Comparison of As removal efficiency and health risks from aqueous solution using as-synthesized Fe and Cu: modelling, kinetics and reusability.

Batch scale removal of arsenic (As) from aqueous media was explored using nano-zero valent iron (Fe) and copper (Cu) particles. The synthesized particles were characterized using a Brunauer-Emmett-Teller (BET) surface area analyzer, a scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR). The BET result showed that the surface area (31.5 m/g) and pore volume (0.0415 cm/g) of synthesized Fe were higher than the surface area (17.56 m/g) and pore volume (0.0287 cm/g) of Cu. The SEM results showed that the morphology of the Fe and Cu was flowery microspheres and highly agglomerated with thin flakes. The FTIR spectra for Fe showed broad and intense peaks as compared to Cu. The effects of the adsorbent dose (1-4 g/L), initial concentration of As (2 mg/L to 10 mg/L) and solution pH (2-12) were evaluated on the removal of As. Results revealed that effective removal of As was obtained at pH 4 with Fe (94.95%) and Cu (74.86%). When the dosage increased from 1 to 4 g L, the As removal increased from 70.59 to 93.02% with Fe and from 67 to 70.59% with Cu. However, increasing the initial As concentration decreased the As removal significantly. Health risk indices, including estimated daily intake (EDI), hazard quotient (HQ), and cancer risk (CR) were employed and a significant decline (up to 99%) in risk indices was observed in As-treated water using Fe/Cu. Among the adsorption isotherm models, the values of R showed that isothermal As adsorption by Fe and Cu was well explained by the Freundlich adsorption isotherm model (R > 0.98) while the kinetic experimental data was well-fitted with the Pseudo second order model. The Fe showed excellent stability and reusability over five sorption cycles, and it was concluded that, compared to the Cu, the Fe could be a promising technology for remediating As-contaminated groundwater.