Fe(II)改性蒙脱石对土壤汞的吸附固定机理探究

为明确Fe-MMT对土壤汞离子(Hg^(2+))的吸附、解吸特性及潜在作用机理,采用FeSO_(4)·7H_(2)O改性钠基蒙脱土(Na-MMT),合成了Fe(II)基蒙脱石(Fe-MMT),并探究了不同pH值、吸附剂用量、Hg^(2+)初始浓度和反应时间等条件下,Fe-MMT对土壤Hg^(2+)的吸附解吸特性、吸附动力学和等温吸附模型。结果发现:在pH=5、吸附剂用量为0.5 g、Hg^(2+)初始浓度为170 mg/L、反应时间为0.5 h的条件下,Fe-MMT对土壤Hg^(2+)的去除率高达76.8%;Fe-MMT对Hg^(2+)+的吸附过程符合Langmuir等温吸附模型,伪二阶动力学模型可较好地拟合吸附动力学行为,表明该吸附过程主要为单分子层吸附,且主要发生在吸附剂表面的均相反应位点上;结合微观结构表征,发现Fe-MMT对土壤Hg^(2+)的吸附主要通过-S^(2-)、-SH和-OH与Hg^(2+)进行络合,以及Fe^(2+)与Hg^(2+)的原位共沉淀络合引起的;Fe-MMT在水-土混合体系中的解吸率为9.7%,表明Fe-MMT对土壤Hg^(2+)具有较强的固定作用。可见,Fe-MMT具有修复Hg污染土壤的潜力。

In-situ electrochemical study on the eff ects of Fe(Ⅲ)on kinetics of pyrite acidic pressure oxidation

Fe(Ⅲ)has been proved to be a more eff ective oxidant than dissolved oxygen at ambient temperature,however,the role of Fe(Ⅲ)in pyrite acidic pressure oxidation was rarely discussed so far.In this paper,in-situ electrochemical investigation was performed using a flow-through autoclave system in acidic pressure oxidation environment.The results illustrated that increasing Fe(Ⅲ)concentrations led to raising in redox potential of the solution,and decreased passivation of pyrite caused by deposition of elemental sulfur.Reduction of Fe(Ⅲ)at pyrite surface was a fast reaction with low activation energy,it was only slightly promoted by rising temperatures.While,the oxidation rate of pyrite at all investigated Fe(Ⅲ)concentrations increased obviously with rising temperatures,the anodic reaction was the rate-limiting step in the overall reaction.Activation energy of pyrite oxidation decreased from 47.74 to 28.79 kJ/mol when Fe(Ⅲ)concentration was increased from 0.05 to 0.50 g/L,showing that the reaction kinetics were limited by the rate of electrochemical reaction at low Fe(Ⅲ)concentrations,while,it gradually turned to be diffusion control with increasing Fe(Ⅲ)concentrations.

Arsenic(III) Remediation from Contaminated Water by Oxidation and Fe/Al Co-Precipitation

Battery grade γ-MnO2 powder was investigated as an oxidant and an adsorbent in combination with Fe/Al coagulants for removal of arsenic from contaminated water. Simultaneous oxidation of As(III) and removal by coprecipitation/adsorption (one step process) was compared with pre-oxidation and subsequent removal by coprecipitation/adsorption (two step process). The rate of As(III) oxidation with MnO2 is completed in two stages: rapid initially followed by a first order reaction. As(III) is oxidised to As(V) by the MnO2 with a release of approximately 1:1 molar Mn(II) into the solution. No significant pH effect on oxidation of As(III) was observed in the pH range 4 - 6. The rate showed a decreasing trend above pH 6. The removal of As(V) by adsorption on the MnO2 decreased significantly with increasing pH from 4 to 8. The adsorption capacity of the γ-MnO2 with particle size 90% passing 10 μm was determined to be 1.5 mg/g at pH 7. MnO2 was found to be more effective as an oxidant for As(III) in the two step process than in the one step process.

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.

