In the present work, an Egyptian bentonitic clay sample has been structurally characterized using different techniques such as XRD, IR, SEM, and EDX analyses then evaluated as a sorbent for heavy metal ions removal. The characterization results showed that the clay sample is in the bentonite form with montmorillonite and kaolinite as mixed-clay minerals. The specific surface area (SSA) and cation exchange capacity (CEC) were determined using methylene blue test and they were found to be 367 m²/g and of 85 meq/100 g, respectively. The applicability of this clay sample for Cd (II) and Zn (II) removal from aqueous media was tested using batch procedures. Experimental parameters affecting the removal process were analyzed to get optimum conditions for the process. The experimental kinetic data were fitted very well to pseudo-second order with very high correlation coefficients. The Freundlich model appeared to correlate the adsorption data much better than Langmuir model with maximum adsorption capacities of 8.2 and 9.45 mg/g for Cd²⁺ and Zn²⁺, respectively. Successful application of the studied adsorbent for the removal of Cd²⁺ and Zn²⁺ ions from natural water samples greatly supports its potential for practical application.

The present work describes a rapid, cost-effective analytical procedure for the determination of lead and cadmium in environmental samples by off-line preconcentration with polyurethane foam (PUF) functionalised with acetylacetone by covalent coupling through the–N=N–group. The optimum pH ranges for quantitative uptake were 5–7, 6–7 for lead and cadmium, respectively. The kinetics of metal uptake by the new foam was found to be fast, reaching equilibrium in a few minutes. Metal ions were sorbed in the minicolumn, eluted with acid solutions and determined by flame atomic absorption spectrometer (FAAS). Under the optimum conditions, the preconcentration factors obtained were 288 for Cd and 224 for Pb. The limits of detection of the proposed procedure were 0.09 and 0.07 µg L⁻¹ for Pb and Cd, respectively. The relative standard deviation (RSD) was less than 10%. The accuracy of the method was estimated by using environmental samples that were spiked with Cd and Pb ions. The capacity of the acetylacetone bonded PUF (AA-BPUF) sorbent at optimum conditions has been found to be 4.5, 6.9 µmol g⁻¹ of sorbent for Pb and Cd, respectively.

In the present paper, an off-line preconcentration procedure for the determination of cadmium and lead by flame atomic absorption spectrometry (FAAS) is proposed. Polyurethane foam (PUF) functionalized with o-aminophenol (o-AP) followed by Pyrazolone (Pyr) packed in a minicolumn was used as a sorbent material. The metals were retained on the modified PUF, from which it could be eluted and effectively preconcentrated. The detection limits were 0.072 and 0.016 μg L⁻¹ for Pb and Cd respectively. Enrichment factors were 250 and 319 for lead and cadmium respectively. The procedure has been applied successfully to metal determination in water samples, fish liver and reference material.

A new solid — phase extraction sorbent was developed based on stepwise anchoring of two ligand molecules for the determination of copper, zinc, lead and cadmium in drinking water by flame AAS. Amberlite XAD-2 functionalized with 4′-(2-hydroxyphenylazo)-3′-methyl-1′-phenyl-2′-pyrazolin-5′-one (HPAPyr) was utilized for preconcentration/separation of these elements. The sorbent was prepared by two successive azo coupling reactions. First, 2-aminophenol was anchored to the amino groups in the resin resulted from nitration followed by reduction. Then, the resulted 2-aminophenol functionalized resin was further diazotized and coupled to the pyrazolone compound and the final product HPAPyr-XAD-2 was characterized by IR and elemental analysis. The optimum pH range for sorption, shaking time, exchange capacity, sample flow rate, preconcentration factor and interference from co-existing ions were investigated. All metal ions were quantitatively desorbed from the resin by 4.5 mol L⁻¹ nitric acid solution. The sorbent provides limit of detection within the range 0.9–3.3 µg L⁻¹ and concentration factor up to 250. The procedure was validated by analysis of certified material NIST-SRM 1577b. Application to drinking water showed satisfactory results with relative standard deviation RSD ≤ 8.5%.