Visible light-induced degradation of organic pollutants using Fe（ll） supported on silica gel as an effective catalyst

Silica gel-supported Fe（ll） （SiOFe） was prepared and used for heterogeneous degradation of sulforhodamine B （SRB） and 2,4-dichlorophenol （DCP） under visible irradiation （λ 〉 420 nm） as an effective catalyst. UV-visible spectra, and infrared Spectrophotometry （IR）, fluorescence, total organic carbon （TOC） and electron spin resonance （ESR） measurements were employed to analyze the photoreaction products. The results showed that SRB could be efficiently degraded by SiOFe/H2O2 system under visible irradiation with 100% decolorization and 72.3% TOC removal after 180 min illumination. The results of ESR and fluorescence measurements indicated that the oxidative process was predominated mainly by the hydroxyl radical （.OH） generated in the system.     

Degradation of 2,4-dichlorophenol catalyzed by the immobilized laccase with the carrier of Fe3O4@MSS–NH2

With the Fe₃O₄@MSS (magnetic mesoporous silica spheres)–NH₂ as the carrier and the glutaraldehyde as crosslinking agent, the immobilized laccase has been prepared and characterized by XRD, IR, SEM and BET etc. Under the optimal conditions, the removal efficiency of 2,4-DCP reached 88 % and the removal efficiency still remained 61.5 % after five cycles of operations. In virtue of GC–MS analysis, 2,5-dimethoxyl-1,4-quinone, 2-chlorine-1,4-dimethoxyl benzene, 3,3′-dichlorine-4,4′-dimethoxyl biphenyl, maleic acid phenol ester, and three kinds of maleic acid, alcohol ester, and para-hydroxyl phenol ester compounds have been identified as intermediate and final degradation products of 2,4-DCP, respectively. Besides, the degradation products of 2,4-DCP have been confirmed by performing the ¹H-NMR and ¹³C-NMR experiments, further demonstrating the degradation mechanism of 2,4-DCP by the immobilized laccase.     

Characterization of nanoscale iron and its degradation of 2,4-dichlorophenol

Nanoscale iron was detected by TEM, X-ray diffraction and X-ray photoelectron spectroscopy. It was found that the size of the nanoscale iron particles is in the range of 30–40 nm according to TEM image, and it contains abundant Fe₃O₄ as passivating layers on the surface of the core-shell structure. To improve its performance, dilute HCl was used for the removal of the passivating layers, and the degradation of 2,4-dichlorophenol (2,4-DCP) was measured for the nanoscale iron samples treated and untreated. Experimental results demonstrated that the removal of 2,4-DCP by untreated nanoscale iron is mainly due to the adsorption of 2, 4-DCP by nanoscale iron, and there are no degradation products detected by HPLC in the process. However, excellent dechlorination of 2,4-DCP was gained by HCl-treated nanoscale iron, and 2-chlorophenol, 4-chlorophenol and phenol were detected during the process. It was concluded that dechlorination is the key reaction pathway for the degradation of 2,4-DCP by activated nanoscale iron, and phenol is found to be the main product.     

生物膜电极法降解2,4-二氯苯酚

以2,4-二氯苯酚（2,4-DCP）为目标污染物, 在隔膜式电解槽中研究不同离子交换膜对生物膜电极法处理2,4-DCP的影响. 结果表明: 阴离子交换膜有利于2,4-DCP在生物膜电极上的转化及去除中间产物; 生物膜电极保存的时间越长, 其对2,4-DCP的降解效果越差, 生物膜电极的使用寿命逐渐下降.     

Photocatalytic degradation pathways and adsorption modes of H-acid in TiO2 suspensions

Effect of adsorption mode on photodegradation of H-acid in TiO2 suspension was studied using DFT calculation,UV-Vis spec-troscopy,FTIR,and ionic chromatography.At pH 2.5,H-acid was adsorbed on TiO2 surfaces by one dissociated sulfonic group.The adsorbed sulfonic group was attacked by surface ·OH,resulting in the production of SO42-and the cleavage of the naphtha-lene ring.At pH 5.0,H-acid was adsorbed on TiO2 surfaces by two sulfonic groups.The two adsorbed sulfonic groups were sim-ultaneously attacked by surface ·OH,leading to a faster initial production of SO42-and initial degradation rate of H-acid than those under pH 2.5.Microscopic adsorption structures may be more important than adsorption amount in controlling the photo-degradation pathways of organic pollutants.     

