,3.00mg/L)铵态氮中暴露14d后,其生物量的变化、叶片游离氨基酸态氮、叶绿素、可溶性蛋白含量以及O2-×信号强度、抗氧化酶活性和丙二醛(MDA)含量的响应.结果表明,各浓度组苦草的生物量无显著变化,但是各生理指标变化显著.当铵态氮浓度为0.30mg/L时,苦草叶片中游离氨基酸态氮的含量即开始显著升高.当铵态氮浓度达到0.60mg/L时,超氧化物歧化酶(SOD)活性显著升高,表明苦草诱导产生氧化应激但未受到氧化损伤.当铵态氮浓度高于1.00mg/L时,SOD和过氧化物酶(POD)活性显著升高,O2-×信号强度显著增强,叶绿素、可溶性蛋白含量显著降低.当铵态氮浓度为0.02mg/L时,O2-×信号强度显著增强.综上,铵态氮浓度低于0.60mg/L苦草生长良好,浓度31.00mg/L苦草光合能力受到抑制、代谢受到干扰.苦草对铵态氮最敏感的生理生化指标是叶片中游离氨基酸态氮含量.铵态氮作为沉水植物的一种营养物质,当其含量较低时,植物由于营养缺乏诱导产生自由基.     

Organophosphorous compounds and oxidative stress: a review

Organophosphorous compounds (OP) have largely been used as pesticides globally. These chemicals induce oxidative stress as a possible mechanism of action, which has been a focus of toxicological research for the last decade. This review evaluated the presence of oxidative stress, balance between total antioxidant capacity, and oxygen free radicals associated with OP compound exposure. Oxidative stress induced by OP leads to disturbances in function of different organs and tissues. Evidence indicates that stimulation of free radical production, induction of lipid peroxidation, and disturbance of the total antioxidant capacity are mechanisms of toxicity induced by most OP. Thus, use of antioxidants may be beneficial in treatment of OP poisoning, which remains to be elucidated with further clinical trials.     

Feasibility study of decomposing methane with hydroxyl radicals

Coal-mine gas disaster is one of the most serious coal-mine disasters in China. The main component of coal-mine gas, methane is chemically stable and very difficult to be degraded by conventional methods. Hydroxyl radical (OH), due to strong oxidizing ability and high electro-negativity, is the primary degradation source of atmospheric methane. In the present study, methane degradation using hydroxyl radicals generated by Fenton’s reagent, Fe²⁺/H₂O₂, has been carried out in the self-designed bubbling reactor. The effects of H₂O₂ concentration, dosage of FeSO₄·7H₂O and initial pH value on methane removal efficiency were investigated respectively. It has been found that the optimal reaction conditions were 100 mM of hydrogen peroxide, 2.00 mM of ferrous ion and initial pH value of 2.5. Under optimal conditions, the removal efficiency of methane reached 25% after 30 min. The preliminary experimental results unambiguously demonstrate that the degradation of methane using hydroxyl radicals generated by Fenton’s reagent is feasible.