A novel use of TiO_2 fiber for photocatalytic ozonation of 2,4-dichlorophenoxyacetic acid in aqueous solution

More efficient oxidation methods are needed to degrade especially newly emerging recalcitrant organic contaminants at low concentrations in the water environment. Reduced photonic efficiency of immobilized TiO2 is a major challenge in TiO2-assisted advanced oxidation processes (AOP). Mineralization of 2,4-dichllorophenoxyacetic acid (2,4-D) in low aqueous solution by O3/UV/TiO2 using the world’s first high-strength TiO2 fiber was investigated and compared with O3, UV/TiO2, and O3/TiO2 in laboratory batch ex...

N-doped carbon-coated Fe_(3)N composite as heterogeneous electro-Fenton catalyst for efficient degradation of organics

Herein,the application of a N-doped graphitic-carbon-coated iron nitride composite dispersed in a N-doped carbon framework(Fe_(3)N@NG/NC)is investigated as a heterogeneous electro-Fenton(HE-EF)catalyst for the efficient removal of organics.The simultaneous carbonization and ammonia etching of iron-based metal organic framework(Fe-MOF)materials yielded well-dispersed N-doped carbon-coated Fe_(3)N nanoparticles with a diameter of~70 nm.The Fe_(3)N and pyridinic N endowed the composite with high HE-EF activity for decomposing the electrogenerated H_(2)O_(2) to•OH.The Fe_(3)N@NG/NC exhibited outstanding HE-EF performance in removing various organic pollutants with low iron leaching.A removal rate of 97-100%could be obtained for rhodamine B(RhB),dimethyl phthalate,methylene blue,and orange Ⅱ in 120 min at a pH of 5.0.When the solution pH was set to 3.0,5.0,7.0,and 9.0,the removal rate of RhB reached 100%,96%,92%,and 81%,respectively,in 60 min at an optimum voltage of 0.0 V(vs.reversible hydrogen electrode(RHE)).Moreover,the concentration of leached iron was expected to be below 0.03 mg/L in a wide pH range of 3.0-9.0.In addition,the RhB removal efficiency remained as high as 90%after six cycles in the reusability experiments.This work highlights the MOF-derived Fe_(3)N composite as an efficient HE-EF catalyst and the corresponding catalytic mechanism,which facilitates its application in wastewater treatment.

Photocatalytic degradation of methylene blue over MIL-100(Fe)/GO composites: a performance and kinetic study

Adsorption coupled with photocatalytic degradation is proposed to fulfill the removal and thorough elimination of organic dyes.Herein,we report a facile hydrothermal synthesis of MIL-100(Fe)/GO photocatalysts.The adsorption and photocatalytic degradation process of methylene blue(MB)on MIL‐100(Fe)/GO composites were systematically studied from performance and kinetic perspectives.A possible adsorption‐photocatalytic degradation mechanism is proposed.The optimized 1M8G composite achieves 95%MB removal(60.8 mg/g)in 210 min and displays well recyclability over ten cycles.The obtained MB adsorption and degradation results are well fitted onto Langmuir isotherm and pseudo‐second order kinetic model.This study shed light on the design of MOFs based composites for water treatment.

Carboxylates as green corrosion inhibitors of magnesium alloy for biomedical application

The efficiency of the green inhibitors(sodium salts of fumarate,glycolate and gluconate)in suppressing corrosion of the structural MA8 magnesium alloy(Mg–Mn–Ce)and the biomedical Mg–0.8Ca alloy was studied using the hydrogen evolution measurements,mass loss test,EIS,PDP,SVET/SIET.The analysis of the morphology,chemical composition,and growth kinetic of corrosion films formed in 0.9 wt%NaCl solution with and without corrosion inhibitors was carried out.The most compact surface film with the smallest thickness was formed in a saline solution with sodium fumarate.The Mg alloy samples exhibited the highest polarization resistance,the lowest localized electrochemical activity,and the lowest corrosion rate in saline with the addition of sodium fumarate and sodium glycolate.The efficiency of the applied inhibitors was up to 81%.The model of the corrosion mechanism based on the sorption of molecules of organic inhibitors is proposed.The results show the high compatibility of the used inhibitors with the calcium-phosphate PEO-matrix,indicating the possibility of forming a self-healing coating by means of these active substances.