Preparation and performance of LiNi0. 8Co0.2O2 cathode material based on Co-substituted α-Ni（OH）2 precursor

Co-substituted α-Ni（OH）2 was synthesized by a novel microwave homogeneous precipitation method in the presence of urea. LiNi0.8Co0.2O2 cathode material was synthesized by calcining Co-substituted α-Ni（OH）2 precursor and LiOH·H2O at 900℃for 10 h in flowing oxygen. XRD, FTIR, FESEM and electrochemical tests were used to study the physical and the electrochemical performances of the materials. The results show that the prepared LiNi0.8Co0.2O2 compound has a good layered hexagonal structure. Moreover, the LiNi0.8Co0.2O2cathode material demonstrates stable cyclability with a high initial specific discharge capacity of 183.9 mAh/g. The good electrochemical performance could be attributed to the uniform distribution of Ni^2＋ and Co^2＋ ions in the crystal structure and a minimal cation mixing in LiNi0.8Co0.2O2 host structure.     

Degradation of 2, 4-D acid using Mn2+ as catalyst under UV irradiation

In this paper, the oxidative degradation of 2, 4-dichlorophenoxyacetic acid (2, 4-D) using Mn²⁺/H₂O₂ reagent under UV irradiation was studied. The results show that 2, 4-D was degraded more completely in Mn²⁺/H₂O₂ solution than traditional Fenton solutions. The effects of the concentration of Mn²⁺, H₂O₂ and pH were also investigated. And under the optimal condition of 1.48×10⁻⁴ mol/L, 8.99×10⁻⁵ mol/L and pH 3.38, the formation of ·OH was the most, both the decomposition rate of H₂O₂ and the degradation rate of 2, 4-D were the fastest. In addition, the photoreaction process was monitored using spin-trapping electron paramagnetic resonance (EPR), and the results indicated that the oxidative process was predominated mainly by the hydroxyl radical (·OH) gennerated in the system. Biography: HUANG Yingping (1964–), Professor, Ph. D., research direction: pollution ecology and water pollution control.     

三维电极法降解苯酚废水中·OH的测定及其影响因素研究

 采用三维电极法电催化氧化降解苯酚废水,研究了苯酚的降解机理,证实了苯酚的降解机理主要是羟基自由基机理。实验结果表明,羟基自由基的生成量决定苯酚的去除率。同时,羟基自由基的生成量与三维电极体系的电极种类、槽电压、溶液pH值和空气流速有密切关系。     

紫外光照射下钴钼杂多酸降解有机染料SRB

制备了不同配比的钴钼杂多酸（CoMox Heteropoly acids,CoMox）,在紫外光（λ≤387 nm）照射下,以有机染料酸性桃红（Sulforhodamine B,SRB）的光催化降解为探针反应,研究了CoMox杂多酸不同配比及用量和体系介质pH值对其降解行为的影响.结果表明,最佳配比的钴钼杂多酸为CoMo12,在pH=3.0,CoMo12用量为1.0 g/L时,对SRB降解效果最好.在紫外光照射下,CoMo12活化O2,3.5 h内SRB脱色率达到96%.通过紫外-可见吸收光谱（UV-vis absorption spectrum）,红外光谱（FTIR）和总有机碳（TOC）测定分析钴钼杂多酸对SRB的降解特性,同时采用苯甲酸荧光光度法跟踪测定降解过程中产生的活性氧化物种,表明CoMo12多酸对SRB的光催化降解过程主要涉及.OH氧化历程.     

