Removal of phosphate by a novel activated sewage sludge biochar: Equilibrium, kinetic and mechanism studies
Min Jiang, Yi Yang, Tingzhou Lei, Zhaolian Ye, Shouqiang Huang, Xiaofei Fu, Peng Liu, Hui Li
Abstract
In this study, a novel biochar adsorbent (Mg-SB) modified by magnesium oxide particles is synthesized via pyrolysis of activated sewage sludge. Its phosphate removal performance is explored in aqueous environment under various conditions. It is found that Mg-SB could effectively remove phosphate with the maximum capacity of 97,450 mg kg−1 PO43−. The values are favorable compared to other adsorbents in the literatures. The pH and ionic strength can obviously affect the adsorption of phosphate onto Mg-SB. The adsorption data are best fitted by the pseudo-first-order model and the Langmuir model. Characterization of adsorbents with SEM-EDS, XRD and FTIR showed magnesium oxide on Mg-SB surface was the main phosphate adsorption site. Furthermore, the high phosphate adsorption efficiency and bioavailability makes the P-load-Mg-SB possible to directly apply to agricultural fields as a slow release fertilizer to improve soil fertility or to restore the contaminate soil.