Preparation of polypropylene chelating fibers by quenching pretreatment and suspension grafting and their Pb2+ adsorption ability

Abstract

To prepare polypropylene (PP) melt-blown fibers with Pb 2 + adsorption ability in water, high-crystalline PP was first pretreated by quenching and then grafted with acrylic acid (AA) by the suspension-grafting method to prepare PP grafted with AA (PP-g-AA). Finally, the chelating fiber, PP-g-AA-DETA, was prepared by the amidation of PP-g-AA fiber, obtained by melt-blown spinning, with diethylenetriamine (DETA). In the quenching pretreatment, the effects of solvent amount on the crystallinity and specific surface area of PP were investigated. The main factors of suspension grafting affecting the PP-g-AA graft rate were investigated, and the melt flow rate (MFR) and water contact angle (WCA) of PP-g-AA were measured. The maximum Pb 2 + adsorption ability of the chelating fiber was determined. The results indicate that the quenching pretreatment increased the size of PP amorphous area and formed pores on the particle surface. The specific surface area of PP and its crystallinity increased simultaneously with increasing solvent amount. The graft rate of PP-g-AA first increased with increasing solvent amount and then deceased. The MFR decreased rapidly after the graft rate reached 13 %, and the WCA dropped from 102 o to 50 o . The adsorption behavior of the chelating fiber matched the Langmuir adsorption isotherm model and showed good selective Pb 2 + adsorption ability with Mg 2 +as competing ion. The maximum adsorption capacities of PP-g-AA and PP-g-AA-DETA fiber calculated by the Langmuir equation were 12.2 and 25.7 mg/g respectively.

Efficient approach to produce functional polypropylene via solvent assisted solid-phase free radical grafting of multi-monomers

“…However, due to the hydrophobic characteristic of PP, the type and amount of monomers are limited due to the solubility in water. At the same time, the mass transfer efficiency of monomer on polypropylene particles is also limited, resulting in low grafting efficiency [15][16][17]. Compared with the other grafting methods, the solid-phase grafting process boasts many advantages such as lower reaction temperature, freedom from the need for solvent recovery and simpler equipment requirement [18,19].…”