Elimination, Kinetics and Thermodynamics of Fe(II) Ions by Adsorption in Static and Dynamic Conditions on Activated Carbons in Aqueous Media

This work investigated the removal, kinetics and thermodynamics of iron(II) ions (Fe(II)) by adsorption in static and dynamic conditions in aqueous media on activated carbons (AC-i30min, AC-i1h, and AC-i24h), prepared from palm nut shells collected in the city of Franceville to Gabon, using potassium hydroxide (KOH) as the activating agent. Results on the elimination of Fe(II) in static and dynamic adsorption on prepared activated carbons (ACs) showed that the AC-i24h adsorbent has the best Fe(II) adsorption capacities at saturation (Qsat). The Qsat obtained on AC-i24h in static and dynamic conditions (17.87 and 10.38 mg/g, respectively) were higher than those of AC-i30min (13.89 and 5.54 mg/g respectively) and AC-i1h (14.92 and 8.64 mg/g respectively). Moreover, the static adsorption was more effective in the removal of Fe(II) ions in aqueous media in our experimental conditions. The percentage removal (%E) of Fe(II) obtained on prepared activated carbons in static conditions was better than those obtained in dynamic conditions, especially on AC-i24h, where the %E was 89.27% in static and 61.56% in dynamic. In kinetics, results showed that the pseudo-second-order kinetic model best described the adsorption mechanisms of Fe(II) on prepared activated carbons in static adsorption, with mainly of chemisorption on the solid surfaces. However, in dynamic conditions, the pseudo-first-order kinetic model was more suitable. In addition to the weak interactions between Fe(II) and the activated carbon surfaces, strong interactions (chemisorption) were also observed. Also, thermodynamic data obtained on AC-i24h in static adsorption indicated that the adsorption of Fe(II) was spontaneous and increased with temperature (ΔG˚ H˚ = 503.54 KJ/mol).

Case Report: Carnitine Palmitoyl Transferase II (CPT II) Deficiency

Carnitine Palmitoyl Transferase II (CPTII) is a very important enzyme that helps with the oxidation of long-chain fatty acid to produce energy. Deficiency in CPTII will lead to energy deficiency in the case of fasting and the accumulation of the long chain fatty in the body. There are three types of CPT II deficiency, the myopathic form, the severe infantile hepatocardiomuscular form and the lethal neonatal form. They are all inherited as an autosomal recessive. Diagnosis of the CPTII are 1) tandem mass spectrometry (MS/MS) in adult form and 2) CPTII polymorphism (F352C), which is linked to reducing the activity of CPTII in infantile form [1]. Glucose is the primary management and medium-chain fatty acid is an alternative due to the bypass of the CPTII enzyme in the pathway. For the prevention of CPTII deficiency are to avoid long chain fatty acid (C12-fatty acid), fasting, prolonged exercise, known triggers, and certain medications such as anti-epileptics and general anesthesia. During the rhabdomyolysis and myoglobinuria attack, it is very important to maintain hydration to avoid acute renal failure. If, however, renal failure occurs, dialysis is recommended. We present a case of a 27-year-old African American woman with the significant past medical history of CPT II deficiency leading to recurrent rhabdomyolysis and myoglobinuria. Together with all the research studies from diagnosis to treatment of CPTII deficiency will help in clinical management of patients. And this case report will add to the existing case reports of patients who have CPTII deficiency in terms of how we diagnose, how we treat, and how we prevent symptoms from re-occurring.

低温下Fe(II)对Ferrihydrite相转化的催化作用研究

研究了在低温、近中性条件下,在微量Fe(II)离子存在下Ferrihydrite(又称为水合氧化铁hydrousironoxide)的相转化过程.结果表明,微量Fe(II)离子的存在不仅可以加速Ferrihydrite的相转化过程,而且其相转化产物的组成也与没有Fe(II)离子存在时产物的组成有所不同,即除了α-FeOOH和α-Fe2O3外,还形成了γ-FeOOH;相转化过程既与阴离子的种类、反应温度、反应时间等因素有关,也与Fe(II)离子存在状态有关;Fe(II)离子通过催化Ferrihydrite的溶解过程,从而加速整个相转化过程.对该过程的深入研究将对认识和了解自然条件下铁氧化物的形成与相互转化具有重要意义.

