用离子交换树脂回收钼酸根离子、钨酸根离子的研究

分别采用静态和动态的方法,对W305-C钨钼吸附专用树脂吸附钨、钼的最佳条件及最大吸附容量进行了深入地研究。采用静态的方法研究的各种条件如pH值等对树脂吸附钨、钼的影响,测定了最适宜的条件及最大静态吸附量;采用动态的方法测定了树脂的吸附容量,研究了流速对钨、钼离子在W305-C树脂上的吸附量的影响,同时也研究了氨水浓度对树脂解吸的影响。结果表明,在pH=3.74,流速为3mL／min树脂对钨的吸附量最大;pH=3,流速为3mL/min时,树脂对钼的吸附量最大。     

Mn_3O_4@SiO_2核壳磁性复合材料对钼(Ⅵ)的吸附性能

以一水硫酸锰和正硅酸乙酯为原料,采用氧化法和水解法制备了Mn_3O_4@SiO_2核壳结构磁性纳米材料,并研究了其对水溶液中钼(Ⅵ)的吸附效果。运用X射线衍射仪(XRD)、扫描电镜(SEM)、透射电镜(TEM)、傅里叶变换红外光谱仪(FTIR)及磁强计(VSM)对Mn_3O_4@SiO_2核壳磁性复合材料进行了表征,并考察了溶液的初始pH、钼(Ⅵ)的初始质量浓度和温度对钼(Ⅵ)吸附量的影响。结果表明:在pH为2.8,温度25℃,钼(Ⅵ)初始质量浓度为160mg/L条件下,Mn_3O_4@SiO_2核壳结构磁性复合材料对Mo(Ⅵ)的饱和吸附量为145.35 mg/g;Mn_3O_4@SiO_2对钼(Ⅵ)的吸附过程符合Langmuir等温吸附模型,吸附动力学行为符合准二级动力学模型;吸附热力学分析表明,Mn_3O_4@SiO_2复合材料对钼(Ⅵ)的吸附行为是自发的放热过程。     

D314树脂吸附钼离子的热力学和动力学

采用静态实验法研究D314树脂吸附钼离子的机理,在实验条件下分别用弗伦德利希(Freundlich)和朗格缪尔(Langmuir)等温吸附模型分析了D314树脂对钼离子的吸附热力学过程。结果表明,Langmuir方程相关性较高,可拟合钼离子的吸附过程。ΔH0表明离子交换过程为吸热过程,热力学函数ΔG0表明D314树脂吸附钼离子过程能够自发进行,ΔS0表明钼离子吸附是熵增过程。准二级动力学模型其相关系数R~2在0.99以上能够很好拟合D314树脂吸附钼离子的过程,颗粒扩散为钼离子吸附过程的主要控速步骤。     

D314树脂吸附钼离子的热力学和动力学

采用静态实验法研究D314树脂吸附钼离子的机理,在实验条件下分别用弗伦德利希(Freundlich)和朗格缪尔(Langmuir)等温吸附模型分析了D314树脂对钼离子的吸附热力学过程。结果表明,Langmuir方程相关性较高,可拟合钼离子的吸附过程。ΔH>0表明离子交换过程为吸热过程,热力学函数ΔG<0表明D314树脂吸附钼离子过程能够自发进行,ΔS>0表明钼离子吸附是熵增过程。准二级动力学模型其相关系数R²在0.99以上能够很好拟合D314树脂吸附钼离子的过程,颗粒扩散为钼离子吸附过程的主要控速步骤。     

弱酸性阴离子交换纤维吸附钼（Ⅵ）的性能研究

研究了弱酸性阴离子交换纤维对钼（Ⅵ）的吸附性能,考察了酸度、温度和时间等因素对吸附性能的影响。实验结果表明在pH为3时吸附性能最好,离子交换纤维对钼（Ⅵ）的吸附以液膜扩散为主,交换速度很快,30 min即可达到吸附饱和,吸附速率常数为0.231 s-1,离子交换过程服从Freundlish等温式,温度和流速影响动态吸附性能,使得穿透曲线和穿透时间发生改变,具有吸附速度快、吸附量大的优点,且解吸性能良好,可以进行再生使用。     

