The Influence of Phosphate on the Adsorption–Desorption Kinetics of Vanadium in an Acidic Soil

Abstract

Quantitative understanding of the mechanisms controlling the competitive retention and transport of V and phosphate on soils is essential for accurately evaluating the environmental risks of contaminants in the environment. Batch and stir‐flow chamber experiments were performed to quantify the extent of kinetics of V and phosphate competitive retention in an acidic soil (Sharkey clay). In this study, a stir‐flow model was used to describe tracer and competitive reactive solute adsorption, and desorption processes in soils. Based on optimized and predictive modeling results, a fully reversible–irreversible multi‐reaction model successfully described the time‐dependent competitive V and phosphate retention and transport process in Sharkey soil. Adsorption for V and phosphate were highly nonlinear and time dependent, where V binding affinities were stronger than those for phosphate. Results from batch experiments indicated that that the rate and extent (amount) of V released increased significantly in the presence of phosphate. Breakthrough curves for V, from stir‐flow experiments, were asymmetrical and exhibited slow release or tailing, indicating that nonequilibrium retention on the surface of soil was the dominant mechanism of the time‐dependent adsorption of V. Results of stir‐flow experiments indicated that increased mobility of V was observed in the presence of phosphate caused by direct competition for available retention sites. In conclusion, increased addition of phosphate causes decreasing sorption capacity and increasing mobility of V and needs to be considered in modeling the fate and transport of V in soil. Core Ideas Retention mechanisms of V and phosphate were different. The presence of P results in increased mobility of V. The stir‐flow multi‐reaction model successfully described time‐dependent V transport.

Sorption and Desorption of Vanadate, Arsenate and Chromate by Two Volcanic Soils of Equatorial Africa

“…The very-little desorption of vanadate promoted by the addition of phosphate is in accordance with the assertions that vanadate is more strongly bound than phosphate to iron hydrous oxides [16,28,29] or soils [73].…”

Modeling the kinetics of competitive sorption and desorption of Zn(II), Ni(II), and Pb(II) in an acidic soil: Stirred‐flow experiments

“…The inclusion of the competitive exchange‐type reaction of Equation allowed for the model to correctly predict the competitive displacement of Ni by Zn and Zn by Pb (Figure 3, bottom left, and Figure 4 bottom left, respectively), as well as lower sorbed concentrations observed in the concurrent pulse experiments of the Zn–Ni and Zn–Pb binary systems. Such predictions are beyond the capabilities of single‐ion models that have been used previously (Fernández‐Calviño et al., 2010, 2014; Sun et al., 2019) and emphasize the importance of considering the behavior of multiple species simultaneously when predicting retention of solutes by soils in competitive systems.…”

“…As such, several kinetic models have been advanced to describe stirred‐flow sorption and desorption data ranging in complexity from single site equations (Fernández‐Calviño et al., 2010) to multiple reaction approaches (Peng, Shi, et al., 2018; Sun & Selim, 2019). Attempts to model the behavior of chemical species in competitive systems under stirred‐flow conditions have thus far relied on single component formulations that do not account for interactions between species, resulting in the use of different sets of parameters to describe single‐ and multiple‐ion systems separately (Fernández‐Calviño et al., 2010; Sun et al., 2019). This suggests a need for a modeling approach that considers the behavior of multiple species simultaneously.…”

“…Fernández‐Calviño et al (2010), used the stirred‐flow technique to investigate the competitive sorption of Zn and Cu by four acidic soils where Cu substantially reduced Zn sorption in all cases. The stirred‐flow technique has also been used to study competition between As and Cr (Fernández‐Calviño et al., 2014), V and phosphate (Sun et al, 2019), Cu and phosphate (Pérez‐Novo et al., 2011a), and Zn and phosphate (Pérez‐Novo et al, 2011b). Besides these investigations, the stirred‐flow reactor remains underused in studying competitive sorption of heavy metals in soils.…”

Fate and transport in environmental quality

“…Studying concurrent F&T of several substances appeared to be valuable, as in the research of the nitrate-inhibiting effect on selenate (SeO 4 ) reduction (Bailey et al, 2012) or phosphate effect on the adsorption-desorption kinetics of vanadium (Sun et al, 2019). In a uranium F&T study, acidic water F I G U R E 1 Frequency of fate and transport papers for major pollutant groups created secondary precipitants that cemented quartz grains together and modified pore geometry in the center of the experimental column.…”