Enhanced activation of peroxymonosulfate by Fe/N co-doped ordered mesoporous carbon with dual active sites for efficient removal of m-cresol

The novel Fe-N co-doped ordered mesoporous carbon with high catalytic activity in m-cresol removal was prepared by urea-assisted impregnation and simple pyrolysis method.During the preparation of the Fe-NC catalyst,the complexation of N elements in urea could anchor Fe,and the formation of C3N4during urea pyrolysis could also prevent migration and aggregation of Fe species,which jointly improve the dispersion and stability of Fe.The FeN4sites and highly dispersed Fe nanoparticles synergistically trigger the dual-site peroxymonosulfate (PMS) activation for highly efficient m-cresol degradation,while the ordered mesoporous structure of the catalyst could improve the mass transfer rate of the catalytic process,which together promote catalytic degradation of m-cresol by PMS activation.Reactive oxygen species (ROS) analytic experiments demonstrate that the system degrades m-cresol by free radical pathway mainly based on SO_(4)^(-)·and·OH,and partially based on·OH as the active components,and a possible PMS activation mechanism by 5Fe-50 for m-cresol degradation was proposed.This study can provide theoretical guidance for the preparation of efficient and stable catalysts for the degradation of organic pollutants by activated PMS.

Dissimilatory reduction of Fe^III (EDTA) with microorganisms in the system of nitric oxide removal from the flue gas by metal chelate absorption

In the system of nitric oxide removal from the flue gas by metal chelate absorption, it is an obstacle that ferrous absorbents are easily oxidized by oxygen in the flue gas to ferric counterparts, which are not capable of binding NO. By adding iron metal or electrochemical method, Fe III (EDTA) can be reduced to Fe II (EDTA). However, there are various drawbacks associated with these techniques. The dissimilatory reduction of Fe III (EDTA) with microorganisms in the system of nitric oxide removal by metal chelate absorption was investigated. Ammonium salt instead of nitrate was used as the nitrogen source, as nitrates inhibited the reduction of Fe III due to the competition between the two electron acceptors. Supplemental glucose and lactate stimulated the formation of Fe II more than ethanol as the carbon sources. The microorganisms cultured at 50℃ were not very sensitive to the other experimental temperature, the reduction percentage of Fe III varied little with the temperature range of 30—50℃. Concentrated Na 2CO 3 solution was added to adjust the solution pH to an optimal pH range of 6—7 The overall results revealed that the dissimilatory ferric reducing microorganisms present in the mix culture are probably neutrophilic, moderately thermophilic Fe III reducers.

Fabrication of Poly（y-glutamic acid）-coated Fe3O4 Magnetic Nanoparticles and Their Application in Heavy Metal Removal

In this study, poly（y-glutamic acid）-coated Fe3O4 magnetic nanoparticles （y-PGA/Fe304 MNPs） were successfully fabricated using the co-precipitation method. Fe3O4 MNPs were also prepared for comparison. The av erage size and specific surface area results reveal that 7-PGA/Fe304 MNPs （52.4 nm, 88.41 m2.g-1） have smaller particle size and larger specific surface area_ than Fe3O4 MNPs （62.0 nm, 76.83 mLg-1）. The y-PGA/Fe3O4 MNPs

High Efficient Removal of Trace Molybdenum from Water by FeCl_3:Effects of p H and Affecting Factors in the Presence of Co-existing Background Constituents

The effect of FeCl_3 coagulation-filtration on the removal of trace Mo(Ⅵ) from water is investigated in the p H range of 4. 00 to 9. 00 and the effects of sulfate,silicate,phosphate and humic acid( HA) on the process were determined. Overall,the removal of Mo(Ⅵ) is determined by two factors: the content of Fe intercepted from water( Intercepted Fe) and the affinity between Mo(Ⅵ)( or co-existing background constituents) and adsorption sites. At low p H,where the agglomeration of the iron flocs is limited,the former factor is dominant,so the methods that can promote the agglomeration of the iron flocs,such as increasing the p H,adding co-existing constituents( sulfate,phosphate or HA),can increase the removal of Mo(Ⅵ). While at high p H,the second factor dominated. Increasing the p H weakens the affinity between Mo(Ⅵ) and the iron flocs,and co-existing background constituents( sulfate,phosphate,silicate or HA) compete with Mo(Ⅵ) for adsorption sites,both effects result in a decrease in Mo(Ⅵ) removal. The Mo(Ⅵ) removal efficiency of FeCl_3 in natural water decreases as the p H increases from 4. 00 to 9. 00,and it is better to operate the coagulation process at p H 5.00 in the practical water treatment engineering.

