Cerium-based sorbent with 100% Ce(III) and high dispersion for enhanced phosphate removal from wastewater

Abstract

Under the double pressure of eutrophication and phosphorus deficiency, there is an urgent need to remove excess phosphate from wastewater efficiently. Preparing cerium-based materials with excellent application potential inevitably leads to Ce(III) oxidation to Ce(IV), which reduces the phosphate adsorption effect and restricts its development. To solve this problem, we introduced a protective agent and successfully synthesised cerium-modified activated carbon sorbent containing 100 % Ce(III) during the synthesis process. Compared with CeAC without a protecting agent, CeAC-A contained more Ce(III) (100 %) and exchange groups (–OH accounted for 82.76 %), achieving an adsorption capacity of up to 448.57 mg-P/g Ce, improving of 4.3 times. At the same time, the size of the cerium active component was reduced from the micron level to the nanometer level, and the mass transfer rate was significantly improved. In addition, with the enormous specific surface area and well-developed pore structure of activated carbon, it showed high dispersibility, with P/Ce molar ratio as high as 2.03, which is 1.1–4.8 times higher than other cerium-based adsorbents. Phosphate was removed primarily through electrostatic attraction and ligand exchange. In treating municipal wastewater with complex water quality, CeAC-A showed strong selectivity, a wide range of adaptability and easy repeat regeneration, making it a promising adsorbent for phosphate uptake from wastewater.