基于医用纱布负载的二氧化锰纳米颗粒用于亚甲蓝染料的去除

以医用纱布(medical gauze,MG)同时作为模板和还原剂,通过原位氧化还原反应,简便地制备了MG负载的MnO₂纳米颗粒(MnO₂ NPs/MG),并对其形貌、成分进行表征。结果表明,MnO₂ NPs均匀地分散于MG纤维表面。结合MnO₂纳米材料的吸附性能和MG复合材料的操作便捷性,将MnO₂ NPs/MG进一步应用于亚甲蓝染料的去除。结果表明,在中性条件下,通过简单的浸泡搅拌,MnO₂ NPs/MG对亚甲蓝的去除率可达85.09%,并且可以通过增大吸附材料用量与染料初始浓度的比例提高去除率。等温吸附和动力学研究证明,MnO₂ NPs/MG对亚甲蓝的吸附符合Langmuir吸附等温模型和拟二级动力学模型。     

纳米颗粒跟踪分析仪用于二氧化钛纳米颗粒分散及检测

以纳米颗粒跟踪分析仪为检测手段,建立了二氧化钛(TiO2)纳米颗粒分散和检测的方法,考察了分散剂种类、超声方式、超声时间、超声温度、分散试剂浓度、pH值对TiO2分散的影响,以及本分散方法对于一般商品TiO2的通用性.采用NTA测定粒径和颗粒数量浓度,对检测过程中稀释试剂浓度、稀释倍数等检测条件进行了优化,颗粒数量浓度...     

超级电容器用纳米二氧化锰的合成及其电化学性能

应用低温固相法和化学沉淀法制备4种用于电化学电容器的纳米级二氧化锰.由XRD、SEM和循环伏安等表征和测试其物化性能及电容特性.结果表明,该二氧化锰材料的颗粒尺寸约几十nm,在0.1 A.g-1电流密度下放电时产物的比电容最高,可达149F.g-1,二氧化锰的大倍率放电性能与其结构特征直接相关,材料的晶体结构越完整其大倍率放电性能越好.     

碳纳米管负载铂-二氧化钌纳米颗粒用于葡萄糖传感器的研究

建立了多壁碳纳米管(MWNTs)负载铂二二氧化钌纳米颗粒的液相化学还原法.以Nafion为固定剂,将Pt-RuO2/MWNTs复合材料修饰于玻碳电极的表面,制备了一种无酶型葡萄糖传感器.实验表明:复合材料修饰的电极对葡萄糖响应电流明显,并且受抗坏血酸(AA)、多巴胺(DA)和尿酸(UA)的干扰小.本实验采用安培法测定葡萄糖,线性范围为2 0×10 3～1.0×10-2 mol/L(R～0.9965);灵敏度为119.26 μA cm-2(mmol/L)-1;检出限为1.25×10 -5 mol/L(信噪比为3);响应时间为4.8 s.PtRuO2/MWNTs修饰电极可作为性能良好的无酶型葡萄糖传感器.     

二氧化锰纳米颗粒调控的紫外可见吸收-荧光双通道传感器的构建及D-青霉胺的检测

以聚乙烯亚胺(PEI)同时作为模板和还原剂,基于原位氧化还原反应,一步法制备二氧化锰纳米颗粒(MnO₂ NPs),并对其形貌、组成、紫外可见吸收、催化氧化特性进行了表征。结果表明,MnO₂ NPs能够催化氧化邻苯二胺(OPD)为2,3-二氨基吩嗪(DAP),产生420 nm处的紫外可见吸收和560 nm处的荧光发射。D-青霉胺(DPA)中的活性巯基可与MnO₂发生特异性反应,还原降解催化剂,抑制其催化氧化活性,使得体系紫外可见吸收-荧光信号减弱甚至消失。基于DPA浓度与体系光谱信号变化的关系,我们建立了MnO₂ NPs介导的紫外可见吸收-荧光双通道传感DPA的新方法。荧光传感通道具有更好的线性范围和灵敏度,该方法线性范围为1~80 μmol·L^-1,检出限为0.54 μmol·L^-1。此外,MnO₂ NPs介导的荧光传感DPA应用于人体尿液样品分析中的回收率为98.31%~107.76%,证明了该方法的可靠性。     

