Magnetic separation of phosphate contaminants from starch wastewater using magnetic seeding

Chunjie Du; Yuehua Hu; Haisheng Han; Wei Sun; Panpan Hou; Runqing Liu; Li Wang; Yue Yang; Ruohua Liu; Lei Sun; Tong Yue

doi:10.1016/j.scitotenv.2019.133723

Magnetic separation of phosphate contaminants from starch wastewater using magnetic seeding

Sci Total Environ. 2019 Dec 10:695:133723. doi: 10.1016/j.scitotenv.2019.133723. Epub 2019 Aug 3.

Authors

Chunjie Du¹, Yuehua Hu¹, Haisheng Han², Wei Sun³, Panpan Hou¹, Runqing Liu¹, Li Wang¹, Yue Yang¹, Ruohua Liu¹, Lei Sun¹, Tong Yue¹

Affiliations

¹ School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, Central South University, Changsha 410083, China.
² School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, Central South University, Changsha 410083, China. Electronic address: hanhai5086@csu.edu.cn.
³ School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China; Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, Central South University, Changsha 410083, China. Electronic address: sunmenghu@csu.edu.cn.

PMID: 31425986
DOI: 10.1016/j.scitotenv.2019.133723

Abstract

Traditional chemical precipitation of phosphates from wastewater is somewhat inefficient because it produces some ultrafine hydroxyapatite particles that are difficult to settle. In this study, magnetic seeds with a core-shell structure were prepared by sulfation roasting for magnetic flocculation of those fine particles. Zeta potential measurements show that the hydroxyapatite particles are positively charged at pH 10, whereas the magnetic seeds are negatively charged. The Derjaguin-Landau-Verwey-Overbeek calculation indicates that the van der Waals force between the magnetic seeds and hydroxyapatite particles is always attractive. Moreover, the electrostatic attraction also contributes to aggregation of the magnetic seeds and hydroxyapatite particles. Orthogonal experiments show that the main factor affecting the magnetic flocculation is the dosage of magnetic seeds, and polymeric ferric sulfate also plays an important role. Under the optimal magnetic flocculation experimental conditions, the turbidity of wastewater after magnetic separation was only 16.388 NTU, contributing to the removal of phosphate contaminants. Therefore, magnetic flocculation and magnetic separation may provide an alternative solution for efficient purification of phosphate-containing wastewater.

Keywords: DLVO theory; Magnetic flocculation; Phosphates; Purification; Suspended solids.