RhB Adsorption Performance of Magnetic Adsorbent Fe3O4/RGO Composite and Its Regeneration through A Fenton-like Reaction

Abstract Adsorption is one of the most effective technologies in the treatment of colored matter containing wastewater. Graphene related composites display potential to be an effective adsorbent. However, the adsorption mechanism and their regeneration approach are still demanding more efforts. An effective magnetically separable absorbent, Fe3O4 and reduced graphene oxide (RGO) composite has been prepared by an in situ coprecipitation and reduction method. According to the characterizations of TEM, XRD, XPS, Raman spectra and BET analyses, Fe3O4 nanoparticles in sizes of 10–20 nm are well dispersed over the RGO nanosheets, resulting in a highest specific area of 296.2 m2/g. The rhodamine B adsorption mechanism on the composites was investigated by the adsorption kinetics and isotherms. The isotherms are fitting better by Langmuir model, and the adsorption kinetic rates depend much on the chemical components of RGO. Compared to active carbon, the composite shows 3.7 times higher adsorption capacity and thirty times faster adsorption rates. Furthermore, with Fe3O4 nanoparticles as the in situ catalysts, the adsorption performance of composites can be restored by carrying out a Fenton-like reaction, which could be a promising regeneration way for the adsorbents in the organic pollutant removal of wastewater.</jats:p

The effect of iron catalyzed graphitization on the textural properties of carbonized cellulose: Magnetically separable graphitic carbon bodies for catalysis and remediation

Whereas pyrolysis of pristine microcrystalline cellulose spheres yields nonporous amorphous carbon bodies, pyrolysis of microcrystalline cellulose spheres loaded with iron salts leads to the formation of magnetically separable mesoporous graphitic carbon bodies. The microcrystalline cellulose spheres loaded with either iron(III) nitrate, ammonium iron(III) citrate or iron(III) chloride were pyrolyzed up to 800 °C. Temperature dependent X-ray diffraction analysis shows that the iron salts are transformed into iron oxide nanoparticles; their size and distribution are influenced by the anion of the iron salt. The iron oxide nanoparticles are subsequently carbothermally reduced by the amorphous carbon that is obtained from the pyrolysis of the microcrystalline cellulose. Next, the iron nanoparticles catalyze the conversion of the amorphous carbon to graphitic carbon nanostructures as shown with XRD, electron microscopy and Raman spectroscopy. The extent of graphitization depends on the iron nanoparticle size. Nitrogen physisorption measurements show that this graphitization process introduces mesopores into the carbon bodies. The benefits of the properties of the resulting carbon bodies (ferromagnetic character, graphitic content, mesoporosity) are discussed in connection with applications in liquid-phase catalysis and remediation

Removal of Tetracycline Pollutants by Adsorption and Magnetic Separation Using Reduced Graphene Oxide Decorated with Alpha-Fe₂O₃ Nanoparticles

Nanocomposites of reduced graphene oxide (RGO) with ferromagnetic alpha-Fe₂O₃ nanoparticles have been prepared in-situ by thermal treatment. The structure and morphology of the hybrid material were studied by X-ray photoelectron spectroscopy, Raman, X-ray diffraction, and transmission electron microscopy. The results show a hybrid material highly modified with alpha-Fe₂O₃ nanoparticles distributed on the graphene surface. The adsorption kinetics show the presence of alpha-Fe₂O₃ nanoparticles on the RGO surface, and the amount of remaining functional groups dominated by ionization and dispersion. The adsorption kinetics of this adsorbent was characterized and found to fit the pseudo-second-order model. The alpha-Fe₂O₃ nanoparticles on RGO modify the electrostatic interaction of RGO layers and tetracycline, and adsorption properties decreased in the hybrid material. Adsorption isotherms fit with the Langmuir model very well, and the maximum capacity adsorption was 44.23 mg/g for RGO and 18.47 mg/g for the hybrid material. Magnetic characterization of the hybrid material shows ferromagnetic behavior due to the nanosize of alpha-Fe₂O₃ with a saturation magnetization, Ms = 7.15 Am/kg, a remanence Mr = 2.29 Am/kg, and a coercive field, Hc = 0.02 T.Rodolfo Cruz-Silva acknowledges the support from the Center of Innovation (COI) Program “Global Aqua Innovation Center for Improving Living Standards andWater-sustainability” from Japan Science and Technology Agency, JST. Authors thank M. Nava for the specific surface area measurements of the materials

Магніточутливі адсорбенти на основі активованого вугілля: синтез та властивості

В роботі проаналізовано сучасний стан в галузі створення та використання магніточутливих адсорбентів на основі композитів синтетичного вугілля СКН і СКС та технічного вугілля БАУ з магнетитом; запропоновано перспективну для практичного впровадження методику синтезу магніточутливих вуглецевих адсорбентів різних типів та досліджено їх пористу структуру, адсорбційні та магнітні властивості

