Mn促进Fe/C微电解反应速率及降解污染物机理

为了扩宽铁炭微电解工艺的适用范围及提高处理效率,以铸铁屑、椰壳活性炭为原料,添加Mn构建Fe/Mn/C三元微电解体系处理甲基橙(MO)模拟染料废水。利用SEM-EDS、FTIR及Raman光谱分析了Fe、Mn和活性炭表面形貌及元素组成,采用UV和三维荧光光谱(EEM)探究了有机物成分的变化,对比了Fe/Mn/C和Fe/C微电解体系对MO的降解效果,揭示了Fe/Mn/C三元微电解体系降解MO的反应机理和反应动力学。结果表明,反应后的Fe、Mn和炭填料表面存在铁氧化物、铁氢氧化物及锰氧化物,Fe/Mn/C三元微电解体系可断裂MO的氮氮双键,破坏苯环结构。MO的降解过程符合准一级反应动力学模型;Fe/Mn/C微电解体系对MO降解的反应速率常数由Fe/C微电解体系的5.7381×10^–4 min^–1提高至9.3834×10^–4 min^–1,降解速率和降解效果显著优于Fe/C微电解体系。     

Mn强化Fe/C微电解工艺条件优化及降解油墨废水机理

为了提高Fe/C微电解工艺对油墨废水的处理效率,以金属锰改变传统铁碳填料的成分,采用响应面法优化微电解工艺条件,通过三维荧光光谱、紫外可见光谱、气-质联用色谱等分析处理前后油墨废水的有机物成分及填料表面结构的变化,探究絮凝和降解机理。结果表明：在初始pH为2.79,反应时间为1.58 h,Fe/Mn质量比为3.11,填料总投加量为93.36 g/L的条件下,COD去除率达到87.9%,预测值(87.8%)与实测值相差0.1%,采用响应面法可准确预测COD去除率的变化。经Fe/Mn/C微电解工艺处理后,油墨废水Zeta电位上升,絮凝作用增强。Fe/Mn/C微电解工艺可破坏苯环及共轭双键结构,对类溶解性微生物代谢产物、类芳香族蛋白质类物质以及类腐殖酸类物质的降解效果显著,微电解过程中填料表面生成了铁、锰氧化物,部分氧化物附着在活性炭表面。     

铁碳微电解法降解C.I.酸性橙7废水的过程研究

采用铁碳微电解法处理C.I.酸性橙7生产废水,通过研究铁碳微电解过程中C.I.酸性橙7及其还原产物的浓度变化,得到较优实验条件。结果表明:在C.I.酸性橙7的浓度为1 000 mg/L、调节废水p H为2、铁碳填加量为6 g、微电解时间为60 min的条件下较为经济实用,C.I.酸性橙7去除率高达89%,COD去除率可达40%;此外,通过紫外分光光谱图和循环伏安曲线对降解C.I.酸性橙7过程的中间产物进行分析,推断其还原降解的路径。     

新型微电解材料降解印染废水研究

针对传统微电解材料只适用于酸性废水的局限,对铁碳微电解材料进行改性,用于甲基橙模拟印染废水的处理,确定了处理的最佳工艺参数。结果表明:新型微电解材料在pH为4～5、11～12内对甲基橙均有较好的降解效果,最佳反应时间为3 h,最佳投加量为340 g/L。采用印染退浆废水进行对比实验,结果表明:新型微电解材料在COD去除率和可生化性提高方面均明显优于市售微电解材料,经新型微电解材料预处理后B/C提高了近5倍。     

Fe/C微电解法处理甲基紫染料废水

利用Fe/C固定床反应器,对Fe/C微电解法处理甲基紫染料废水的反应进行了研究。考察了进水pH值、进水流量、微电解反应柱中的Fe/C体积比、反应时间对处理效果的影响。结果表明,Fe/C微电解法可较好地处理甲基紫染料废水,甲基紫染料去除率高,脱色率好,最佳工艺条件为:进水pH值3.19,水流量为0.16 mL/s,微电解反应柱中的Fe/C体积比为1∶2,反应时间为3.5 h,甲基紫的去除率可达98.2%。     