Absorption performance of DMSA modified Fe_3O_4@SiO_2 core/shell magnetic nanocomposite for Pb^(2+) removal

The purpose of this study is to explore the adsorption performance of meso-2,3-dimercaptosuccinic acid(DMSA)modified Fe3O4@SiO2 magnetic nanocomposite(Fe3O4@SiO2@DMSA)for Pb2+ions removal from aqueous solutions.The effects of solution pH,initial concentration of Pb2+ions,contact time,and temperature on the amount of Pb2+adsorbed were investigated.Adsorption isotherms,adsorption kinetics,and thermodynamic analysis were also studied.The results showed that the maximum adsorption capacity of the Fe3O4@SiO2@DMSA composite is 50.5 mg/g at 298 K,which is higher than that of Fe3O4 and Fe3O4@SiO2 magnetic nanoparticles.The adsorption process agreed well with Langmuir adsorption isotherm models and pseudo second-order kinetics.The thermodynamic analysis revealed that the adsorption was spontaneous,endothermic and energetically driven in nature.

Removal of tungsten from molybdate solution by Fe-Mn binary oxide adsorbent

Considering the different geochemical enrichment behaviors of W and Mo,Fe?Mn binary oxide(FMBO),ferric hydroxide(Fe(OH)3)and manganese dioxide(MnO2)were studied to separate W from molybdate solution,respectively.The experimental results demonstrated that Fe?Mn binary oxide(FMBO)was the most suitable adsorbent for the separation.Under a wide pH(6.9?11.3)region,more than80%W removal efficiency and less than3%Mo loss could be obtained.In addition,the Fe?Mn binary oxide adsorbent can be regenerated by treating with3mol/L NaOH,and the W adsorption efficiency was retained after five adsorption?desorption?regeneration cycles.All these indicate that the Fe?Mn binary oxides have the potential for the separation of W from molybdate solution.

Efficient removal of Al(Ⅲ)and P507 from high concentration MgCl_(2)solution based on in-situ reaction strategy

For a highly efficient recycling of a wastewater containing a high concentration of MgCl_(2),Al(Ⅲ)and P507 were scheduled to be removed in advance.In this study,the in-situ removal of Al(Ⅲ)and P507 from a high concentration MgCl_(2)solution at different pH values and Al/P molar ratios was investigated.The results showed that P507 formed organic complexes of Al_(x)(OH)_y^(Z+)-P507 at pH of 2.0-4.0.At pH of 4.0-5.0,Al(Ⅲ)precipitated and transferred into Al(OH)_(3)with a flocculent amorphous morphology.Active sites on the Al(OH)_(3)surface enhanced the removal efficiency of P507.At pH of 6.0-6.5,Al(Ⅲ)and Mg(Ⅱ)formed layered crystalline Al(OH)_(3)and MgAl_(2)(OH)_(8with)small pore channels and fewer active sites,resulting in a reduced removal efficiency of P507.When the Al/P molar ratio exceeded 13 and the pH was between 4.0 and 5.0,the removal rates of both Al(Ⅲ)and P507 were higher than98%,while the concentration loss of Mg(Ⅱ)was only 0.2%-0.9%.

