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利用冷冻-解冻法制备了具有较高光催化活性的PVA/TiO_2复合薄膜,长期实验结果显示,冷冻-解冻次数对复合薄膜的光催化性能、材料耐用性以及纳米TiO_2包埋效率有明显影响。相比冷冻-解冻1次和3次的复合薄膜,冷冻-解冻5次得到的复合薄膜在长期实验中的光催化速率更高,包埋TiO_2的损失量更少,膜重量和膜厚度的变化也更小。结合电镜、红外、热重和结晶度数据阐明了纳米TiO_2在PVA载体上固定化作用,以及冷冻-解冻次数影响复合薄膜光催化性能和薄膜耐用性的原因。
PVA / TiO 2 composite films with high photocatalytic activity were prepared by freeze-thaw method. The results of long-term experiments showed that the number of freeze-thaw cycles significantly affected the photocatalytic activity, material durability and nano-TiO 2 embedding efficiency of the composite films. The composite films obtained after freeze-thawed five times had higher photocatalytic activity in long-term experiments, less loss of entrapped TiO 2, and less changes in film weight and film thickness compared to frozen-thawed composite films of 1 and 3 times Also smaller. The effects of immobilization of nano-TiO2 on PVA carrier and the number of freeze-thaw cycles affecting the photocatalytic performance and the durability of the composite film were elucidated by TEM, IR, TG and crystallinity data.