Fe(III)EDTA作为氧化羰化苯酚合成碳酸二苯酯一种有效的氧化还原催化助剂(英文)

研究了氧化羰化苯酚合成碳酸二苯酯反应。发现了Fe（Ⅲ）EDTA在PdCl2／Fe（Ⅲ）EDTA／1，4-苯醌／四丁基溴化铵催化体系中具有很好的助催化效果。讨论了上述催化体系中的每一组分的作用，并提出了一个催化反应机理。氧化羰化苯酚合成碳酸二苯酯反应的最佳温度为100℃-120℃。当反应在100℃、PCO=2．0MPa、PO2=0．5MPa、苯酚0．5mol、PdCl20．28mmol、n（PdCl2）：n（Fe（Ⅲ）EDTA）：n（苯醌）：n（四丁基溴化铵）=1：1：10：40、4A分子筛5．0g、4h进行时，碳酸二苯酯的产率和选择性分别为8．35％和97．5％。压力越高对生成碳酸二苯酯越有利。

氧化乳糖与Fe(II)盐配合物特性

通过化学方法得到多活性反应基团的氧化乳糖,研究其与Fe(II)配位性能。利用pH值滴定法测定氧化乳糖在不同温度下的加质子常数及其与Fe(II)配位的稳定常数。结果表明温度越低,加质子常数和配合物稳定常数值都更高,说明温度越低,配离子稳定性越大或形成的配合物越难离解。红外光谱证明氧化乳糖和Fe(II)盐溶液确实发生了反应,同时根据所得的13CNMR图谱可以知道具体发生反应的C位,最后根据Job法测得配合物发生反应的配合比接近1∶1,同时推测出反应结构式。

氨基功能化纳米Fe_3O_4的制备及在痕量Pb(II)分析中的应用研究

采用一步法合成出氨基功能化Fe3O4纳米粒子,并借助XRD、FT-IR、等对产品进行表征。所制备的氨基化纳米Fe3O4材料粒径在100nm左右,大小分布均匀,分散性较好。提出一种新的方法,氨基化纳米Fe3O4分离富集与火焰原子吸收光谱法联用测定水样中痕量Pb(II),考察该纳米材料对水溶液中痕量Pb(II)的分离富集性能。结果表明:在pH为7、T=303.15K的条件下,氨基化Fe3O4纳米材料对Pb(II)离子的吸附率可达98%。该方法的检出限(3σ)为0.17μg·mL-1(n=11),相对标准偏差(RSD)为2.02%(n=6)。

Mn(II)-Fe(II)-MCF的制备及催化性能

以改性玉米苞叶纤维为载体(MCF),负载Mn(II)和Fe(II)制备了Mn(II)-Fe(II)-MCF复合材料,催化H_(2)O_(2)氧化水中染料。通过傅立叶变换红外/近红外成像系统和扫描电子显微镜对其结构和形貌进行表征。实验结果表明:当染料浓度为10 mg·L^(-1),Mn(II)-Fe(II)-MCF用量为4 g·L^(-1),H_(2)O_(2)初始浓度为1.56 mmol·L^(-1),Mn(II)-Fe(II)-MCF对四种染料的催化效率明显不同。阳离子蓝X-GRRL(CBX-GRRL)降解效果最好,其次是甲基橙(MO)、次甲基蓝(MB)和罗丹明B(RhB)。对染料的氧化反应进行动力学分析,MO的降解反应为二级反应,CBX-GRRL、MB和RhB的降解反应均为一级反应。Mn(II)-Fe(II)-MCF适合催化氧化偶氮染料废水。

Comparison of Fe^(2+) oxidation by Acidithiobacillus ferrooxidans in rotating-drum and stirred-tank reactors

Fe2＋ oxidation by Acidithiobacillus ferrooxidans（At.ferrooxidans） under different solid contents by adding inert Al2O3 powder was examined in rotating-drum and stirred-tank reactors.The results show that the bioactivity of At.ferrooxidans in the stirred-tank is higher than that in the rotating-drum in the absence of Al2O3 powder,but the biooxidation rate of Fe2＋ decreases markedly from 0.23 g/（L·h） to 0.025 g/（L·h） with increasing the content of Al2O3 powder from 0 to 50%（mass fraction） in the stirred-tank probably due to the deactivation of At.ferrooxidans resulting from the collision and friction of solid particles.The increase in Al2O3 content has a little adverse effect on the bioactivity of At.ferrooxidans in the rotating-drum due to different mixing mechanisms of the two reactors.The biooxidation rate of Fe2＋ in the rotating-drum is higher than that in the stirred-tank at the same content of Al2O3 powder,especially at high solid content.The higher bioactivity of At.ferrooxidans can be maintained for allowing high solid content in the rotating-drum reactor,but its application potential still needs to be verified further by the sulfide bioleaching for the property differences of Al2O3 powder and sulfide minerals.

