Adsorption of As(V) by the Novel and Efficient Adsorbent Cerium-Manganese Modified Biochar

Arsenic has become a global concern in water environment, and it is essential to develop efficient remediation methods. In this study, a novel adsorbent by loading cerium and manganese oxide onto wheat straw-modified biochar (MBC) was manufactured successfully aiming to remove arsenic from polluted water. Through scanning electron microscopy and energy-dispersive spectroscopy (SEM-EDS), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrometer (FT-IR), and other techniques, it was found the loading of cerium and manganese oxide on MBC played a significant role in As(V) adsorption. The results of the batch test showed that the adsorption of MBC followed the pseudo-second order kinetics and Langmuir equation. The adsorption capacity of MBC was 108.88 mg As(V)/g at pH = 5.0 (C-0 = 100 mg/L, dosage = 0.5 g/L, T = 298 K) with considerable improvement compared to the original biochar. Moreover, MBC exhibited excellent performance over a wide pH range (2.0 similar to 11.0). Thermodynamics of the sorption reaction showed that the entropy (Delta S), changes of enthalpy (Delta H) and Gibbs free energy (Delta G), respectively, were 85.88 J/(moL.K), 22.54 kJ/mol and -1.33 to -5.20 kJ/mol at T = 278 similar to 323 K. During the adsorption, the formation of multiple complexes under the influence of its abundant surface M-OH (M represents the Ce/Mn) groups involving multiple mechanisms that included electrostatic interaction forces, surface adsorption, redox reaction, and surface complexation. This study indicated that MBC is a promising adsorbent to remove As(V) from polluted water and has great potential in remediating of arsenic contaminated environment.