Synthesis, Characterization, and Utilization of Water Hyacinth (<i>Eichhornia crassipes</i>) Magnetic Biochar for Nitrate Removal from Simulated Wastewater

Abstract

The research centered on creating magnetic water hyacinth biochar (MWHB) by chemically co-precipitating Fe2+ and Fe3+ ions onto the initial biomass, which was pyrolyzed at 450°C for an hour. This MWHB was then utilized in a series of batch adsorption experiments to evaluate its effectiveness in removing nitrates from simulated wastewater. The investigation focused on understanding the impact of pH, amount of adsorbent used, and duration of contact on nitrate removal efficiency. These parameters were selected using a 2k+1 Full Factorial Design of Experiments (DOE). The data collected from the experiments underwent analysis in JMP® (SAS institute) using Pearson’s Correlation test, providing a comprehensive statistical analysis beyond utilizing the software's Prediction Profiler. The findings revealed that the quantity of adsorbent used significantly affected the nitrate removal efficiency of the magnetic biochar, demonstrating a correlation coefficient (r) of 0.8459. On the other hand, pH and contact time exhibited relatively weaker effects, obtaining correlation coefficients of-0.1943 and 0.2915, respectively. The DOE suggested the optimal conditions for nitrate removal to be at pH 3, utilizing 0.40 grams of adsorbent, and maintaining a contact time of 90 minutes, with a predicted nitrate removal efficiency of approximately 99.10%, while the actual removal efficiency stood at 97.31%. Additionally, Scanning Electron Microscopy (SEM) analysis was employed to examine the surface morphology of the MWHB before and after nitrate removal, aiding in understanding the factors contributing to the observed nitrate removal efficiency.