Synthesis and application of a unified sorbent for simultaneous preconcentration and determination of trace metal pollutants in natural waters

摘要

A flat sheet sorbent with poly(hydroxamic acid) groups anchored on the microporous structure of poly(propylene) membrane was developed and applied for the preconcentration and determination of heavy elements from natural waters. The designing of the sorbent involved UV-irradiation induced graft polymerization of acrylamide using N,N'-methylene-bis-acrylamide (MBA) as the crosslinker on the poly(propylene) base followed by chemical modification of the grafted membrane to generate crosslinked poly(hydroxamic acid) (PHA) groups in its pores. The synthesized PHA-membrane was found to precon-centrate U, V, Cu, Cr, Fe and Pb quantitatively (95%) from aqueous samples over a wide pH range of 4-9. The sorbed trace elements were quantified by direct analysis of the membrane using Energy Dispersive X-ray Fluorescence (EDXRF). To test the applicability of the developed sorbent to real samples, interference effect of common matrix elements like Na, K, Ca and Mg on the uptake of the analytes at sub μg mL~(-1) level was studied. The PHA sorbent was found to be immune to interferences from Na, K and Mg up to 1000 μg mL~(-1) and Ca up to 100 μg mL~(-1) for an analyte concentration of 1 μg mL~(-1). The method detection limit for EDXRF measurement was 6-30 ng using a 2 cm × 2 cm sorbent.