The decommissioning of nuclear power plants produces radioactive wastewater containing hazardous radionuclides, among which strontium Sr90 poses serious environmental and health risks. Adsorption is an effective removal strategy, particularly when polymer mediated structural control is applied. In this study, millimeter sized mesoporous silica beads were fabricated via a polymer templated sol gel process using alginic acid as a biopolymer framework. Ca2+ induced gelation directed bead formation and mesopore development during silica condensation. The resulting TBOS based silica beads exhibited mesoporous structures with pore sizes of 7 to 8 nm and high surface areas exceeding 270 m2·g-1. Owing to polymer-controlled design, the beads showed a high Sr2+ adsorption capacity of 497.5 mg·g-1 and a removal efficiency of 95.8 %, demonstrating the effectiveness of biopolymer templating for polymer–inorganic hybrid adsorbents.