Tang Z, Tang X, Liu H, Xiao Z. Immobilizing arsenic-enriched wastewater from utilization of crude antimony oxides as scorodite using a novel multivalent iron source.
CHEMOSPHERE 2023;
339:139751. [PMID:
37557998 DOI:
10.1016/j.chemosphere.2023.139751]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Revised: 07/31/2023] [Accepted: 08/05/2023] [Indexed: 08/11/2023]
Abstract
Arsenic-enriched wastewater (A-EW) is a hypertoxic sewage from the utilization of crude antimony oxides in lead anode slime metallurgy. In traditional methods, the H+ accumulation inhibits the arsenic immobilization during scorodite synthesis. In this study, a novel multivalent iron source comprised of Fe(OH)3 and FeSO4·7H2O was proposed to resolve the adverse effects of pH fluctuation during immobilizing A-EW as scorodite. Various approaches, such as scanning electron microscopy and X-ray photoelectron spectroscopy, were applied to characterize the synthesized scorodite. This work was divided into two parts. In thermodynamics, HnAsO4(3-n)- (n = 1, 2, 3) and Fe(OH)n(3-n)+ (n = 0, 1, 2, 3) can feasibly coprecipitate as scorodite according to their △rGm,Tθ ranged from -111.10 kJ mol-1 to -33.53 kJ mol-1. In experimental research, A-EW was immobilized as scorodite by optimizing conditions as initial pH = 2.0, molar ratio of Fe to As = 1.2, molar ratio of Fe(II) to Fe(III) = 4:6, arsenic concentration = 40 g/L, and temperature = 95 °C. The arsenic precipitation ratio is 99.60%, and the micromorphology of synthesized scorodite presents a regular octahedron having size of 5-10 μm. The low leachability of As (0.41 mg/L) in toxicity characteristic leaching procedure (TCLP) confirmed that the prepared scorodite is nonhazardous. The solution pH is stable at 2.0 as the H+ depletion (0.5660 mol) by Fe(OH)3 dissolution and Fe2+ oxidization balanced with that (0.5657 mol) generated from As(V)-Fe(III) coprecipitation. In general, the A-EW was effectively immobilized by proposed multivalent iron source, and can be potentially applied to safely dispose other industrial effluents, such as high arsenic leachates and arsenic-bearing waste acid from nonferrous metallurgy.
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