壳聚糖吸附水溶液中磷的热力学和动力学机理的探讨

通过研究质子化壳聚糖对水溶液中H2PO4^-吸附的热力学和动力学行为,探讨其吸附机理,为优化壳聚糖处理水溶液中磷的工艺提供理论依据。利用在稀硫酸介质中,磷-铋-钼三元配合物可被抗坏血酸还原生成磷铋钼蓝,700nm处进行比色,测量浓度变化,研究吸附行为。实验结果表明,△H=-10．6594 kJ·mol^-1,△S=3．0329 J·mol^-1·K^-1,温度对壳聚糖吸附磷的影响,可用热力学公式表示：△G=-10．6594×10^3-3．0329T;吸附表观活化能Ea=141．828 kJ·mol^-1。壳聚糖对磷的吸附是放热反应,熵增加效应是驱使壳聚糖吸附磷的重要推动力。     

腐植酸对铜、锌、钼和锰的吸附研究

研究了腐植酸对水溶液中重金属铜、锌、钼和锰等离子的吸附行为,并对分析的最佳条件进行了探讨。泥炭经磺化处理,制备不溶性腐植酸,其温度和吸附时间等对吸附的影响结果表明,随着pH的增大,腐植酸对铜、锌、钼和锰的吸附率增加。当pH=5时,铜、锌、钼和锰在腐植酸中的吸附率达到最大值。吸附进行20min后,腐植酸对4种离子的吸附率达到最大值。吸附等温线分别以Freundlich方程和Langmuir方程进行拟合,结果显示：锰、钼和铜吸附的最佳模型为Langmuir方程,锌的最佳吸附模型是Freundlich方程。同时发展了ICP测定重金属铜、锌、钼和锰的分析方法。     

辉钼矿中钼和铼分离过程研究

采用D201树脂对辉钼矿氯酸钠浸出体系所得反萃液中的钼、铼吸附分离性能进行考察。试验结果表明,树脂对溶液中的铼具有良好的吸附选择性,在吸附温度为30℃,pH=8的条件下吸附1 h,钼、铼吸附率分别为3.26%、93.18%,分离因子为197.68,能够满足钼、铼分离提纯的需要。吸附过程符合Boyd液膜扩散方程,树脂对钼、铼的吸附过程受液膜扩散控制。     

树脂吸附法从含钼废水中回收制备三氧化钼

采用A325树脂对某含钼废水进行吸附,回收废水中的钼并制得了三氧化钼产品。整个过程分为废水中钼的吸附、解吸、除杂净化和三氧化钼的制备等几个步骤。在钼的吸附过程中,当原料液钼浓度2．8g／L时,适宜的工艺条件是：v（料液）：v（树脂）=45：1,料液pH值为3．0、料液温度25±2℃、料液流速10mL／min,钼的吸附率可达到94.3％。解吸时,采用10％的氨水溶液作为解吸液,口（解吸液）：v（树脂）=2：1进行配料。富钼解吸液再经除杂净化、酸化沉淀、过滤、洗涤、烘干、煅烧,制得三氧化钼产品。     

钼尾矿对Cr(Ⅵ)吸附性能的研究

以钼尾矿为吸附剂,研究了其对模拟废水中Cr(Ⅵ)的吸附性能。考察了尾矿的目数、尾矿的量、Cr(Ⅵ)的初始浓度、时间等因素对吸附性能的影响,同时探索了钼尾矿对Cr(Ⅵ)的吸附动力学和热力学特性。结果表明:在尾矿目数120目、Cr(Ⅵ)初始浓度40mg/L、尾矿量为12g、吸附27h后,钼尾矿对Cr(Ⅵ)的吸附容量可高达3.22mg/g,Cr(Ⅵ)离子去除率可达到最高90%以上;钼尾矿对Cr(Ⅵ)吸附过程更好符合Langmuir等温线和准二级动力学方程。     

