Facile synthesis of magnetic hybrid metal–organic frameworks with high adsorption capacity for methylene blue

A magnetic hybrid material (Fe₃O₄‐COOH/HKUST‐1) was easily synthesized via a two‐step simple solvothermal method. Through adding sodium acrylate directly into the synthesis of Fe₃O₄ spheres, the surface has more carboxyl groups. It is notable that the reactions proceed without use of organic surfactants. The magnetic hybrid material was characterized using various techniques. The magnetic hybrid material has a high specific surface area (430.15 m² g⁻¹) and excellent magnetism (23.65 emu g⁻¹). It is an efficient adsorbent for removing organic dyes like methylene blue (MB) from aqueous solution. It also can be easily recovered from liquid media using an external magnetic field. Adsorption experiment shows the magnetic hybrid material possesses a high adsorption capacity (118.6 mg g⁻¹), and has high adsorption efficiency (94.3%) after five adsorption cycles with ethanol (0.2% HCl) as eluent. The sorption kinetics and isotherm analysis indicate these sorption processes are better fitted to the pseudo‐second‐order and Langmuir equations. Thermodynamic study shows the sorption processes are spontaneous and endothermic.     

Ionic polyacrylamide hydrogel improved by graphene oxide for efficient adsorption of methylene blue

Research on Chemical Intermediates - The ionic polyacrylamide/graphene oxide (PAM/GO) hydrogel as an excellent methylene blue (MB) adsorbent was prepared by an improved one-step radical...     

Phosphorylated cellulose for water purification: a promising material with outstanding adsorption capacity towards methylene blue

Cellulose - Enhancing the sorption properties of cellulose is a prerequisite for its efficient use in water purification as an alternative to costly activated carbon. Here, solvent-free...     

Mussel-inspired polydopamine functionalized recyclable coconut shell derived carbon nanocomposites for efficient adsorption of methylene blue

Relatively cheap or at no cost, easily available, renewable agricultural waste has been given a new purpose. Using coconut shells as the raw material, and being obtained from agricultural, industry by-products, or even waste materials were used as carbon resource. Acid etching coconut shells carbon (AC) rendered micro/nanoscale hierarchical structures and made the surface available for further modification. Then, the surface of acidified coconut shell carbon was engineered via mussel inspired chemistry. The polydopamine functionalized AC composites (AC-PDA) were applied for efficient removal of methylene blue (MB) dye. Further, the surface morphology, and chemical structure were evaluated by means of scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR). Through the combination of acid etching and mussel inspired chemistry, organic functional groups can be successfully introduced onto the surface of the coconut shells carbon. The improvement of adsorption capacity of AC-PDA compared with AC is probably due to the increased number of active binding sites resulting from surface modification and formation of new functional groups.     

Functionalization effect of Fe-type MOF for methylene blue adsorption

Water pollutant such as dyes had danger the water quality. Todays, porous materials are great potential for dye adsorption from water bodies. In this study, the iron-based metal–organic framework (MOF-Fe) of MIL-101 is synthesized through a facile solvothermal method. The amine-functionalization effect of the MOF-Fe (amine-MOF-Fe) is evaluated for the adsorptive removal of methylene blue (MB) from aqueous solution. The adsorption behaviour had shown a rapid MB adsorption within the first hour of the process due to the pore-filling mechanism of the porous MOF-Fe structure. The electrostatic interaction between the amino group of amine-MOF-Fe and MB had contributed to the high adsorption capacity. The amine-functionalization effect also found the amine-MOF-Fe is having two times higher adsorption capacity when used with the loading two times lower than non-functionalized MOF-Fe. The maximum equilibrium adsorption capacities were measured at 149.25 and 312.5 mg/g with optimum MOFs loading of 0.8 and 0.4 g/L for MOF-Fe and amine-MOF-Fe, respectively. The adsorption mechanism proposed includes the electrostatic interaction, pore filling, hydrogen bonding, and π–π stacking. The regeneration study showed the MOFs could be recycled without interfering with the removal efficiency. Hence, the results indicate that the MOFs had desirable reusability for the practical adsorption of cationic dyes with its features of fast adsorption and high capacity.     

