Study On The Adsorption Properties Of Amino Modified Chitosan/Microcrystalline Cellulose

With the continuous development of industry,agriculture and technology,the development and utilization of heavy metals are increasing,and the heavy metals discharged into the water are increasing year by year.Excessive concentrations of heavy metal ions in water will lead to a serious threat to human health.Therefore,the studies for effective heavy metal ions adsorption materials to improve the environmental pollution and protect the human health are very important.1.In this paper,dialdehyde cellulose(DAC)was prepared by sodium periodate oxidation of microcrystalline cellulose(MCC).Based on the mechanism of Schiff Base Reaction,chitosan/cellulose-based adsorbent(TCM)was produced through cross-linking reaction of thiosemicarbazide(TS)with DAC and chitosan(CS).(1)The preparation process of TCM was optimized using the single factor method.The experimental results showed that the optimum preparation process of TCM was 20 0C,15 h,0.45 g TS,0.5 g DAC,4 mL formaldehyde.The process conditions of TCM adsorption on Cr6+ were studied by Response Surface Methodology.The results showed that the optimum pH was 2.5,the optimum initial concentration of Cr(?)was 273.32 mg/L,and the optimum dosage of TCM was 2.01 g/L,the theoretical removal rates and practical removal rates were 90.97%and 90.01%respectively under the optimum conditions.(2)The Structural characterization of TCM revealed that CS and DAC were successfully crosslinked with TS.The adsorption kinetics and isothermal adsorption of Cr(?)showed that the adsorption of Cr(?)was in accordance with the Pseudo-second-order kinetics and Langmuir isothermal adsorption model,which belonged to single molecular layer and chemical adsorption.2.Under the same reaction principle of TCM,another chitosan/cellulose-based adsorbent(DCM)was prepared with 2,5-dithiobiurea(DB).The adsorption process of DCM for Pb(?)was optimized using the single factor method.The optimum conditions were as follows:adsorption temperature 50 ?,DCM dosage 5 g/L,pH 5.0,the maximum removal rate of DCM for Pb(?)was 99.31%.The adsorption kinetics and isothermal adsorption of DCM on Pb(II)showed that the adsorption was carried out on the surface of DCM and adsorbed on the monolayer,which was in accordance with the second-order kinetics and Langmuir isothermal adsorption model.FTIR,elemental analysis and XRD analysis showed that the crystallinity of DCM decreased,more active groups were exposed.The ion exchange between the active group and Pb(?)was improved,which made the adsorption of Pb(?)more easily.