Improvement of a Mesh-Type Cu/Ni/γ-Al2O3/Al Catalyst for Steam Reforming of Dimethyl Ether by Metal (Fe, Zn or La) Addition for CO in Situ Removal

A mesh-type structured anodic alumina supported Cu/Ni bi-functional catalyst was developed for steam reforming of dimethyl ether (SRD). It was found that the Cu/Ni/γ-Al2O3/Al catalyst had remarkable catalytic activity and stability, but a high CO selectivity. Therefore, a multi-functional catalyst was proposed by metals (Fe, Zn, or La) addition to inhibit CO formation during the SRD process. The results show that promoter Fe can improve the Cu dispersion and decrease the reduction temperature of catalyst, and CO selectivity was minimized from 27% to around 3%. However, the addition of Zn and La only can decrease the CO selectivity to 12%. Furthermore, there was an excellent synergetic effect between Cu/Ni/γ-Al2O3 and Fe over the Cu/Ni/Fe/γ-Al2O3/Al catalyst by evaluating catalytic performance of catalysts with different packing structures. And the synergetic mechanism of the active components (γ-Al2O3, Cu or Cu2O, and Fe3O4) for SRD and CO in suit removal was proposed. Finally, a 400-h durability test was carried out and the results show that the Cu/Ni/Fe/γ-Al2O3/Al catalyst had an excellent stability with a 100% DME conversion and low CO selectivity.

Removal and Recovery of Chromium(III) from Aqueous Chromium(III) Using <i>Arthrobacter nicotianae</i>Cells

The removal of Cr(III) from aqueous Cr(III) using Arthrobacter nicotianae cells was examined. Cr(III) removal was strongly affected by the pH of the solution and the amounts of Cr(III) removed increased as the pH (1 - 5) of the solution increased. The removal of Cr(III) using the cells was also strongly affected by the Cr(III) concentration of the solution, and obeyed the Langmuir isotherm. The percentage of Cr increased as the cell quantity increased, whereas the amount of Cr (μmol/g dry wt. cells) decreased. The removal of Cr(III) using the cells was very fast, and reached an equilibrium within 6 h from the supply of Cr(III) in the solution. A small amount of Cr(III) absorbed by immobilized cells was desorbed at 30oC;however, most was desorbed at reflux temperature using diluted HCl. Cr(III) adsorption-desorption cycles can be repeated 5 times using immobilized cells. These results have practical implications for industrial wastewater management.

Removal of Chromium(VI) from Aqueous Solution Using Persimmon Tannin Gel and Subsequent Recovery as Chromium(III)

This study herein was investigated the removal of chromium(VI) from an aqueous solution using persimmon tannin gel and its subsequent recovery as chromium(III). At pH 2, Cr(VI) was effectively adsorbed (~80% adsorption) and ppm solution was reduced to Cr(III) on the persimmon gel within 10 min. Although desorption of the Cr(III) species was challenging at 30°, it was increased upon increasing the temperature and was quantitatively desorbed in the presence of 1 M hydrochloric acid under reflux. In addition, although the quantity of retained Cr(VI) on the tannin gel increased upon increasing the chromium concentration of the original aqueous solution, all the desorbed chromium was successfully reduced to Cr(III). Finally, Cr(VI) removal and recovery as Cr(III) was repeated effectively 8 times using the same persimmon tannin gel sample, thus demonstrating the recyclability of this system.

Removal, Recovery and Recycle of Gold (III) from Aqueous Solution Using Persimmon Tannin Gel

In order to recover much amount of gold, gold removal-recovery cycle was examined using immobilized persimmon gel, which could remove much amount of gold (III) from the tetrachloroaurate solution at 30°C. Removal of gold has proceeded different 2 mechanisms stages. At first, gold (III) was adsorbed rapidly on the surface of the persimmon gels until 2 hours and reached adsorption equilibrium. After that, the amount of gold removed was re-increased slowly and also reached equilibrium until 48 hours. The amount of gold removed was affected by the pH of the solution. The amount of Au removed was the highest at pH 5, which was decreased with decreasing or increasing the pH of the solution. The amount of gold removed (mol/g-dry wt. gels) was increased with increasing the gold concentration in the solution, whereas gold removed ratio was decreased. Gold removed ratio was increased with increasing the amount of persimmon gel used, whereas the amount of removed Au (mol/g-dry wt. gels) was decreased. Gold removal-recovery cycles were also examined in detail.

