Biochar-alginate beads derived from argan nutshells for effective methylene blue removal: A sustainable approach to wastewater treatment

This study explores the use of biochar derived from Argan Nutshells as a core component in alginate beads for the removal of methylene blue (MB) from aqueous solutions. The characterization of BC/Alg composite was conducted using techniques like Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), and size distribution to assess its structural properties and confirm the strong interaction between both components. The adsorbent exhibited surface functional groups characteristic of both biochar and alginate, and SEM confirmed the spherical morphology of the beads. A response surface methodology (RSM) was used to optimize the adsorption process by evaluating the effects of key parameters including pH, temperature, adsorbent mass, and dye concentration. The results showed that the BC/Alg effectively removed 96.4 % of MB. The pseudo-second order (PSO) kinetic model best described the MB removal process (R2 = 0.9990), while the Langmuir isotherm model accurately represented the adsorption equilibrium (R2 = 0.96879). After four cycles of regeneration trials, BC/Alg retained 82 % MB removal efficiency, indicating high reusability and stability. The remarkable adsorption capability of BC/Alg showed that it may be employed as an economical and environmentally friendly adsorbent in aqueous solutions, strengthening the case for employing Argan nutshells for water treatment. •The preparation of an outstanding biochar adsorbent through the pyrolysis of Argan nutshells.•The biochar/alginate combination is eco-friendly and effective at removing 96.4 % of methylene blue.•Methylene blue removal was best fit by the PSO model, while the Langmuir explained isotherm models.•Excellent methylene blue desorption using an acidic solution and strong stability at reuse.