Mesoporous Zirconium Titanium Oxides. Part 3. Synthesis and Adsorption Properties of Unfunctionalized and Phosphonate-Functionalized Hierarchical Polyacrylonitrile-F-127-Templated Beads

Abstract

A method is presented for the preparation of zirconium titanate mixed oxides in bead form having hierarchical pore structure. This method entailed the use of both preformed polyacrylonitrile (PAN) polymer beads and surfactants as templates. The templates were removed by calcination at temperatures below about 500 degrees C, resulting in mixed oxide beads with trimodal pore size distributions and interconnected pores. The pore size distributions as determined using nitrogen adsorption-desorption showed clear maxima at 4.5 and 45 nm length scales and also clear evidence of microporosity. The macroporous framework morphology was a replica of the PAN beads with radial structure. The mesoporous framework possessed wormhole-like pores with pore size of about 6 nm that was consistent with the F-127 triblock copolymer template used. The mixed oxide beads exhibited surface areas of 215 and 185 m2/g after calcination at 500 and 600 degrees C. Thermal stability up to 650 degrees C is unprecedented for bulk systems. The adsorption properties were characterized using uranyl as the target cation and the mass transport in the beads with the present hierarchical architectures has been shown to be exceptional. The beads were functionalized with 4-amino,1-hydroxy,1,1-bis-phosphonic acid (HABDP) and amino-tris-methylene phosphonic acid (ATMP) and the adsorption properties for the extraction of uranyl sulfate complexes from acidic solution examined. Of the two molecules investigated, ATMP functionalization resulted in the best extraction efficiency with equilibrium uptake of about 90% of uranium available in solution between pH 1 and 2. The beads could potentially be utilized as catalysts, catalyst supports, adsorbents, and separation materials.

Effective Am(iii)/Eu(iii) separations using 2,6-bis(1,2,4-triazin-3-yl)pyridine (BTP) functionalised titania particles and hierarchically porous beads

“…This is desirable as hierarchical porosity often improves mass transport properties and increases the number of readily available reaction sites. 15 Two types of hysteresis are also evident in Fig. 2.…”

Mesoporous Transition Metal Oxide Ceramics

“…Recently it has also been found that ATMP coordinates well to surfaces of mesoporous materials and successfully used as a metal adsorbent material for Cu(II), Hg(II), Cd(II), U(VI), and other radionuclides [131][132][133]. Depending on the interaction type, ATMP ligands surrounding a metal center ideally coordinate with both deprotonated phosphoryl oxygens and an N-central donor atom, creating an octahedral coordination structure (Fig.…”

Oxide-based inorganic/organic and nanoporous spherical particles: synthesis and functional properties

“…The titania–zirconia hybrids have affinity to phosphopeptides so that concentration of the phosphopeptides on the surface was achieved [ 111 ]. Sizgek et al reported the preparation of millimeter-sized spherical nanoporous titania–zirconia particles with a variable Zr/Ti ratio [ 112 – 114 ]. The titania–zirconia hybrid particles were easy to handle owing to their large size, and the authors suggested that they can be used for adsorbing vanadium and uranium species.…”