Comparison of As removal efficiency and health risks from aqueous solution using as-synthesized Fe0 and Cu0: modelling, kinetics and reusability

Batch scale removal of arsenic (As) from aqueous media was explored using nano-zero valent iron (Fe-0) and copper (Cu-0) 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(2)/g) and pore volume (0.0415 cm(3)/g) of synthesized Fe-0 were higher than the surface area (17.56 m(2)/g) and pore volume (0.0287 cm(3)/g) of Cu-0. The SEM results showed that the morphology of the Fe-0 and Cu-0 was flowery microspheres and highly agglomerated with thin flakes. The FTIR spectra for Fe-0 showed broad and intense peaks as compared to Cu-0. 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-0 (94.95%) and Cu-0 (74.86%). When the dosage increased from 1 to 4 g L-1, the As removal increased from 70.59 to 93.02% with Fe-0 and from 67 to 70.59% with Cu-0. 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-0/Cu-0. Among the adsorption isotherm models, the values of R-2 showed that isothermal As adsorption by Fe-0 and Cu-0 was well explained by the Freundlich adsorption isotherm model (R-2 > 0.98) while the kinetic experimental data was well-fitted with the Pseudo second order model. The Fe-0 showed excellent stability and reusability over five sorption cycles, and it was concluded that, compared to the Cu-0, the Fe-0 could be a promising technology for remediating As-contaminated groundwater.

Automated summary

Nano-zero valent iron (Fe-0) and copper (Cu-0) particles were used for batch scale removal of arsenic (As) from aqueous media. The Fe-0 exhibited higher surface area and pore volume compared to Cu-0, while the morphology of the particles differed. The Fe-0 showed excellent removal efficiency of As at pH 4 and demonstrated good stability and reusability.