Equilibrium single and co-adsorption of nutrients from aqueous solution onto aluminium-modified biochar

The pristine biochars are negatively charged, hindering the adsorption of NO3− and PO43− in water. The current study developed a 2 M AlCl3 - modified biochar and elucidated the co-adsorption behaviour of these ions at the equilibrium condition. The adsorption of NO3− and PO43− onto the biochar modelled by Langmuir and Freundlich isotherms. The results demonstrate that the max adsorption capacity of NO3−, and PO43− in the solution containing one solute ion were 31.80 mg/g and 95.05 mg/g; in the mixed solution of two solute ions were 26.67 mg/g and 78.99 mg/g, respectively. This modified biochar was evidenced as an effective adsorbent to remove simultaneously NO3- and PO43- from aqueous solutions. Adsorption using this material is an appropriate method for eutrophication mitigation.