Preparation Of Chitosan Nanoparticles And Studies On Adsorption Situation Of Cu²⁺,Pb²⁺,Cd²⁺ In Water

Metallic ion pollution in water attract more and more people'attention.Research and develop new effective adsorbent is the focus for the present. On the basis of a large number of relevant literature and the current research status of chitosan, the nano-chitosan as a new modified adsorbent will mainly be researched in water environment application,the main contents and results are as follows:The first part is based on chitosan and sodium polyphosphate as raw material to make the nanoparticles prepared by ionic crosslinking of chitosan particles.Detailed study of the molecular weight of chitosan, chitosan and multi-mass ratio of sodium tripolyphosphate, the pH value and reaction temperature on the preparation of chitosan nanoparticles. The formation of chitosan nanoparticles finalized the optimum conditions:H2O2 oxidative degradation of chitosan by 6h; acetic acid content was 1%; pH value of 4.5; Chitosan (CS)concentration 2mg/mL; Sodium tripolyphosphate(STPP)concentration 1mg/mL; the mass ratio of CS and STPP is 5:2; magnetic stirring time : 30min; ultrasonic time: 15min; By scanning electron microscopy, transmission electron microscopy and UV spectrophotometer on the structure and morphology of chitosan nanoparticles were characterized by particle size of 200nm-400nm, stable and uniform nano-chitosan;The second part mainly researched the Cu²⁺,Pb²⁺,Cd²⁺ adsorption in one-component system of chitosan nanoparticles and multi-component system from the optimum adsorption time,pH,optimum chitosan dosage,adsorption isotherm line,adsorption rate,adsorption selectivity of other areas to study.The results show that chitosan nanoparticles has a good advantage in metal ions adsorption capacity and adsorption rate under the same conditions than Chitosan and to explore the best adsorption of chitosan nanoparticles acidic environment: pH = 6.0; Required to reach adsorption equilibrium time was 120min; optimum dosage of chitosan nanoparticles as 12 times the amount of metal ions; By Langmuir-type adsorption isotherm equation and the Freundlich-type isotherm equation could well describe the nano-chitosan on Cu²⁺, Pb²⁺, Cd²⁺'s adsorption behavior, but relatively speaking, Cu2 + of the Langmuir-type adsorption isotherms are better than the Freundlich Type adsorption isotherm on the fitting degree,while the Pb²⁺,Cd²⁺ are more consistent with Freundlich-type adsorption isotherm;When the system reaches equilibrium,nano-chitosan'adsorption capacity on Cu²⁺,Pb²⁺,Cd²⁺ was 89.9mg / g, 69.6mg / g, 53.7mg / g; adsorption rates were: 96.7%, 92.5%, 89.7%; In the multi-component system, before equilibrium the chitosan nanoparticles has a corresponding decreases on metal ion adsorption rate and adsorption capacity compared to one-component system;but the adsorption capacity and adsorption rate has not much difference in the two-component system When the system reaches equilibrium and has longer tine; Under the two-component system,the adsorption of cadmium has greater extent on copper greater extent,The second is the adsorption of cadmium on levels of lead,adsorption of lead on the extent of copper is the weakest.