泡沫镍上原位生长CoMn2O4多级空心纳米球作为超级电容器电极材料的电化学性能研究

采用水热法结合空气气氛中的热处理过程,在泡沫镍（NF）表面生长了锰酸钴（CoMn₂O₄）多级空心纳米球,通过X射线衍射仪（XRD）、场发射扫描电镜（FE-SEM）和X射线光电子能谱（XPS）等测试手段对纳米球进行了表征.在三电极电化学测量系统中,0.1Co²⁺-250电极材料在5 mA·cm^-2时的面积比电容高达6 184 mF·cm^-2.以0.1Co²⁺-250为正极,商用活性炭（AC）为负极组装而成的混合超级电容器,在1.6 mW·cm^-2时的最大能量密度为0.112 mWh·cm^-2.即使在功率密度为16 mW·cm^-2时,能量密度仍达到0.064 mWh·cm^-2.在2 mA·cm^-2的电流密度下,经过10 000次充放电循环后,电容保持了初始值的93%.因其优越的电化学性能和低成本的便捷合成方法,CoMn₂O₄多级空心纳米球作为电极材料具有重要的应用前景.     

Study on the reaction of carbon disulfide with hydroxyl radical in aqueous solution

Carbon disulfide is an important sulfur-containing compound in the environment, and its oxidation produces about 30% of the atmospheric COS[1]. In situ measure- ments show that CS2 is widespread in the sea surface wa- ters[2―4], and more recently, the continental water seems to be especially rich sources of CS2 due to industrial waste- water effluents. It is generally accepted that the ocean is an important source for atm. CS2, and Xie et al.[5] found that marine photochemical reaction of…     

Preparation and photocatalytic properties of ilmenite NiTiO<Subscript>3</Subscript> powders for degradation of humic acid in water

The powders of ilmenite structure NiTiO₃ were prepared by a modified Pechini process using tetrabutyl titanate and nickel acetate as raw materials, and using citric acid and ethanol as a chelating agent and a solvent respectively. The powder samples were characterized by thermogravimetric and differential thermal analysis (TG-DTA) and X-ray diffraction (XRD). The photocatalytic activity of NiTiO₃ under the irradiation of ultraviolet rays (UV) light was evaluated by degrading humic acid (HA) in water as a probe reaction. The possible photodegradation mechanism was studied by the examination of active species ·OH, ·O₂⁻, and holes (h⁺) through adding scavengers. The TG-DTA and XRD results indicated that the good crystal structure of ilmenite phase NiTiO₃ could be obtained when the Ni-Ti citrate complex was calcined at 600°C. The photocatalytic activity experiments indicated that NiTiO₃ had favourable photocatalytic activity under the irradiation of UV light, and the photocatalytic degradation rate of HA reached 95.3% after a 2.5 h reaction with the photocatalyst calcined at 600°C and a photocatalyst dosage of 0.4 g/L. The possible photocatalytic mechanism was deduced that holes (h⁺) and ·OH radicals are the major reactive active species in the photocatalytic reaction, and dissolved oxygen plays a weak role in the degradation of HA.     

日光/草酸铁络合物/H2O2降解水中2,4-二氯苯酚

以日光作光源 ,Fenton 草酸铁络合物为光氧化剂 ,对水中 2 ,4 -二氯苯酚进行了光氧化降解试验研究。结果表明 :草酸铁络合物 /H2 O2 光氧化降解 2 ,4 -二氯苯酚的速率显著高于Fenton试剂 ,前者的光解初始速率大约是后者的 4倍 ;溶液 pH值对光氧化有很大影响 ,pH值在 3左右 ,2 ,4 -二氯苯酚的光降解脱氯的效果较佳 ,pH超过 4 ,光降解脱氯效率明显下降 ;在晴天和多云日照下草酸铁络合物 /H2 O2 光氧化降解有机物的速率很快 ,在阴天的光解速率相对较慢 ,但效率仍然很高     

Dechlorination of 2,4-dichlorophenol by nickel nanoparticles under the acidic conditions

