TY - JOUR
T1 - Comparison of two carbonaceous supported Fe-rich adsorbents for arsenate removal: A functionalisation and mechanistic study with applicability to groundwater treatment
AU - Pap, Sabolc
AU - Turk sekulic, Maja
AU - Tran, Hai nguyen
AU - Chao, Huan-Ping
AU - Gilbert, Peter j.
AU - Gibb, Stuart w.
AU - Taggart, Mark a.
N1 - © 2024 The Authors. Published by Elsevier Ltd.
PY - 2024/5/2
Y1 - 2024/5/2
N2 - The presence of arsenic in groundwater, and through this in drinking water, has been shown to present a serious risk to public health in many regions of the world. In this study, two iron-rich carbonous adsorbents were compared for the removal of arsenate (As(V)) from groundwater. Biochars (FeO-biochar and FeO-pyrochar) derived from biomass waste were functionalised in two different ways with iron chloride for comparation. Batch and dynamic parameters were optimised to achieve >99% As(V) removal efficiency. Experimental data best described by the pseudo-second order kinetic model, while multi-stage diffusion appeared to limit mass transfer of As(V). Among the isotherm models evaluated, the Freundlich model best described the experimental results with high correlation coefficients (R2≥0.94) for both adsorbents. Monolayer adsorption capacities were found to be 4.34 mg/g and 8.66 mg/g for FeO-biochar and FeO-pyrochar, respectively. Batch studies followed by instrumental characterisation of the materials indicated the removal mechanisms involved to be electrostatic interactions (outer-sphere), OH- ligand exchange (inner-sphere complexation) and hydrogen bonding with functional groups. Higher pHpzc (9.1), SBET (167.2 m2/g), iron/elemental content and functionalisation technique (e.g., functionalisation of biochar after pyrolysis instead of biomass) for FeO-pyrochar, compared with FeO-biochar, suggested that both the surface chemistry and porosity/surface were important in adsorption. Dynamic studies showed FeO-pyrochar can be used to remove As(V) from groundwater even at low ‘environmental’ concentrations to legislative limit (<10 μg/L), where 7 g of FeO-pyrochar was able to treat 5.4 L groundwater.
AB - The presence of arsenic in groundwater, and through this in drinking water, has been shown to present a serious risk to public health in many regions of the world. In this study, two iron-rich carbonous adsorbents were compared for the removal of arsenate (As(V)) from groundwater. Biochars (FeO-biochar and FeO-pyrochar) derived from biomass waste were functionalised in two different ways with iron chloride for comparation. Batch and dynamic parameters were optimised to achieve >99% As(V) removal efficiency. Experimental data best described by the pseudo-second order kinetic model, while multi-stage diffusion appeared to limit mass transfer of As(V). Among the isotherm models evaluated, the Freundlich model best described the experimental results with high correlation coefficients (R2≥0.94) for both adsorbents. Monolayer adsorption capacities were found to be 4.34 mg/g and 8.66 mg/g for FeO-biochar and FeO-pyrochar, respectively. Batch studies followed by instrumental characterisation of the materials indicated the removal mechanisms involved to be electrostatic interactions (outer-sphere), OH- ligand exchange (inner-sphere complexation) and hydrogen bonding with functional groups. Higher pHpzc (9.1), SBET (167.2 m2/g), iron/elemental content and functionalisation technique (e.g., functionalisation of biochar after pyrolysis instead of biomass) for FeO-pyrochar, compared with FeO-biochar, suggested that both the surface chemistry and porosity/surface were important in adsorption. Dynamic studies showed FeO-pyrochar can be used to remove As(V) from groundwater even at low ‘environmental’ concentrations to legislative limit (<10 μg/L), where 7 g of FeO-pyrochar was able to treat 5.4 L groundwater.
U2 - 10.1016/j.chemosphere.2024.142205
DO - 10.1016/j.chemosphere.2024.142205
M3 - Article
SN - 0045-6535
JO - Chemosphere
JF - Chemosphere
M1 - 142205
ER -