伯胺(N1923)-正辛烷在硫酸体系中萃取和反萃Fe(III)机理的研究

对伯胺—正辛烷萃取体系在萃取和反萃过程中有机相组成和水含量的变化用FTIR和光子相关谱进行分析研究。结果表明:伯胺与水相酸作用生成了阳离子型表面活性剂的结构,在有机相中易生成反相胶团。其萃取和反萃过程的实质是反相胶团内外的阳离子交换过程。Fe(Ⅲ)以水合形式萃取入有机相中,Fe(Ⅲ)的水解可能发生在反相胶团的微环境中。

水杨醛缩三乙烯四胺Schiff碱Fe(III)配合物的合成、结构和光谱性质

合成水杨醛缩三乙烯四胺Schiff碱Fe(Ⅲ)配合物[(saltrien)Fe]Cl.2H2O。采用元素分析、红外光谱、电子光谱对其结构进行了表征,晶体结构通过X-射线衍射法测定。该化合物的化学计量式为:20H29ClFeN4O4,晶体属单斜晶系,其空间群为P21/c。晶胞参数:a = 18.517(4), b = 9.985(2), c = 12.035(2) , b = 103.43(2)o, V = 2164.3(7) 3, Z = 4, F(000) = 1008, r = 1.475 g/cm3, Mr = 480.77, m (MoKa) = 0.855 cm-1。结构偏离因子R1 = 0.0345, wR2 = 0.0469。共收集到4566个独立衍射点,其中I>2 (I)的可观测点为3730个。

双水杨醛邻苯二胺与Fe(III)的显色反应研究及应用

研究了双水杨醛邻苯二胺(SALOPHEN)与Fe(III)的显色反应,试验表明,在pH=2.21的氨基乙酸-盐酸缓冲介质中,在阴离子表面活性剂十二烷基磺酸钠(SDS)存在下,Fe(III)与双水杨醛邻苯二胺(SALOPHEN)形成1:1稳定的棕色配合物。其最大吸收峰位于462nm处,表观摩尔吸光系数为4.1'104。铁浓度在0-4.5mg/ml范围内符合比尔定律。方法具有较高的灵敏度和选择性。应用于食品样品中微量铁的测定,结果满意。

Fe(Ⅱ)对CANON工艺处理城镇污水脱氮性能的影响

全程自养脱氮(CANON)工艺,作为新型脱氮工艺应用于城镇污水深度脱氮过程中,有望降低污水处理的运行费用。考察了亚铁离子[Fe(Ⅱ)]对CANON工艺启动及稳定运行时脱氮性能的影响。结果表明:15~23℃条件下投加6.3 mg/L Fe(Ⅱ)时,可有效启动并稳定运行CANON工艺处理城镇污水,该工艺氮去除负荷(NRR)、总氮去除率(TNRE)和氨氮去除率(ARE)分别为(4.8±1.1)g-N/(L^(3)·d)、(97±1)%和(44.2±9.3)%;相关性分析表明,通过调控Fe(Ⅱ)投加量可有效抑制亚硝酸盐氧化菌(NOB)的活性;本次优化的Fe(Ⅱ)投加量为6.3 mg/L,其对CANON工艺脱氮性能的影响机制与CANON工艺中功能微生物活性的提高、Fe(Ⅱ)与进水氨氮及其他氮化合物的循环反应、铁型反硝化过程以及铁型厌氧氨氧化过程的耦合有关。

Thermodynamics and kinetics of fluoride removal from simulated zinc sulfate solution by La(Ⅲ)-modified zeolite

To understand the mechanism of fluoride removal from the simulated zinc sulfate solution by the La(III)-modified zeolite,the adsorbent was characterized by XRD,SEM and EDS.The effects of absorbent dose and contact time,the adsorption isotherms and the sorption kinetics were investigated.The experimental results were compatible with the Langmuir isotherm model.The theoretical maximum adsorption capacities are 20.83 and 23.04 mg/g at 303 and 313 K,respectively.And the physisorption is revealed using the Temkin isotherm model and the D-R isotherm model.The sorption process is more suitable by the pseudo-second-order kinetic models.Thermodynamic parameters such as standard free energy change(ΔGΘ<0 kJ/mol),standard enthalpy change(ΔHΘ=8.28 kJ/mol)and standard entropy change(ΔSΘ=0.030 kJ/(mol?K))indicate the spontaneity of adsorption and endothermic physical sorption.Furthermore,the fluoride concentration in the industrial zinc sulfate solution decreases from 98.05 to 44.09 mg/L with the adsorbent dosage of 15 g/L.

