Preparation of a novel carboxylate-rich wheat straw through surface graft modification for efficient separation of Ce(III) from wastewater

Highlights: • A novel poly(methacrylic acid) brush-decorated wheat straw composite was prepared. • The preparation method can achieve evenly and efficient graft at mild conditions. • The outstanding adsorption ability of 298.56 mg·g⁻¹ for Ce³⁺ was achieved. • The adsorbent exhibited good reusability with a satisfactory desorption rate. The objective of this work is development of a high efficiency biomass adsorbent on the base of a carboxylate-rich wheat straw for separation and recovery of Ce³⁺ from wastewater. Surface-initiated atom-transfer radical polymerization (SI-ATRP) was adopted to prepare the material with uniform and well-defined polymethacrylic acid (PMAA) brushes grafted on wheat straw (WS) surface under mild conditions. The adsorption performance of the modified wheat straw (WS-g-PMAA) was then systematically investigated. Due to the presence of abundant and highly accessible carboxyl groups in the PMAA brushes, WS-g-PMAA demonstrated exceptional adsorption capacity of 298.56 mg·g⁻¹ for Ce³⁺, significantly higher than most reported bio-adsorbents. Moreover, the adsorption equilibrium could be achieved quickly (< 180 min). Full kinetic and thermodynamic investigations as well as isotherm analysis were also undertaken. In addition, the regeneration experiment indicated that the adsorbent has the advantages of good reutilization character and a stable desorption efficiency. The study suggests that the carboxylate-rich wheat straw composite is a promising adsorbent for recovery of REE ions from aqueous solution.