Microbial Degradation of Organic Contaminants in Streambed/Floodplain Sediments in Passaic River—New Jersey Area

This paper is intended to explore soil organic matter and carbon isotope fractionation at three locations of the Passaic River to determine if microbial degradation of organic contaminants in soil is correlated to the surrounding physical environment. Microbial degradation of organic contaminants is important for the detoxification of toxic substances thereby minimizing stagnation in the environment and accumulating in the food chain. Since organic contaminants are not easily dissolved in water, they will penetrate sediment and end up enriching the adjacent soil. The hypothesis that we are testing is microbial activity and carbon isotope fractionation will be greater in preserved soils than urban soils. The reason why this is expected to be the case is the expectation of higher microbial activity in preserved environments due to less exposure to pollutants, better soil structure, higher organic matter content, and more favorable conditions for microbial growth. This is contrasted with urban soils, which are impacted by pollutants and disturbances, potentially inhibiting microbial activity. We wish to collect soil samples adjacent to the Passaic River at a pristine location, Great Swamp Wildlife Refuge, a suburban location, Goffle Brook Park, Hawthorne NJ, and an urban location, Paterson NJ. These soil samples will be weighed for soil organic matter (SOM) and weighed for isotope ratio mass spectrometry (IRMS) to test organic carbon isotopes. High SOM and δ13C depletion activity indicate microbial growth based on the characteristics of the soil horizon rather than the location of the soil sample which results in degradation of organic compounds.

Persistence of fertilization effects on soil organic carbon in degraded alpine wetlands in the Yellow River source region

In the restoration of degraded wetlands,fertilization can improve the vegetation-soil-microorganisms complex,thereby affecting the organic carbon content.However,it is currently unclear whether these effects are sustainable.This study employed Biolog-Eco surveys to investigate the changes in vegetation characteristics,soil physicochemical properties,and soil microbial functional diversity in degraded alpine wetlands of the source region of the Yellow River at 3 and 15 months after the application of nitrogen,phosphorus,and organic mixed fertilizer.The following results were obtained:The addition of nitrogen fertilizer and organic compost significantly affects the soil organic carbon content in degraded wetlands.Three months after fertilization,nitrogen addition increases soil organic carbon in both lightly and severely degraded wetlands,whereas after 15 months,organic compost enhanced the soil organic carbon level in severely degraded wetlands.Structural equation modeling indicates that fertilization decreases the soil pH and directly or indirectly influences the soil organic carbon levels through variations in the soil water content and the aboveground biomass of vegetation.Three months after fertilization,nitrogen fertilizer showed a direct positive effect on soil organic carbon.However,organic mixed fertilizer indirectly reduced soil organic carbon by increasing biomass and decreasing soil moisture.After 15 months,none of the fertilizers significantly affected the soil organic carbon level.In summary,it can be inferred that the addition of nitrogen fertilizer lacks sustainability in positively influencing the organic carbon content.

A Z-scheme LaFeO_(3)-CuFe_(2)O4 composite for sulfate radical-based photocatalytic process:Synergistic effect and mechanism

The sulfate radical-based photocatalytic process is supposed to be the most promising way to degrade organic pollutants.However,the development of a suitable and efficient photocatalyst is very challenging.The 40LaFeO_(3)-CuFe_(2)O_(4)(40LFO-CFO)nanocomposite was constructed and its catalytic performance was studied using Rhodamine B(RhB)as the target pollutant.40LFO-CFO exhibited excellent RhB degradation by the persulfate(PS)-assisted photocatalytic process compared to the pristine LFO and CFO.The degradation rate constant for RhB by 40LFO-CFO in the Vis/PS system was 2.22h^(-1)which is 3.04 times and 5.05 times higher than the pristine LFO(0.73 h^(-1))and CFO(0.44h^(-1)),respectively.Furthermore,the trapping experiments and EPR spectra proved that h^(+) plays a leading role in the bleaching of RhB for the 40LFO-CFO/PS/Vis system.The enhanced photocatalytic oxidation activity of 40LFO-CFO could be attributed to the unique charge carriers flow in 40LFO-CFO due to the Z-scheme and the cooperation effect between photocatalysis and PS activation.The recycle tests confessed the stability of 40LFO-CFO.Additionally,the intermediates and products of RhB are detected by liquid chromatographymass spectrometry(LC-MS),and the photocatalytic degradation routes of RhB for the 40LFO-CFO/Vis/PS system were proposed.Moreover,the 40LFO-CFO nanocomposite has a superior catalytic performance for other organics,suggesting that it is a promising heterocatalyst because of its high catalytic activity and stability for the PS-assisted photocatalytic process.

