Magnetic Biochar Prepared with Residue as Adsorbents for Congo Red Removal.

In this work, magnetic biochars (MBCs) were produced with the chemical coprecipitation method. The resulting materials were dried at 50 °C for 12 h and characterized via SEM-EDS, XRD, FT-IR, BET, TGA, and VSM techniques to evaluate their efficacy in removing Congo red (CR). The effects of solution pH, CR concentration, MBC1:1 mass, and a variety of ions on the adsorption performance were systematically examined. According to the experimental results, for 200 mL of 50 mg/L CR, the highest adsorption capacity of 20 mg MBC1:1 was 172.88 mg/g in a 2 h period at pH 7. Additionally, the pseudo-second-order (PSO) model-based kinetic analysis exhibited that the process of adsorption adhered to this model. Furthermore, the interaction between MBC1:1 and CR was best described by Langmuir multilayer adsorption, according to isotherm analysis. All of these theoretical and practical findings point to the great potential of MBC1:1 as adsorbents for the applications of wastewater treatment.