海藻酸钠/微晶纤维素复合水凝胶对水中甲基橙和亚甲基蓝的吸附性能与机理

Adsorption performance and mechanism of sodium alginate/ microcrystalline cellulose composite hydrogel for aqueous methyl orange and methylene blue

以海藻酸钠(SA)和微晶纤维素(MCC)为原料,合成海藻酸钠/微晶纤维素复合水凝胶(SA/MCC),对制备的复合水凝胶进行结构表征,并研究其对水中甲基橙(MO)和亚甲基蓝(MB)的吸附性能、模型和机理。结果表明,SA/MCC-20去除MO和MB的最佳pH分别为2和12,吸附模型更符合拟二级模型和Langmuir模型,最大吸附容量可达331.25mg/g、253.31mg/g。通过改变水溶液的pH,MO和MB均可在SA/MCC-20表面实现有效的吸附和解吸从而回收利用。经过5次吸附-解吸循环后,在最佳pH下SA/MCC-20对MO和MB的解吸率仍达91.52%和85.41%。SA/MCC对MO和MB具有较强的吸附能力,吸附机理主要包括静电吸引、范德华力、氢键作用、π-π堆积、孔扩散、孔填充等,并以化学吸附为主,物理吸附为辅。

A sodium alginate/microcrystalline cellulose(SA/MCC)composite hydrogel was synthesized using sodium alginate(SA)and microcrystalline cellulose(MCC)as raw material.The structure of the prepared hydrogel was characterized,and the adsorption properties,model and mechanism of the hydrogel for aqueous methyl orange(MO)and methylene blue(MB)were studied.The results showed that the optimal pH of SA/MCC-20 removing MO and MB were 2 and 12,respectively.The adsorption model was more consistent with the pseudo-second-order model and Langmuir model,and the maximum adsorption capacity of MO and MB could reach 331.25mg/g and 253.31mg/g,respectively.By changing the pH of the aqueous solution,both MO and MB could achieve effective adsorption and desorption on SA/MCC-20 for recycling.After 5 times of sorption-desorption cycles,the desorption efficiency of MO and MB of SA/MCC-20 remained 91.52%and 85.41%at optimal pH.SA/MCC possessed excellent adsorption capacity for MO and MB,and the adsorption mechanism mainly included electrostatic attraction,van der Waals force,hydrogen bonding,π-πstacking,pore diffusion and filling,etc,and chemisorption played a leading role with the auxiliary of physical adsorption.