Synthesis of bio-inspired magnetic composite functionalized-lanthanide from silk fibroin as an efficient phosphate sequestration

The conversion of biowaste into sophisticated materials was essential for sustainable water treatment. This study documented the transformation of silk fibroin, a renewable biopolymer, into a high-performance, magnetically separable adsorbent via a simple one-pot synthesis. A lanthanum-functionalized magnetic bio-hybrid (MSF-La) was created by co-incorporating La³⁺ ions and Fe₃O₄ nanoparticles into the silk fibroin matrix. It possesses widely distributed active sites and inherent magnetic separation properties, and we have added varying amounts of lanthanum to the silk fibroin polymeric matrix. An outstanding phosphate adsorption capacity of 167.86 milligrams of P per gram of La is demonstrated, surpassing the capacity of pure La(OH)2, which is 71.42 milligrams of P per gram of La. The adsorbent demonstrated considerable selectivity for phosphate, and its reusability is exceptional, maintaining 89% efficiency across eight consecutive cycles. Remarkably, La and Fe leached from MSF-La8.5 were consistently measured at 0.2 mg/L across a broad pH range, indicating outstanding structural stability. Mechanistic studies demonstrated that the adsorption process involves synergistic interactions of electrostatic attraction, ligand exchange, and surface precipitation. This study established a sustainable method for converting biowaste into advanced functional materials. Thus, completing the transition from biomass waste to wastewater treatment and purification applications.