8. Conclusion

A pH-responsive smart PAm-ZTS was prepared by prepared via reactions between zirconium titanosilicate and polyacrylamide under different preparation conditions for testing some lanthanide ions, namely, Ce4+, Pr3+, Sm3+, Gd3+, Dy3+, and Ho3+ for their active rejection. The pH response of the membrane was demonstrated using static adsorption and hydraulic permeation results. The water flux of the PAm-ZTS membrane decreased with the decreasing pH value, with the most drastic decrease occurring between pHs 4 and 7, and was both reversible and durable with interchanging pHs between 3 and 8. At pH 3, the membrane pores were in a closed state due to the extended conformation of the amide chains on the pore surfaces. In contrast, at pH 8, the membrane pores were in non-closed state because of the collapsed conformation of the amide chains. The outcomes in this paper afford clear indication to the availability of manufacture and production of pH-responsive composite membranes and can inspire further works on design and preparation of stimuli-responsive membranes through addition of molecularly designed macromolecular additives synthesized by controlled polymerization.

#### Author details

Gehan Mohamed Ibrahim and Belal El-Gammal\*

\*Address all correspondence to: belalelgammal@hotmail.com

Faculty of Science, Chemistry Department, University of Bisha, Kingdom of Saudi Arabia