用于抗结核药物异烟肼检测的碳点/二氧化锰纳米探针的构建

采用微波法快速合成了一种生物相容性好、稳定性高的荧光碳点（CDs）,并将该碳点与二氧化锰纳米片（MnO2）混合形成纳米荧光探针用于抗结核药物异烟肼（INH）的检测。采用透射电子显微镜（TEM）、X射线光电子能谱（XPS）、X射线衍射（XRD）、傅里叶变换红外光谱（FT－IR）、紫外可见光谱（UV－Vis）和荧光光谱等手段对碳点和二氧化锰纳米片的形貌、成分、表面基团进行了表征。实验发现,MnO2纳米片通过荧光共振能量转移（FRET）猝灭CDs的荧光,而加入的INH可与MnO2纳米片发生氧化还原反应使后者降解,进而使CDs的荧光得以恢复,基于此构建了一种定量检测INH的纳米荧光探针。该探针对INH表现出良好的灵敏度和选择性,对INH检测的线性范围为0.5 ~ 60 μmol/L,检出限为0.02 μmol/L,并成功地应用于血样、尿样以及片剂中INH的测定,回收率分别为94.8% ~ 116%,99.0% ~ 105%和96.8% ~ 102%,相对标准偏差均小于5%,结果令人满意。该探针为INH的检测提供了新的思路,在生物样品检测方面具有广阔的应用前景。     

二氧化锰纳米颗粒调控的紫外可见吸收-荧光双通道传感器的构建及D-青霉胺的检测

以聚乙烯亚胺(PEI)同时作为模板和还原剂,基于原位氧化还原反应,一步法制备二氧化锰纳米颗粒(MnO₂ NPs),并对其形貌、组成、紫外可见吸收、催化氧化特性进行了表征。结果表明,MnO₂ NPs能够催化氧化邻苯二胺(OPD)为2,3-二氨基吩嗪(DAP),产生420 nm处的紫外可见吸收和560 nm处的荧光发射。D-青霉胺(DPA)中的活性巯基可与MnO₂发生特异性反应,还原降解催化剂,抑制其催化氧化活性,使得体系紫外可见吸收-荧光信号减弱甚至消失。基于DPA浓度与体系光谱信号变化的关系,我们建立了MnO₂ NPs介导的紫外可见吸收-荧光双通道传感DPA的新方法。荧光传感通道具有更好的线性范围和灵敏度,该方法线性范围为1~80 μmol·L^-1,检出限为0.54 μmol·L^-1。此外,MnO₂ NPs介导的荧光传感DPA应用于人体尿液样品分析中的回收率为98.31%~107.76%,证明了该方法的可靠性。     

基于碳纳米管-纳米二氧化锰增强的H2O2修饰电极的研制

将碳纳米管(CNT)和纳米二氧化锰(Nano-MnO2)分散在壳聚糖(CHIT)溶液中,用涂敷法固定到玻碳电极表面,制成修饰电极.由于碳纳米管具有良好的电子传递性能,使纳米二氧化锰对H2O2的电催化活性明显提高,通过循环伏安法、计时电流法对传感器的性能进行了研究.在最佳测试条件下,该传感器对H2O2的线性范围为1.5×10-6 ～5.0×10-2 mol/L,检出限为4×10-7 mol/L.用于实际样品的测定,结果满意.     

二氧化锰纳米棒的固相合成与表征

上世纪90年代以来,纳米科技向化学电源领域渗透,科技工作者开始研发纳米级MnO2电极材料,主要包括MnO2纳米粉体的制备[1-8]和将其作为碱锰电池正极材料[1-3]、高能量密度锂电池正极材料以及超级电容器电极材料的性能研究[4-8].     