Effect of CO2 activation of carbon xerogels on the adsorption of methylene blue

The effect of physical activation with CO₂ of carbon xerogels, synthesized by pyrolysis of a resorcinol-formaldehyde aqueous gel, on the adsorption capacities of Methylene Blue (MB) was studied. The activation with CO₂ lead?to carbon materials with micropore volumes ranging from $0.28\ \mathrm{to}\ 0.98~\mathrm{cm}^{3}\,\mathrm{g}_{\mathrm{C}}^{-1}$ . MB-adsorption isotherm studies showed that the increase of micropore volume and corresponding surface area led to: (i) a significant improvement in the capacity of MB-adsorption at monolayer coverage, from $212\ \mathrm{to}\ 714~\mathrm{mg}\,\mathrm{g}_{\mathrm{C}}^{-1}$ , and (ii) an increase of the binding energy related to Langmuir isotherm constant up to 45 times greater than those of commercial microporous activated carbons used as reference (NORIT R2030, CALGON BPL and CALGON NC35). It is proposed that the increase of the binding energy results from chemical cleaning of the O-groups onto carbon surface as a consequence of CO₂-activation, increasing the π–π interaction between MB and graphene layers of the carbon xerogels. Finally, a series of batch kinetics were performed to investigate the effect of CO₂-activation conditions on the mechanism of MB-adsorption. Experimental data were fitted using pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models. From pseudo-second-order kinetic model, one observes an increase in the initial rate of MB-adsorption from 0.019 to 0.0565 min^?1, by increasing the specific surface area from $630\ \mathrm{to}\ 2180~\mathrm{m}^{2}\,\mathrm{g}_{\mathrm{C}}^{-1}$ via CO₂-activation. Depending on the activation degree of the carbons, two different mechanisms control the MB-adsorption rate: (i) at low activation degree, the intraparticle diffusion is the rate-limiting phenomenon, whereas (ii) at high activation degree, the reactions occurring at the solid/liquid interface are the rate-limiting steps.     

功能化的石墨烯和磁铁掺杂的还原氧化石墨烯对亚甲基蓝的吸附作用

用简单可行的方法合成了功能化的石墨烯(GNSPF6)和磁铁掺杂的还原氧化石墨烯(RGO-Fe3O4),并进一步研究了pH值、接触的时间和温度对它们吸附亚甲基蓝(MB)的影响.结果表明,随着pH值和温度的增加其吸附量也随之变大,从而说明该吸附过程是自发吸热的.因为GNSPF6的吸附过程只用了不到20min的时间,所以它的吸附是高效的.用经典的准一级反应、准二级反应和粒内扩散模型对其吸附过程进行动态分析,从结果可以发现,准二级动力学模型比准一级动力学模型更适用于描述吸附过程.采用传统的Langmuir,Freundlich和L-F吸附等温线模型来模拟分析数据,在20℃时,由Langmuir吸附等温线模型模拟分析得知GNSPF6和RGO-Fe3O4对MB的最大吸附量分别为374.4和118.4mg/g.     

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.     

A graphene oxide-based AIE biosensor with high selectivity toward bovine serum albumin

Graphene oxide (GO) was found to effectively enhance the selectivity of aggregation-induced emission (AIE) biosensors, and a new method based on GO and AIE molecules was proposed to detect bovine serum albumin (BSA) with high sensitivity and selectivity.     

氧氮共掺杂石墨烯光催化降解高浓度亚甲基蓝性能研究

本文采用原位合成法及混酸氧化法制备氧氮共掺杂石墨烯(ONG).通过透射电子显微镜分析(TEM)、X射线能谱分析(XPS)、紫外可见光漫反射(UV-vis DRS)、光致发光光谱(PL)等测试方法对所制得催化剂进行了表征,并以亚甲基蓝为目标降解物探究了材料的光催化活性及降解机理.结果表明:混酸氧化法制备的氧氮共掺杂石墨烯...     

