Revisiting syntheses of Ti(iv)/H2PO4–HPO4 functional ion-exchangers, properties and features. (10th November 2017)

• Record Type: Journal Article
• Authors: Trublet, Mylène; Rusanova, Daniela; Antzutkin, Oleg N.
• Is Part Of: New journal of chemistry. Volume 42:Number 2(2018)
• Page Start: 838
• Page End: 845
• Publication Date: 2017-11-10
• Subjects: Chemistry -- Periodicals; Chimie -- Périodiques; 540
• DOI: 10.1039/c7nj03065g
• Languages: English
• ISSNs: 1144-0546

Abstract

Abstract : Systematic and readily obtainable ion-exchanger, TiO(OH)(H2 PO4 )·H2 O, with excellent Na + uptake and strong affinity towards divalent metal ions. Abstract : Amorphous titanium phosphate ion-exchangers are often of a "mixed type", i.e., they contain a mixture of –HPO4 and –H2 PO4 active groups. Their synthesis requires careful handling to obtain the same proportion of active units and sorption characteristics. This article focuses on the influence of titanium sources and post-synthetic treatments on the uniform synthesis of amorphous TiP1 (TiO(OH)(H2 PO4 )·H2 O). It also describes a mild and straightforward method for obtaining crystalline α-TiP (Ti(HPO4 )2 ·H2 O). Amorphous TiP1 was successfully synthesized using five sources of titanium providing that the content of titanium and H2 SO4 in the primary solution was 60–110 g L −1 and 400 ± 50 g L −1, respectively. Observations revealed that organic and inorganic acids could also be comparably used in post-synthetic treatments to protonate the phosphate groups into –H2 PO4 units. The Na + uptake (up to 7.2 meq g −1 ) and ion-exchange capacities towards divalent ions (up to 3.8 meq g −1 ) of all the TiP1-type sorbents studied are among the highest reported for TiP systems. Despite differences in the surface characteristics, the TiP1 materials synthesized in this study displayed comparable sorption properties, supporting the fact that chemisorption is the governing factor behind the sorption processes. Crystalline α-TiP is obtained under similar mild synthesis conditions when the P2 O5 : TiO2 molar ratio is greater than 1 : 1, regardless of the titanium source. The possibility of using various types of TiOSO4 as a titanium source for TiP1 and α-TiP syntheses is emphasized and all reported data are re-considered from a synthetic perspective.