Fe^(2+)/Mn^(2+)活化亚硫酸盐降解盐酸土霉素的机理研究

盐酸土霉素常被用于治疗畜禽疾病,但是它不能被畜禽完全代谢,残留的盐酸土霉素进入水体危害水环境的健康。铁锰作为常见的过渡金属,通常以二价态活化亚硫酸盐来降解有机污染物,反应条件温和、操作简单,但是单独的二价铁与二价锰氧化还原电势低,活化亚硫酸盐效果较差。本研究采用Fe^(2+)/Mn^(2+)共活化Na_(2)SO_(3)降解水中的盐酸土霉素,考察药剂用量、pH、溶解氧、氯离子、碳酸根及腐殖酸对Fe^(2+)/Mn^(2+)/Na_(2)SO_(3)体系降解盐酸土霉素的影响;通过焦磷酸盐实验、自由基淬灭实验和EPR实验分析Fe^(2+)/Mn^(2+)/Na_(2)SO_(3)体系中的活性物种;利用紫外可见光谱、傅里叶红外光谱、气相色谱-质谱联用仪识别盐酸土霉素的官能团及其降解中间产物的变化,推断盐酸土霉素的降解途径。结果表明:当Fe^(2+)/Mn^(2+)/Na_(2)SO_(3)浓度比为1∶4∶20(浓度分别为0.1、0.4和2 mmol/L)时,在反应45 min、pH为9.0条件下,盐酸土霉素的去除率和矿化率最高,分别达到94%和49%。随着溶解氧从9 mg/L下降至1.89 mg/L,盐酸土霉素去除率从94%下降至17%;氯离子、腐殖酸和碳酸根均对盐酸土霉素的降解产生抑制作用。Mn(Ⅲ)和SO_(4)·^(-)是降解盐酸土霉素的主要活性氧化剂,盐酸土霉素的降解经过电子转移、开环与酰基化等过程。

Fe-ZSM-5催化S_(2)O_(8)^(2-)脱除烟气中Hg 0的研究

烟气中的零价汞Hg^(0)难以被脱除,是燃煤电厂汞排放的主要形式。过硫酸根可以有效地氧化脱除Hg^(0),但其本身反应效率不佳限制了其在燃煤电厂中氧化脱除Hg^(0)的工业应用。为此,从催化S_(2)O_(8)^(2-)与Hg^(0)的氧化反应入手,以商用H-ZSM-5为原料,通过浸渍法成功制备了不同Fe含量的Fe-ZSM-5催化剂。结合ESEM-EDS、XRD、BET和XPS等分析方法对制备的催化剂进行了表征,发现随着Fe负载量的增大,分子筛表面的分散度越大且Fe均匀分布在表面上,有助于催化反应的进行,同时浸渍的Fe主要以Fe^(2+)和Fe^(3+)形式存在于ZSM-5,Fe负载量的增大也会导致Fe^(2+)占比增大,而Fe^(2+)对氧化反应有极大的促进作用,Fe主要以Fe-Si-O形式存在,ZSM-5被铁改性后仍保持其完整的骨架结构和孔隙形状。实验结果表明,3.0Fe-ZSM-5作催化剂时效果最佳,氧化脱除Hg^(0)效率最高能达到88.31%。

Anti-oxidant effect of picroside II in a rat model of cerebral ischemia/reperfusion injury

Picroside II,the major active component of picroside,has been shown to induce PC12 cell axonal growth and relieve free radical damage.In vivo experiments have demonstrated that picroside II can improve neurological function in rats with cerebral ischemia/reperfusion injuries.In the present in vivo study,enzyme-linked immunosorbent assay and immunohistochemistry revealed that picroside II increased superoxide dismutase content and reduced inducible nitric oxide synthase content in the ischemic hemisphere.The effects of picroside II were similar to those of salvianic acid A sodium,an active control drug.These results indicate that picroside II exerts a neuroprotective effect,possibly by downregulating inducible nitric oxide synthase expression,increasing superoxide dismutase activity,and inhibiting neuronal apoptosis.