Poly(methylene blue) functionalized graphene modified carbon ionic liquid electrode for the electrochemical detection of dopamine

An ionic liquid 1-butylpyridinium hexafluorophosphate based carbon ionic liquid electrode (CILE) was used as the substrate electrode and a poly(methylene blue) (PMB) functionalized graphene (GR) composite film was co-electrodeposited on CILE surface by cyclic voltammetry. The PMB–GR/CILE exhibited better electrochemical performances with higher conductivity and lower electron transfer resistance. Electrochemical behavior of dopamine (DA) was further investigated by cyclic voltammetry and a pair of well-defined redox peaks appeared with the peak-to-peak separation (ΔE_p) as 0.058 V in 0.1 mol L⁻¹ pH 6.0 phosphate buffer solution, which proved a fast quasi-reversible electron transfer process on the modified electrode. Electrochemical parameters of DA on PMB–GR/CILE were calculated with the electron transfer number as 1.83, the charge transfer coefficients as 0.70, the apparent heterogeneous electron transfer rate constant as 1.72 s⁻¹ and the diffusional coefficient (D) as 3.45 × 10⁻⁴ cm² s⁻¹, respectively. Under the optimal conditions with differential pulse voltammetric measurement, the linear relationship between the oxidation peak current of DA and its concentration was obtained in the range from 0.02 to 800.0 μmol L⁻¹ with the detection limit as 5.6 nmol L⁻¹ (3σ). The coexisting substances exhibited no interference and PMB–GR/CILE was applied to the detection of DA injection samples and human urine samples with satisfactory results.     

Amino modified mesostructured silica nanoparticles for efficient adsorption of methylene blue

In this work, mesostructured silica nanoparticles (MSN(AP)) with high adsorptivity were prepared by a modification with 3-aminopropyl triethoxysilane (APTES) as a pore expander. The performance of the MSN(AP) was tested by the adsorption of MB in a batch system under varying pH (2-11), adsorbent dosage (0.1-0.5gL(-1)), and initial MB concentration (5-60mgL(-1)). The best conditions were achieved at pH 7 when using 0.1gL(-1) MSN(AP) and 60mgL(-1)MB to give a maximum monolayer adsorption capacity of 500.1mgg(-1) at 303K. The equilibrium data were evaluated using the Langmuir, Freundlich, Temkin, and Harkins-Jura isotherms and fit well to the Freundlich isotherm model. The adsorption kinetics was best described by the pseudo-second order model. The results indicate the potential for a new use of mesostructured materials as an effective adsorbent for MB.     

Mechanism of methylene blue dye adsorption on siliceous minerals

Summary The present experiments were undertaken to establish the mechanism of methylene blue dye adsorption from aqueous solution on common siliceous minerals found in petroleum reservoir formations. Three minerals (a montmorillonite, a kaolinite, and a silica-sand flour) were prepared so that all thecec sites on the mineral surfaces were occupied by sodium (²³Na +²²Na). Methylene blue (Cl^–) dye adsorption isotherms were measured on these three minerals prepared in the sodium form. Measurement of the transmittance of the equilibrium solutions and measurement of the gamma-counting activity (²²Na) of the equilibrium solutions permitted a quantitative determination of dye cation adsorption and of sodium cation displacement.In the case of the clays (montmorillonite and kaolinite) the saturation dye adsorption capacity must be attributed to two mechanisms: first, to cation exchange resulting from isomorphous substitution in the alumino-silicate lattice and, second, to an adsorption mechanism which might be either physical (van der Waals) adsorption or chemisorption (hydrogen bonding) with the surface SiOH and AlOH of the aluminosilicate lattice.Dye adsorption on silica is due to the physical or chemisorption mechanisms alone. It was demonstrated that the distribution of this type of adsorption site on the two clays after correction for the distribution of thecec sites ranged from 4.9 to 6.1×10^–8 me/cm² and was in good agreement with the value 5.1×10^–8 me/cm² for the total adsorption sites on silica.In spite of the existence of mechanisms other than cation exchange, methylene blue dye adsorption can nonetheless be used as a rapid, approximate method for estimation ofcec of siliceous sediments owing to the fortuitous circumstance that in a saturated monomolecular layer of dye adsorbate the effective coverage area of the dye molecule approximates the area available per exchange site on the common clay minerals, e. g., montmorillonite and kaolinite.

