Fuguang Lu

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

A novel magnetic composite bioadsorbent composed of magnetic chitosan and graphene oxide (MCGO) was prepared as the magnetic adsorbent. The morphology, chemical structure and magnetic property of the MCGO were characterized by Fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD) and Scanning electronic microscope (SEM), respectively. Adsorption of methyl blue (MB) onto MCGO was investigated with respect to pH, adsorption time, initial MB concentration and temperature. Kinetics data and adsorption isotherm, obtained at the optimum pH 5.3, were better fitted by pseudo-second-order kinetic model and by Langmuir isotherm, respectively. The values of activation parameters such as free energy (ΔG, -0.74∼-1.46kJmol(-1)), enthalpy (ΔH, -10.28kJmol(-1)) and entropy (ΔS, -36.35Jmol(-1)K(-1)) were determined, respectively, indicating that the adsorption was spontaneous, favorable and exothermic process in nature. Moreover, the MCGO was stable and easily recovered, the adsorption capacity was about 90% of the initial saturation adsorption capacity after being used four times.

Preparation of novel magnetic chitosan/graphene oxide composite as effective adsorbents toward methylene blue.

A novel magnetic composite bioadsorbent composed of magnetic chitosan and graphene oxide (MCGO) was prepared as the magnetic adsorbent toward methylene blue. The magnetic composite bioadsorbent was characterized by SEM, FTIR and XRD measurements. The effect factors including pH, contact time and temperature on the adsorption properties of methylene blue onto MCGO were investigated. The resulting shows extraordinary adsorption capacity and fast adsorption rates for removal of methylene blue. The kinetics are well-described by pseudo-second-order kinetic. The experimental data of isotherm followed the Langmuir isotherm model and the Freundlich model, respectively. This work shows that the MCGO could be utilized as an efficient, magnetically separable adsorbent for the environmental cleanup.

Removal of Ag+ from water environment using a novel magnetic thiourea-chitosan imprinted Ag+.

A novel, thiourea-chitosan coating on the surface of magnetite (Fe(3)O(4)) (Ag-TCM) was successfully synthesized using Ag(I) as imprinted ions for adsorption and removal of Ag(I) ions from aqueous solutions. The thermal stability, chemical structure and magnetic property of the Ag-TCM were characterized by the scanning electron microscope (SEM), Fourier transform infrared spectrometer (FT-IR) and vibrating sample magnetometer (VSM), respectively. Batch adsorption experiments were performed to evaluate the adsorption conditions, selectivity and reusability. The results showed that the maximum adsorption capacity was 4.93 mmol/g, observed at pH 5 and temperature 30°C. Equilibrium adsorption was achieved within 50 min. The kinetic data, obtained at the optimum pH 5, could be fitted with a pseudo-second order equation. Adsorption process could be well described by Langmuir adsorption isotherms and the maximum adsorption capacity calculated from Langmuir equation was 5.29 mmol/g. The selectivity coefficient of Ag(I) ions and other metal cations onto Ag-TCM indicated an overall preference for Ag(I) ions, which was much higher than non-imprinted thiourea-chitosan beads. Moreover, the sorbent was stable and easily recovered, the adsorption capacity was about 90% of the initial saturation adsorption capacity after being used five times.

Synthesis and characterization of magnetic β-cyclodextrin–chitosan nanoparticles as nano-adsorbents for removal of methyl blue

A novel nano-adsorbent, β-cyclodextrin-chitosan (CDC) modified Fe(3)O(4) nanoparticles (CDCM) is fabricated for removal of methyl blue (MB) from aqueous solution by grafting CDC onto the magnetite surface. The characteristics results of FTIR, SEM and XRD show that CDC is grafted onto Fe(3)O(4) nanoparticles. The grafted CDC on the Fe(3)O(4) nanoparticles contributes to an enhancement of the adsorption capacity because of the strong abilities of CDCM, which includes the multiple hydroxyl, carboxyl groups, amino groups and the formation of an inclusion complex due to the β-CD molecules through host-guest interactions, to adsorb MB. The adsorption of MB onto CDCM is found to be dependent on pH and temperature. Adsorption equilibrium is achieved in 50 min and the adsorption kinetics of MB is found to follow a pseudo-second-order kinetic model. Equilibrium data for MB adsorption are fitted well by Langmuir isotherm model. The maximum adsorption capacity for MB is estimated to be 2.78 g/g at 30°C. The CDCM was stable and easily recovered. Moreover the adsorption capacity was about 90% of the initial saturation adsorption capacity after being used four times.

Removal of alizarin red from water environment using magnetic chitosan with Alizarin Red as imprinted molecules

A novel, chitosan coating on the surface of magnetite (Fe(3)O(4)) (MIMC) was successfully synthesized using alizarin red (AR) as a template for adsorption and removal of AR from aqueous solutions. Characterization of the obtained MIMC was achieved by FTIR spectra, SEM micrographs and XRD. Batch adsorption experiments were performed to investigate the adsorption conditions, selectivity and reusability. The results showed that the maximum adsorption capacity was 40.12 mg/g, observed at pH 3 and temperature 30°C. Equilibrium adsorption was achieved within 50 min. The kinetic data, obtained at the optimum pH 3, could be fitted with a pseudo-second-order equation. Adsorption process could be well described by Langmuir adsorption isotherms and the maximum adsorption capacity was calculated as 43.08 mg/g. The selectivity coefficient of AR and other dyes onto MIMC indicated an overall preference for AR, which was much higher than non-imprinted magnetic chitosan beads. Moreover, the sorbent represented high stability and good repeatability.

