A dual-cycle regeneration to recover high-value and high-purity FePO4 from real wastewater for Li-battery application

Kaikai Zheng; Yan Wang; Li Xiang; Chou Huang; Haichuan Zhang; Ji Li

doi:10.1016/j.watres.2023.120300

A dual-cycle regeneration to recover high-value and high-purity FePO₄ from real wastewater for Li-battery application

Water Res. 2023 Aug 15:242:120300. doi: 10.1016/j.watres.2023.120300. Epub 2023 Jul 5.

Authors

Kaikai Zheng¹, Yan Wang¹, Li Xiang¹, Chou Huang¹, Haichuan Zhang², Ji Li³

Affiliations

¹ Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China.
² Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China. Electronic address: zhc20@jiangnan.edu.cn.
³ Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China; Jiangsu College of Water Treatment Technology and Material Collaborative Innovation Center, Suzhou 215009, China. Electronic address: liji@jiangnan.edu.cn.

PMID: 37441872
DOI: 10.1016/j.watres.2023.120300

Abstract

The recovery of high-purity and high-value FePO₄ raw materials from wastewater has great prospects in LiFePO₄ battery industry due to the huge demand for new energy vehicle. However, the conventional in-situ FePO₄ precipitation, as well as ex-situ PO₄^3- adsorption-alkali regeneration, was incapable of efficiently obtaining high-purity products. To solve these problems, a dual-cycle regeneration method of Fe-NH₂-polyacrylonitrile (PAN) adsorbent and H₂SO₄ desorbing solution was proposed to ex-situ FePO₄ recovery from wastewater for Li-battery application. Benefitted from coordination interaction and electrostatic attraction, the maximum PO₄^3- adsorption capacity of Fe-NH₂-PAN reached 73.1 ± 0.4 mg/g. The average PO₄^3- removal rate of continuous flow devices were 88.5% and 91.3% when treating low-P-concentration (0.22 mg/L) municipal wastewater (MW) and high-P-concentration (48.9 mg/L) slaughterhouse wastewater (SW) respectively. Furthermore, high-purity FePO₄ analyzed by XRD spectra was achieved from the desorption solution at pH ∼1.6, resulting in the ultrahigh P recovery efficiencies of 91.4 ± 3.2%-96.3 ± 2.5% for SW and 82.7 ± 3.5% for MW. Besides, the LiFePO₄/C electrodes made of recycled FePO₄ exhibited a better discharge capacity (37.3 - 55.8 mAh/g) than that of commercial FePO₄ agent (32.2 - 35.1 mAh/g) from 80 to 132 cycles, which showed the promising feasibility of recovering FePO₄ from wastewater for Li-battery application.

Keywords: Dual-cycle regeneration; FePO(4); Li-battery; Phosphate adsorption; Phosphorous recovery.

MeSH terms

Adsorption
Electrodes
Ions
Phosphates*
Wastewater*

Substances

Phosphates
Wastewater
Ions