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...     

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.     

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.     

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.     

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.     

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.     

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.     

Fabrication of controllable graphene aerogel with superior adsorption capacity for organic solvents

Controllable graphene aerogel with relative homopores was fabricated with the assistance of block copolymer (P123) and vacuum drying. Thermogravimetric analysis was conducted to obtain the optimum temperature for template removal. The Brunauer–Emmett–Teller method, scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy and X-ray diffraction were performed to characterise the obtained aerogel. Results showed that P123 was successfully removed on the surface, and a controlled multi-level porous structure was generated. The optimum ratio of GO and P123 was 1:4 (ca. 2.5 mg/ml), and the adsorption capacities of the produced aerogels for methylene blue, oils and organic solvents were excellent and superior to those aerogels fabricated by traditional approaches. Adsorption kinetics were also further studied.     

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。     

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.     

Thermodynamic studies of methylene blue adsorption onto Fe-doped sulfated titania

Adsorption equilibrium of methylene blue onto Fe-doped sulfated titania (FST) samples was studied at different temperatures (298, 303, and 308 K). Based on the wavelength scanning from 580 to 760 nm, the wavelength of maximum absorbance of methylene blue was determined to be 666 nm and the corresponding calibration curve can be described by the equation of A = 0.0068 + 0.1514C. The adsorption of methylene blue onto FST samples was conformed to the Langmuir isotherms. The absorption capacity of each FST sample for methylene blue increases with increasing temperature. The increase in the adsorption parameters (q _m, b, and K ₀) and the positive ΔH ^θ reveal the endothermic feature of this adsorption process. The negative ΔG ^θ shows the adsorption of methylene blue onto FST samples can be carried out spontaneously at the examined temperatures. Furthermore, with the calcination temperature increases, the variation in crystallization degree, the surface and the sulfur species will obviously influence the adsorption properties of FST samples and the thermodynamic parameters of this adsorption process.     

A graphene oxide-based nano-beacon for DNA phosphorylation analysis

We designed a single-fluorophore-tagged hairpin-structured nano-beacon probe by using a superquencher, graphene oxide (GO), based on which a new method for the analysis of DNA phosphorylation detection was developed.     

Facile preparation of hierarchically porous carbon using diatomite as both template and catalyst and methylene blue adsorption of carbon products

Hierarchically porous carbons were prepared using a facile preparation method in which diatomite was utilized as both template and catalyst. The porous structures of the carbon products and their formation mechanisms were investigated. The macroporosity and microporosity of the diatomite-templated carbons were derived from replication of diatom shell and structure-reconfiguration of the carbon film, respectively. The macroporosity of carbons was strongly dependent on the original morphology of the diatomite template. The macroporous structure composed of carbon plates connected by the pillar- and tube-like macropores resulted from the replication of the central and edge pores of the diatom shells with disk-shaped morphology, respectively. And another macroporous carbon tubes were also replicated from canoe-shaped diatom shells. The acidity of diatomite dramatically affected the porosity of the carbons, more acid sites of diatomite template resulted in higher surface area and pore volume of the carbon products. The diatomite-templated carbons exhibited higher adsorption capacity for methylene blue than the commercial activated carbon (CAC), although the specific surface area was much smaller than that of CAC, due to the hierarchical porosity of diatomite-templated carbons. And the carbons were readily reclaimed and regenerated.     

Thermodynamics’ study of the adsorption process of methylene blue on activated carbon at different ionic strengths

The adsorption constant of aqueous solution of methylene blue (MB), (800 · 10⁻⁶ mol · dm³) on activated carbon (AC) has been investigated by means of UV–Visible spectroscopy. The adsorption process is very fast and is physical in nature; however, it is complicated by the factors inherent in the structures of both the MB solution and AC, such as tendency of MB to form molecular aggregates in solution. In this work, the effects of various experimental parameters such as temperature and ionic strength have been investigated, using a batch adsorption technique to obtain information on treating effluents from the dye industry. Utilizing the van’t Hoff relation, which describes the dependence of equilibrium constant on temperature, as a constraint, we determine the spectral responses of the free and adsorbed amounts, as well as the enthalpy of the adsorption equilibrium.