Recovery of phosphorus as soluble phosphates from aqueous solutions using chitosan hydrogel sorbents

Tomasz Jóźwiak; Agata Kowalkowska; Urszula Filipkowska; Joanna Struk-Sokołowska; Ludmila Bolozan; Luminita Gache; Marius Ilie

doi:10.1038/s41598-021-96416-2

Recovery of phosphorus as soluble phosphates from aqueous solutions using chitosan hydrogel sorbents

Sci Rep. 2021 Aug 18;11(1):16766. doi: 10.1038/s41598-021-96416-2.

Authors

Tomasz Jóźwiak¹, Agata Kowalkowska², Urszula Filipkowska², Joanna Struk-Sokołowska³, Ludmila Bolozan⁴, Luminita Gache⁴, Marius Ilie⁴

Affiliations

¹ Department of Environmental Engineering, University of Warmia and Mazury in Olsztyn, Warszawska St. 117a, 10-957, Olsztyn, Poland. tomasz.jozwiak@uwm.edu.pl.
² Department of Environmental Engineering, University of Warmia and Mazury in Olsztyn, Warszawska St. 117a, 10-957, Olsztyn, Poland.
³ Department of Environmental Engineering Technology, Bialystok University of Technology, Wiejska St. 45E, 15-351, Bialystok, Poland.
⁴ Faculty of Chemical Engineering and Environmental Protection, Gheorghe Asachi Technical University of Iaşi, Bulevardul Profesor Dimitrie Mangeron 67, 700050, Iaşi, Romania.

Abstract

This manuscript presents new method of phosphorus recovery from aqueous solutions in a convenient form of readily-soluble phosphates using chitosan hydrogels. Non-modified chitosan hydrogel granules (CHs) and chitosan hydrogel granules crosslinked with epichlorohydrin (CHs-ECH) served as orthophosphate ion carriers. The developed method was based on cyclic sorption/desorption of orthophosphates, with desorption performed in each cycle to the same solution (the concentrate). The concentrations of orthophosphates obtained in the concentrates depended on, i.a., sorbent type, sorption pH, source solution concentration, and desorption pH. Phosphorus concentrations in the concentrates were even 30 times higher than these in the source solutions. The maximum concentrate concentrations reached 332.0 mg P-PO₄/L for CHs and 971.6 mg P-PO₄/L for CHs-ECH. The experimental series with CHs-ECH were characterized by higher concentrations of the obtained concentrate, however the concentrates were also more contaminated with Cl^- and Na⁺ ions compared to series with CHs. The high content of chlorine and sodium ions in the concentrates was also favored by the low pH of sorption (pH < 4) and very high pH of desorption (pH > 12) in the cycles. After concentrate evaporation, phosphorus content in the sediment ranged from 17.81 to 19.83% for CHs and from 16.04 to 17.74% for CHs-ECH.

Publication types

Research Support, Non-U.S. Gov't