Affiliation:
1. Industrial Chemistry Department Addis Ababa Science, and Technology University P.O.Box 1647 Addis Ababa Ethiopia
2. Nanotechnology Center of Excellence Addis Ababa Science, and Technology University P.O.Box 1647 Addis Ababa Ethiopia
Abstract
AbstractPhosphate removal/recovery is essential to maintain the quality of aquatic systems and ensure sustainable use of phosphorous. Herein Mg‐nano biochar (Mg/NBC) is prepared as an effective phosphate adsorbent through the valorization of spent coffee grounds into nanobiochar by hydrothermal acid digestion of its biochar resulting from a slow pyrolysis. Characterization of the adsorbent was done by SEM, FTIR, BET, and XRD. Mg/NBC showed a 12.84 % higher adsorption capacity than the unmodified nanobiochar. Adsorption studies confirmed that phosphate adsorption on Mg/NBC is favored in acidic conditions removing 95 % of the initial concentrations at pH 1. The Langmuir adsorption isotherm model is better fitted to the equilibrium data with a maximum adsorption capacity of 100 mg/g suggesting uniform monolayer adsorption. Phosphate adsorption on Mg/NBC was initially rapid and followed a pseudo‐second‐order kinetic with an equilibrium constant (K2) of 0.029 g/mg.min. Thermodynamic investigation at different temperatures revealed negative ΔG°, positive ΔH° and ΔS° values suggesting a spontaneous endothermic process involving the chemisorption of phosphate at the later stage of the adsorption. Further, the application of the prepared adsorbent in real wastewater resulted in 90 % phosphate removal suggesting the promising potential of the prepared adsorbent for practical use in phosphate removal/recovery.