Dioxygen Affinity and Catalytic Performance of Bis-(furaldehyde) Schiff Bases Co(II) Complexes in Cyclohexene Oxidation

Oxygenation constants and thermodynamic parameters DeltaH degrees and DeltaS degrees of cobalt (II) complexes with bis-(furaldehyde) Schiff bases (1, 2, 3, 4)were obtained by mearsuring saturated dioxygen uptake of these complexes in pyridine at different temperature. These complexes could activate molecular oxygen and were used as catalysts in cyclohexene oxidation. The influence of ligand structure on the dioxygen affinity and catalytic activity of the complexes were discussed.

Optimization of preparation conditions of Fe-Co nanoparticles in low-temperature CO oxidation reaction by taguchi design method

Mixed iron-cobalt oxide （Co/Fe molar ratio = 1/5） are prepared using a simple co-precipitation procedure and studied for the catalytic oxidation of carbon monoxide. In particular, the effects of a range of preparation variables such as pH value when precipitation, aging temperature, precipitation agent type and aging time are investigated on the catalytic performance of synthesized Fe-Co oxides in CO oxidation reaction. In addition, the preparation factors were optimized by Taguchi design method. The optimized sample was characterized by XRD, N2 adsortion/desorption, TEM and TGA/DTA techniques. The results reveal that the optimized sample shows a mesoporous structure with a narrow pore size distribution centered in the range of 2-7 nm. The sample prepared under optimized conditions has high activity and stability toward removal of carbon monoxide at lower temperatures. It is shown that different preparation variables influence the catalytic performance of Fe-Co oxide in CO oxidation reaction.

Self-supported Ni2P nanosheets on low-cost three-dimensional Fe foam as a novel electrocatalyst for efficient water oxidation

Electrochemical water splitting into hydrogen and oxygen is a promising strategy for future renewable energy conversion devices.The oxygen evolution reaction(OER)is considered as the bottleneck reaction in an overall water splitting system because it involves 4e- and 4H+ transfer processes.Currently,it is highly desirable to explore low-cost alternative catalysts for OER at ambient conditions.Herein,we report for the first time that nickel phosphide(Ni2P)nanosheets can be facilely grown on Fe foam(FF)as an efficient electrocatalyst for OER with excellent durability and catalytic activity under alkaline conditions.To reach a current density of 10 m A/cm2,the Ni2P-FF catalyst required a low overpotential of only 198 mV for OER.The catalyst’s high OER activity and durability were well maintained at a high current density.The required overpotentials were only 267 and 313 mV to achieve the current densities of 100 and 300 m A/cm2,respectively.The combination of low-cost Fe foam with Ni2P provides a promising low-cost catalyst for large-scale application of electrocatalytic water splitting.

Effect of La on Partial Oxidation of Ethanol to Hydrogen over Ni/Fe Catalysts

The partial oxidation of ethanol to hydrogen was investigated over Ni/Fe/La catalysts prepared by the co precipitation method. The effects of introduction of La promoter and the reaction temperature on the catalytic performance were studied. It was found that the introduction of La into Ni/Fe catalysts is helpful to increase the selectivity to hydrogen and the stability of the catalysts. The results of XRD and XPS characterization show that the structure of the catalyst was changed during the reaction. The existence of LaFeO 3 species is possibly the main reason of the increase of the catalyst stability.

Oxidation and Antioxidation of Nanocrystalline Powders of Nd-Fe-B

The Nd Fe B magnet powders were treated by organosilicon resins, silane coupling agent and dichromate salts. Using temperature tests, high temperature and high humidity tests, and DTA, the antioxidation behavior was studied. The results show that antioxidation characte ristics are improved remarkably.