Flow injection chemiluminescence sensor based on core-shell magnetic molecularly imprinted nanoparticles for determination of sulfadiazine.

A novel flow injection chemiluminescence (FI-CL) sensor for determination of sulfadiazine (SDZ) using core-shell magnetic molecularly imprinted polymers (MMIPs) as recognition element is developed. Briefly, a hydrophilic MMIPs layer was produced at the surface of Fe(3)O(4)@SiO(2) magnetic nanoparticles (MNPs) via combination of molecular imprinting and reversible stimuli responsive hydrogel. And it provided the MMIPs with excellent adsorption capacity and rapid adsorption rate due to the imprinted sites mostly situated on the surface of MMIPs. Then the prepared SDZ-MMIPs were packed into flow cell to establish a novel FI-CL sensor. The sensor provided a wide linear range for SDZ of 4.0×10(-7) to 1.0×10(-4) mol L(-1) with a detection limit of 1.54×10(-7) mol L(-1). And the relative standard deviation (RSD) for the determination of 1.0×10(-6) mol L(-1) SDZ was 2.56% (n=11). The proposed method was applied to determine SDZ in urine samples and satisfactory results were obtained.

Preparation of magnetic modified chitosan and adsorption of Zn2+ from aqueous solutions

The performance of a cross-linked magnetic modified chitosan (CMMC), which has been coated with magnetic fluids and cross-linked with glutaraldehyde, has been investigated for the adsorption of Zn(2+) from aqueous solutions. The CMMC with a diameter range of 20-50 nm was prepared. The effects of pH and the contact time for the adsorption have been discussed, and the optimal adsorption conditions for the adsorption of Zn(2+) have been obtained. The research results showed that CMMC was highly efficient for fast adsorption of Zn(2+) within the first 25 min, and adsorption equilibrium could be achieved in 30 min. Equilibrium studies showed that the data of Zn(2+) adsorption followed the Langmuir model. The maximum adsorption capacity for Zn(2+) was estimated to be 32.16 mg/g with a Langmuir adsorption equilibrium constant of 0.01 L/mg at 298 K, which demonstrated that the CMMC had obvious efficient adsorption of Zn(2+). The CMMC was stable and easily recovered. Moreover, the adsorption rate was about 90% of the initial saturation adsorption capacity after being used five times.

Fabrication of magnetic chitosan nanoparticles grafted with β-cyclodextrin as effective adsorbents toward hydroquinol.

The adsorption characteristics of hydroquinol from aqueous solutions onto the β-cyclodextrin modified magnetic chitosan nanoparticles (CMCN) had been investigated. The characteristics results of FTIR, SEM and XRD showed that CMCN was successfully prepared. The influences of the pH of the solution and the contact time on the adsorption amounts had been discussed, and the appropriate process conditions for the adsorption of hydroquinol had been obtained. Equilibrium experiments fitted well with the Freundlich isotherm model, and the maximum adsorption capacity of the CMCN at 303 K was determined to be 1.75 mmol/g for hydroquinol at the concentration of 9.0 mmol/L, much higher than some conventional adsorbents. The CMCN was stable and easily recovered. Moreover, the adsorption capacity was about 90% of the initial saturation adsorption capacity after being used four times.

A chemiluminescence array sensor based on graphene-magnetite-molecularly imprinted polymers for determination of benzenediol isomers

A chemiluminescence (CL) array sensor for determination of benzenediol isomers simultaneously using the system of luminol-NaOH-H(2)O(2) based on a graphene-magnetite-molecularly imprinted polymer (GM-MIP) is described. Use of graphene in the GM-MIP thus prepared is helpful to improve the adsorption capacity, while use of magnetite nanoparticles can facilitate the isolation of GM-MIP at end of their synthesis, and rendering easier the use of the polymers in the array sensor. The adsorption performance and properties were characterized. The GM-MIP was used to increase the selectivity in CL analysis. In addition, the sensor was reusable and of good selectivity and adsorption capacity. The array sensor was finally used for the determination of hydroquinone, resorcinol and catechol in waste water samples simultaneously.

Determination of L-tryptophan based on graphene oxide-magnetite-molecularly imprinted polymers and chemiluminescence.

A new method for determination of L-tryptophan (L-try) using the flow injection chemiluminescence (FI-CL) system of KMnO(4)-SnCl(2)-CHOH based on a graphene oxide-magnetite-molecularly imprinted polymer (GM-MIP) is described. The L-try GM-MIP was synthesized using graphene oxide (G) which improved the adsorption capacity as carrier, and magnetite nanoparticles which made the polymers easier to use in the sensor. The adsorption performance and properties were characterized. The GM-MIP was used in CL analysis to increase the selectivity and the possible mechanism was also discussed. The CL sensor responded linearly to the concentration of L-try over the range from 2.10×10(-7) to 7.09×10(-4) M with a detection limit of 2.11×10(-8) M (3σ). The relative standard deviation (RSD) for the determination of 3.0×10(-5) M L-try was 2.40% (n=11). On the basis of speediness and sensitivity, the sensor is reusable and shows a great improvement in selectivity and adsorption capacity over other sensors. The sensor has been used for the determination of L-try in drug samples.