丙烯酸/醋酸纤维素超滤膜的改性及制备

Preparation of acrylic acid modified cellulose acetate ultrafiltration membrane

亲水性差、水通量低制约了醋酸纤维素膜在水处理等方面的应用。本研究以丙烯酸(AA)为单体对醋酸纤维素粉末进行亲水性接枝改性,以N-甲基吡咯烷酮(NMP)为溶剂,制备改性醋酸纤维素(CA-g-PAA)膜,并通过添加正硅酸乙酯增加膜的孔洞数量,进而提高膜的水通量。采用傅里叶变换红外光谱、静态接触角测试仪、扫描电镜对改性前后的醋酸纤维素膜的形貌结构、组成及其润湿性能进行表征与分析,并通过力学性能测试及透过性测试,考察改性后醋酸纤维素膜的机械强度及透过性的变化。结果表明:醋酸纤维素接枝丙烯酸单体后,醋酸纤维素膜的亲水性、机械性能及渗透性明显改善,而正硅酸乙酯的添加使得膜的孔洞数量增加,截留率略有下降,膜水通量显著提高。

Cellulose acetate（CA）is a kind of thermoplastic resin prepared through catalytic esterification of cellulose and acetic acid anhydride. Cellulose acetate has been widely used as a raw material in membrane production process due to its low cost, high mechanical strength and thermal stability. However, the poor hydrophilicity and low water flux have greatly limited the application of the cellulose acetate membrane in water treatment and other related fields. In this study, cellulose acetate powder was modified with hydrophilic acrylic acid（AA）monomer, and the modified cellulose acetate（CA-g-PAA）membrane was prepared by using N-methyl pyrrolidone（NMP）as the solvent. To improve the pore numbers and thus the water flux of the CA-g-PAA membrane, ethyl silicate（TEOS）was used as a pore-foaming agent during the membrane preparation process. The surface morphology and micro-structure of the resulting membrane were characterised by Fourier transform infrared spectroscopy（FTIR）and scanning electron microscopy（SEM）. The hydrophilicity, mechanical properties and permeability of the modified cellulose acetate membrane were also characterized by contact angle measurement, tensile strength test and permeability test, respectively. The results demonstrated that after been grafted with acrylic acid monomer, the hydrophilicity, mechanical property and permeability of cellulose acetate membrane have been improved significantly. With the adding of ethyl silicate, the pore numbers and the water flux of cellulose acetate membrane were also improved. The interception rate of cellulose acetate membrane decreased slightly.