铁碳微电解与Fenton试剂法耦合去除甲基橙

采用铁炭微电解与Fenton试剂氧化相结合的方法处理甲基橙模拟废水,考察铁碳微电解法对甲基橙去除的影响以及铁碳微电解法与Fenton试剂法联用对甲基橙溶液的去除效果。试验结果表明:铁碳微电解过程中,当pH值为3～4、电解时间为40 min时,铁碳微电解的去除效果最好;经铁碳微电解预处理的甲基橙溶液进一步进行芬顿试剂氧化过程,当pH值为3、0. 3%H_2O_2为3 mL、0. 1%Fe SO_4为4 mL条件下时,去除效率可达98%。     

铁碳微电解处理印染废水的效能及机理研究

针对印染废水色度高、成分复杂、难降解等问题,利用铁碳微电解工艺处理该废水,提高其可生化性和处理效率。考察初始pH、铁投加量、铁/碳质量比及反应时间对工艺的影响,通过扫描电子显微镜（SEM）、红外光谱、X射线能谱（EDS）及X射线衍射（XRD）分析反应前后铁碳结构的变化,采用Zeta电位和紫外可见光谱等对比废水处理前后有机物成分的变化,探究印染废水的降解机理。结果表明：在初始pH为4、铁投加量为80 g/L、铁/碳质量比为0.8及反应时间为90 min时,COD、浊度、色度、氨氮和TOC去除率分别为75.48%、87.88%、75.34%、92.01%和81.09%。反应前铁碳反应器的成分以Fe、C为主,活性炭的孔隙结构发达,反应后铁碳表面附着Al、K等其他金属物质和铁的氢氧化物絮体。铁碳微电解工艺可降解酯、醇类有机物为小分子物质,提高废水可生化性。     

US/Fe~(3+)/H_2O_2体系超声催化降解甲基橙的研究

采用US/Fe3+/H2O2体系超声催化降解甲基橙,考察了超声波功率、Fe3+初始质量浓度、H2O2用量、甲基橙溶液的初始质量浓度及初始pH值对超声催化降解甲基橙的影响,初步探讨了其降解动力学规律。结果表明,US/Fe3+/H2O2体系能有效降解甲基橙,且超声波与Fenton试剂对甲基橙废水的降解存在强烈的协同作用;在pH=3、超声波功率500 W、Fe3+和H2O2的初始质量浓度分别为30 mg/L和150 mg/L时,对含30 mg/L的甲基橙溶液降解120 min,其去除率达到99.5%;甲基橙的超声催化降解符合一级反应动力学规律,且甲基橙的一级反应速率常数随其初始质量浓度增大而降低。     

2D/2D WO3/Ag:ZnIn2S4 Z型异质结复合物的构筑及可见光催化性能

构筑Z型异质结复合物是光催化领域解决电子-空穴对复合较快的常用方法,其独特的双光子体系能高效的提升光催化速率而备受关注。本文通过水热法原位构筑二维/二维(2D/2D)WO₃/Ag:ZnIn₂S₄ Z型异质结复合物,并且利用透射电子显微镜(TEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)、紫外-可见漫反射光谱(UV-Vis DRS)、光电化学(PEC)和荧光光谱(PL)对其微观形貌、物相结构、元素化学态和光电性能等进行表征分析,以及采用可见光(加λ>420 nm的滤光片)照射来评价2D/2D WO₃/Ag:ZnIn₂S₄ Z型异质结复合物光解水制氢气和光降解甲基橙(MO)的催化性能。结果表明,在2D/2D WO₃/Ag:ZnIn₂S₄ Z型异质结复合物中,随着Ag:ZnIn₂S₄的含量增加,光催化性能也显著增强。当Ag:ZnIn₂S₄的质量分数为35.0%时,复合物表现出最佳的制氢速率(158.93 μmol.g_-1^.h_-1⁾与降解速率(0.18 min_-1^),这为基于WO₃纳米片设计和构筑2D/2D Z型异质结复合物用于可见光催化制氢和污染物降解提供了新的见解。     

