Solvent-Free Synthesis of MgO-Modified Biochars for Phosphorus Removal from Wastewater
Siyu Xu, De Li, Haixin Guo, Haodong Lu, Mo Qiu, Jirui Yang, Feng Shen
Abstract
Adsorption is an efficient technology for removing phosphorus from wastewater to control eutrophication. In this work, MgO-modified biochars were synthesized by a solvent-free ball milling method and used to remove phosphorus. The MgO-modified biochars had specific surface areas 20.50–212.65 m2 g−1 and pore volume 0.024–0.567 cm3 g−1. The as-prepared 2MgO/BC-450-0.5 had phosphorus adsorption capacities of 171.54 mg g−1 at 25 °C and could remove 100% of phosphorus from livestock wastewater containing 39.51 mg L−1 phosphorus. The kinetic and isotherms studied show that the pseudo-second-order model (R2 = 0.999) and Langmuir models (R2 = 0.982) could describe the adoption process well. The thermodynamic analysis indicated that the adsorption of phosphorus on the MgO-modified biochars adsorbent was spontaneous and endothermic. The effect of pH, FTIR spectra and XPS spectra studies indicated that the phosphorus adsorption includes a protonation process, electrostatic attraction and precipitation process. This study provides a new strategy for biochar modification via a facile mechanochemical method.