Novel Fe-Mn binary oxide-biochar as an adsorbent for removing Cd(II) from aqueous solutions

Abstract

In this study, a pristine biochar (BC) and Fe-Mn binary oxide-biochar (FMBC) were prepared using Pennisetum sp. straw as the feedstock for Cd(II) removal from aqueous solutions. Scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and specific surface area (SSA) analyses revealed the physico-chemical characteristics of the pristine and designer adsorbents, suggesting that an ultrasonic treatment during synthesis enhanced the SSA and pore volume of the BC, and assisted successful loading of Fe-Mn binary oxide particles on the BC surface. The Cd(II) adsorption data of the adsorbents were fitted to the Langmuir isothermal and pseudo-second-order kinetic models. At a system temperature of 25 ℃ and pH 5, the maximum Cd(II) adsorption capacities of BC (30.58 mg/g) and FMBC (95.23 mg/g) were obtained. Multiple Cd(II) adsorption mechanisms by FMBC were identified, including precipitation with minerals, complexation with surface functional groups, Cd(II)-π interactions，and cation exchange. As the most dominant adsorption mechanism, Cd-O bonds were formed on the FMBC surfaces precipitating Cd(OH)2 (63.9 wt%) and CdO (36.1 wt%). The FMBC thus could be potentially used as an effective adsorbent for Cd(II) removal from aqueous solutions.

Iron-modified biochar and water management regime-induced changes in plant growth, enzyme activities, and phytoavailability of arsenic, cadmium and lead in a paddy soil

“…Furthermore, researchers suggested that iron (Fe) oxides could reduce the mobility of PTEs (especially As) in the soil, and thus mitigate PTE bioavailability and leaching potential (Qiao et al, 2019;Tang et al, 2020;. Studies also suggested the feasibility of using biochar loaded Fe materials to remove As and other toxic elements from aqueous solutions (e.g., Niazi et al, 2018;Xia et al, 2019;Yin et al, 2020).…”

High‐efficiency adsorption of various heavy metals by tea residue biochar loaded with nanoscale zero‐valent iron

“…The structure and properties of the materials were further analyzed by nitrogen adsorption desorption experiments. According to the classification of IUPAC, its isotherm is typical type IV 15 . In addition, the desorption hysteresis suggested that PBC was a kind of mesoporous material with lamellar structure and nZVI/PBC was a material with both micropores and mesopores (Figure 1(g)).…”

Chemically Dual-Modified Biochar for the Effective Removal of Cr(VI) in Solution

“…The O1s spectrum had three peaks ( Figure 3 d): the peak of 531.6 eV can be ascribed to the lattice oxygen (CO, C=O) [ 28 ]; the peaks of 532.6 eV and 530.5 eV are attributed to the oxygen from organic matter (–OH or C–O–C) [ 29 ] and inorganic matter (MO and M–OH, M was metal), respectively [ 28 ]. The spectrum of Al2p and Mn2p3/2 represented elemental aluminum and manganese from Al 2 O 3 and MnO ( Figure 3 e,f), respectively [ 30 ]. The loaded Al/Mn oxides with different chemical states on the surface of AMKBC 3/4 could react with Cr 2 O 7 2− and HCrO 4 − through a complex reaction and electrostatic attraction, which enhanced Cr(VI) removal (Equations (8) and (9)).…”