The Preparation Of The Chitosan And Its Application In Wastewater Treatment

Tenebrio molitor, belongs to Tenebrio in genus, Tenebrionidae in order, Coleptera in order in the entomology. It attracts more and more attention from researchers in different countries because the adult and larva have abundant chitin in the body surface, and the extracted chitin can be processed to Chitosan through deacetylation, which has high utilization value. This article conducts a preliminary research on the extraction of chitin and Chitosan from Tenebrio moliter, and put emphasis on the use of Chitosan that previously extracted to treat wastewater, to be specifically, to study the Chitosan's effect factors in the ion adsorption of heavy metal and the effects of Chitosan of different concentrations in sterilization, so that Chitosan could be used wildly in the industry.In the study of distilling chitin, we use the Acid-alkali Method to find a suitable way to extract Chitin and Chitosan from the body wall of the larvae of Tenebrio molitor. Choosing from the concentrated hydrochloric acid, desalting time, desalting temperature, concentrated sodium hydroxide, removing protein time, removing protein temperature from experimental materials, finally we got the following results: when the temperature is 30℃, the concentration of hydrochloric acid is 1.0mol/L, and the time of desalting is 12h. When the temperature is 30℃, the concentration of sodium hydroxide solution is 2mol/L, and the time of removing protein is 16h. When the temperature is 100℃, the quality score of sodium hydroxide is 50%, and the time of removing acetyl is 6h.In this study, adsorption of Zn2+ onto the Chitosan were studied at different parameters, such as particle size, adsorbent dose, contact time, pH and initial concentrations and solution temperature. The adsorption kinetic and thermodynamic equilibrium parameters were investigated. The results showed that the effect of pH on the adsorption was small, at the optimized conditions,the adsorption quantity of using Chitosan for removal Zn2+ (10mg/L) was 6.95mg?g-1.Both of the adsorption laws conform to the adsorption isotherm equations of Langmuir and Freundlich. The adsorption was found to be endothermic in nature. And adsorption dynamics data also conforms to the quasi- second- order kinetic model.Based on the data of different concentrations of Chitosan in the study of sterilization, it comes to a conclusion that the higher concentration the Chitosan, the better result the sterilization, and the best point is at 4g/L, while the worst point is at 1g/L. It also comes to a conclusion from the Gram stain experiment that after the process of sterilization with Chitosan, the ratio between G-and G+ changed from 5:5 to 8:2, which means Chitosan can sterilize more G+ bacteria than G- ones.