title: [The modified process for preparing natural organic polymer flocculant chitosan].
abstract: The modified process for preparing chitosan from crab or lobster shells was developed. In the decalcification stage, 10% HCl was used as soaking solution with addition of a small quantity of A as a promoter, and the mass ratio of reactants was 10% HCl:A:crab or lobster shells = 3.5:0.5:1, continuously stirring the crab or lobster shells at 30 degrees C for 3 h in place of simply soaking the crab or lobster shells at room temperature for 16-24 h in the previous process. In the deacetylation stage, 40% NaOH solution was used with addition of a small quantity of B as a promoter, and the mass ratio of reactants was 40% NaOH:B:chitin = 4:0.2:1, keeping reaction at 105 degrees C for 2 h in place of at 115 degrees C for 6 h in the previous process. By this new process, the cost of the raw materials used for preparing chitosan was cut down 49%, the preparation time was shortened by one half, and the main properties of this chitosan such as viscosity, deacetylation and molecular weight all approached or exceeded those of the Sigma' commercial chitosan (Chitosan C-3646).
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, Dept. of Environmental Science & Engeneering, Tsinghua University, Beijing 100084, China.
authors.forename: D
authors.initials: D
authors.lastname: Zeng
authors.forename: G
authors.initials: G
authors.lastname: Yu
authors.forename: P
authors.initials: P
authors.lastname: Zhang
authors.forename: Z
authors.initials: Z
authors.lastname: Feng
mesh_terms: D002686:Chitin / Q000031:analogs & derivatives / Q000138:chemical synthesis* / Q000737:chemistry; D048271:Chitosan
chemical_list: D002686:Chitin; D048271:Chitosan