Preparation of Nitrogen-Doped Glucose-Derived Activated Carbon and Its Application for the Efficient Removal of Phosphate Ions from Aqueous Solution

In this study, aiming to address the issue of phosphate contamination in water, a novel activated carbon adsorbent with excellent adsorption performance for phosphate ions was designed and synthesized through a nitrogen-doped surface modi-fication method. The adsorption experiment results revealed that the sample obtained after the second activation at 600 degree celsius (MeUrGlu-6.0Z0.5-2nd) exhibited a high adsorption capacity of up to 0.42 mmol/g for phosphate ions. The surface modification method using nitrogen-doping significantly enhanced the adsorption capacity of the adsorbent for phosphate anions. The surface characteristics of the sample were analyzed by Brunauer-Emmett-Teller method, elemental analysis, and X-ray photoelectron spectroscopy (XPS). The characterization results indicated that the increase in adsorption capacity primarily attributed to the successful introduction of quaternary nitrogen (N-Q) onto the activated carbon surface. Additionally, the adsorbent demonstrated high adsorption capacity for phosphate ions in acidic solution (pH <4.5), overcoming the limitation of commercial anion exchange resin HP555 which cannot be used effectively in acidic environment. The Langmuir isotherm model was found to accurately describe the adsorption process which is a monolayer adsorption. Finally, the regenerability of MeUrGlu-6.0Z0.5-2nd and the recovery of phosphate ions were investigated in a continuous flow adsorption mode.