Nitrogen Adsorption on Zirconium Bis Monohydrogenphosphate with α-Type Structure

Abstract

ABSTRACT.Different samples of layered a-zirconium bis (monohydrogen phosphate) monohydrate, prepared by HF method, were outgased from room temperature to 300°C and their specific surface area determined by nitrogen adsorption. The specific surface area increases from 0.64 to 0.77 m 2 /g as the outgasing temperature increases from r. t. to 200°C. A small decrease is observed at 300°C. Adsorption and desorption isotherms showed that this layered compound possesses only a negligible porosity. Thus the a-zirconium phosphate prepared according to the HF method can be used as a non porous reference material for the study of the porosity of the other M(IV) phosphates or/and phosphonates which have similar surface chemical properties. An empirical equation, interpolating adsorption data, is proposed and compared with standard isotherms reported in literature.

A new photo-functional material constituted by a spirooxazine supported on a zirconium diphosphonate fluoride

“…The BET treatment 20 of the isotherms gave a specific surface area of 12.74 ¡ 0.09 m 2 g 21 . The t-plot analysis, 20 performed by using a-zirconium phosphate as reference material, 21 provided a negligible micropore volume, in agreement with the low amount of nitrogen adsorbed at low pressure. The narrow hysteresis observed in the adsorption-desorption isotherms (see Fig.…”

“…5) indicated that the solid phase has a negligible mesoporosity. Accordingly, BJH analysis 21 gave a very low mesopore volume and the few mesopores observed had dimensions in the 20-50 A ˚. range.…”

“…Surface area and porosity were determined by N 2 adsorption-desorption isotherms at 77 K taken with a Micromeritics ASAP 2010 instrument, after degassing the sample for 1 day at 393 K. Thermogravimeter-differential thermal analysis (TG-DTA) was performed in air using a Stanton Redcroft STA781 instrument at a heating rate of 5 K min 21 . CHN elemental analyses were carried out with a Carlo Erba Model 1106 Analyser.…”

“…(PM) n A (PM) n 2 1 1 PM k (PM) n ~(0.0015 ¡ 0.00030) s 21 The bleaching observed at 610 nm is due to the closure of the PMs, formed from the SOs by irradiation, or detached from the (PM) n stacks: PM A SO k PM ~(0.014 ¡ 0.003) s 21 The slowest detachment process is the rate-determining step of the bleaching kinetics for the PMs originating from the aggregate. This can be reasonably inferred based on the similarity of k (PM) n and the slow decay component at 610 nm.…”