The solid phase extraction of some metal ions using palladium nanoparticles attached to silica gel chemically bonded by silica-bonded N-propylmorpholine as new sorbent prior to their determination by flame atomic absorption spectroscopy

Lead Remediation Using Smart Materials. A Review

The nanoparticles have been prepared and employed as excellent adsorbents for the sequestration of heavy metal ions and hazardous impurities from the aqueous media. The surface morphological, textural and structural properties of nanoparticles have been modified, which are capable and potentially useful for the remediation of metal ions. Several metals (oxides, doped, nanocomposites of Fe, Ti, Zn, SiO2, SiC, Mo, Co, Ni, Zr, Mn, Si, S, Al, Cu, Ce, graphene, CNTs) were reported an efficient adsorbents for the removal of lead (Pb) ions from aqueous media and polluted water. The present review focuses on different kinds of nanoparticles such as metal oxides, carbon based and host supported employed for removal of Pb ions under varying experimental conditions such as pH, temperature, contact time and concentrations. The preparation strategies, physicochemical properties and adsorption are also discussed. Based on studies, it was found that the smart materials are affective adsorbents for the purification of wastewater containing Pb ions and could possibly extended for the remediation of other heavy metal ions.

Selective Preconcentration of Gold from Ore Samples

A simple and selective method has been developed for preconcentration of gold in ore samples. The method is based on use of N, N-diethyl-N'-benzoylthiourea (DEBT) as selective chelating agent and Amberlite XAD-16 as solid sorbent. Sorption behavior of gold with DEBT impregnated resin under optimized conditions has been studied in batch process. The gold ion capacity of the impregnated resin is calculated as 33.48 mg g⁻¹ resin (0.17 mmol g⁻¹ resin). The selective preconcentration of metal was examined using gold chelates prepared in column process under optimized conditions: pH, flow rate, volume of sample solution, nature of eluent, flow rate, and volume of eluent. Under optimum conditions, gold ions at the concentration of 0.015 μg mL⁻¹ with a preconcentration factor of 6.7 have been determined by flame atomic absorption spectrometry (FAAS). The accuracy of the proposed method was validated by the analysis of a Cu-ore (semi-certified) supplied by CMC (Cyprus Mining Company, North Cyprus) and a certified reference material, Gold Ore (MA-1b Canmet-MMSL). Satisfactory results were obtained with a RSD of 7.6%. The highly selective proposed method does not require any interference elimination process.

Preparation and application of chlorpyrifos molecularly imprinted solid-phase microextraction probes for the residual determination of organophosphorous pesticides in fresh and dry foods

A solid-phase microextraction probe was prepared on the surface of a stainless-steel wire through molecular sol-gel imprinting technology using chlorpyrifos as a template molecule, tetraethoxysilane as a sol-gel precursor, and acrylamide and β-cyclodextrin as functional monomers. The polymer was characterized by infrared spectrometry and scanning electron microscopy. Moreover, the selectivity and the parameters including the type and volume of the extraction solvents, ionic strength, pH, temperature, extraction time, stirring speed, and desorption time affecting extraction performance were evaluated. Under the optimum solid-phase microextraction and gas chromatography conditions, the linear ranges were 0.25-25.0 μg/L for chlorpyrifos, quinalphos, triazophos, pirimiphos-methyl, and chlorpyrifos-methyl with the correlation coefficient above 0.99. The detection limits (S/N = 3) were in the range of 0.02-0.07 μg/L and the RSDs were <7.3%. The developed method was successfully used to determine the multi-residues of chlorpyrifos, quinalphos, triazophos, pirimiphos-methyl, and chlorpyrifos-methyl in green peppers and cinnamon with satisfactory recoveries.