Understanding the Reduction Kinetics of Aqueous Vanadium(V) and Transformation Products Using Rotating Ring-Disk Electrodes

Abstract

Vanadium(V) is an emerging contaminant in the most recent Environmental Protection Agency's candidate contaminant list (CCL4). The redox chemistry of vanadium controls its occurrence in the aquatic environment, but the impact of vanadium(V) speciation on the redox properties remains largely unknown. This study utilized the rotating ring-disk electrode technique to examine the reduction kinetics of four pH- and concentration-dependent vanadium(V) species in the presence and the absence of phosphate. Results showed that the reduction of VO, HVO (V), and HVO proceeded via a one-electron transfer, while that of NaHVO (V) underwent a two-electron transfer. Koutecky-Levich and Tafel analyses showed that the intrinsic reduction rate constants followed the order of V > VO > V > HVO. Ring-electrode collection efficiency indicated that the reduction product of V was stable, while those of VO, HVO, and V had short half-lives that ranged from milliseconds to seconds. With molar ratios of phosphate to vanadium(V) varying from 0 to 1, phosphate accelerated the reduction kinetics of V and V and enhanced the stability of the reduction products of VO, V, and HVO. This study suggests that phosphate complexation could enhance the reductive removal of vanadium(V) and inhibit the reoxidation of its reduction product in water treatment.

Vanadium contamination and associated health risk of farmland soil near smelters throughout China

“…This value was also significantly higher than vanadium contents in topsoil from the USA (80 mg/kg) (p < 0.05) and Europe (68 mg/kg) (p < 0.01) (Gao et al, 2017). During smelter operations, dust clouds containing vanadium were discharged and became deposited on the soil, contributing to the high occurrence of vanadium in farmland soil (Chen and Liu, 2017). The two regions possessing the highest contents of vanadium were SW and NC, with average values of 198.0 ± 231.9 mg/kg (n = 13) and 158.3 ± 110.0 mg/kg (n = 4), respectively, both of which are abundant in vanadium resource and contain many plants for its intensive processing (Moskalyk and Alfantazi, 2003).…”

Microbial Community Responses to Vanadium Distributions in Mining Geological Environments and Bioremediation Assessment

“…Phosphate metabolism can be adversely affected by vanadium (Zhang et al, ). Ingestion of vanadium can lead to serious diseases, including pulmonary tumors (Chen & Liu, ). Additional exposure ailments include allergic reactions such as asthma, conjunctivitis, and rhinitis.…”

“…Vanadium enters water naturally through geological weathering of vanadium‐containing minerals (Cole et al, ). Anthropogenic activities, especially intensive mining of vanadium‐bearing minerals, result in excessive amounts of vanadium being released into regional geological environments, causing severe public health issues (Chen & Liu, ; Zhang et al, ).…”

Synchronous microbial vanadium (V) reduction and denitrification in groundwater using hydrogen as the sole electron donor

“…Vanadium is a transition metal prevalent in the Earth's crust and is extensively used in modern technologies (Naeem et al, 2007;Sturini et al, 2013;Cao et al, 2017). Geological weathering and discharges from industrial processes lead to the presence of vanadium in groundwater (Chen and Liu, 2017). In the U.S., substantial vanadium contamination has been recorded at 283 superfund sites, with vanadium concentration reaching 100 μM in an aquifer at a site near Rifle, Colorado (Yelton et al, 2013), far exceeding the 0.2 μg/L minimum reporting level proposed by the U.S.…”