| Chitosan is the unique cationic polysaccharide which is widely distributed in nature. Interests in basic and application studies of chitosan and its ramification are rapidly growing because of its advantages of innocuity, biocompatibility, multiple functions, antibacterial and flocculating activity. But the expensive chitosan is not suit to be used in water treatment. Thus, the process chitosan preparation by immersing method under compressed conditions was developed to reduce the cost. At the same time, a kind of derivative was prepared to remove NO3-N from drinking water.Two-Point Potentiometric Titration was established to determine the D.D of chitosan. CTS was solved in 0.1 M HCl first, then a standard addition of 0.1 M NaOH was made giving a pH in the range of 2.84～3.10 (pH1), and the volume of NaOH solution was recorded(V1); A further NaOH addition is made giving a pH increase of 0.3～0.4 units and total alkalinity are calculated from pH2 and pH1. Compared with traditional Potentiometric Titration, the relative error of Two-Point Potentiometric is less than 0.65%. It's applicable to all kinds of chitosan.CT and P-CT was used as raw materials to prepared chitosan, and the influence of NaOH concentrations and reaction time on chitosan properties under compressed conditions of 0.15 MPa was compared with that of atmospheric pressure. The result shows that, the D.D of chitosan prepared by three kinds of technics is in a sequence below: Immersing method under compressed conditions (CT)> Immersing method under compressed conditions (P-CT)> Immersing method under atmospheric pressure (CT); The viscosity-average molecular weights of chitosan prepared under compressed conditions is larger than that under atmospheric pressure when CT was used as material, but the chitsoan prepared from P-CT had the lower viscosity-average molecular weights than that prepared from CT under atmospheric pressure. Compared with traditional technics, immersing method under compressed conditions decreased reaction time from 6h to lh, and consumption of NaOH was reduced by 65% without change in chemical and crystal structures of chitosan.With chitosan as the raw material, a new type chitosan resin (CCR) was prepared. The effect of the operating conditions on the properties of the resin was investigated. The results revealed that CTS concentration and the dosage of formaldehyde, epichlorohydrin, acetic eater and disperser affected the properties of the resin and the adsorption ability of NO3-largely. The adsorption of NO3- on CCR had large capacity in acid condition, which was...
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