Recovery of Phosphorus from Aqueous Solution by Iron–Aluminum–Zirconium-Modified Anthracite: Performance and Mechanism
Xujing Guo, Qingfeng Cheng, Ting Zhou, Meng Xie, Jing He, Jinsong Guo, Yang Huang
Abstract
Adsorptive removal of phosphorus from wastewater is a good alternative to solve pollution problems, as well as provides the potential to recover phosphorus after the desorption process. The work herein reveals the development of novel Fe–Al–Zr-modified anthracite materials, which present a total adsorption capacity of 12.83 mg/g. The adsorption mechanism includes electrostatic forces, ligands exchange, and surface deposition. Micropores provide the major adsorption sites for phosphorus, and the amount of available adsorptive sites is a key factor in controlling the adsorption rate. Two-dimensional correlation spectroscopy coupled with Fourier transform infrared reveals that Fe, Al, and Zr ions that preferentially combine with the N–H of amine or amide(I) could competitively complex with phosphate in the initial 5 h of the adsorption stage, whereas metal ions presenting in the C–O group of alcohols, ethers, and esters on a microporous surface play a leading role in the time period of 5–12 h. The modified anthracites can be repeatedly used in four operation cycles until the adsorption rate decreases below 50%. Finally, phosphorus can be effectively and quickly recovered in the form of hydroxyapatite by adding CaCl2 (n(Ca)/n(P) = 2:1) under alkaline conditions. The methodological framework proposed in this work provides extensive possibilities for phosphorus resource utilization.