Adsorption of Sr(II) from water by mercerized bacterial cellulose membrane modified with EDTA

The treatment of low-level radioactive wastewater is a critical and considerable challenge. Bacterial cellulose membrane (BCM) modified with ethylenediaminetetraacetic acid (EDTA) using (3-aminopropyl) triethoxysilane (APTES) as a crosslinker were used to remove Sr²⁺ in this work. SEM, XPS, and FTIR were used to characterize the morphology, structure, chemical shift, and functional groups of the as-prepared adsorbent. The synthesized BCM@APTES-EDTA presented a three-layer structure of membrane-net-membrane with nano-sized fibers (<100 nm). The adsorption of Sr²⁺ onto BCM@APTES-EDTA was investigated as a function of contact time and initial concentration of Sr²⁺. Results showed that the adsorption of Sr²⁺ followed the pseudo second-order kinetic model (R² = 0.999), and fitted well with the Langmuir isotherm model (R² = 0.996). The maximum adsorption capacity was calculated to be 44.86 mg g^-1, which was comparable to other adsorbents. Additionally, the mechanism of Sr²⁺ adsorbed by the as-prepared adsorbent was studied through FTIR and XPS analysis, which indicated that the tertiary amines and carboxylate from grafted EDTA participated in the adsorption of Sr²⁺.