Effective removal of arsenic from contaminated groundwater using an iron-based metal organic framework

This study investigates the potential of an iron-based metal–organic framework (MOF) material, Fe-benzene-1,3,5-tricarboxylate (Fe-BTC), for arsenic removal from water. We conducted batch and column experiments to evaluate the effects of varying mass dosages of MOF and pH ranges on arsenic adsorption. Our batch experiments revealed that increasing the mass of Fe-BTC MOF led to higher adsorption capacity. Furthermore, within the range of pH values analyzed, Fe-BTC demonstrated stable arsenic adsorption capacity, suggesting that pH conditions did not significantly affect its performance. In the column experiments, we used granitic material amended with compost and compared arsenic concentration breakthrough curves with and without the presence of MOF to assess its efficiency in arsenic removal. Without MOF, we observed rapid arsenic arrival followed by a slow increase in concentration, indicating anomalous transport dynamics induced by the compost. The addition of MOF resulted in prolonged arsenic arrival and a stabilized lower concentration, indicating effective arsenic adsorption. Fe-BTC MOF exhibited a six-fold increase in arsenic adsorption compared to its absence when added to the soil material. We employed a fractional order advection–dispersion equation model to characterize and predict the physical and chemical dynamics in the column experiments. The transport model accurately matched the arsenic breakthrough curves in the column experiments by capturing the non-Fickian transport and sorption chemical dynamics. The model indicated that compost had an insignificant impact on arsenic adsorption due to flow heterogeneity, while higher dosages of MOF resulted in increased arsenic adsorption and non-Fickian dynamics.