可磁力回收的Fe3O4纳米颗粒负载纤维素酶生物催化剂用于玉米芯降解

面对日益枯竭的化石能源和资源危机,科研工作者加速了对生物资源回收利用的研究.其中,作为生物资源主要成分的纤维素被证实是一种可以重新利用的原料,甚至可以作为工业产品潜在的前驱体.因此,回收利用富含纤维素的农作物副产品显得尤为重要.目前,多数纤维素资源并没有得到充分利用,例如玉米芯,全世界只有大约0.5％被利用.为了高效利用玉米芯资源,人们尝试各种分解方法将其主要成分纤维素和半纤维素转化成葡萄糖、木糖、糠醛以及酒精等.其中,最有效的策略是利用纤维素酶来分解玉米芯中的纤维素.然而,纤维素酶在实际应用过程中缺乏长久稳定性,将纤维素酶从反应体系中回收并重复利用非常困难.将纤维素酶负载到固体载体上是提高传统生物酶稳定性和可回收性的有效方法.固载纤维素酶在批生产处理和连续生产中比自由酶更具优势,可使生物酶催化剂从反应体系中分离出来变得容易和可操控.可以作为纤维素酶载体的物质有很多,例如浮石、静电纺丝的PAN纤维、纳米纤维膜、甲基丙烯酸甲酯共聚物和石墨烯等.一般来讲,任何含有表面功能基团从而提供了可以和纤维素酶形成强物理、化学作用的载体都可以采用.纳米尺寸的载体具有特殊性,一方面纳米颗粒提供了较大的比表面积从而可以拥有可观的负载能力,另一方面纳米颗粒可以轻易解决大颗粒载体应用中产生的反应底物和催化剂之间的扩散受阻问题.目前,纳米磁性颗粒已广泛用于负载蛋白质、多肽和生物酶.另外,用纳米磁性粒子作载体可方便地借助外加磁场实现生物酶催化剂的选择性分离回收,避免了传统载体所需的过滤或离心等单元操作,从而降低了生产成本,使生物酶催化技术实现连续化操作并用于规模化工业生产.本文通过水热法制备了颗粒均匀的纳米Fe3O4磁性颗粒,然后用3-氨丙基三乙氧基硅烷(KH550)化学修饰,再用戊二醛作交联剂将纤维素酶通过键合作用负载到修饰后的磁性载体上,从而高效制备了一种可磁力回收的生物酶催化剂.采用透射电镜和X射线衍射表征了磁性纳米粒子、修饰后的磁性纳米粒子以及制备的生物酶催化剂的粒径、外观形貌和品格结构,用红外光谱验证了磁性纳米颗粒上固载化纤维素酶的存在,用热重分析了固载化酶和自由酶的热稳定性,计算了制备的生物酶催化剂负载量和磁性粒子含量.对影响负载酶活性的多种因素进行了考察,合适的负载温度和pH值分别为40℃和6.0,戊二醛最佳添加浓度为2.0％,适宜的固载时间为4h.在最优负载条件下得到的固载化生物酶的活性可以保持自由酶活性的99.1％.经过15次重复使用后,固定化酶活性仍能保持91.1％.将制备的生物酶催化剂用于玉米芯分解制葡萄糖反应,预处理后的玉米芯最大分解率可达61.94％.     

Photocatalytic degradation of methylene blue on Fe3+-doped TiO2 nanoparticles under visible light irradiation

Fe³⁺-doped TiO₂ composite nanoparticles with different doping amounts were successfully synthesized using sol-gel method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and ultravioletvisible spectroscopy (UV-Vis) diffuse reflectance spectra (DRS). The photocatalytic degradation of methylene blue was used as a model reaction to evaluate the photocatalytic activity of Fe³⁺/TiO₂ nanoparticles under visible light irradiation. The influence of doping amount of Fe³⁺ (ω: 0.00%–3.00%) on photocatalytic activities of TiO₂ was investigated. Results show that the size of Fe³⁺/TiO₂ particles decreases with the increase of the amount of Fe³⁺ and their absorption spectra are broaden and absorption intensities are also increased. Doping Fe³⁺ can control the conversion of TiO₂ from anatase to rutile. The doping amount of Fe³⁺ remarkably affects the activity of the catalyst, and the optimum efficiency occurs at about the doping amount of 0.3%. The appropriate doping of Fe³⁺ can markedly increase the catalytic activity of TiO₂ under visible light irradiation. __________ Translated from Journal of Northwest Normal University (Natural Science), 2006, 42(6): 55–56 [译自: 西北师范大学学报(自然科学版)]     

