Amino-bacterial cellulose（amino-BC） was prepared by chemical modification of bacterial cellulose（BC）.The adsorption characteristics and mechanism of amino-BC were studied.The results show that adsorption data can be fitted well by Langmuir equation and the pseudo-second order kinetics,indicating that the adsorption of amino-BC would obey monolayer molecule adsorption and the main action was chemisorption.Meanwhile,the adsorption process was studied by the Elovich equation and the intra-particle diffusion model,indicating that the absorption characteristics of metal ions on amino-BC is controlled by both film diffusion and particle diffusion.The increase of reaction temperature will accelerate the adsorbing rate because of endothermic reaction.
A new adsorbent, ammonium sulfamate-bacterial cellulose （ASBC）, was prepared through chemical modifications of bacterial cellulose. The process of adsorbing Cr（VI） including its isotherm and kinetics, was measured and studied. The results showed that pH value was a very important parameter to the adsorbing efficiency. The adsorption kinetics can be described by a pseudo-second rate model and a particle diffusion equation. Both physical and chemical adsorptions existed in the adsorption process, but chemical adsorption was more dominatant. And particles internal diffusion was not the only rate controlling step. The adsorption equilibrium can be described by the Langmuir type, which indicated that a typical single-molecule layer adsorption of Cr（VI） by ASBC could be described. And the rate of adsorption followed the Slips model well, which indicated that ASBC had some multiphase and asymmetry. The coordination adsorption and ion exchange effect were the main mechanisms of chemical adsorption. The absorbed Cr（V1） can be desorbed effectively by 0.5 mol/L EDTA or HCI from the adsorbent, which could make it be reusable
The adsorption capability of bacterial cellulose（BC） for anionic dye acid fuchsine was studied. Meanwhile, the processes of the adsorption were investignted and fitted by adsorption isotherm models, adsorption thermodynamics and adsorption kinetics models, respectively. The changes of BC before and after adsorbing acid fuchsine were investigated via scanning electron microscopy（SEM） and Fourier transform infrared spectroscopy（FTIR） to further explain the adsorption mechanism. The results show that acid fuchsine could be effectively adsorbed by BC. The adsorption process was fitted well by Langmuir equation and the pseudo-second order kinetics, indicating that the adsorption process was monolayer molecule adsorption with the main action of chemical adsorption. The adsorption process was spontaneous and endothermic. Glucuronic acid groups and hydroxyl groups were responsible for the adsorption of acid fuchsine on BC.
In order to improve the efficiency of new adsorbent, grafting-allylamine bacterial cellulose（al-BC）, response surface methodology（RSM） was used for the optimization of preparation process. Three factors affecting the yield of grafting reaction are the amount of allylamine, the concentration of ceric ammonium nitrate（CAN） and the concentration of nitric acid. Based on the regression coefficient analysis in the Box-Behnken design, a relationship between the preparation variable and grafting yield was obtained. Square error analysis on main factors, and multi-variable interactions were employed for studying grafting yield. The results show that at the conditions of CAN of 23.00 mmol/L CAN, 0.17 mol/L nitric acid, adding an amount of grafting-allylamine bacterial cellulose of 26.49 mL/L made grafting rate reach maximum of 24.25% at 40℃ after the reaction for 4 h. The experimental results are in good agreement with the calculation values via proposed regression equation, indicating that the equation could be used to nredict and optimizate the preparation of grafting al-BC.
LU Min A Runa GUAN Xiaohui XU Xiaohui CUI Yingshengnan GAO Tingting