Metal nanoparticles are effective for remediation of contamination with a range of compounds including chlorinated organics.However,the sorption process of the passivation oxide layers on the metal nanoparticle surfaces may result in incomplete degradation of contaminants.This phenomenon can be prevented by an acidic washing procedure or reaction in an acidic medium.In this paper,nickel nanoparticles manufactured via the carbonyl powder process were analyzed using scanning electron microscopy,transmission electron microscopy,X-ray diffraction and energy-dispersive X-ray spectroscopy.The sorption and degradation of 2,4-dichlorophenol (2,4-DCP) by nickel nanoparticles under acidic conditions was then investigated.Transmission electron microscopy and XRD results showed that the nickel nanoparticles range in size from 10 to 20 nm,and a thin passivation layer of NiO is present on the surface.This oxide layer can be removed by pretreatment washing with acidic solutions.It was indicated that dechlorination was the key reaction pathway for degradation of 2,4-DCP by nickel nanoparticles under acidic conditions.The main degradation products were 4-Chlorophenol,2-Chlorophenol,and Phenol,and among these,Phenol was dominant.The acidic medium promoted degradation by providing an appropriate pH,and H+ may be involved in the reaction.Dechlorination of 2,4-DCP by nickel nanoparticles under the acidic condition follows the second order kinetic model,and the rate constants at 298,306,316 K are 0.02,0.2 and 0.3 (g L h)-1,respectively.     

Photoelectrochemical synergetic degradation of Acid Orange II with TiO2 modified β-PbO2 electrode

Electrochemically assisted photocatalysis is an effective approach to improve photocatalytic efficiency. In this paper, modified β-PbO2 electrode was prepared by TiO2 co-deposition and characterized by SEM and XRD. Then 2.0g TiO2 modified β-PbO2 electrode (2.0 g TiO2 involved in the 200 mL co-deposition solution) was used in electrochemically assisted photocatalytic degradation of Acid Orange II and the influence of initial pH values was investigated when the potential applied across the electrodes was 1.5 V. When the potential applied was 2.5 V, the difference of the degradation process and the final products were studied. The results indicated that 2.0 g TiO2 modified β-PbO2 electrode was different from the unmodified one in that the β-PbO2 crystals became finer and the electrode became more compact and more uniform. The synergetic effect in electrochemically assisted photocatalytic degradation of Acid Orange Ⅱ was observed and degradation efficiency and TOC removal were the highest at initial solution pH 2.0. By UV-visible spectral analysis, it was proved that photoelectrochemical synergetic degradation of Acid Orange Ⅱ went through the step of producing main product maleic acid for the solution at the initial pH 2.0 within 2 h, but the degradation was slow for the solution at the initial pH 12.0.     

Perovskite-type B-site Bi-doped ceramic membranes for oxygen separation

Novel mixed conducting oxides, B-site Bi-doped perovskites were exploited and synthesized.Cubic perovskite structures were formed for BaBi0.2CoyFe0.8-yO3-δ (y≤0.4) and BaBixCo0.2Fe0.8-xO3-δ(x=0.1-0.5).The materials exhibited considerable high oxygen permeability at high temperature.The oxygen permeation flux of BaBi0.2Co0.35Fe0.45O3-δ membrane reached about 0.77×10-6 mol/cm2.s under an air/helium oxygen partial pressure gradient at 900℃, which was much higher than that of other bismuth-contained mixed conducting membranes.The permeation fluxes of the materials increased with the increase of cobalt content, but no apparent simple relationship was found with the bismuth content.The materials also demonstrated excellent reversibility of oxygen adsorption and desorption.Stable time-related oxygen permeation fluxes were found for BaBi0.2Co0.35Fe0.45O3-δ and BaBi0.3Co0.2Fe0.5O3-δ membranes at 875℃.     

