Microcrystalline cellulose(MCC) was activated with ultrasonic wave. The changes in supramolecular structure and morphology structure of MCC were studied by XRD and SEM. The influence of ultrasonic treatment on accessi...Microcrystalline cellulose(MCC) was activated with ultrasonic wave. The changes in supramolecular structure and morphology structure of MCC were studied by XRD and SEM. The influence of ultrasonic treatment on accessibility and oxidation reactivity of MCC with periodate sodium was investigated. The mechanism of the change of reactivity after ultrasonic treatment was discussed. The results showed that crystalline type of cellulose was not changed and no significant changes in crystalline size of cellulose were observed. However, after treatment with ultrasonic wave the crystallinity of cellulose decreased and morphology changes of the treated MCC was significant. These changes contributed to the increase of specific surface area and WRV, which implied the increase of accessibility. The reactivity of MCC with periodate sodium was successfully improved after ultrasonic treatment. The aldehyde content of its oxidized products dialdehyde cellulose(DAC) was improved from 71.3% to 85.0%. As the increase of ultrasonic treating time the aldehyde content first increased and then decreased.展开更多
Natural cellulose and oxycellulose are heterogeneous highly hydrated substances. They have the same chemical composition, but different size of molecules and representation of COOH groups organized into complex supram...Natural cellulose and oxycellulose are heterogeneous highly hydrated substances. They have the same chemical composition, but different size of molecules and representation of COOH groups organized into complex supramolecular structure. The oxycellulosic adsorption capacity of organic cationic dyes increases with increasing -COOH group content and distinctly increases with other competitive ions in the aqueous solution.展开更多
This paper reported the preparation and application of novel chitosan-cellulose composite absorbents for the adsorption of Pb(II)and Cr(VI)ions in water.First,oxycellulose or dialdehyde cellulose(DAC)was prepared by s...This paper reported the preparation and application of novel chitosan-cellulose composite absorbents for the adsorption of Pb(II)and Cr(VI)ions in water.First,oxycellulose or dialdehyde cellulose(DAC)was prepared by sodium periodate oxidation of microcrystalline cellulose(MCC).Second,based on the mechanism of the Mannich reaction,a chitosan/cellulose-based adsorbent(TSFCD)was produced through a cross-linking reaction of thiosemicarbazide(TS)with DAC and chitosan(CS),which was designed specifically for the adsorption of Cr^(6+)ions from water.Similarly,another chitosan/cellulose-based adsorbent(DBFCM)was also prepared with 2,5-dithiobiurea(DB)as the cross-linking agent for the adsorption of Pb^(2+)ions in water.The adsorption performance of TSFCD and DBFCM for Cr^(6+)and Pb^(2+)ions,respectively,was investigated under various process conditions.Variables included adsorption temperature,time,initial metal ion concentration,pH,and adsorbent dosage.The adsorption kinetics of TSFCD and DBFCM were studied,and isothermal models were developed.Results showed that the adsorption amount increased with the increase of the reaction time,and reached a maximum at about 300 min for the TSFCD/Cr^(6+)system,and at about 240 min for DBFCM/Pb^(2+)system.The adsorption performance of TSFCD for Cr^(6+)and DBFCM for Pb^(2+)improved at higher temperature,and leveled off at 40℃ and 50℃,respectively.In addition,the removal rate of Cr^(6+)increased from 49.96%to 70.22%when the TSFCD dosage increased from 0.5 g/L to 3.5 g/L.Similarly,the removal rate of Pb^(2+)increased from 22.23%to 99.45%with the increase of DBFCM dosage from 0.5g/L to 5.0g/L.The adsorption processes of Pb^(2+)and Cr^(6+)were in line with the pseudo-second-order kinetic and the Langmuir isothermal model.展开更多
文摘Microcrystalline cellulose(MCC) was activated with ultrasonic wave. The changes in supramolecular structure and morphology structure of MCC were studied by XRD and SEM. The influence of ultrasonic treatment on accessibility and oxidation reactivity of MCC with periodate sodium was investigated. The mechanism of the change of reactivity after ultrasonic treatment was discussed. The results showed that crystalline type of cellulose was not changed and no significant changes in crystalline size of cellulose were observed. However, after treatment with ultrasonic wave the crystallinity of cellulose decreased and morphology changes of the treated MCC was significant. These changes contributed to the increase of specific surface area and WRV, which implied the increase of accessibility. The reactivity of MCC with periodate sodium was successfully improved after ultrasonic treatment. The aldehyde content of its oxidized products dialdehyde cellulose(DAC) was improved from 71.3% to 85.0%. As the increase of ultrasonic treating time the aldehyde content first increased and then decreased.
文摘Natural cellulose and oxycellulose are heterogeneous highly hydrated substances. They have the same chemical composition, but different size of molecules and representation of COOH groups organized into complex supramolecular structure. The oxycellulosic adsorption capacity of organic cationic dyes increases with increasing -COOH group content and distinctly increases with other competitive ions in the aqueous solution.
基金Innovation research team of Guangxi Natural Science Foundation (No.2013GXNSFFA019005)the National High Technology Research and Development Program (No.2009AA06A416)Guangxi scientific and technological project (No.14251009)for their financial support.
文摘This paper reported the preparation and application of novel chitosan-cellulose composite absorbents for the adsorption of Pb(II)and Cr(VI)ions in water.First,oxycellulose or dialdehyde cellulose(DAC)was prepared by sodium periodate oxidation of microcrystalline cellulose(MCC).Second,based on the mechanism of the Mannich reaction,a chitosan/cellulose-based adsorbent(TSFCD)was produced through a cross-linking reaction of thiosemicarbazide(TS)with DAC and chitosan(CS),which was designed specifically for the adsorption of Cr^(6+)ions from water.Similarly,another chitosan/cellulose-based adsorbent(DBFCM)was also prepared with 2,5-dithiobiurea(DB)as the cross-linking agent for the adsorption of Pb^(2+)ions in water.The adsorption performance of TSFCD and DBFCM for Cr^(6+)and Pb^(2+)ions,respectively,was investigated under various process conditions.Variables included adsorption temperature,time,initial metal ion concentration,pH,and adsorbent dosage.The adsorption kinetics of TSFCD and DBFCM were studied,and isothermal models were developed.Results showed that the adsorption amount increased with the increase of the reaction time,and reached a maximum at about 300 min for the TSFCD/Cr^(6+)system,and at about 240 min for DBFCM/Pb^(2+)system.The adsorption performance of TSFCD for Cr^(6+)and DBFCM for Pb^(2+)improved at higher temperature,and leveled off at 40℃ and 50℃,respectively.In addition,the removal rate of Cr^(6+)increased from 49.96%to 70.22%when the TSFCD dosage increased from 0.5 g/L to 3.5 g/L.Similarly,the removal rate of Pb^(2+)increased from 22.23%to 99.45%with the increase of DBFCM dosage from 0.5g/L to 5.0g/L.The adsorption processes of Pb^(2+)and Cr^(6+)were in line with the pseudo-second-order kinetic and the Langmuir isothermal model.