改性活性半焦吸附-Fe/C微电解-Fenton联用技术处理焦化废水

采用改性活性半焦吸附-Fe/C微电解-Fenton联用技术处理焦化废水,探究联用技术工艺参数对焦化废水化学需氧量(COD)去除率的影响,结果表明:(1) 针对Fe/C微电解处理焦化废水的最佳操作条件为:pH=3,Fe与C质量比2.0∶1,Fe/C投加量30 g·L^-1,反应时间60 min,反应温度35 ℃;(2) 采用Fe/C微电解-Fenton氧化处理焦化废水最佳操作条件为:过氧化氢投加量25 mL·L^-1,pH=3,Fe与C质量比2.0∶1,Fe/C投加量30 g·L^-1,反应时间8 h。在最佳吸附-Fe/C-Fenton联用工艺条件下操作,对焦化废水COD降解率达到85.23%,COD由199.27 mg·L^-1降至29.43 mg·L^-1。动力学研究表明,动力学方程能很好的拟合Fe/C微电解降解过程。     

Low-Temperature SCR of NO with NH3 over USY-Supported Manganese Oxide-Based Catalysts

A series of catalysts of manganese oxide, manganese–cerium and iron–manganese oxide supported on USY (ultra-stable Y zeolite) were studied for the low-temperature selective catalytic reduction (SCR) of NO with ammonia in the presence of excess oxygen. It was found that MnO_x/USY have high activity and high selectivity to N₂ in the temperature range 80-180 °C. The addition of iron and cerium oxide increased NO conversion significantly although the single-component Fe/USY and Ce/USY catalysts had low activities. Among the catalysts studied in this work, the 14% Ce-6% Mn/USY showed the highest activity. The results showed that this catalyst yielded nearly 100% NO conversion at 180 °C at a space velocity of 30 000 cm³ g^-1 h^-1. The only product is N₂ (with no N₂O) below 150 °C. The effects of the concentration of oxygen, NO and NH₃ were studied and the steady-state kinetics were also investigated. The reaction order is 1 with respect to NO and zero with respect to NH₃ on the 14% Ce-6% Mn/USY catalyst at 150 °C.     

Comparison of catalytic ozonation of phenol by activated carbon and manganese-supported activated carbon prepared from brewing yeast

Activated carbon (AC) was prepared using brewing yeast as precursor by chemical activation and manganese was supported on activated carbon (Mn/AC) by adsorption-activation method. The characterizations of prepared AC and Mn/AC and their performance as ozonation catalysts was tested. The results indicated that the crystalline phase of supported manganese was MnO. The total BET surface areas of prepared AC and Mn/AC were found to be 1603.0 m²/g and 598.9 m²/g, with total pore volumes of 1.43 and 0.49 cm³/g, respectively. The average pore diameters of AC and Mn/AC were found to be 3.5 nm and 3.3 nm. Adsorption capacities of phenol onto the produced AC and Mn/AC were determined by batch test, at 25 °C and pH 7. Langmuir and Freundlich isotherm models were used to fit the isotherm experimental data, and the Langmuir isotherm model fitted these two adsorption systems well. The maximum uptakes of phenol by AC and Mn/AC were estimated to be 513.5 mg/g and 128.2 mg/g. The presence of AC prepared from brewing yeast was advantageous for TOC reduction of phenol solution compared with single ozonation, and the greatest TOC removal efficiency was obtained in the presence of Mn/AC. All ozonation reactions followed the pseudofirst-order kinetics model well, the degradation rate of phenol was enhanced in the presence of catalysts, and the more pronounced degradation rate was achieved in O₃/Mn/AC system. The rate constants were determined to be 2.16×10⁻² min⁻¹ for O₃ alone, 5.70×10⁻² min⁻¹ for O₃/AC and 6.82×10⁻² min⁻¹ for O₃/Mn/AC.     

