Application of Monoclinic Bismuth Vanadate in Photooxidation of Arsenic-Polluted Water

HighlightsPhotooxidation of trivalent arsenic to pentavalent arsenic was catalyzed by s-m BiVO4 under visible light irradiation.The roles of catalyst, light, and oxygen were investigated.The photooxidation mechanism was studied, and a possible reaction route is proposed.Abstract. Oxidation is a necessary step for inorganic arsenic removal. In this study, monoclinic bismuth vanadate (BiVO4) was synthesized to photooxidize trivalent arsenic to pentavalent arsenic in water in the presence of light and oxygen. Light irradiation initiates photooxidation after physical absorption of arsenite on BiVO4. Addition of oxygen slightly improved the photooxidation efficiency. Photooxidation parameters were optimized; 2.6 mM of BiVO4 synthesized at pH 2 was effective to photooxidize 0.1 M of arsenite in alkaline solution, and 99.8% removal of trivalent arsenic was achieved with a photooxidation efficiency of 85.5%. Photooxidation by BiVO4 might be initiated by hydroxyl radicals resulting from irradiation by visible light. Appropriate BiVO4 morphology and alkalinity of the reaction mixture facilitated photooxidation. Keywords: Arsenic, BiVO4, Photooxidation, Speciation.

Novel 3D lightweight carbon foam as an effective adsorbent for arsenic(v) removal from contaminated water

An efficient removal of pentavalent arsenic (As(v)) from water has been developed using novel three-dimensional (3D) light weight carbon foam which exhibit adoption capacity of 38.4 μg g−1.

Synthesis and Crystal Structure of K3AsSe4 and K4As2Se5 Containing [AsSe4]3- Anions and a Novel [As2Se5]4- Isomer Featuring an As–As Bond

Two novel selenoarsenates, K3AsSe4 and K4As2Se5, were synthesized by the mild solvothermal reaction of potassium carbonate and arsenic and selenium powder in the presence of superheated ethylenediamine and structurally characterized by single-crystal X-ray diffraction. K3AsSe4 crystallizes in the orthorhombic space group Pnma (no. 62) with a = 9:4169(4), b = 10:9695(5), c = 9:7568(8) Å, Z = 4 and V = 1007:86(10) Å3 and contains [AsSe4]3- anions with pentavalent arsenic. K4As2Se5 crystallizes in the monoclinic space group P21/n (no. 14) with a = 7:6167(2), b = 22:8733(4), c = 8:4687(2) Å, b = 107:241(2)°, Z = 4 and V = 1409:14(5) Å3, and shows isolated [As2Se5]4- anions. The most prominent feature of the latter anions is the presence of arsenic in two different formal oxidation states (+4/+2) due to the presence of an As-As bond.