Cavity microelectrode for studying manganese dioxide powder as pH sensor

The potential-pH response of an electrolytic manganese dioxide is investigated by means of a cavity microelectrode (CME). The potential-pH curves show a complex evolution that could be explained by the disporportionation of MnOOH species, leading to the formation of Mn²⁺ ions on the MnO₂ surface. Such a behaviour is not suited for pH sensor application. However when the tip of the electrode is coated by a Nafion membrane, the potential-pH evolution shows a unique slope close to −60 mV pH⁻¹. In addition, the sensor exhibits short time responses to pH variations, a good selectivity, and it can be easily renewed compared to classical sensors.     

Photocatalytic synthesis of ZnO/Ag nanostructure sensitized by methylene blue

The possibility of photochemical synthesis of ZnO/Ag nanoheterostructures by the action of visible light absorbed by methylene blue as sensitizer was established. It was shown that sensitization of the ZnO nanoparticles results from electron transfer from the singlet-excited molecules of the dye to the conduction band of the ZnO nanoparticles. A scheme for the mechanism of the photoprocesses that occur is proposed.__________Translated from Teoreticheskaya i Éksperimentalnaya Khimiya, Vol. 41, No. 1, pp. 12–16, January–February, 2005.     

Fabrication of silane-modified magnetic nano sorbent for enhanced ultrasonic wave driven removal of methylene blue from aqueous media: Isotherms,kinetics, and thermodynamic mechanistic studies

In this study, we report a simple and economic one-pot synthesis of magnetite (Fe₃O₄) nanostructure and its modification with tetraethyl orthosilicate by coprecipitation method. The synthesized (Fe₃O₄@SiO₂) nano sorbent was applied for enhanced adsorptive removal of methylene blue by ultrasonic wave driven batch experiments. After successful synthesis, the nanostructure was characterized for their physical structure by FT-IR, VSM, TEM, and XRD. For the maximum adsorptive performance of nano sorbent, various parameters were optimized, such as dose, pH, time, concentration, and temperature. The adsorption mechanism was best fitted by Langmuir isotherm with a maximum capacity of 148.69 mg/g, while kinetics best fitted by pseudo-second-order kinetic. The synthesized nano sorbent was successfully applied for enhanced adsorptive removal of toxic methylene blue from aqueous media. The proposed method is promising and effective in terms of simplicity, cost operation, green energy consumption, reproducible, excellent reusability, and magnetically separability with fast kinetic.     

Novel alkylimidazolium/vanadium pentoxide intercalation compounds with excellent adsorption performance for methylene blue

Novel alkylimidazolium-intercalated V₂O₅ compounds were synthesized by a redox reaction between iodide ion and V₂O₅. The X-ray photoelectron spectroscopy and the diffuse reflectance UV-vis spectrometry experiments reveal that the vanadium in the intercalated V₂O₅ products was partially reduced by an iodide ion and the resultant iodine can be removed in the final products. The transmission electron microscope observation and X-ray diffraction analysis testify that the prepared alkylimidazolium/V₂O₅ intercalation compounds have typical lamellar structure with different d₁₀₀ interlayer spacing values and the special straw-like nanofiber morphology with the length of 0.5-10 μm. Systematic investigation indicates that new intercalation compounds possess the extraordinary adsorption performance for methylene blue in an aqueous solution.     

Equilibrium and kinetic study of novel methyltrimethoxysilane magnetic titanium dioxide nanocomposite for methylene blue adsorption from aqueous media

Novel magnetic titanium dioxide nanoparticles decorated with methyltrimethoxysilane (Fe₃O₄@TiO₂‐MTMOS) were successfully fabricated via a sol–gel method at room temperature. The synthesized material was characterized using Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, thermogravimetric analysis and vibrating sample magnetometry. The removal efficiency of the adsorbent was evaluated through the adsorption of methylene blue (MB) dye from water samples. The adsorption isotherm and kinetics were evaluated using various models. The Langmuir model indicated a high adsorption capacity (11.5 mg g^?1) of Fe₃O₄@TiO₂‐MTMOS. The nanocomposite exhibited high removal efficiency (96%) and good regeneration (10 times) compared to Fe₃O₄ and Fe₃O₄@TiO₂ at pH = 9.0. Based on the adsorption mechanism, electrostatic interaction plays a main role in adsorption since MB dye is cationic in nature at pH = 9, whereas the adsorbent acquired an anionic nature. The newly synthesized Fe₃O₄@TiO₂‐MTMOS can be used as a promising material for efficient removal of MB dye from aqueous media.     

