Adsorption of Heavy Metal Ions,Dyes and Proteins by Chitosan Composites and Derivatives-A Review

Chitosan composites and derivatives have gained wide attentions as effective biosorbents due to their low costs and high contents of amino and hydroxyl functional groups.They have showed significant potentials of removing metal ions,dyes and proteins from various media.Chemical modifications that lead to the formation of the chitosan derivatives and chitosan composites have been extensively studied and widely reported in literatures.The aims of this review were to summarize the important information of the bioactivities of chitosan,highlight the various preparation methods of chitosan-based active biosorbents,and outline its potential applications in the adsorption of heavy metal ions,dyes and proteins from wastewater and aqueous solutions.

Preparation and characterization of eco-friendly poly(p-phenylenediamine) and its composite with chitosan for removal of copper ions from aqueous solutions

Poly(p-phenylenediamine)/chitosan (PPPDA/Chi) composite was prepared by in situ chemical oxidative polymerization of p-phenylenediamine (PPPDA) into chitosan (Chi) using ammonium persulphate (APS) as an oxidant. PPPDA and PPPDA/Chi composite were characterized by FT-IR spectra and SEM before and after copper loading. In batch adsorption method, the maximum removal of copper was experienced when 1 g/L of PPPDA and PPPDA/Chi composite dosages were used at pH 5.0 for PPPDA and 6.0 for PPPDA/Chi composite for 360 min for both sorbents. PPPDA showed adsorption capacity qemax of 650 mg/g whereas its composite achieved qemax of 573 mg/g. The experimental data correlate well with the Freundlich isotherm equation and the pseudo-second order kinetic model. The Cu(II), loaded PPPDA and its composite can be efficiently reused for as many as four cycles. The Cu(II)-loaded sorbents showed high antibacterial efficiency against Gram-positive and Gram-negative bacteria than their unloaded forms.

In vitro corrosion behavior and cytotoxicity property of magnesium matrix composite with chitosan coating

Mg-6%Zn-10%β-Ca3(PO4)2 composite was prepared through powder metallurgy methods with different chitosan coatings on its surface. The properties of the chitosan coatings on the surface of Mg-6%Zn-10%β-Ca3(PO4)2 composite, such as the adhesion ability, the corrosion behavior and the cytotoxicity properties, were investigated, and the microstructure of the chitosan coating was observed by scanning electron microscope(SEM). The results show that chitosan coating improves the corrosion resistance of the magnesium composite specimens significantly. Mg-6%Zn-10%β-Ca3(PO4)2 composite specimens exhibit good corrosion resistance and low p H values in simulated body fluid(SBF) at 37 °C in the immersion test with 7-layer chitosan coating whose relative molecular mass is 30×104 Da. The cytotoxicity tests indicate that Mg-6%Zn-10%β-Ca3(PO4)2 with chitosan coating is nontoxic with a cytotoxicity grade of zero against L-929 cells, which is better than that of uncoated composites.

Polypyrrole Chitosan Cobalt Ferrite Nanoparticles Composite Layer for Measuring the Low Concentration of Fluorene Using Surface Plasmon Resonance

Fluorene is a polycyclic aromatic hydrocarbon, which is a hazardous toxic chemical in the environment. The measurement of low concentrations of fluorene is a subject of intense interest in chemistry and in the environment. Polypyrrole chitosan cobalt ferrite nanoparticles are prepared using the electrochemical method. The prepared layers are characterized using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy. The layers are used to detect fluorene using the surface plasmon resonance technique at room temperature. The composite layer is evaluated after detection of fluorene using atomic force microscopy. The fluorene is bound on the layer, and the shift of the resonance angle is about 0.0052°, corresponding to the limitation of 0.01 ppm.

Novel Mesoporous Hydroxyapatite/Chitosan Composite for Bone Repair

The objective of the present investigation was to evaluate the osteogenic properties of mesoporous Hydroxyapatite/Chitosan （HAJCS） composite in vitro and in vivo. HA/CS composite was successfully prepared and synthesized using a freeze-drying method, and then characterized by Scanning Electron Microscope （SEM）. Results show that the mesoporous HA/CS composite presents high surface area and porosity. The effects of mesoporous HA/CS on early adhesion, proliferation and differentiation of osteoblast cells in vitro were measured. MTT cytotoxicity test and cell adhesion test show that the composite has good biocompatibility and promotes cell viability and proliferation. In vitro tests show that osteoblast-like cells on the composite surfaces are able to adhere, proliferate, and migrate through the pores. These cells maintained similar expression levels of osteoblastic-associated markers namely Collagen type I （COL-I）, Bone Morphogenetic Protein 2（BMP-2）. Histologic analysis and radiological analysis in vivo also prove that mesoporous HA/CS composite can be used to repair bone defect as a new kind of bone grafting materials.

Chitosan-based self-healing hydrogel for bioapplications

By using an easily available PEG derivative and biopolymer chitosan, a self-healing hydrogel has been facilely prepared through the dynamic Schiff base. This biocompatible self-healing hydrogel can be used for drug-delivery, 3D cell culture and as a basic platform to develop some organic-inorganic biohybrids. This mini-review summarized recent research about that chitosan based self-healing hydrogel and related materials, and discussed some future bio-applications of that hydrogel

On-Chip Fabrication of Carbon Nanoparticle–Chitosan Composite Membrane

The on-chip fabrication of a carbon nanoparticle-chitosan composite membrane （i.e. a sorbent membrane or a mixed matrix membrane） using laminar flow-based interfacial deprotonation technology was presented in this paper. In addition, the effects of carbon nanoparticles and reactant flow rates on membrane formation were investigated. Finally, the permeability and adsorption capacities of the membrane were discussed. During fabrication, an acidic chitosan solution and a basic buffer solution that contained carbon nanoparticles were introduced into a microchannel. At the flow interface, a freestanding composite membrane with embedded carbon nanoparticles was formed due to the deprotonation of the chitosan molecules. The membrane growth gradually stopped with time from upstream to downstream and the thickness of the membrane increased rapidly and then slowly along the reactant flow direction. The formation of the membrane was divided into two stages. The average growth rate in the first stage was significantly larger than the average growth rate in the second stage. Carbon nanoparticles in the basic solution acted as nucleating agents and made the membrane formation much easier. As the flow rate of the chitosan solution increased, the averaged membrane thickness and the membrane hydraulic permeability initially increased and then decreased. Because of the addition of carbon nanoparticles, the formed membrane had adsorption abilities. The carbon nanoparticle-chitosan composite membrane that was fabricated in this study could be employed for simultaneous adsorption and dialysis in microdevices in the future.