Preparation And Properties Of Adsorption Functional Chitosan Microspheres

Dye and heavy metal ions in industrial wastewater cause environmental pollution,which needs to be solved urgently.Chitosan(CS)is a natural polymer material with excellent adsorption properties.It has good biocompatibility,biodegradability and renewability.CS microspheres have the characteristics of large specific surface area,more adsorption sites,and high adsorption efficiency.The amino and hydroxyl groups on CS have specific chelating and adsorption properties for heavy metal ions and toxic dyes.The study of CS microspheres with adsorption function to treat polluted wastewater has important social significance and economic values.This study aims to improve the adsorption performance of CS microspheres.Chitosan microspheres(CSM)were prepared by emulsion crosslinking technique.Porous CS microspheres(CSMf)loaded with Carboxyl Multi-walled Carbon Nanotubes(f MWNTs)were prepared using the simple microfluidic technology and freeze-drying technology.Using citric acid as the biological crosslinking agent and glutaraldehyde(GA)as the linking agent,thiosemicarbazide(TSC)was grafted onto the surface of porous CS microspheres,leading to functional CS microspheres containing a large number of amino groups(TSC-CACS).The structure and performance of the prepared CS microspheres were characterized by SEM,FT-IR,TG,XRD,EDX,XPS and so on.The water solution containing Methyl Orange(MO),Acid Red 27(AR)and Indigo Carmine(CI)were selected as the simulated wastewater,and the adsorption performance of each CS microsphere to three dyes and heavy metal ion chromium(Cr(?))has been investigated.The research results showed that:when addition of GA was 0.8?L/g,CSM-2 had the best adsorption effect on MO and Cr(?).When the initial concentration of MO was 150 mg/L,the maximum adsorption quality of MO by CSM-2 reached 143.55 mg/g.When the initial concentration of Cr(?)was320 mg/L,the maximum adsorption quality of CSM-2 on Cr(?)reached 301 mg/g.when f MWNTs addition of was 0.01%,CSMf₂ porous microspheres had the good adsorption performance for MO and AR.When the initial concentration of MO was 150mg/L,the adsorption quality of CSMf₂ porous microspheres for MO was 147.62 mg/g.When the initial concentration of AR was 100 mg/L,the adsorption quality of CSMf₂porous microspheres for AR was 97 mg/g.Compared with the adsorption performance of CSM,the adsorption rate of CSMf porous microspheres for MO was significantly faster than that of CSM.When CTS addition of was 0.32 g,and the initial concentration of AR and CI was 100 mg/L,the maximum adsorption quality of TSC-CACS-3 for CI was 99.32 mg/g,and the adsorption rate reached 99.32%.The maximum adsorption quality of TSC-CACS-4(CTS addition of was 0.4 g)for AR was 90.5 mg/g.By comparison to the adsorption performance of CSMf porous microspheres on AR,the adsorption rate of TSC-CACS was significantly higher than that of CSMfs.The above results showed that the adsorption performance of chemically modified TSC-CACS microspheres was better than that of physically modified CSMf porous microspheres and unmodified CSM microspheres.