| Fulvic acids was one of the main factors to form water's chroma, and it could determine the transfer and translation of metal ions , certain organic pollutant and inorganic pollutant in aqueous solution by complexation and adsorption. At the same time, it was also one of the sources to produce Chloroorganics in water treatment and concerned with some endemic diseases. All the charactristic revealed the environment importance to remove fulvic acids. The main method was coagulation as well as adsorption to remove it in aqueous solution. But the removal of fulvic acids in aqueous solution by chitosan has not been reported. In consequence, the removal of fulvic acid by chitosan hydrogel bead was studied in this thesis, and the condition to prepare chitosan hydrogel bead was determined. The modification of chitosan hydrogel bead had been done. The kinetic adsorption, thermodynamics, the impact to adsorption by intensity of ions and pH value were also discussed.The results show that the pHpzc (point of zero charge) was 9.9 and reduced to 6.5 after adsorption. Kinetics test at different initial concentration of fulvic acid revealed that intra-particle model well described the adsorption and the adsorption capacity increased with temperature Compared with Freundlich isotherm, Langmuir isotherm fitted the adsorption better and the maximum adsorption capacity (Q0) was determined as 2.07 mg/g. The pH of solution had significant effect on the adsorption. The adsorption capacity decreased slightly with pH in the acidic range; the negative effect of pH was obvious in the alkaline range. The effect of non hydrolysis ions could be neglected and the physical adsorption was occurred. The FTIR indicated that no obvious change of functional groups was observed and further confirmed physical adsorption. |