Catalysis of organic pollutant photodegradation by metal phthalocyanines immobilized on TiO<Subscript>2</Subscript>@SiO<Subscript>2</Subscript>

A TiO2@SiO2 hybrid support was prepared by the sol-precipitation method using n-octylamine as a template.The photocatalyst manganese phthalocyanine tetrasulfonic acid (MnPcS) was immobilized on the support to form MnPcS-TiO2@SiO2.X-ray diffraction (XRD) and UV-Visible diffuse reflectance spectra (UV-Vis DRS) were employed to characterize the catalyst.The photocatalytic degradation of rhodamine B (RhB) and the catalytic oxidation of o-phenylenediamine (OPDA) under visible light irradiation were used as probe reactions.The mineralization efficiency and the degradation mechanism were evaluated using chemical oxygen demand (COD Cr) assays and electron spin resonance (ESR),respectively.RhB was efficiently degraded by immobilized MnPcS-TiO2@SiO2 under visible light irradiation.Complete decolorization of RhB occurred after 240 min of irradiation and 64.02% COD Cr removal occurred after 24 h of irradiation.ESR results indicated that the oxidation process was dominated by the hydroxyl radical (·OH) and superoxide radical (O-·2) generated in the system.     

自由基抑制剂对不同晶型TiO2光催化反应的影响

以荧光光谱法研究了不同晶型 TiO₂ 的光催化反应体系中羟基自由基(·OH)的产生情况,表明在H₂O₂存在条件下,金红石型 TiO₂ 经可见光激发可持续稳定产生·OH,而以锐钛矿型 TiO₂ 作光催化剂时,则检测不到·OH的生成。光催化结果表明,在H₂O₂存在条件下,苯酚可被 TiO₂ 可见光催化降解;往反应体系加入自由基抑制剂(叔丁醇或甲醇)时,明显降低了金红石型 TiO₂ 的降解效率,但对锐钛矿型 TiO₂ 的影响较弱。以金红石型 TiO₂ 作光催化剂时,苯酚的降解反应主要发生在溶液中;而以锐钛矿型 TiO₂ 作光催化剂时,则苯酚的降解反应主要发生在催化剂的表面。     

pH effect of· OH radical induced oxidation of phosphoryl- methionine in aqueous solution

Conclusion The results of pulse radiolytical research on the · OH radical-induced oxidation of NDM in aqueous solution demonstrate that pH value has a great influence on the radiolytical mechanism of NDM. At low pH value, the product is mainly stabilization of the oxidizing sulfur centre in the three-electron-bonded cation radical NDM₂ ·⁺ [S]; with the increase of pH value, NDM₂ ·⁺ [S] gradually decays to become the reducing α-amino radical which was verified by the chemical method and whose yield was also calculated. Compared with Met₂ ·⁺ [S] produced by the · OH radical-induced oxidation in aqueous solution [1], the stability of NDM₂·⁺ [S] increases and the yield of α-amino radical decreases. This suggests that the introduction of phosphoryl group has a coordinating effect on the radioprotection of methionine to biological systems, and provides the essentially theoretical foundation for the thorough clarification of the reversible phosphorylation of proteins.     

Preparation and catalytic effect of porous Co3O4 on the hydrogen storage properties of a Li-B-N-H system

A porous Co_3O_4 with a particle size of 1–3 μm was successfully prepared by heating Co-based metal organic frameworks MOF-74(Co) up to 500 °C in air atmospheric conditions. The as-prepared porous Co_3O_4 significantly reduced the dehydrogenation temperatures of the LiBH_4-2LiNH_2 system and improved the purity of the released hydrogen. The LiBH_4-2LiNH_2-0.05/3Co_3O_4 sample started to release hydrogen at 140 °C and released hydrogen levels of approximately 9.7 wt% at 225 °C. The end temperature for hydrogen release was lowered by 125 °C relative to that of the pristine sample. Structural analyses revealed that the as-prepared porous Co_3O_4 is in-situ reduced to metallic Co, which functions as an active catalyst, reducing the kinetic barriers and lowering the dehydrogenation temperatures of the LiBH_4-2LiNH_2 system. More importantly, the porous Co_3O_4-containing sample exhibited partially improved reversibility for hydrogen storage in the LiBH_4-2LiNH_2 system.