Studies On Preparation And Aplication Of Modified Chitosan Flocculant And Its Complexes

Water soluble chitosan derivatives ,N-(2-hydroxy)propyl-3-trimethyl ammoniumchitosan chloride(HTCC), N,N,N-trimethyl-chitosan chloride(TMC) andN-(2-methyl-carboxylmethyl)-chitosan(MCC) are synthesized by reaction of chitosanwith epoxypropyl trimethyl ammonium chloride, methyl iodide and pyruvic acidrespectively. Influences of reacting time,temperture,monormeric weight ratio on thedegree of substitution and solubility of HTCC are discussed. The modified chitosanderivatives are characterized by FT-IR,1H-NMR to observe changes in chemicalstructures.X-ray diffraction and differential scanning calorimetry are applied focusingon changes in crystallity of chitosan and its affinity for water. It shows quaternaryand carboxyl of chitosan greatly reduced the hydrogen bonds among chitosanmolecules and crystallization,make HTCC,TMC have stonger affinity for water. Flocculation of modified chitosan on tannin, one of the main foreign matter inherb extraction liquid are explored . The result shows that HTCC,TMC has higherflocculation efficiency than that of chitosan on removing tannin . Moreover HTCCworks in a wide range of dosage with fast floc formation and growth. Flocculation of HTCC ,TMC,MCC on extraction liquid of Carthamus tinctoriusL. are studied to explore the clarification effect and influence on the activeconstituents.The result indicates that HTCC at 0.2-0.4g/L can remarkably clarify theextraction liquid. Chitosan /HTCC – Polyanion (Carageenan/Alginate) complexes are used ascoagulants for treating the extraction liquid of Carthamus tinctorius L.FT-IR analysesshows electrostatic interaction between the chitosan-NH3 and Carrageenan –SO3 + -group to be responsible for complex formation.The flocculation experiment showsthat the coagulation efficiency was improved significantly by the complex ofchitosan/HTCC-carrageenan with lager floc and higher settling velocity.