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Zusammenfassung Die beschriebenen Untersuchungen wurden durchgeführt, um den Mechanismus der Adsorption von Methylenblau aus wäßriger Lösung an bekannten Silikaten, wie sie in erdölführenden Schichten gefunden werden, aufzuklären. Drei Minerale, ein Montmorillonit, ein Kaolinit und ein mehliger Silicium-Sand, wurden so behandelt, daß alle Kation-Austauschstellen (Cation Exchange Capacity) auf den Oberflächen des Minerales von Natrium besetzt waren (²³Na +²²Na). Isothermen der Adsorption des Farbstoffes Methylenblau-Chlorid wurden an den Natrium-Formen dieser Minerale aufgenommen. Die Messung der Lichtdurchlässigkeit der Lösung im Gleichgewicht und die Messung der Gamma-Aktivität (²²Na) dieser Gleichgewichtslösung erlaubten es, quantitativ die Adsorption von Farbstoff-Kation und den Ersatz von Natrium-Kation festzustellen.Im Falle der Tone, Montmorillonit und Kaolinit, muß die Sättigungsfähigkeit der Farbstoffadsorption zwei Mechanismen zugeschrieben werden: in erster Linie dem Kationenaustausch, der sich aus der isomorphen Substitution im Gitter des Aluminiumsilikates herleitet, in zweiter Linie einem Adsorptionsmechanismus, der entweder aus physikalischer Adsorption (van der Waals) oder Chemisorption (Wasserstoffbindung) mit den Oberflächengruppen SiOH und AlOH des Aluminosilikatgitters besteht.Farbstoffadsorption an Siliciumdioxid kann nur der physikalischen oder der aktivierten Adsorption zugeschrieben werden. Es wurde gezeigt, daß die Verteilung dieser Art von Adsorptionsstellen an den beiden Tonen von 4,9–6,1×10^–8 Milliäquivalenten pro cm² reichte (nach Korrekturen für die Verteilung der Kationen-Austauschstellen). Das stimmt sehr gut mit dem Wert 5,1×10^–8 Milliäquivalenten pro cm² für alle Adsorptionsstellen an Siliciumdioxid überein.Obwohl es einen anderen Mechanismus als den Kationenaustausch gibt, kann doch die Adsorption von Methylenblau als schnelle Feldmethode dazu dienen, die Kationen-Austauschstellen (cec) von Silikatsedimenten abzuschätzen. Und zwar, einmolekulare Bedeckung mit adsorbiertem Farbstoff vorausgesetzt, weil die vom Farbstoffmolekül effektiv bedeckte Fläche der zugänglichen Fläche pro Austauschstelle entspricht; jedenfalls bei gewöhnlichen Tonmineralen wie Montmorillonit und Kaolinit.

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Publication No. 358, Exploration and Production Research Laboratory, Shell Development Company (a Division of the Shell Oil Company), Houston, Texas.     

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.     

Removal of methylene blue from aqueous solution by graphene oxide

Graphene oxide (GO) is a highly effective absorbent of methylene blue (MB) and can be used to remove MB from aqueous solution. A huge absorption capacity of 714 mg/g is observed. At initial MB concentrations lower than 250 mg/L, the removal efficiency is higher than 99% and the solution can be decolorized to nearly colorless. The removal process is fast and more efficient at lower temperatures and higher pH values. The increase of ionic strength and the presence of dissolved organic matter would further enhance the removal process when MB concentration is high. The results indicate that GO can be applied in treating industrial effluent and contaminated natural water. The implications to graphene-based environmental technologies are discussed.     