光催化协同Fenton技术有效降解水中有机污染物的应用研究进展

随着工业化进程的不断加快,越来越多的污染物排放造成了地表水的严重污染。科学界已经证实,高级氧化技术(AOPs)是解决严重水污染问题的有效措施。在众多的有机污染物处理方法中,光-Fenton法由于其环境友好、价格适宜和应用范围广泛,已成为一种具有吸引力的水体污染物去除替代方法。本文重点回顾了近年来光催化协同Fenton在处理印染、抗生素、多酚类难降解废水方面的主要催化氧化作用,比较和分析了当前光Fenton与单一光催化和Fenton技术的降解机理。然后提出了光Fenton技术大规模发展与应用的策略,以期为光Fenton催化领域的未来发展提供新的思路。

水力空化协同Fenton联合光催化法降解有机废水

本文研究了水力空化法分别与芬顿法和光催化法联合降解处理有机废水的最优工艺。采用自建体系,优化了相关操作参数,探讨了初始pH值、H2O2浓度、水力空化入口压力、溶液初始浓度等条件对水力空化分别与Fenton或光催化法联合降解效果的影响。结果表明,酸性条件下罗丹明B的降解效果更佳,H2O2的最佳浓度为15mg·L^(-1),罗丹明B的初始浓度为10mg·L^(-1),水力空化的最佳入口压力为0.3MPa。在最优条件下,水力空化协同Fenton联合光催化降解罗丹明B的效果最佳,降解率达到89.8%,显著高于单独使用水力空化、Fenton法或光催化降解的效果。这种协同作用主要归因于多种技术的相互协同增效,进而增强了罗丹明B的降解效果。本研究可为高效降解罗丹明B等污染物提供新的途径。

锰渣/H_(2)O_(2)非均相Fenton体系催化降解亚甲基蓝的研究

采用锰渣和H_(2)O_(2)构成的非均相Fenton体系降解亚甲基蓝,研究了初始pH值、H_(2)O_(2)浓度、锰渣加入量及反应温度对降解性能的影响,考察了锰渣的循环稳定性能,探讨了锰渣/H_(2)O_(2)体系去除亚甲基蓝的机理。结果表明,反应温度25℃、亚甲基蓝浓度20 mg/L、H_(2)O_(2)浓度10 mmol/L、初始pH值2.5、锰渣加入量2 g/L条件下反应120 min,锰渣/H_(2)O_(2)体系对亚甲基蓝的去除率超过98.1%;锰渣循环使用5次后,反应300 min时对亚甲基蓝的去除率仍可达95.5%。在锰渣/H_(2)O_(2)非均相Fenton体系中,·OH对亚甲基蓝的降解起主导作用。

Preparation of three-dimensional interconnected mesoporous anatase TiO_2-SiO_2 nanocomposites with high photocatalytic activities

In this article, we report the preparation of a three-dimensional（3D） interconnected mesoporous anatase TiO2-SiO2 nanocomposite. The nanocomposite was obtained by using an ordered two-dimensional（2D） hexagonal mesoporous anatase 70 TiO2-30 SiO2-950 nanocomposite（crystallized at 950 °C for 2 h） as a precursor, NaO H as an etchant of SiO2 via a ＂creating mesopores in the pore walls＂ approach. Our strategy adopts mild conditions of creating pores such as diluted NaO H solution, appropriate temperature and solid/liquid ratio, etc. aiming at ensuring the integrities of mesopores architecture and anatase nanocrystals. XRD, TEM and N2 sorption techniques have been used to systematically investigate the physico-chemical properties of the nanocomposites. The results show that the intrawall mesopores are highly dense and uniform（average pore size 3.6 nm）, and highly link the initial mesochannels in a 3D manner while retaining mesostructural integrity. There is no significant change to either crystallinity or size of the anatase nanocrystals before and after creating the intrawall mesopores. The photocatalytic degradation rates of rhodamine B（RhB, 0.303 min^–1） and methylene blue（MB, 0.757 min^–1） dyes on the resultant nanocomposite are very high, which are 5.1 and 5.3 times that of the precursor; even up to 16.5 and 24.1 times that of Degussa P25 photocatalyst, respectively. These results clearly demonstrate that the 3D interconnected mesopores structure plays an overwhelming role to the increments of activities. The 3D mesoporous anatase TiO2-SiO2 nanocomposite exhibits unexpected-high degradation activities to RhB and MB in the mesoporous metal oxide-based materials reported so far. Additionally, the nanocomposite is considerably stable and reusable. We believe that this method would pave the way for the preparation of other 3D highly interconnected mesoporous metal oxide-based materials with ultra-high performance.

超声-Fenton试剂联合降解水中十二烷基苯磺酸钠的研究

采用功率超声与Fenton试剂联合的新方法降解水中十二烷基苯磺酸钠(SDBS).实验研究了超声反应时间、硫酸亚铁用量、氧化剂H2O2用量和初始溶液pH值等因素对降解效果的影响.结果表明:在超声波频率59kHz、功率45W、反应时间45min、溶液起始pH值3、硫酸亚铁和双氧水质量浓度分别为0.65g/L和1.2g/L的最佳降解条件下,SDBS的降解率可达80%,说明超声-Fenton试剂联合法是一种有效降解SDBS的方法.

