Evaluation of nitrate removal efficiency from aqueous solutions using modified biochar derived from coffee husk

Abstract

This study presents the fabrication and evaluation of the nitrate adsorption capacity of modified biochar derived from coffee husk. The coffee husks were initially pyrolyzed at 350 °C for 1 hour, then soaked in 1 M KOH solution for 24 hours, followed by a second pyrolysis step at 700 °C for 2 hours. The resulting biochar was characterized using FT-IR, BET, and SEM techniques, and its nitrate removal efficiency from aqueous solutions was investigated. The highest nitrate removal efficiency (82,38%) was achieved under the following conditions: pH 3, biochar dosage of 1,5 g/100 mL, nitrate concentration of 50 mg/L, and reaction time of 210 minutes. The pseudo-first-order kinetic model and the Langmuir isotherm model were applied to describe the adsorption behavior, showing good agreement with the experimental data.