Photocatalytic degradation of methyl orange by PbXO4 (X=Mo, W)

PbMoO4 and PbWO4 are prepared by the simple precipitation method in this work, they show the photocatalytic activities for the degradation of methyl orange in water under the UV light illumination. In the above photocatalytic degradation processes, methyl orange concentration decreases quickly, the total organic carbon (TOC) decreases slowly; inorganic ions (SO4(2-), NO3(-), NO2(-), NH4(+)) can be formed and measured by the ion chromatograph; the pH value in the systems decreases gradually; a small quantity of HO˙(-)·can be generated and measured by the terephthalic acid (TA) indirectly. In order to estimate the roles of active species during the above photocatalytic degradation processes, isopropanol, (NH4)2C2O4, and 1,4-benzoquinone as the scavengers for HO˙, h(+), O2˙(-) are introduced into the systems, respectively. Isopropanol and (NH4)2C2O4 are effective scavengers for active species HO˙ and h(+) respectively, but 1,4-benzoquinone is not a satisfactory scavenger in all cases to capture O2˙(-), at least in this work. At last, PbMoO4 and PbWO4 are characterized by nitrogen sorption, DRS, SEM, TEM and XRD.