سید ناصر عزیزی

A new electrode based on carbon paste (CP) modified with Ag-doped SBA-16 mesoporous silica was used to determine H2O2 concentration in phosphate buffer solution (PBS). Mesoporous silica SBA-16 nanoparticles were synthesized hydrothermally under the acidic medium using SiO2/F127/BuOH/HCl/H2O gel. Pure SiO2 powder is prepared from inexpensive and environmentally friendly silica source of stem cane ash (SCA). The physico-chemical characteristics of the mesoporous silica SBA-16 such as surface area, pore size distribution, pore volume, chemical composition and crystallite size were studied using various techniques such as X-ray diffraction (XRD), scanning electronic microscopy (SEM), transmission electron microscopy (TEM), Brumauer–Emmett–Teller (BET) and FT-IR techniques. The sizes of mesoporous silica SBA-16 nanoparticles are in the range of 30–60 nm. The modified electrode was used to investigate the electrocatalytic reduction of H2O2 by cyclic voltammetry and amperometry. Cyclic voltammetry method indicates that the current intensity of H2O2 reduction on the surface of modified electrode is higher than that on nonmodified CPE. This sensor could detect H2O2 in two linear ranges of 20 M to 8 mM and 8 to 20 mM with a detection limit of 2.95 M at a signal-to-noise ratio of 3 and a response time of 2 s. Furthermore, this sensor exhibits good anti-interference property and selectivity. The Ag/SBA-16/CPE has good reproducibility and long term stability, and it was successfully applied for the determination of H2O2 in pharmaceutical sample: a hair dying cream.