Fabrication of novel magnetic chitosan grafted with graphene oxide to enhance adsorption properties for methyl blue

High performance agar/graphene oxide composite aerogel for methylene blue removal

A novel three-dimensional (3D) agar/graphene oxide (AGO) composite aerogel was prepared by a vacuum freeze drying method. The AGO aerogel was tested for its adsorption capacity of methylene blue (MB) and was found to have a maximum adsorption capacity of 578mg/g, as determined from the Langmuir isotherm. The adsorption kinetic studies revealed that adsorption followed pseudo-second-order model. The thermodynamic parameters calculated from the Van't Hoff equation indicate that the adsorption was an endothermic and spontaneous process. The adsorption mechanism may be attributed to electrostatic interaction between MB and AGO aerogel. Furthermore, the AGO aerogel can easily be recycled with a dilute NaOH solution wash, retaining over 91% of the adsorption capacity after recycling three times.

Adsorption of Heavy Metals by Graphene Oxide/Cellulose Hydrogel Prepared from NaOH/Urea Aqueous Solution

By taking advantage of cellulose, graphene oxide (GO), and the process for crosslinking using epichlorohydrin (ECH), we propose a simple and novel method to prepare GO/cellulose hydrogel with good potential to adsorb metal ions. GO nanosheets containing carboxyl and hydroxyl groups were introduced into the surface of the cellulose hydrogel with retention of the gel structure and its nanoporous property. Due to the introduction of GO, the GO/cellulose composite hydrogels exhibited good compressive strength. Adsorption capacity of Cu2+ significantly increases with an increase in the GO/cellulose ratio and GO/cellulose hydrogel showed high adsorption rates. The calculated adsorption capacities at equilibrium ( q e cal ) for GO/cellulose hydrogel (GO:cellulose = 20:100 in weight) was up to 94.34 mg·g-1, which was much higher than that of the pristine cellulose hydrogels. Furthermore, GO/cellulose hydrogel exhibited high efficient regeneration and metal ion recovery, and high adsorption capacity for Zn2+, Fe3+, and Pb2+.

Photocatalytic degradation of Maxilon C.I. basic dye using CS/CoFe2O4/GONCs as a heterogeneous photo-Fenton catalyst prepared by gamma irradiation

CS/CF/GONCs were synthesized via gamma irradiation cross-linking method with the aid of sonication. The nanocomposites exhibited a photo-Fenton catalytic feature for the degradation of Maxilon C.I. basic dye in aqueous medium using sunlight. The effects of pH, H2O2 concentration, and dosage of the catalyst, on the degradation rates of the dyes were examined. The optimal degradation rate was reached with 10mM H2O2 at pH 9.5. It was verified that the Maxilon C.I. basic dye degradation rate fits a pseudo-first-order kinetics for different initial concentrations of Maxilon C.I. dye. Fourth cyclic tests for Maxilon C.I. degradation showed that the magnetic catalyst was very stable, recoverable, highly active, and easy to separate using an external magnet. Hence, this magnetic catalyst has potential use in organic pollutant removal.

Fabrication of highly hydrophobic organic-inorganic hybrid magnetic polysulfone microcapsules: A lab-scale feasibility study for removal of oil and organic dyes from environmental aqueous samples

In this work, three kinds of organic-inorganic hybrid materials (vinyl benzene linear polymer modified SBA-15, attapulgite and halloysite nanotubes) in the shape of powder and the corresponding magnetic polysulfone microcapsules were developed for removal of oil and dyes from environmental aqueous samples, respectively. As determined from the oil and dye adsorption studies, the developed magnetic polysulfone microcapsules exhibited high adsorption capacity of 13.8-17.3g/g for oil. The prepared functionalized materials and the corresponding microcapsules can remove 85.0-91.6% and 81.8-87.8% Sudan I in 80 min and 7.6h, respectively. The results showed a significant improvement in their adsorption capacities and removal efficiencies compared to the parent matrices, indicating that the introducing of the vinyl benzene linear polymer was a major factor in the removal of the hydrophobic pollutants. At the same time, the adsorption capacity for the investigated pollutants also depended on the textural feature of matrix itself. In view of the utilization of low-cost clay minerals (attapulgite and halloysite nanotubes), these proposed functionalized materials and the corresponding magnetic polysulfone microcapsules had a great promise to be used as an efficient sorbent for removal of pollutants from environmental aqueous samples.