Catalytic wet peroxide oxidation of phenol solution over Fe–Mn binary oxides diatomite composite

Mn–Fe binary oxides incorporated into diatomite (denoted as FM-diatomite) was prepared by the redox reaction of KMnO₄ and FeSO₄ with pH ranging from 3 to 9. The catalytic activities of FM-diatomite were studied for phenol oxidation and were compared with iron oxide modified diatomite (F-diatomite) and manganese oxide modified diatomite (M-diatomite). The obtained catalysts were characterized by scanning electron microscope, powder X-ray diffraction, energy dispersive spectroscopy, transmission electron microscope, X-ray photoelectron spectroscopy, and nitrogen adsorption/desorption isotherms. The results show that Fe–Mn binary oxides were highly dispersed on the diatomite surface in which manganese oxide and iron oxide displayed multiple oxidation states including Mn⁴⁺, Mn³⁺, Fe²⁺ and Fe³⁺. The phenol oxidation by H₂O₂ through the use of Mn–Fe-diatomite as a catalyst was conducted. FM-diatomite exhibited as an excellent catalyst for the total oxidation of phenol and main intermediates (catechol and hydroquinone). The conversion of phenol and main intermediates by means of FM-diatomite was 100 % under 50 min while that by F-diatomite also was 100 % after 110 min but other intermediates still remained. While phenol conversion by M-diatomite was close to zero due to speedy hydroperoxide decomposition over the manganese oxide catalyst. These results show that there was a synergized effect of iron and manganese oxide present in FM-diatomite.     

Synthesis of AgBiS2/gC3N4 and its application in the photocatalytic reduction of Pb(II) in the matrix of methyl orange,crystal violet,and methylene blue dyes

The removal of lead ions in contaminated water by the reduction of Pb(II) ions to the useful metallic Pb is challenging, especially in water polluted by other contaminants such as dye molecules. Most investigations focussed on the removal of Pb(II) in a single system. In reality, contaminated water contains a mixture of organic pollutants and heavy metals. Herein, we synthesized graphitic carbon nitride functionalized with ternary silver bismuth sulphide (AgBiS₂/gC₃N₄) for the photocatalytic removal of Pb(II) from dye-containing water. The as-synthesized gC₃N₄, AgBiS₂, and AgBiS₂/gC₃N₄ composite were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and transmission electron microscopy (TEM). The composite was used for the photocatalytic reduction of Pb(II) in the matrix of methyl orange, crystal violet, and methylene blue. The effect of the presence of easily-oxidizable organics and persulphate on the photocatalytic reduction of Pb(II) was also investigated. The results revealed that the presence of easily-oxidizable organics has synergistic effects on the photocatalytic reduction of Pb(II), while persulphate displayed inhibitive effect on Pb(II) reduction. The removal of Pb(II) in the dyes matrix was influenced by the type of dyes that were present in the water. The rate of Pb(II) reduction was reduced in the presence of methylene blue and methyl orange, but crystal violet displayed synergistic effects. Finally, the rate of degradation of dyes in the presence of Pb(II) was investigated. The rate of photocatalytic reduction of Pb(II) decreased from 0.0045 min^?1 to 0.0036 min^?1 and 0.0016 min^?1 in the matrix of methyl orange and methylene blue respectively. On the contrary, there was an increase in the rate of photocatalytic reduction of Pb(II) from 0.0045 to 0.0096 min^?1 in the matrix of crystal violet.     

超声波/铁-炭微电解耦合处理直接大红4BE染料废水

对超声波/铁-炭微电解耦合处理直接大红4BE染料废水进行了研究。结果表明,超声波与铁-炭微电解耦合可产生协同效应,4BE染料废水的去除率可超过90%,理论分析了协同机理。4BE染料废水的去除过程经历了快反应和慢反应两个阶段,两阶段均符合零级动力学模型,速率常数分别为3.56×10-2nmol/min和3.88×10-3nmol/min。反应主要受到溶液pH的影响,pH为2.4时有利于4BE的去除。