Reduction of water-soluble colloidal manganese dioxide by thiourea: a kinetic and mechanistic study

Kinetic data for the colloidal MnO₂–thiourea redox system are reported for the first time. The reduction of water-soluble colloidal MnO₂ by thiourea (sulfur containing reductant) in aqueous perchloric acid medium has shown that it proceeds in two stages, i.e., a fast stage followed by a relatively slow second stage. The log (absorbance) versus time plot deviates from linearity. The kinetics of both the stages was investigated spectrophotometrically. The first-order kinetics with respect to [thiourea] at low concentration shifts to zero-order at higher concentration. The reaction rate increases with [HClO₄] and the kinetics reveals complex order dependence in [HClO₄]. Addition of P₂O ₇ ⁴⁻ and F⁻ in the form of Na₄P₂O₇ and NaF, respectively, has inhibitory effect on the reaction rate. The reaction proceeds through the fast adsorption of thiourea on the surface of the colloidal MnO₂. A mechanism involving the protonated thiourea as the reactive reductant species is proposed. The observed results are discussed in terms of Michaelis–Menten/Langmuir–Hinshelwood model. From the observed kinetic data, colloidal MnO₂–thiourea adsorption constant (K _ad1) and rate constant (k ₁) were calculated to be 1.25×10¹⁰ mol⁻¹ dm³ and 3.1×10⁻⁴ s⁻¹, respectively. The variation of temperature does not have any effect on the reaction rate.     

Immunosensor based on carbon nanotube/manganese dioxide electrochemical tags

This article reports on carbon nanotube/manganese dioxide (CNT–MnO₂) composites as electrochemical tags for non-enzymatic signal amplification in immunosensing. The synthesized CNT–MnO₂ composites showed good electrochemical activity, electrical conductivity and stability. The electrochemical signal of CNT–MnO₂ composites coated glassy carbon electrode (GCE) increased by nearly two orders of magnitude compared to bare GCE in hydrogen peroxide (H₂O₂) environment. CNT–MnO₂ composite was subsequently validated as electrochemical tags for sensitive detection of α-fetoprotein (AFP), a tumor marker for diagnosing hepatocellular carcinoma. The electrochemical immunosensor demonstrated a linear response on a log-scale for AFP concentrations ranging from 0.2 to 100 ng mL⁻¹. The limit of detection (LOD) was estimated to be 40 pg mL⁻¹ (S/N = 3) in PBS buffer. Further measurements using AFP spiked plasma samples revealed the applicability of fabricated CNT–MnO₂ composites for clinical and diagnostic applications.     

Glycine‐functionalized reduced graphene oxide for methylene blue removal

Glycine‐functionalized reduced graphene oxide (GRGO) was prepared through the reaction of glycine and chlorine‐functionalized reduced graphene oxide. The product was characterized by SEM, HRTEM, IR, Raman, and XPS. The nitrogen content (8.28%) was high in product, peak at 285.8 eV was assigned to the C–N bond, which implied that the chlorine residues in raw material were substituted by amine group of glycine. The intensity ratio of D and G peak was about 1.5, which also implied that more saturated carbon atoms were present in the product. Results of SEM, IR, and XPS confirmed that glycine molecules were attached to graphene sheets. Compared with reduced graphene oxide (61.5 mg/g) and active carbon (45.2 mg/g), GRGO had a good adsorption capacity (98.9 mg/g) for methylene blue. The adsorption process was fitted to three kinetic models and three adsorption isotherm models. The adsorption process complied with pseudo‐second order kinetic model and Langmuir model.