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PubMed2001

[The modified process for preparing natural organic polymer flocculant chitosan].

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).

Chitin↗
PubMed2002

[Decolorization of dyestuff and dying waste water by laccase solution with self-flocculent mycelial pellets of Coriolus versicolor].

Both laccase production by the white-rot fungus Coriolus versicolor and decolorization of dyestuff and dying waste water with crude solution of laccase were studied in this work. Laccase production meets the definition of secondary metabolism. For laccase production the optimum initial pH is 4.5. Addition of veratryl alcohol or elevated trace metals could both enhance the laccase activity, while Tween80 showed some inhibition. The immobilized mycelia of C. versicolor in polyurethane foam had less laccase production ability than mycelial pellets. A repeated batch cultivation process was found to be a very economical way for laccase harvest. The same pellets could be used for at least 14 times and average laccase activity of each batch could maintain 6.72 IU/mL. This method reduces the enzyme production course, medium consumption and the possibility of contamination, showing high efficient and great economic benefit. Good results were also obtained in decolorization experiments with the crude solution of laccase. With 3.3 IU/mL initial laccase activity, color removal of Acid Orange reached 98.5% after 24 h reaction. Also with 2.6 IU/mL initial laccase activity, color removal of dying waste water reached 93% after 24 h reaction.

Biodegradation, Environmental↗