Phosphonium-enhanced chitosan for Cr(VI) adsorption in wastewater treatment

Sebastian Sessarego; Simone C G Rodrigues; Ye Xiao; Qingye Lu; Josephine M Hill

doi:10.1016/j.carbpol.2019.02.003

Phosphonium-enhanced chitosan for Cr(VI) adsorption in wastewater treatment

Carbohydr Polym. 2019 May 1:211:249-256. doi: 10.1016/j.carbpol.2019.02.003. Epub 2019 Feb 1.

Authors

Sebastian Sessarego¹, Simone C G Rodrigues², Ye Xiao³, Qingye Lu⁴, Josephine M Hill⁵

Affiliations

¹ Department of Chemical and Petroleum Engineering, University of Calgary, 2500 University Drive N.W., Calgary, AB, T2N 1N4, Canada. Electronic address: ssessare@ucalgary.ca.
² IFPI - Federal Institute of Education, Science and Technology of Piaui., BR-402, Km 3, s/n Parnaiba-PI, 65215-000, Brazil. Electronic address: simonecristiane.gall@ucalgary.ca.
³ Department of Chemical and Petroleum Engineering, University of Calgary, 2500 University Drive N.W., Calgary, AB, T2N 1N4, Canada. Electronic address: ye.xiao@ucalgary.ca.
⁴ Department of Chemical and Petroleum Engineering, University of Calgary, 2500 University Drive N.W., Calgary, AB, T2N 1N4, Canada. Electronic address: qingye.lu@ucalgary.ca.
⁵ Department of Chemical and Petroleum Engineering, University of Calgary, 2500 University Drive N.W., Calgary, AB, T2N 1N4, Canada. Electronic address: jhill@ucalgary.ca.

PMID: 30824086
DOI: 10.1016/j.carbpol.2019.02.003

Abstract

Adsorption is a commonly used method for industrial wastewater treatment because of its low-cost, easy operation and high efficiency. In this work, chitosan was crosslinked and functionalized with a low-cost phosphonium salt, tetrakis(hydroxymethyl)phosphonium sulfate (THPS), to enhance its adsorption capacity for Cr(VI). The novel phosphonium-crosslinked chitosan (PCC) was characterized using elemental analysis, XRF, FTIR, NMR and SEM-EDX. At pH 6, PCC had a higher Langmuir equilibrium constant than the unmodified chitosan (0.19 ± 0.02 L mg^-1 versus 0.0044 ± 0.0005 L mg^-1) and PCC demonstrated higher adsorption capacity than chitosan at equilibrium Cr(VI) concentrations below 120 mg L^-1. Additionally, magnesium sulfate or magnesium chloride was shown to desorb Cr(VI) and recycle PCC. When treated with THPS, chitosan is activated for Cr(VI) adsorption at pH 6; therefore, PCC can be used in wastewater treatment over a wider pH range than chitosan.

Keywords: Adsorption; Chitosan; Chromium; Phosphonium; Wastewater.