Preparation of poly(methacrylic acid) grafted on SiO 2 -NH 2 /PSF composite membranes for amlodipine removal

Firstly, the SiO2 microspheres were prepared by Stӧber method, and then modified by 3-Aminopropyltrimethoxysilane (KH-540) to introduce –NH2 onto the microspheres. Then, SiO2-NH2 microspheres were mixed into polysulfone casting solution, and SiO2-NH2/PSF composite membrane was prepared by the phase conversion method. On this basis, the functional adsorbent SiO2-NH2/PSF-g-PMAA was prepared by grafting polymerization of methacrylic acid (MAA) as a functional monomer using –NH2/S2O82− surface initiation system. The samples were characterized by Fourier infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), the Brunauer–Emmett–Teller (BET) and weighing method. The adsorption properties of amlodipine (ADP) by functional adsorbents were investigated, and the adsorption mechanism was further studied. The results show that the adsorption reaches equilibrium at 180 min, and the adsorption kinetics can be well fitted by the pseudo-second-order model. The adsorption capacity of SiO2-NH2/PSF-g-PMAA for amlodipine in methanol with 1.4 mg/mL at 15 °C is 137 mg/g. The adsorption ability increases with the decrease of ionic strength and temperature via the hydrogen bond and ionic interactions, and the adsorption of ADP by SiO2-NH2/PSF-g-PMAA is consistent with the D-R adsorption isotherm model. Thermodynamic parameters imply that adsorption is a spontaneous and exothermic process.