Poly(ethylene glycol methacrylate phosphate-co-2-acrylamido-2-methyl-1-propane sulfonate) pore-filled substrates for heavy metal ions sorption

Abstract

Bi-functional membranes/sorbents have been prepared by anchoring cross-linked poly(ethylene glycol methacrylate phosphate-co-2-acrylamido-2-methyl-1-propane sulfonate) (poly(EGMP-co-AMPS)) in pores of the microporous substrates by in situ photo-polymerization. Thus prepared materials are found to sorb U(VI) from seawater (98%) as well as from 4molL−1 HNO3 (80%). The poly(EGMP-co-AMPS) (1:1) could be anchored 170wt.% in grafted fibrous poly(propylene) membrane. This membrane is found to take up 200wt.% water, and has U(VI) loading capacity 2.9×10−3molg−1. The metal ions sorption kinetics has been found to be dependent not only on physical structure of host substrate but also on proportion of EGMP and AMPS in the guest component poly(EGMP-co-AMPS). The competitive sorption of U(VI) and Fe(III) has suggested that the selectivity of poly(EGMP-co-AMPS) towards U(VI) decreases with increase of AMPS proportion in the polymer, and selectivity is completely lost when AMPS units are more than 4 times with respect to EGMP (phosphate bearing units). However, the kinetics of U(VI) sorption increases with increase of AMPS units in poly(EGMP-co-AMPS). U(VI) sorption efficiency is not affected by the presence of 10,000times excess of moles of representative ions like Ca, Cu and V in solution. However, Fe(III) compete with U(VI) for sorption in poly(EGMP-co-AMPS) anchored membrane. Desorptions of U(VI), Fe(III) and other ions from the membrane samples are found to be quantitative in equilibration with 0.5molL−1 Na2CO3, 0.2molL−1 EDTA, and 1molL−1 HCl, respectively.