Abstract
This research prepared magnetic nanoparticles (MNPs) surface modified with polyethyleneimine (PEI), demonstrated their use as adsorbent in gas and liquid phase. MNPs possess the characteristics of high surface area per volume and easy handling by external magnetic field. These novel properties are of great interest for researches from a wide range of disciplines. Both polar groups (amine) and apolar groups (ethylene) are present on the macromolecular chains of PEI, which enable MNPGAPEI to adsorb compounds like organic acids. PEI is a water-soluble polymeric amine and with many nitrogen atoms on the chains, which can produce very strong chelating action for inorganic cations. Besides, PEI is a cationic polyelectrtolyte in aqueous solutions, so there is a strong electrostatic interaction with negatively charged species like inorganic anions. The dual features of PEI permit MNPGAPEI as a universal adsorbent for both inorganic cations and anions. MNPGAPEI were demonstrated as adsorbents for carboxylic acids (analytes are acetic acid, propionic acid, butanoic acid, valeric acid and iso-valeric acid), inorganic cation (Pb), and anion (As). FT-IR and zeta potential analysis were used to verify the surface functional group. Results demonstrated that organic acids were effectively adsorbed onto 50-mg of MNPGAPEI packed in a glass sorbent tube. MNPGAPEI show better adsorption and desorption ability for organic acids than Tenax TA. Optimal desorption temperature and time was 225 ℃ and 6 min, respectively. MNPGAPEI show better selectivity toward organic acid than benzene-like compounds. In aqueous solution, MNPGAPEI possess dual affinity toward both caions (Pb) and anions (As) at pH 6. Desorption study of inorganic cation or anion shows good recoveries. It is expected that the MNPGAPEI could be used as a novel and functional solid adsorbent material for trapping carboxylic acids from atmosphere and inorganic cations and anions from aqueous sample.