Biosynthesis of a Functional Silica-Based Biohybrid Material with High Pb(II) Capture Ability

Abstract

Lead contamination of water sources poses a serious risk to ecosystems and human health. We developed a silica-based biosorbent incorporating poly-tannic acid to efficiently remove Pb(II) ions from water. The laccase was immobilized on silica bead surfaces via an enzymatic process facilitated by a protective layer of silicatein. This approach prevents enzyme leaching, ensuring immobilized laccase stability under harsh conditions. Polytannic acid was formed on the bead surface through laccase-mediated polymerization. Successful laccase immobilization was confirmed by scanning electron microscopy, revealing a porous structure on the bead surface. The biosorbent demonstrated high laccase loading and retained 48% of its activity under alkaline conditions. Further confirmation of successful tannic acid polymerization was obtained through SEM-EDS indicated changes in surface composition, and FTIR spectra revealed alterations in functional groups. Practical application of the silicatein-treated biosorbent revealed its effectiveness in removing Pb(II) ions from aqueous solutions, with a maximum adsorption capacity of 52.4 mg/g, a threefold increase compared to a biosorbent without silicatein. The adsorption isotherm for Pb(II) ions fits the Langmuir model, indicating that the silicatein-treated biosorbent optimally fits a monolayer adsorption model. This biohybrid material offers promising advantages over conventional methods, including improved adsorption capacity and stability, making it an environmentally friendly solution for heavy metal water source bioremediation.