Modified Chitosan Treating Wastewater

This experiment uses a kind of highly molecular natural compound chitosan as the material to produce N,O-Carboxymethyl chitosan, whitch used to treate dyeing wastewater. Then, the carboxymethyl chitosan made by ourselves is used as material to produce Magnesium salt coordination of Carboxymethyl chitosan, and the adsorbability of dyeing wastewater is investigated.The chitosan and chloroacetic are used as reaction monomers to make the O,N-Carboxymethyl chitosan, and the mass ratio is 5:14, the basifier is 50% liquor NaOH, the reacting temperature is 60℃, the reacting time is 3 hours.Carboxymethyl chitosan has the flocculate capability to dyeing wastewater. When the pH value is 5.0, the dosage is 87.5mg/L, the time of sedimentation is 2 hours, the decolorizing rate is 85%, the capability of flocculation is better than poly-ferric chloride, and equal as ferrous sulfate, the dosage is 1/5 of ferrous sulfate.When use a little ferric salt as coagulant aid, the effect is better than that use Carboxymethyl chitosan only, and the decolorizing value of wastewater is more than 93%.The N,O-Carboxymethyl chitosan made by ourselves, in the alkalinesolution, reacts with magnesium salt to produce Magnesium salt coordination of Carboxymethyl chitosan. The best reaction condition is that the mass ratio of Carboxymethyl chitosan and MgCl₂·6H₂O is 12:17.5, the injection of 0.1 mol/L NaOH aq. is 40mL, the injection of glutaraldehyde is 0.80mL,the reaction time is 100 minutes.The adsorption of Magnesium salt coordination of Carboxymethyl chitosan to dyeing wastewater is studied, the adsorption quantity reaches to 258.7 mg/g, at normal temperature, in the acidity liquor, with surging 3 hours. And the adsorption is more accord with the Langmuir equation, the second-order kinetics equation, and it is a kind of endothermic, spontaneous, physical adsorption.