Dual-stabilized branched hollow magnetic adsorbent with salt resistance for boron separation in salt lakes

Salt lake brine, as a naturally enriched liquid boron resource, necessitates a green and efficient adsorbent for its separation. Given the complex composition of brine components, there is an urgent need to develop an adsorbent formulation characterized by easy recyclability, structural stability, and strong anti-interference capability. In this study, hollow magnetic branched polyol microspheres (HMBPM) were constructed under mild conditions via in-situ precipitation, followed by the loading of amino hyperbranched polymers and polyols through a straightforward method. Compared with the unbranched counterpart HMPM (11.21 mg g⁻¹), HMBPM exhibits a significantly higher boron adsorption capacity (44.97 mg g⁻¹), which also outperforms other boron-specific magnetic adsorbents reported in the literature. X-ray photoelectron spectroscopy (XPS) analysis reveals that the cis-diol groups on the adsorbent surface form stable C-O-B bonds with borate anions, confirming the effective boron-fixation capability of the synthesized adsorbent. Notably, HMBPM demonstrates excellent anti-interference performance against coexisting ions such as Na⁺, K⁺, Mg²⁺, and Li⁺. When applied to actual brine samples, it achieves a borate ions separation efficiency of 114.732 mg g⁻¹. Both the anti-interference property and the extraction efficiency in real samples validate the potential of the proposed adsorbent for the effective separation of boric acid from salt lake brine.