次氯酸钠处理多孔PAN纤维的结构与吸附性能研究

Structure and adsorption property of porous PAN fiber treated with sodium hypochlorite

以聚丙烯腈/聚乙烯吡咯烷酮/二甲基亚砜(PAN/PVP/DMSO)三元体系为纺丝液,以DMSO/H_2O为凝固浴,在凝固浴温度为60℃下,通过湿法纺丝制备了具有介孔结构的多孔PAN/PVP纤维;用次氯酸钠(NaClO)对多孔PAN/PVP纤维进行处理,制得了NaClO@PAN/PVP纤维,采用场发射扫描电镜、元素分析仪和氮气气体吸附仪对处理前后纤维的表面形貌、元素组成、比表面积和孔径进行了表征,研究了凝固浴浓度和温度对PAN/PVP纤维和NaClO@PAN/PVP纤维的PVP含量及比表面积和孔径的影响。结果表明:经NaClO处理后,NaClO@PAN/PVP纤维中氧含量减少,氮含量增多,PVP含量减少,纤维表面变得光滑,平均孔径减小,孔数增多,比表面积增大;随着凝固浴DMSO浓度增大或温度升高,PAN/PVP纤维,NaClO@PAN/PVP纤维中的PVP含量降低,但其比表面积随凝固浴浓度的增大而减小,随凝固浴温度的升高而先升高后减小;在凝固浴DMSO质量分数为0,温度为60℃的条件下制得的PAN纤维、PAN/PVP纤维、NaClO@PAN/PVP纤维的比表面积分别为38,96,108 m^2/g,平均孔径分别为22.7,20.4,19.0 nm;PAN/PVP纤维、NaClO@PAN/PVP纤维的最可几孔径分布在40 nm左右,属于介孔结构。

A porous polyvinylpyrrolidone/polyacrylonitrile（PAN/PVP） fiber with mesoporous structure was prepared from a ternary system of PAN/PVP/dimethylsulfoxide（DMSO） as spinning solution in DMSO/H_2O coagulation bath at 60 ℃ via wet spinning process,which was treated with sodium hypochlorite（NaClO） to produce a NaClO@PAN/PVP fiber.The surface morphology,elemental composition,specific surface area and pore size of the fiber were characterized before and after the treatment by field emission scanning electron microscopy,elemental analysis,nitrogen adsorption instrument.The effects of the coagulation bath concentration and temperature on the PVP content,specific surface area and pore size of PAN/PVP fiber and NaClO@PAN/PVP fiber were studied.The results showed that the oxygen and PVP content of the NaClO@PAN/PVP fiber was decreased,the nitrogen content was increased,the fiber surface became smooth,the average pore size was decreased,the pore number was increased,and the specific surface area was increased after NaClO treatment; the PVP content of the PAN/PVP fiber and NaClO@PAN/PVP fiber was decreased as the DMSO concentration or the temperature of coagulation bath was increased,but the specific surface area was decreased with the increase of the coagulation bath concentration and was firstly increased and then decreased with the increase of the coagulation bath temperature; the produced PAN fiber,PAN/PVP fiber and NaClO@PAN/PVP fiber had the specific surface area of 38,96,108 m^2/g and the average pore size of 22.7,20.4,19.0 nm,respectively,and the latter two fibers had the most probable pore size distribution about 40 nm,indicating a mesoporous structure,when the DMSO mass fraction of coagulation bath was 0 and the coagulation bath temperature was 60 ℃.