新型Fenton试剂氧化降解有机物

在酸性条件下用NaC lO或Ca(C lO)2生成HC lO,利用HC lO代替H2O2进行Fenton反应有效地降解了废水中的有机物。当pH=1.7、反应4 h时,β-萘酚、R盐、二羟基R盐、酸性红、实际废水的化学需氧量(COD)去除率分别可达40%、38%、12%、50%和73%;对比实验显示,反应时间为1 h时,β-萘酚和R盐的COD去除率分别为10.2%和16.2%,而用H2O2则分别为23.4%和18.1%。辅以光照,相应的COD去除率则分别为35.0%和23.1%、29.8%和21.3%。结果说明,用HC lO代替H2O2进行Fenton反应是可行的。

Fenton试剂处理难降解有机废水及其应用

介绍了 Fenton试剂处理难降解有机废水的机理和影响因素 ,列举了 Fenton试剂处理一些难降解有机废水的反应条件及处理效果 ,并概述了其在实践中的应用。

Fenton试剂强化双低频超声降解对氯苯酚的研究

研究了Fenton试剂强化双低频超声波氧化对氯苯酚(4-CP)的降解效果、降解机理和动力学.探讨了影响4-CP降解的各种因素,最佳实验条件为22kHz超声波声强为15W/cm2,40kHz超声波输出电功率50W不变,25℃,初始pH为3～5,H2O2∶Fe2+(摩尔比)=20∶1,H2O2为(0.3～0.5)×10-3,富氧作为饱和气体.双频超声波处理4-CP降解速率比22和40kHz单独超声波处理提高了1.4倍;Fenton试剂强化双频超声波催化技术比单独双频超声波处理4-CP降解速率提高了1.3倍,并且降解过程符合一级反应动力学.双频超声波处理和Fenton试剂强化双频超声波氧化技术都具有明显的协同效应.

微波-改性活性炭-Fenton试剂氧化法降解水中2,4-二氯酚

以经Fe2(SO4)3溶液浸渍改性的活性炭作催化剂、Fenton试剂作氧化剂,采用微波-改性活性炭-Fenton试剂氧化法降解水中的2,4-二氯酚。考察了改性活性炭加入量、H2O2与Fe2+摩尔比、Fenton试剂加入量、微波功率和2,4-二氯酚溶液初始pH对2,4-二氯酚降解效果的影响。在改性活性炭加入量1.0g/L、n(H2O2):n(Fe2+)=16.7(H2O2加入量6.0mmol/L、Fe2+加入量0.36mmol/L)、Fenton试剂加入量为6.36mmol/L、微波功率600W、微波辐射时间10min、2,4-二氯酚溶液初始pH为6.0的条件下,2,4-二氯酚降解率和TOC去除率分别可达98.7%和84.0%。

零价铁-Fenton试剂体系降解有机污染物的研究进展

零价铁-Fenton试剂体系在对许多有机污染物有着较好的处理效果的同时,有效地克服了单独零价铁还原与传统Fenton反应的缺点。本文分析了零价铁-Fenton试剂体系的作用机理,总结了零价铁-Fenton试剂体系在处理有机污染物中的新进展,介绍了零价铁-Fenton试剂体系与其他技术联用降解有机污染物的研究成果。并讨论了对该反应有较大影响的几种因素。针对目前的研究中出现的一些问题,结合实际的需要,提出了今后需关注的研究方向。

光助Fenton试剂氧化降解染料直接耐晒黑G的研究

文章研究了影响Fenton试剂氧化降解持久性有机污染物直接耐晒黑G的因素,如光源的选择、初始pH值、H2O2的用量、Fe2+的用量、阳离子交换树脂载体的引入等,通过研究确定了各因素的优化条件。研究结果表明:太阳光照能有效的促进直接耐晒黑G染料的降解脱色,大大缩短反应时间;引入阳离子交换树脂后,可增强Fenton氧化反应的活性,降解效果更好。

Photo-Fenton技术处理难降解有机废水的研究进展

Photo-Fenton氧化法是将紫外或可见光引入到Fenton体系中形成的一种高级氧化技术.介绍了Photo-Fen-ton技术处理难降解有机废水的作用机理,探讨了不同外界影响因素对处理效果的影响,阐述了该技术在水处理中研究和应用的最新进展,并提出了Photo-Fenton试剂的发展方向和前景.

单体同位素判识地下水MTBE衰减的研究进展

有机单体同位素分析(CSIA)技术能够测定有机化合物单体中特定元素的稳定同位素比值,是一种发展中的新的技术方法。依靠CSIA提供的数据可以确定污染物MTBE来源,判识生物降解的途径,量化降解的程度。更重要的是,通过同位素动力学分馏模型的建立,CSIA技术可以作为评价和预测污染物衰减的程度和衰减时间的强有力工具。文章主要综述了应用CSIA技术解析污染物MTBE衰减过程的应用进展。