Preconcentration and separation of iron, zinc, cadmium and mercury, from waste water using Nile blue a grafted polyurethane foam

The present work describes a novel method for the incorporation of Nile blue A into polyurethane foam matrix. This foam material was found to be very suitable for the extraction of metal ions from aqueous solutions. The characterization of Nile blue A grafted foam and the effect of halide concentration, pH, shaking time, extraction isotherm and capacity have been investigated. This foam material was found to be suitable for the separation and preconcentration of iron (III), zinc (II), cadmium (II) and mercury (II) from waste water. The extraction was accomplished in (15-20) minutes. Iron was separated from acid medium (2-4 M HCl), zinc from (3-5 M HCl), cadmium from (4-6 M HCl) as thiocyanate complexes and mercury was separated from (1-2 M HCl) as chloride.     

Preparation,characterization and applications of polyurethane foam functionalized with resorcinol for quantitative separation and determination of silver(I) and mercury(II) from tap and wastewater

A stable chelating resin matrix was prepared by covalently linking resorcinol with polyurethane foam matrix through a –N=N– group. Preconcentration and determination of trace Ag⁺ and Hg²⁺ ions from samples of different origin, using Res-PUF, were studied. Various conditions influencing the sorption of these metal ions onto Res-PUF were optimized. The kinetics of sorption of the Ag⁺ and Hg²⁺ by Res-PUF were found to be fast, reached equilibrium in few minutes (5–10?min) and followed a first-order rate equation with an overall rate constant k in 0.102 and 0.267/min, respectively. Study of the variation of the sorption of the tested metal ions with temperature yielded average values for ΔG, ΔH and ΔS of ?3.94, ?22.02 and ?58.37, respectively. The mean free sorption energy (E) computed from the Dubinin–Radushkevich (D–R) isotherm was found to be equal to 8.91 kJ/mol, which reflects the chelation sorption process. The capacities of the foam material were 0.15 and 0.07?mmol/g for Ag⁺ and Hg²⁺, respectively. Preconcentration factors of?>?50 were achieved (RSD?≈?5.99). The proposed preconcentration procedure was applied successfully to the determination of trace metal ions in natural and wastewater samples.     

Secondary ion yields produced by keV atomic and polyatomic ion impacts on a self-assembled monolayer surface

A suite of keV polyatomic or 'cluster' projectiles was used to bombard unoxidized and oxidized self-assembled monolayer surfaces. Negative secondary ion yields, collected at the limit of single ion impacts, were measured and compared for both molecular and fragment ions. In contrast to targets that are orders of magnitude thicker than the penetration range of the primary ions, secondary ion yields from polyatomic projectile impacts on self-assembled monolayers show little to no enhancement when compared with monatomic projectiles at the same velocity. This unusual trend is most likely due to the structural arrangement and bonding characteristics of the monolayer molecules with the Au(111). Copyright 1999 John Wiley & Sons, Ltd.     

Preparation of novel ion exchange polyurethane foam and its application for separation and determination of palladium in environmental samples

The new strong anion exchanger (PUFIX) from polyurethane foam was prepared by coupling of the primary amine of the foam matrix with ethyl iodide. PUFIX was characterized using different tools (IR spectra, elemental analysis, density and thermal analysis). The sorption properties of the new anion exchanger (PUFIX) and chromatographic behaviour for separation and determination of palladium(II) ions at low concentrations from aqueous iodide or thiocyanate media were investigated by a batch and dynamic processes. The maximum sorption of Pd(II) was in the pH range of 0.3–2. The kinetics of sorption of the Pd(II) by the PUFIX was found to be fast with average values of half-life of sorption (t_1/2) of 3.32 min. The variation of the sorption of Pd(II) with temperature gives average values of ΔH, ΔS, ΔG and ΔE to be −38.3 kJ mol⁻¹, −100.7 J K⁻¹ mol⁻¹, −8.3 and 11.8 kJ mol⁻¹, respectively. The sorption capacity of PUFIX was 1.69 mmol g⁻¹ for Pd(II), preconcentration factors of values ≈250 and the recovery 99–100% were achieved (R.S.D. ≈ 1.24%). The lower detection limit, 1.28 ng mL⁻¹ was evaluated using spectrophotometric method (R.S.D. ≈ 2.46%).