Coagulation Behavior of Graphene Oxide on Nanocrystallined Mg/Al Layered Double Hydroxides: Batch Experimental and Theoretical Calculation Study

Graphene oxide (GO) has attracted considerable attention because of its remarkable enhanced adsorption and multifunctional properties. However, the toxic properties of GO nanosheets released into the environment could lead to the instability of biological system. In aqueous phase, GO may interact with fine mineral particles, such as chloridion intercalated nanocrystallined Mg/Al layered double hydroxides (LDH-Cl) and nanocrystallined Mg/Al LDHs (LDH-CO3), which are considered as coagulant molecules for the coagulation and removal of GO from aqueous solutions. Herein the coagulation of GO on LDHs were studied as a function of solution pH, ionic strength, contact time, temperature and coagulant concentration. The presence of LDH-Cl and LDH-CO3 improved the coagulation of GO in solution efficiently, which was mainly attributed to the surface oxygen-containing functional groups of LDH-Cl and LDH-CO3 occupying the binding sites of GO. The coagulation of GO by LDH-Cl and LDH-CO3 was strongly dependent on pH and ionic strength. Results of theoretical DFT calculations indicated that the coagulation of GO on LDHs was energetically favored by electrostatic interactions and hydrogen bonds, which was further evidenced by FTIR and XPS analysis. By integrating the experimental results, it was clear that LDH-Cl could be potentially used as a cost-effective coagulant for the elimination of GO from aqueous solutions, which could efficiently decrease the potential toxicity of GO in the natural environment.

Graphene oxide/chitin nanofibril composite foams as column adsorbents for aqueous pollutants

A novel graphene oxide/chitin nanofibrils (GO-CNF) composite foam as a column adsorbent was prepared for aqueous contaminant disposal. The structures, morphologies and properties of composite foams supported by nanofibrils were characterized. As a special case, the adsorption of methylene blue (MB) on GO-CNF was investigated regarding the static adsorption and column adsorption-desorption tests. Results from equilibrium adsorption isotherms indicated that the adsorption behavior was well-fitted to Langmuir model. The composite foams reinforced by CNF were dimensionally stable during the column adsorption process and could be reused after elution. The removal efficiency of MB was still nearly 90% after 3 cycles. Furthermore, other inorganic or organic pollutants adsorbed by composite foams were also explored. Therefore, this novel composite foam with remarkable properties such as dimensional stability, universal adsorbent for cationic pollutants, high adsorption capacity, and ease of regeneration was a desirable adsorbent in the future practical application of water pollutant treatment.

Removal of dyes by a novel fly ash–chitosan–graphene oxide composite adsorbent

A novel FCGO adsorbent is synthesized from fly ash cross-linked with chitosan and graphene oxide and characterized using SEM, XRD and FTIR analyses. The adsorbent effectively removes anionic and cationic dyes.

Decontamination of methylene blue from aqueous solution by magnetic chitosan lignosulfonate grafted with graphene oxide: effects of environmental conditions and surfactant

In this study, magnetic chitosan lignosulfonate grafted with graphene oxide (MCLS/GO) as an innovative adsorbent was prepared successfully through a hydrothermal reaction.

A graphene–melamine-sponge for efficient and recyclable dye adsorption

The submersible graphene–melamine-sponges present fast and highly efficient adsorption for water soluble dyes.

Adsorptive removal of toxic metals and cationic dyes by magnetic adsorbent based on functionalized graphene oxide from water

Adsorption of heavy metal ions and cationic dyes from aqueous solutions by superparamagnetic GO-based polymeric nanocomposite.

Dye removal from textile industrial effluents by adsorption on exfoliated graphite nanoplatelets: kinetic and equilibrium studies

The concept of physical adsorption was applied for the removal of direct and reactive blue textile dyes from industrial effluents. Commercial graphite nanoplatelets were used as substrate, and the quality of the material was characterized by atomic force and transmission electron microscopies. Dye/graphite nanoplatelets water solutions were prepared varying their pH and initial dye concentration. Exceptionally high values (beyond 100 mg/L) for adsorptive capacity of graphite nanoplatelets could be achieved without complicated chemical modifications, and equilibrium and kinetic experiments were performed. Our findings were compared with the state of the art, and compared with theoretical models. Agreement between them was satisfactory, and allowed us to propose novel considerations describing the interactions of the dyes and the graphene planar structure. The work highlights the important role of these interactions, which can govern the mobility of the dye molecules and the amount of layers that can be stacked on the graphite nanoplatelets surface.

Fast adsorption of methyl blue on zeolitic imidazolate framework-8 and its adsorption mechanism

Zeolitic imidazolate framework-8 (ZIF-8) is synthesized and the adsorption behavior and mechanism of methyl blue (MB) are studied in detail.

Equilibrium and kinetic studies on MB adsorption by ultrathin 2D MoS2 nanosheets

MoS₂ ultrathin nanosheets display excellent adsorption ability towards methylene blue, with a maximum adsorption capacity of 146.43 mg g⁻¹ in 300 seconds. Moreover, the adsorbent can be resued by washing with deionized water.

A novel magnetic calcium silicate/graphene oxide composite material for selective adsorption of acridine orange from aqueous solutions

The adsorption behavior of acridine orange on magnetic calcium silicate/graphene oxide composite material.

