Shakib Farzaneh, Dadvand Koohi Ahmad, Kamran Pirzaman Arash
Chemical Engineering Department, Engineering Faculty, University of Science and Technology of Mazandran, Behshahr, Iran.
Chemical Engineering Department, Engineering Faculty, University of Guilan, Rasht, Iran E-mail:
Water Sci Technol. 2017 Apr;75(7-8):1932-1943. doi: 10.2166/wst.2017.077.
In this study, novel chitosan-g-itaconic acid/bentonite (CTS-g-IA/BT) and chitosan/bentonite (CTS/BT) nanocomposites were synthesized for adsorption of methylene blue (MB) from aqueous solution. The process was pH-sensitive and maximum sorption was obtained at pH 6 (CTS-g-IA/BT) and 7 (CTS/BT) in 76 h agitation time using 0.03 g of nanocomposites for 50 mL of MB solution. The results showed that in pH less than 6, the adsorption capacity of CTS-g-IA/BT nanocomposite due to the existence of IA monomer is less than that of CTS/BT nanocomposite. The Fourier transform infrared spectroscopy (FTIR) spectrum of CTS-g-IA/BT revealed that both itaconic acid and BT present in the nanocomposite structure, and also the -OH groups of BT, -NH and -OH of CTS participated in nanocomposite formation. According to the FTIR results, a schematic diagram of the nanocomposite synthesis was presented. The kinetic results indicated that the adsorption of MB fitted well with the pseudo-second-order kinetic model. The equilibrium data followed Langmuir isotherm with the maximum adsorption capacity of 500 and 181.818 mg/g for CTS-g-IA/BT and CTS/BT nanocomposites, respectively. The negative values of Gibbs free energy change (ΔG) and the positive values of ΔH confirmed that the adsorption process is spontaneous and endothermic. The positive values of ΔS suggested the randomness of adsorption at interface.
在本研究中，合成了新型壳聚糖-g-衣康酸/膨润土（CTS-g-IA/BT）和壳聚糖/膨润土（CTS/BT）纳米复合材料，用于从水溶液中吸附亚甲基蓝（MB）。该过程对pH敏感，在76小时搅拌时间内，使用0.03 g纳米复合材料处理50 mL MB溶液时，在pH为6（CTS-g-IA/BT）和pH为7（CTS/BT）时获得最大吸附量。结果表明，在pH小于6时，由于IA单体的存在，CTS-g-IA/BT纳米复合材料的吸附容量小于CTS/BT纳米复合材料。CTS-g-IA/BT的傅里叶变换红外光谱（FTIR）表明，衣康酸和膨润土均存在于纳米复合材料结构中，并且膨润土的-OH基团、壳聚糖的-NH和-OH参与了纳米复合材料的形成。根据FTIR结果，给出了纳米复合材料合成的示意图。动力学结果表明，MB的吸附符合准二级动力学模型。平衡数据遵循Langmuir等温线，CTS-g-IA/BT和CTS/BT纳米复合材料的最大吸附容量分别为500和181.818 mg/g。吉布斯自由能变化（ΔG）的负值和ΔH的正值证实吸附过程是自发的且吸热。ΔS的正值表明界面吸附的随机性。