Magnetic graphene oxide as adsorbent for the removal of lead(II) from water samples

Magnetic Fe3O4 nanoparticles were prepared on graphene oxide (Fe3O4/GO) in situ in a one step process. The obtained Fe3O4/GO was used as an adsorbent for the removal for Pb(II) from environmental water samples prior to flame atomic absorption spectroscopy measurement. The adsorption procedure was optimized as follows: 60 min adsorption time, 50 mL sample volume, solution pH 4.5, and 25 mg adsorbent dosage. Under the optimum conditions, the adsorption efficiency obtained was greater than 75% (C = 50 mg L-1). The adsorption isotherm of Fe3O4@GO magnetic adsorbent was studied for Pb(II) adsorption using two isotherm adsorption models namely Langmuir and Freundlich. The adsorption isotherm data fits well with Langmuir isotherm (R2 = 0.9988) rather than with Freundlich isotherm. The maximum adsorption capacity (qm) obtained was 86.2 mg g-1. The results signified that the prepared Fe3O4/GO nanocomposite has a great adsorptive ability towards the Pb(II) from environmental water samples

Hydrothermal synthesis of reduced graphene oxide-CoFe2O4 heteroarchitecture for high visible light photocatalytic activity: Exploration of efficiency, stability and mechanistic pathways

RGO-CoFe2O4 heterostructure nanocomposite was prepared by hydrothermal method and was characterized by various analytical techniques such as Powder X-ray Diffraction method (PXRD), UV-vis absorbance, Photoluminescence (PL), Fourier Transform Infra Red (FTIR) spectroscopic techniques, BET surface area measurements, Field Emission Scanning Electron Microscopy (FESEM), Raman Spectroscopy and Vibrating Sample Magnetometer (VSM). The results confirmed the formation of hybrid structure with CoFe2O4 particles embedded in RGO sheets. Photocatalytic activity of the nanocomposites was probed for the degradation of 4-Chlorophenol (4-CP) as the model compound under the visible light illumination. The photocatalytic activity decreases in the following order RGO-CoFe2O4 &gt; CoFe2O4 &gt; RGO. Further the activity of RGO-CoFe2O4 composite was explored in the presence of peroxymonosulfate (PMS) as an oxidant. LUMO of PMS can accommodate photogenerated electrons, thereby suppresses the recombination process. The enhanced activity of RGO-CoFe2O4 hybrid is compared to its individual counterparts and the higher activity is accounted to its unique electronic structure. RGO serves as electron acceptor from CoFe2O4 and electron donor to the oxygen molecule. During the photocatalysis, transformation of the native structure from normal spinel to inverse spinel and vice versa may take place continuously from the process of electron trapping and detrapping by Fe3+ and Co2+ions. The observed continuous absorption for RGO-CoFe2O4 composite in the UV-vis spectra implies active d-d transitions involving transition metals present in the nanocomposite. © 2017 Elsevier Ltd. All rights reserved

吸着技術に基づく水中の微量無機物汚染物質の除去・検出技術開発に関する研究

筑波大学 (University of Tsukuba)201

The Molecularly Imprinted Polymers. Influence of Monomers on The Properties of Polymers - A Review

The synthesis of MIPs for two types of templates (herbicides, and flavonoids) and their application in analytical chemistry are discussed. Particular attention has been paid the issue of bonding the template and selection of appropriate monomer in different types of compounds. This short review aims at presenting the molecular imprinting technology (MIT) which is considered as an attractive method to produce impressive receptors for application in analytical chemistry. The challenge of designing and synthesizing a molecularly imprinted polymer (MIP) can be a daunting prospect to the uninitiated practitioner, simply because of the number of experimental variables involved, e.g. the nature and levels of template, functional monomers, cross-linkers, solvents, initiators and even the method of initiation and the duration of polymerization. Indubitably, the most important place of the polymer is its quotheartquot or the cavity corresponding to the template and the waynbs

Role of activated carbon features on the photocatalytic degradation of phenol

[EN] In this work we have investigated the role of porous carbon material used as a photocatalyst and a catalyst support in the carbon/titania composite in the photodegradation of phenol, and compared the results to those of bare titanium oxide. The immobilization of titania on an activated carbon provoked acceleration of the degradation rate under UV irradiation, which is likely to be attributed to the porosity of the carbon support. The identification of the degradation intermediates detected in the solution showed that the presence of the carbon support affects the nature of phenol degradation mechanism through the formation of different intermediates. Additionally, phenol photodecomposition rate over the carbon support outperformed that attained in the carbon/titania composite, suggesting an important self-photoactivity of the carbon support.This work was supported by the Spanish MICINN (CTM2008-01956). COA is grateful to the Spanish MEC for the Ramon y Cajal Research Contract. LFV is grateful to CSIC for the JAE predoctoral fellowship.Peer reviewe