Simple detection of trace Pb2+ by enrichment on cerium phosphate membrane filter coupled with color signaling

A Pb2+ selective membrane filter was fabricated from the fibrous CeO(H2PO4)2·2H2O (CeP) crystals by blending with cellulose fiber. Enrichment of ppb level of Pb2+ was achieved simply by filtration of aqueous sample solution through the membrane filter. Pb2+ was strongly retained on the membrane filter by accommodation into the interlayer gallery of a CeP crystal. Visual detection of the enriched Pb2+ was achieved by subsequent color signaling as PbS deposit upon treatment of the membrane filter with 3% Na2S solution. The analytical procedure and sample treatment conditions were optimized with respect to pH of the sample solution, filtration rate and masking of interfering ions. Detection of 20 ppb of Pb2+ was not interfered by the presence of 1000-fold of Ca2+, Mg2+, and up to 100-fold of Fe3+and Cu2+ by masking with 1 × 10−3 mol dm−3 of iminodiacetic acid (IDA). Most anions including phosphate (20 000 times) did not interfere with the determination of Pb2+. The present simple method was applied to the determination of Pb2+ in real samples like mine valley water.