Experimental study on the inhibition of biological reduction of Fe(III)EDTA in NO_x absorption solution

Scrubbing of NOx from the gas phase with Fe(II)EDTA has been shown to be highly effective. A new biological method can be used to convert NO to N2 and regenerate the chelating agent Fe(II)EDTA for continuous NO absorption. The core of this biological regeneration is how to effectively simultaneous reduce Fe(III)EDTA and Fe(II)EDTA-NO, two mainly products in the ferrous chelate absorption solution. The biological reduction rate of Fe(III)EDTA plays a main role for the NOx removal efficiency. In this paper, a bacterial strain identified as Klebsiella Trevisan sp. was used to demonstrate an inhibition of Fe(III)EDTA reduction in the presence of Fe(II)EDTA-NO. The competitive inhibition experiments indicted that Fe(II)EDTA-NO inhibited not only the growth rate of the iron-reduction bacterial strain but also the Fe(III)EDTA reduction rate. Cell growth rate and Fe(III)EDTA reduction rate decreased with increasing Fe(II)EDTA-NO concentration in the solution.

基于柔性配体5-[N-乙酸根(4-吡啶基)]四唑(a4-pytz)与Fe(II)和Sm(III)两个配合物的合成与表征

5-[N-乙酸根(4-吡啶基)]四唑钾盐(简写为Ka4-pytz)与(NH4)2Fe(SO4)2和SmCl3·6H2O在水-甲醇体系中反应,得到两个新的配合物,[Fe(a4-pytz)2·2H2O]·2H2O (1)和[Sm4(a4-pytz)8(H2O)18]Cl3·10H2O (2)。通过元素分析,红外光谱分析及X-射线单晶衍射对两个配合物进行结构表征。单晶衍射结果显示了配合物1和2都具有一维链状结构。但不同的是,配合物1的一维链是通过a4-pytz作为双齿配体,经四唑环上的氮原子和羧基的一个氧原子与Fe(II)相连而成的;而配合物2的结构形成源于羧基的桥联作用,氮原子未配位。通过氢键作用,配合物1和2形成了三维结构。室温下研究了配合物1和2的荧光性质。

Photooxidation of Methacrolein in Fe(III)-Oxalate Aqueous System and Its Atmospheric Implication

Iron and oxalic acids are widely distributed in the atmosphere and easily form ferric oxalate complex(Fe(III)-Ox).The tropospheric aqueous-phase could provide a medium to enable the photo-Fenton reaction with Fe(III)-Ox under solar irradiation.Although the photolysis mechanisms of Fe(III)-Ox have been investigated extensively,information about the oxidation of volatile organic compounds(VOC),specifically the potential for Secondary Organic Aerosol(SOA)formation in the Fe(III)-Ox system,is lacking.In this study,a ubiquitous VOC methacrolein(MACR)is chosen as a model VOC,and the oxidation of MACR with Fe(III)-Ox is investigated under typical atmospheric water conditions.The effects of oxalate concentration,Fe(III)concentration,MACR concentration,and pH on the oxidation of MACR are studied in detail.Results show that the oxidation rate of MACR greatly accelerates in the presence of oxalate when compared with only Fe(III).The oxidation rate of MACR also accelerates with increasing concentration of oxalate.The effect of Fe(III)is found to be more complicated.The oxidation rate of MACR first increases and then decreases with increasing Fe(III)concentration.The oxidation rate of MACR increases monotonically with decreasing pH in the common atmospheric water pH range or with decreasing MACR concentration.The production of ferrous and hydrogen peroxide,pH,and aqueous absorbance are monitored throughout the reaction process.The quenching experiments verify that·OH and O_(2)^(+)are both responsible for the oxidation of MACR.MACR is found to rapidly oxidize into small organic acids with higher boiling points and oligomers with higher molecular weight,which contributes to the yield of SOA.These results suggest that Fe(III)-Ox plays an important role in atmospheric oxidation.