Complete Column Trials for Water Refinement Using Titanium(IV) Phosphate Sorbents

A titanium phosphate sorbent with linked active units (LTP) is synthesized. XRD, 31P MAS NMR, and TGA techniques are used to disclose the relation between the ion-exchange units of −HPO4 (crystalline α-TiP) and of −H2PO4 (amorphous TiP1) type. The reported kinetics data of TiP1 sorbent in batch mode have been reprocessed according to the nonlinear approach in order to explore further the sorption mechanism. It was found that the data could be well described by the pseudo-second-order model in the case of Ni2+ ions. Consequently, fixed-bed column sorption experiments of Ni2+ ions on LTP were designed, and the effects of both the amount of nickel(II) ions in the feed solution and the flow rates on the sorption equilibrium were studied. The ion-exchange capacity is estimated to be 1.6 meq·g–1 during the first four cycles before decreasing to 1.2 meq·g–1 for cycles five and six. The experimental data were simulated following the Thomas model, and desorption experiments with HCl were performed. Observations sh...