氧缺陷位MoO3- x 的制备及其吸附性能研究

纺织印染废水中的有机污染物如亚甲基蓝的高效吸附净化是环境领域的重要研究课题,三氧化钼独特的片层结构极具吸附应用潜力。通过微波一步法制备了不同氧空穴浓度的氧化钼,具有不同的表面电荷分布,利用氧空穴氧化钼表面所带负电荷选择性高效吸附阳离子偶氮染料亚甲基蓝。揭示了氧空穴浓度与吸附性能之间的关系,发现氧空穴浓度越高则氧化钼吸附速率越快;吸附过程符合Langmuir等温线模型和准二级动力学模型,表明该吸附过程属于单分子层吸附,并分析了其吸附机理。氧空穴氧化钼(MoO_{3- x} )为金属氧化物在染料吸附领域的发展和应用提供一定的基础数据和理论基础。     

MoO3掺杂对二氧化硅吸附Cu(Ⅱ)影响的Monte Carlo模拟

利用Monte Carlo方法，分别模拟二氧化硅和钼掺杂二氧化硅对Cu(Ⅱ)的吸附行为。结果表明，Cu(Ⅱ)被吸附于该纳米材料的表面和原子间隙之中；模拟发现加入少量氧化钼于二氧化硅中不会显著改变对Cu(Ⅱ)的吸附能力。同时采用广义梯度近似(GGA)的密度泛函理论(DFT)对其过程进行验证，并通过微量热技术佐证了二氧化硅及钼掺杂二氧化硅对水中Cu(Ⅱ)的吸附行为，实验发现，吸附过程的ΔH<0，ΔS<0，范德华力为吸附驱动力，分子模拟与实验结果相吻合。     

活性炭吸附法分离铼钼的研究

活性炭吸附法分离铼钼的研究表明,调整吸附液的pH值,使铼钼能有效分离,且当pH>8.2时,分离系数SRe/Mo>3042,铼的吸附符合Freundlich等温式,即lga=0.69+0.81lgc。     

Adsorption Behavior of Molybdenum on Modified Mesoporous Zirconium Silicates

In this study, mesoporous MCM-41 has been modified by the incorporation of zirconium ion as a rapid, simple, and inexpensive method for modification. The adsorbent is characterized using powder X-ray diffraction and nitrogen adsorption-desorption isotherm data. The distribution coefficient of molybdenum ion on the mesoporous zirconium silicates has been enhanced with the increase of the zirconium in the framework of the adsorbent. The adsorption behavior of molybdenum on the Zr10MCM-41 adsorbent has been studied and the experimental adsorption isotherm is successfully described by the Langmuir model. The effect of pH and adsorption kinetics have also been studied by batch method. The adsorption capacity is very high in the pH range of 2–3 and decreases with increasing of the pH value.     

Selective Adsorption of Mo(VI) From Re(VII) Containing Effluent on Orange Waste Gel Modified by Ethylenediamine,Diethylamine, and Triethylamine

New adsorption gels were prepared by chemically immobilizing functional groups of ethylenediamine, diethylamine and/or triethylamine on orange waste, named OW-en, OW-DEA, and OW-TEA, respectively. By comparing with the adsorption of other coexisting metals, such as Re(VII), Pb(II), Fe(III), Zn(II), Mn(VII), Ca(II), and Cu(II), the novel gels exhibited selectivity only for Mo(VI) and the adsorption behavior obeys the Langmuir model. The maximum adsorption capacity for molybdenum was in the order, OW-en (2.17 mol/kg) > OW-TEA (1.26 mol/kg) > OW-DEA (0.88 mol/kg). A kinetic study for the adsorption of molybdenum at various temperatures confirmed that the endothermic adsorption process followed pseudo-second order kinetics. In addition, its excellent adsorption characteristics for Mo(VI) were confirmed by the adsorption and elution tests using a column packed with the OW-en gel, especially by separation of Mo(VI) from Mo-Re containing industrial effluent.     

