One-pot synthesis of brewer's spent grain-supported superabsorbent polymer for highly efficient uranium adsorption from wastewater

Yi Su; Marco Wenzel; Silvia Paasch; Markus Seifert; Thomas Doert; Eike Brunner; Jan J Weigand

doi:10.1016/j.envres.2022.113333

One-pot synthesis of brewer's spent grain-supported superabsorbent polymer for highly efficient uranium adsorption from wastewater

Environ Res. 2022 Sep;212(Pt C):113333. doi: 10.1016/j.envres.2022.113333. Epub 2022 Apr 26.

Authors

Yi Su¹, Marco Wenzel¹, Silvia Paasch², Markus Seifert¹, Thomas Doert³, Eike Brunner², Jan J Weigand⁴

Affiliations

¹ Chair of Inorganic Molecular Chemistry, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, 01062, Dresden, Germany.
² Chair of Bioanalytical Chemistry, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, 01062, Dresden, Germany.
³ Chair of Inorganic Chemistry II, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, 01062, Dresden, Germany.
⁴ Chair of Inorganic Molecular Chemistry, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, 01062, Dresden, Germany. Electronic address: jan.weigand@tu-dresden.de.

PMID: 35483410
DOI: 10.1016/j.envres.2022.113333

Abstract

High-efficient and fast adsorption of uranium is important to reduce the hazards caused by the uranium contamination of water environment due to the increased human activities. Herein, brewer's spent grain (BSG)-supported superabsorbent polymers (SAP) with different cross-linking densities are prepared as cheap and eco-friendly adsorbents for the first time via one-pot swelling and graft polymerization. A 7 wt% NaOH solution is used to swell BSG before grafting and subsequently neutralize the acrylic acid to control the reaction rate without producing alkaline wastewater. Compared with the traditional methods, swelling improves the grafting density and the utilization of raw materials due to the increased disorder degree of the BSG fibers. This results in the grafting of abundant carboxyl and amide groups onto the BSG backbone, forming a strongly hydrophilic polymer network of the BSG-SAP. Compared with the reference polymers without BSG, BSG-SAP presents higher adsorption capacity and enhanced reusability. The highly cross-linked BSG-SAP (BSG-SAP-H) shows an outstanding adsorption capacity of U(VI) (1465 mg/g at pH₀ = 4.6), a fast adsorption rate (81% of equilibrium adsorption capacity in 15 min), and a high selectivity in the presence of competing ions. Adsorption mechanism studies reveal the involvement of amide groups, a bidentate binding structure between UO₂²⁺ and the carboxyl groups, and a cation exchange between Na⁺ and UO₂²⁺. More importantly, the adsorption capacity of BSG-SAP-H reaches 254.4 mg/g in the fixed-bed column experiment at a low initial concentration (c₀(U) = 30 mg/L) and keeps 80% of the adsorption capacity after four cycles, indicating a great potential for uranium removal from wastewater. This work shows a suitable approach to explore the untreated biomass to prepare SAP with enhanced adsorption performance via a general and low-cost strategy.

Keywords: Brewer's spent grain; Fixed-bed column; Reusable; Superabsorbent polymer; Uranium adsorption.

Publication types

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

MeSH terms

Adsorption
Amides / analysis
Amides / metabolism
Edible Grain / chemistry
Humans
Polymers / analysis
Uranium* / analysis
Wastewater* / analysis

Substances

Amides
Polymers
Waste Water
Uranium