While PM becomes blue membrane(BM) by deionixation, the protonated neutral red with positive charge could occupy the binding sites, causing BM to regenerate PM.

• 紫膜经去离子化处理变成蓝膜后，带有正电荷的质子化中性红也可以占据此金属离子结合位点，使蓝膜再生为紫膜。