Abstract:

Dialdehyde cellulose(DAC)was prepared from microcrystalline cellulose with periodate sodium as oxidant. The influences of oxidant concentration, reaction temperature, reaction time and pH of solution on the aldehyde content were investigated. DAC was characterized by XRD, FTIR, element analysis and measuring the aldehyde group. The relation between aldehyde content of DAC and urea adsorption capacity (AC) was discussed. The adsorption equilibrium and kinetics of urea onto dialdehyde cellulose were studied. Experimental results showed that the optimal synthetical condition was that the ration of NaIO₄ to MCC was 2.4 by weight, reaction temperature was 35 ℃, reaction time was 3.5 h and pH was 2, and the DAC with aldehyde content of 97.74% under this condition. As the increase of aldehyde content, the AC for urea first increased and then decreased. The max. AC for urea was 59.23 mg ·g^-1 and it is ten times as much as that coated dialdehyde-starch adsorption capacity of urea adsorption(6 mg ·g^-1), that is four times as much as what capsulated enzymie starch dialdehyde AC,equilibrium reached after 4 h. The adsorption isotherm curve of DAC fit well with Freundich equation.

Key words: dialdehyde cellulose, aldehyde content, urea, adsorption equilibrium, adsorption isotherm curve