Magnetic chitosan-graphene oxide composite for anti-microbial and dye removal applications

Magnetic chitosan-graphene oxide (MCGO) nanocomposite was prepared as a multi-functional nanomaterial for the applications of antibacterial and dye removal. The nanocomposite was characterized by scanning electronic microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectrometer (FTIR). The antibacterial performance for MCGO against Escherichia coli was varied depending on the concentration of MCGO. SEM images of E. coli cells demonstrated that the antimicrobial performance of MCGO nanocomposite was possibly due to the damage of cell membrane. This work also explored MCGO's adsorption performance for methyl orange (MO). The experimental parameters including adsorbent mass, pH value, contact time and concentration of MO on the adsorption capacity were investigated. The maximum adsorption capacity of MCGO for MO was 398.08 mg/g. This study showed that the MCGO offered enormous potential applications for water treatment.

Synthesis of magnetic graphene nanocomposites decorated with ionic liquids for fast lead ion removal

Seeking highly-efficient, low-cost and robust methods to remove metal ions from aqueous solutions is very much in demand. Here, we developed a novel magnetic composite bio-adsorbent, graphene oxide and magnetic chitosan-ionic liquids (GOMCS-ILs), for removing Pb(II) from water. This was the first time to combine ionic liquids and graphene oxide and magnetic chitosan, and apply to the adsorption of metal ions. The addition of ionic liquids can not only improve the dispersivity of the adsorbent, but also increase the adsorption sites. The characteristic result of FTIR, SEM, and XRD showed that GOMCS-ILs were prepared with large surface area and good magnetic responsiveness. The influence of various analytical parameters on the adsorption of Pb(II) such as pH, contact time, and initial ion concentration were studied in detail. The adsorption followed a pseudo second order kinetics. The equilibrium adsorption was well-described by the Langmuir isotherm model and the maximum adsorption capacity was to be 85mgg(-1). Moreover, the GOMCS-ILs could be repeatedly used by simple treatment without obvious structure and performance degradation. These results demonstrated the potential applications of GOMCS-ILs microspheres in efficient removal of Pb(II) from wastewater and deep-purification of polluted water.

Hierarchically porous silicon-carbon-nitrogen hybrid materials towards highly efficient and selective adsorption of organic dyes

The hierarchically macro/micro-porous silicon–carbon–nitrogen (Si–C–N) hybrid material was presented with novel functionalities of totally selective and highly efficient adsorption for organic dyes. The hybrid material was conveniently generated by the pyrolysis of commercial polysilazane precursors using polydivinylbenzene microspheres as sacrificial templates. Owing to the Van der Waals force between sp2-hybridized carbon domains and triphenyl structure of dyes, and electrostatic interaction between dyes and Si-C-N matrix, it exhibites high adsorption capacity and good regeneration and recycling ability for the dyes with triphenyl structure, such as methyl blue (MB), acid fuchsin (AF), basic fuchsin and malachite green. The adsorption process is determined by both surface adsorption and intraparticle diffusion. According to the Langmuir model, the adsorption capacity is 1327.7 mg·g⁻¹ and 1084.5 mg·g⁻¹ for MB and AF, respectively, which is much higher than that of many other adsorbents. On the contrary, the hybrid materials do not adsorb the dyes with azo benzene structures, such as methyl orange, methyl red and congro red. Thus, the hierarchically porous Si–C–N hybrid material from a facile and low cost polymer-derived strategy provides a new perspective and possesses a significant potential in the treatment of wastewater with complex organic pollutants.

Fabrication of mesoporous Al-SBA-15 as a methylene blue capturer via a spontaneous infiltration route

Mesoporous Al-SBA-15 materials were synthesized via a facile solvent-free method and they present much higher MB adsorption capacity than the siliceous SBA-15.

Preparation and characterization of exfoliated graphene oxide–l-cystine as an effective adsorbent of Hg(ii) adsorption

Hg(ii) adsorption involves,l-cystine bears amino group (–NH₂) could interact with GO hydroxyl and carboxyl groups through covalent bond interaction.

Microbial preparation of magnetite/reduced graphene oxide nanocomposites for the removal of organic dyes from aqueous solutions

Magnetite/rGO nanocomposites synthesized by microbial cells can function as effective dye adsorbents and be regenerated through a Fenton-like reaction.

An ultrasensitive molecularly imprinted electrochemical sensor based on graphene oxide/carboxylated multiwalled carbon nanotube/ionic liquid/gold nanoparticle composites for vanillin analysis

Schematic diagram of GO/CCNTs/IL/AuNPs/MIPs composites applied to the electrode.

Poly(4-styrenesulfonic acid-co-maleic acid)-sodium-modified magnetic reduced graphene oxide for enhanced adsorption performance toward cationic dyes

PSSMA-modified magnetic reduced graphene oxide nanocomposites (PSSMA/M-rGO) were prepared and used for enhanced adsorption of cationic dyes.