EPR studies on NO interaction with MoOx/t-ZrO2 catalysts obtained by slurry deposition

Variable temperature adsorption of nitric oxide on MoO₃ supported on tetragonal zirconia (MoO_x/t-ZrO₂), obtained by slurry deposition, was investigated by EPR spectroscopy. The influence of molybdenum loading and co-adsorbed oxygen on the adsorption process of NO was elucidated. Particular attention was devoted to redox character of NO activation. Another important aspect concerned is the nature of surface nitrosyl complexes of molybdenum and their thermal stability. The role of oxygen in NO transformation over catalyst surface was also discussed.     

Catalytic Properties of Molybdenum Carbide, Nitride and Phosphide: A Theoretical Study

The control and optimization of the catalytic properties of nonexpensive early transition metals is an important issue in the chemical industry. Density functional theory was employed to study the relative stability and chemical activities of molybdenum carbides, nitrides and phosphides. The results show that molybdenum phosphides display the highest reactivity toward CO and sulfur adsorption as compared to molybdenum carbides and nitrides. Considering the better catalysts, those that combine high stability and a reasonable chemical activity, we observe that the catalytic potential of these systems should increase following the sequence: Mo<MoC≈MoN<MoP. An electronic analysis is included to understand the better performance of molybdenum phosphide.     

Effect of fluorine on hydrogenation of cyclohexene on sulfided Ni (or Co)Mo/Al2O3 catalysts

The effect of fluorine incorporation on alumina support on the surface structure of unpromoted molybdenum, promoted cobalt—molybdenum and nickel—molybdenum catalysts, and their activity for hydrogenation of cyclohexene has been studied. The incorporation of 0.2 and 0.8 wt.-% fluorine on the alumina was carried out by impregnation with NH₄F solutions. The catalysts in the oxidic state were characterized by X-ray diffraction and ammonia adsorption and in the sulfide state by X-ray photoelectron spectroscopy (XPS) and infra-red spectroscopy (IR) of adsorbed NO. The absence of significant changes in the binding energy values of Mo3d and Ni2p (or Co2p) levels in the XPS spectra of the fluorine-containing catalysts as compared to the fluorine-free counterpart does not support the existence of an electronic effect of fluorine. The quantitative XPS results showed, however, that fluorine clearly increases the dispersion of molybdenum and promoter, this being linearly correlated to surface fluorine content. The IR results of adsorbed NO also indicate that fluorine incorporation leads generally to minor sizes of MoS₂ slabs, and more exposed promoter atoms, except for the cobalt in the CoMo/F(0.2)A catalyst. It is suggested that the increase in the dispersion of the supported active phase is a secondary effect of fluorine incorporation, which may result from the observed textural changes of the alumina and its small partial solubilization provoked by NH₄F solution. It was found that the incorporation of fluorine enhances appreciably, moderately and considerably the hydrogenation activity of molybdenum, cobalt—molybdenum an nickel—molybdenum catalysts, respectively. Such increase in hydrogenation activity is not directly correlated to the exposed atoms probed by NO adsorption, and is only loosely related to molybdenum dispersion for the molybdenum and cobalt—molybdenum catalysts. The lack of similar reliable correlations for the nickel—molybdenum catalysts suggests that other structural parameters such as extent of reduction-sulfidation and certain configurations of molybdenum ions and sulfur vacancies may govern hydrogenation activity.     

Preferential occupation of molybdenum on the thin alumina film: Characterization by CO titration

A thin alumina film, the alumina model surfaces modified by the metallic molybdenum and by the MoO₃ are titrated by CO chemisorption. Two types of CO adsorption sites, namely octahedrally and tetrahedrally coordinated Al³⁺ sites, are present on the thin alumina film. The thin alumina film prepared under UHV conditions can be used to simulate the conventional high-surface-area alumina supports in real catalysis. The deposited metallic molybdenum preferentially occupies octahedrally coordinated Al³⁺ site and suppresses CO chemisorption on this site, and oxidation of the surface molybdenum species enhances this suppression.