Preparation of metal oxide-loaded nickel foam adsorbents modified by biochar for the removal of cationic dyes from wastewater

In this study, metal composite oxides grown on nickel foam were prepared, which were modified by dopamine and biochar to obtain cauliflower-shaped Co₂MnO₄/NF@PDA/BC adsorption material to adsorb cationic dyes from aqueous solutions. The maximum adsorption amounts q_max for methylene blue (MB), malachite green (MG), and crystal violet (CV) were 8.44, 41.03 and 3.39 mg g⁻¹, and the adsorption aligned with the Langmuir isothermal model as single molecular layer adsorption on a homogeneous surface. The adsorption experiments of dyes were conducted using lake water in the environment, and the adsorption rates of MB, MG, and CV were 91.4%, 94.8% and 85.1%, respectively. Meanwhile, the material has wide pH applicability (3–9), and good adsorption-desorption cycle performance. In addition, the synthesized adsorbent Co₂MnO₄/NF@PDA/BC and the control adsorbent were investigated and shown to have good adsorption capacity. In conclusion, the adsorbent materials synthesized in this work have some application prospects in dye wastewater adsorption.