Study of adsorption of methylene blue and new methylene blue in liquid-solid interface by slab optical waveguide spectroscopy

A slab optical waveguide (SOWG) has been used for study of adsorption of both methylene blue (MB) and new methylene blue (NMB) in liquid–solid interface. Adsorption characteristics of MB and NMB on both bare SOWG and silanized SOWG by octadecyltrichlorosilane (ODS) were compared. Effect of pH on adsorption on MB and NMB was investigated. Binding rate constant analysis showed that both MB and NMB on bare SOWG demonstrates larger association constants than those on ODS-SOWG. Interactions of MB and NMB on bare SOWG and ODS-SOWG were analyzed by molecular mechanics calculation method. The binding energy change was in the following order: E_NMB–bare > E_MB–bare > E_NMB–ODS > E_MB–ODS.     

基于静电喷射法活性多孔磁性炭球的制备及其对亚甲基蓝的吸附

在利用静电喷射一步法获得壳聚糖(CS)磁性微球(Fe₃O₄/CS)的基础上,对Fe₃O₄/CS进行高温炭化和碱活化处理获得活性磁性多孔炭球(A-Fe₃O₄/C),并对A-Fe₃O₄/C吸附水中亚甲基蓝(MB)分子的性能进行了研究。在利用扫描电子显微镜、红外吸收光谱仪、比表面分析仪对制备微球的形貌和结构进行分析的基础上,深入研究溶液pH、吸附时间、温度以及活化剂种类等因素对A-Fe₃O₄/C吸附性能的影响。研究结果表明,A-Fe₃O₄/C对MB的吸附量随着pH值的增加而增大,且经KOH活化后的A-Fe₃O₄/C对MB表现出较优的吸附性能。A-Fe₃O₄/C对MB的吸附过程符合伪二级动力学方程和Langmuir等温线模型,理论最大吸附容量可达300.6 mg·g^-1。此外,A-Fe₃O₄/C表现出良好的重复利用性能,6次循环后对MB的去除率没有明显下降。     

稻壳基活性炭对亚甲基蓝吸附平衡与动力学研究

以粮食副产物——稻壳为原料,采用化学活化法制成了微介孔共存的孔隙发达的稻壳基活性炭,此稻壳基活性炭对亚甲基蓝的吸附量可以达到464.8 mg·g-1。通过大量亚甲基蓝吸附实验结果拟合,发现其吸附平衡过程符合Freundlich吸附模型,动力学模型符合准二级吸附动力学模型。通过吸附平衡模型与动力学模型的建立,为此活性炭的实际应用提供理论预测模板。     

基于静电喷射法活性多孔磁性炭球的制备及其对亚甲基蓝的吸附

在利用静电喷射一步法获得壳聚糖(CS)磁性微球(Fe₃O4/CS)的基础上,对Fe₃O4/CS进行高温炭化和碱活化处理获得活性磁性多孔炭球(A-Fe₃O4/C),并对A-Fe₃O4/C吸附水中亚甲基蓝(MB)分子的性能进行了研究。在利用扫描电子显微镜、红外吸收光谱仪、比表面分析仪对制备微球的形貌和结构进行分析的基础上,深入研究溶液pH、吸附时间、温度以及活化剂种类等因素对A-Fe₃O4/C吸附性能的影响。研究结果表明,A-Fe₃O4/C对MB的吸附量随着pH值的增加而增大,且经KOH活化后的A-Fe₃O4/C对MB表现出较优的吸附性能。A-Fe₃O4/C对MB的吸附过程符合伪二级动力学方程和Langmuir等温线模型,理论最大吸附容量可达300.6 mg·g^-1。此外,A-Fe₃O4/C表现出良好的重复利用性能,6次循环后对MB的去除率没有明显下降。