Corn Stalk Biomass as an Efficient Biosorbent for Aqueous Cobalt (II) Ions Removal

This study investigates the adsorption behavior of cobalt(II) ions from aqueous solutions using carbon synthesized from corn-stalk powder as a low-cost and eco-friendly adsorbent. The effects of key operational parameters adsorbent dosage, solution pH, contact time, and initial metal ion concentration were systematically examined to determine their influence on adsorption efficiency and capacity. Results revealed that cobalt(II) adsorption decreased with increasing adsorbent dosage, with a maximum adsorption capacity of 132.13 mg/g observed at a dosage of 0.1 g. The adsorption process was found to be pH-dependent, with the optimal removal recorded at pH 9.1, yielding a capacity of 129.63 mg/g. Contact time significantly influenced adsorption, as the capacity increased with time and peaked at 60 minutes (146.05 mg/g), beyond which equilibrium was attained. Additionally, increasing the initial concentration of cobalt(II) ions led to higher adsorption capacity, with the highest value (202.68 mg/g) observed at 250 mg/L. These findings suggest that corn-stalk-derived carbon is an effective and sustainable adsorbent for removing cobalt(II) ions, and optimizing operational conditions can significantly enhance its performance in water treatment applications.