Surface Coverage Simulation and 3D Plotting of Main Process Parameters for Molybdenum and Vanadium Adsorption onto Ferrihydrite

Abstract

Ferrihydrite, FHY, was synthesized and characterized for morphology, mineralogy, surface area, hydrodynamic diameter and surface charge properties before molybdenum (Mo) and vanadium (V) adsorption. The potentiometric titration results showed first direct evidence that CO2 affects FHY surface sites at pH 6–9. Beside CO2, particles concentration may affect surface properties with an impact on adsorption performance. Additional new adsorption simulation results on theoretical surface coverage vs. experimental results obtained at varying particles concentration help theoreticians and experimentalists to better estimate and apply anion adsorption processes to real environments and suggest that simulation may not always be entirely reliable. Uptake capacities obtained experimentally, varying pH, particles and metals concentrations, were plotted to assess their synergetic effect and derive trends for future process optimization. Adsorption kinetics and isotherms were also considered. Experimentally derived values for maximum uptake capacities (0.43 and 1.20 mmol g−1, for Mo and V, respectively) and partitioning coefficients have applications, such as in making decisions for anions removal from wastewaters to achieve depollution efficiency or concentration required for effluents discharge and also implications in elements cycling from a geochemical perspective. In this work, the 3D plotting of the main adsorption process parameters obtained experimentally showed inter-correlations between significant process parameters that influence the adsorption process, and provides guidelines for its optimization and indicates that laboratory data can be transposed to real systems.

Effects of conservation buffer systems on adsorption of fluorescent‐labeled Escherichia coli

“…Equation represents the Langmuir's isotherm model, which assumes that each sorption active center is equivalent, and it is energetically irrelevant whether adjacent sorption centers are empty or already occupied and the monolayer adsorption onto a homogeneous surface. It accounts for the surface coverage by complementing the relative rates of adsorption and desorption (dynamic equilibrium) with no transmigration of the adsorbate (Ali et al., 2016; Ayawei et al., 2017; Brinza, 2022; Krauklis, 2018). $$$$\begin{equation}S\; = \frac{{{q_{{\rm{max}}}}{\rm{\;}} \cdot {\rm{\;}}{K_{\rm{L}}}{\rm{\;}} \cdot {\rm{\;}}{C_{\rm{e}}}}}{{1 + {K_{\rm{L}}}{\rm{\;}} \cdot {C_{\rm{e}}}}}\;\end{equation}$$$$…”

“…Equation 3 represents the Langmuir's isotherm model, which assumes that each sorption active center is equivalent, and it is energetically irrelevant whether adjacent sorption centers are empty or already occupied and the monolayer adsorption onto a homogeneous surface. It accounts for the surface coverage by complementing the relative rates of adsorption and desorption (dynamic equilibrium) with no transmigration of the adsorbate (Ali et al, 2016;Ayawei et al, 2017;Brinza, 2022;Krauklis, 2018).…”

Adsorption of fluorescent labeled E. coli in selected vegetative buffer systems

“…with no transmigration of the adsorbate. (Ali et al, 2016;Ayawei et al, 2017;Krauklis, 2018;Brinza, 2022). where, Kf (cfu/mL) is the Freundlich constant and used to measure the adsorption capacity, 1/nf is the adsorption intensity which also defines the surface heterogeneity and the exponential distribution of active sites with their energies (Ayawei et al, 2015).…”