Synthesis and characterization of mesoporous titania microspheres and their applications

Mesoporous titanium dioxide microspheres were synthesized by the sol–gel templating method, using calcium alginate as a sacrificial template, and subjecting to different temperatures, under various atmospheres. The gradual changes in composition, crystallinity, phase and surface morphology, due to variation in calcination atmosphere and temperature, were monitored by TGA, XRD, SEM and EDX techniques. The effect of polymeric content on the surface area and the pore size of the titania beads was evaluated by BET analysis. The results show that N2 atmosphere and high temperature influence the phase content and morphology of the microsphere significantly. Anatase to rutile phase transformation and formation of calcium titanate take place under nitrogen atmosphere at lower temperature, as compared to that under air atmosphere. To examine the applications of these synthesized microspheres, photo-catalytic activity and sorption efficiency of the microspheres were evaluated, by carrying out photo-degradation of methylene blue (MB) dye, and removal of arsenic ions from ammoniacal solution. The microspheres showed good photo catalytic activity towards MB dye. Tracer experiments with 76As showed ∼98% sorption of arsenic ions from aqueous solution onto the titania microspheres.

► Synthesis of macroporous titania beads by sol–gel templating.
► Use of bio-compatible calcium alginate beads as a sacrificial template.
► Detailed characterization, using TGA, SEM, EDX, XRD and N2 adsorption techniques.
► The effect of calcining temperature and atmosphere.
► Application of the titania beads in photocatalysis of methylene blue dye.