原位交联聚乙烯醇/白炭黑复合水凝胶的制备、结构与性能

Preparation,Structure and Properties of in Situ Cross-linked Polyvinyl Alcohol/White Carbon Black Composite Hydrogel

采用白炭黑(WCB)与聚乙烯醇(PVA)原位交联制备PVA/WCB复合水凝胶。结果发现WCB表面的邻二羟基与硼酸的交联反应增加了PVA交联反应时硼酸的消耗量;WCB表面对硼酸的吸附作用加速硼酸扩散渗入凝胶内部,促进PVA的交联反应,当WCB含量为1.0%(质量分数)时,交联反应速率常数达到最大值5.05h-1。应变扫描中复合水凝胶的储能模量明显大于其损耗模量,证明网络结构的存在,随WCB含量增加,凝胶线性粘弹增强比上升,WCB的增强效率为30.19。适量WCB能提高PVA凝胶小球的耐水力冲击性能及拉伸力学性能。WCB的加入使复合水凝胶的网孔尺寸增大、孔壁变薄、开孔增多、平衡溶胀率增加,将其固定化微生物用于污水处理,有效提高了污水处理效率,当WCB含量为2.5%(质量分数)时PVA固定化微生物水凝胶的COD去除率为75.73%。

Polyvinyl alcohol（PVA）hydrogel filled with white carbon black（WCB）was prepared by chemical crosslinking in the saturated boric acid solution.During the crosslinking reaction of PVA and boric acid,the ortho-dihydroxyl groups on the surface of WCB increased the consumption of boric acid;and adsorption of boric acid by the surface of WCB promoted the diffusion of boric acid into the gel,resulting in acceleration of the crosslinking reaction of PVA.When the addition of WCB was 1.0wt%,the reaction rate constant kof PVA hydrogel reached the maximum value of 5.05h-1.In strain scan curves at low strain region,the storage modulus was significantly higher than the loss modulus,indicating the complete network structure of PVA/WCB hydrogel.With the increase of WCB content,the gel linear viscoelastic enhancement ratio increased,and the reinforced efficiency of WCB was 30.19.Proper content of WCB could improve tensile property and crushing strength of the gel beads.Through the addition of WCB,many large pores formed in the hydrogel so as to enhance swelling property of PVA hydrogel.And waste water treatment efficiency of the gel beads immobilized with activated sludge by addition of proper content of WCB increased while applied to waste water treatment.The cross-linked PVA/2.5wt%WCB composite hydrogel immobilized with activated sludge exhibited a COD removal ratio of 75.73%.