Promoting dynamic adsorption of Pb2+ in a single pass flow using fibrous nano-TiO2/cellulose membranes

A variety of nano-TiO2/cellulose composite fibers (TiO2/CF) were synthesized via both in situ growing rutile TiO2 nanocrystals and electrostatic self-assembly of commercial nano rutile TiO2 particles onto cellulose fibers. These fibers were then processed into fibrous membrane beds by wet-laid technique. Dynamic adsorption of lead (Pb2+) was subsequently carried out by pumping the feed solution through the bed in a single-pass flow mode. The influence of various parameters including flow rate, bed height and bed stacking pattern on bed breakthrough behavior was investigated. It was found that the in situ-TiO2/CF bed outperformed others; its loading capacity of Pb2+ was 13 times that of pure CF bed, and 9 times that of the self-assembled TiO2/cellulose bed prior to 10% breakthrough. The dynamic adsorption behavior of the in situ-TiO2/CF bed was better predicted by Dose-Response model among other models tested. The bed was also selective for Pb2+ over Ca2+, and was readily regenerable when eluted with 0.1 M HCl solution for repeated use. The outstanding performance of the in situ-TiO2/CF bed was a result of larger fiber adsorption capacity and faster adsorption kinetics compared with the other beds having similar geometric bed structure.