Avocado seed-derived activated carbon for mitigation of aqueous ammonium

• A novel acidic adsorbent was prepared from avocado seeds via methanesulfonic acid activation.
• The adsorbent was effective for ammonium uptake.
• Adsorption was influenced by pH, dosage, and initial adsorbate concentration.
• Adsorption was found to be favorable with a theoretical maximum capacity of 5.4 mg g−1 at 25 °C.

There is a significant interest in value-addition of agricultural residues. In the present research, a novel avocado seed-activated carbon prepared from methanesulfonic acid (denoted as AAC-MA) was systematically tested as an adsorbent for removal of ammonium for the first time. SEM characterization technique was employed to identify the structural and morphological properties of the prepared carbon. The effects of pH, adsorbent dosage, initial NH4+ concentrations, and contact time on ammonium removal from aqueous solution were also investigated. Moreover, different kinetic and isotherm models were fit to the experimental data to gain a better understanding of the efficiency and applicability of the adsorption system. The pseudo-second order kinetic model was found to best describe the ammonium adsorption. The equilibrium data were found to conform best to Langmuir isotherm model with a theoretical maximum adsorption capacity of 5.4 mg g−1 at 25 °C. The results clearly suggested that the novel avocado-derived can potentially mitigate ammonium from aqueous systems.