Photo-oxidation of 4-nitrophenol in aqueous suspensions, catalysed by titania intercalated zirconium phosphate (ZrP) and titanium phosphate (TiP)

Titania pillared zirconium phosphate and titanium phosphate samples were prepared by intercalating titanium(IV) isopropoxide sol inside the phosphate layer. The sol-intercalated samples were calcined at various temperatures and characterised by different techniques. Basal spacing and surface area revealed that highest amount of pillaring in interlayer has taken place with 2 and 4 wt.% TiO2 loading for ZrP and TiP, respectively. These pillared samples are stable up to 500 °C and exhibit highest surface area in the range of 70–172 m2 g−1, basal spacing in the range of 15.5–25.9 Å, which is greater than that of neat ZrP and TiP. These materials also showed greater activity towards photo-oxidation of 4-nitrophenol under solar radiation. The low crystallite size, low pHpzc, high surface area, higher acid sites and larger basal spacing might be responsible for highest activity shown by 2 and 4 wt.% pillared ZrP and TiP, respectively.