A series of the magnetic CuFe₂O₄-loaded corncob biochar (CuFe₂O₄@CCBC) materials was obtained by combining the two-step impregnation of the corncob biochar with the pyrolysis of oxalate. CuFe₂O₄@CCBC and the pristine corncob biochar (CCBC) were characterized using XRD, SEM, VSM, BET, as well as pH_ZPC measurements. The results revealed that CuFe₂O₄ had a face-centered cubic crystalline phase and was homogeneously coated on the surface of CCBC. The as-prepared CuFe₂O₄@CCBC(5%) demonstrated a specific surface area of 74.98 m²·g⁻¹, saturation magnetization of 5.75 emu·g⁻¹ and pH_ZPC of 7.0. The adsorption dynamics and thermodynamic behavior of Pb(II) on CuFe₂O₄@CCBC and CCBC were investigated. The findings indicated that the pseudo-second kinetic and Langmuir equations suitably fitted the Pb(II) adsorption by CuFe₂O₄@CCBC or CCBC. At 30 °C and pH = 5.0, CuFe₂O₄@CCBC(5%) displayed an excellent performance in terms of the process rate and adsorption capacity towards Pb(II), for which the theoretical rate constant (k₂) and maximum adsorption capacity (q_m) were 7.68 × 10⁻³ g·mg^−1··min⁻¹ and 132.10 mg·g⁻¹ separately, which were obviously higher than those of CCBC (4.38 × 10⁻³ g·mg⁻¹·min⁻¹ and 15.66 mg·g⁻¹). The thermodynamic analyses exhibited that the adsorption reaction of the materials was endothermic and entropy-driven. The XPS and FTIR results revealed that the removal mechanism could be mainly attributed to the replacement of Pb²⁺ for H⁺ in Fe/Cu–OH and –COOH to form the inner surface complexes. Overall, the magnetic CuFe₂O₄-loaded biochar presents a high potential for use as an eco-friendly adsorbent to eliminate the heavy metals from the wastewater streams.

To expand the applications of graphene-based materials to biogas purification, a series of reduced graphene oxide aerogels (rGOAs) were prepared from industrial grade graphene oxide using a simple hydrothermal method. The influences of the hydrothermal preparation temperature on the textural properties, hydrophobicity and physisorption behavior of the rGOAs were investigated using a range of physical and spectroscopic techniques. The results showed that the rGOAs had a macro-porous three-dimensional network structure. Raising the hydrothermal treatment temperature reduced the number of oxygen-containing groups, whereas the specific surface area (S_BET), micropore volume (V_micro) and water contact angle values of the rGOAs all increased. The dynamic adsorption properties of the rGOAs towards hexamethyldisiloxane (L2) increased with increasing hydrothermal treatment temperature and the breakthrough adsorption capacity showed a significant linear association with S_BET, V_micro and contact angle. There was a significant negative association between the breakthrough time and inlet concentration of L2, and the relationship could be reliably predicted with a simple empirical formula. L2 adsorption also increased with decreasing bed temperature. Saturated rGOAs were readily regenerated by a brief heat-treatment at 100 °C. This study has demonstrated the potential of novel rGOA for applications using adsorbents to remove siloxanes from biogas.