Effect of aluminium incorporation on physicochemical properties and patent blue V photodegradation of magnesium phosphate materials

A series of magnesium phosphate samples modified by incorporation of aluminium, denoted MgAlP- x (where x indicates the Al molar ratio%; x = 0; 10; 20; 40%), have been prepared by coprecipitation method followed by characterization. Their structures have been investigated by using powder X-ray diffraction, the surface area by physisorption of nitrogen (BET), Fourier transform infrared (FTIR) were used to characterize the functional groups of solids and MAS–NMR spectroscopy. X-ray diffractograms for synthesized materials suggest the formation of mixed solids, such as Mg 3 (PO 4 ) 2 , AlPO 4 and Al 2 O 3 . Incorporation of aluminium into magnesium orthophosphate increased the temperature of crystallization, so that MgAlP- x systems retained amorphous up to 973 K. The specific surface area increases with aluminium content. 31 P MAS–NMR spectra of calcined MgP shows a single peak at δ = +0.4 ppm and two overlapped signals for calcined MgAlP- x ( x = 20 and 40%). But the dry solids present more than a single peak. The varying values of chemical shifts are due to the existence of different types of 31 P structural configurations and oxygen environment. 27 Al MAS-NMR spectra of sample exhibit two peaks, which were characteristic of the octahedral and tetrahedral environments of Al 3+ ions. It was observed that the incorporation of Al in MgP material decreases the patent blue V (PB) photodegradation. The highest dye degradation was obtained over the MgP catalyst (without Al). No correlation between the adsorption before UV irradiation and the rate of photodegradation.