Synthesis, characterization, and application of modified silica in the removal and preconcentration of lead ions from natural river water

This paper describes the synthesis, modification, and application of modified silica for the removal of lead ions from aqueous medium. The modification reaction provided a reduction in surface are from 737 to 399 m(2) g(-1), which was attributed to the 4-amine-2-mercaptopyrimidine molecule attachment onto its surface. The characterization through FTIR spectra demonstrated bands at 3347 cm(-1) assigned to N-H stretching vibrations and the absence of thiol bands at 2600 e 2547 cm(-1) at Si-mod spectrum is an indicative that the attachment occurred via SH groups. The linearization of adsorption isotherm data through the modified Langmuir equation resulted in a maximum adsorption capacity of 2.9 mu mol g(-1). The material was applied in a continuous flow system in the preconcentration of water samples from Parana River and the results were in agreement with metal concentration determined directly through atomic absorption spectrometry with graphite furnace. The method validation was performed through analysis of water standard reference material (1643e), which also presented a 7.2-fold enrichment factor.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Electrochemical study of o-toluidine blue impregnated in mesoporous silica channels

This paper reports an electrochemical study of ordered mesoporous silica impregnated with a cationic dye (o-toluidine blue), prepared with a non-ionic surfactant as the structure-directing agent. O-toluidine blue was chosen because of its utility as an electron transfer mediator (redox catalyst). O-toluidine blue impregnated mesoporous silica was characterized by nitrogen sorption porosimetry, small angle X-ray scattering, infrared spectroscopy, scanning electron microscopy and cyclic voltammetry using chemically modified carbon paste electrodes. Results indicate that the dye is located within the ordered mesopores of micron-sized silica spheres.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

4-amine-2-mercaptopyrimidine modified silica gel applied in Cd(II) and Pb(II) extraction from an aqueous medium

This paper discusses silica surface modification by a process involving a two-step reaction: anchoring of a silylating agent, followed by an attachment of a 4-amino-2-mercaptopyrimidine molecule. The modified material (Si-BP) was successfully characterized by the FTIR spectra, which revealed amine absorption bands, and through (13)C and (29)Si NMR spectra, which confirm the proposed structure of the modified silica (Si-BP). Si-BP was used to extract cadmium and lead from an aqueous medium at 298 K. The Si-BP kinetics towards metal ions was very fast, i.e., about 10 minutes, although extraction was significantly impaired at pH 3. The series of adsorption isotherms were adjusted to a modified Langmuir equation and the maximum extraction capacity was 0.193 and 0.387 mmol g(-1) for Cd(II) and Pb(II), respectively. An analysis of the empty set values lead to the inference that the resulting metal ligand complex was type 1:1.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

4-amine-2-mercaptopyrimidine modified silica gel applied in Cd(II) and Pb(II) extraction from an aqueous medium

This paper discusses silica surface modification by a process involving a two-step reaction: anchoring of a silylating agent, followed by an attachment of a 4-amino-2-mercaptopyrimidine molecule. The modified material (Si-BP) was successfully characterized by the FTIR spectra, which revealed amine absorption bands, and through (13)C and (29)Si NMR spectra, which confirm the proposed structure of the modified silica (Si-BP). Si-BP was used to extract cadmium and lead from an aqueous medium at 298 K. The Si-BP kinetics towards metal ions was very fast, i.e., about 10 minutes, although extraction was significantly impaired at pH 3. The series of adsorption isotherms were adjusted to a modified Langmuir equation and the maximum extraction capacity was 0.193 and 0.387 mmol g(-1) for Cd(II) and Pb(II), respectively. An analysis of the empty set values lead to the inference that the resulting metal ligand complex was type 1:1.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Sediment grain size distribution and heavy metals determination in a dam on the Parana River at Ilha Solteira, Brazil

This paper reports on a preliminary evaluation of the grain size distribution of cadmium, lead and copper in sediment from Catarina Beach, Ilha Solteira, in the state of São Paulo, Brazil. Surface sediments were fractionated with <63 mu m nylon sieves and subjected to three digestion procedures: the proposed open digestion, the standard USEPA-3050B and closed digestion in a Teflon tube. The metals were determined by atomic absorption spectrometry. The results of the three procedures showed no significant differences. The 309 mg Kg(1) concentration of copper found at the P3 sampling point exceeded the PEL (probable effect level) value of 197 mg Kg(1). which represents an environmental hazard to aquatic organisms. The sediments organic matter content determined by the loss on ignition was 6.8, 1.7 and 0.6% in the P3, P1 and P2 samples, respectively. The distribution of metal concentrations in sieved sediment followed the order P3 < P2 < P1 thereby suggesting an interaction with organic matter.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

EVALUATION of HEAVY METAL AVAILABILITY IN CONTAMINATED SEDIMENTS FROM THE ILHA SOLTEIRA HYDROELECTRIC DAM on THE PARANA RIVER AT ILHA SOLTEIRA, SP, BRAZIL

This paper investigates the availability of cadmium, copper and lead in surface sediment from a contaminated area in the Ilha Solteira hydroelectric dam. The surface sediment (first 5 cm) was fractionated with plastic sieves and the < 63 mu m fraction was subjected to a sequential extraction procedure. The pseudototal concentration of metal species, 306.4, 0.092 and 10.1 mg Kg(-1) for Cu(II), Cd(II) and Pb(II), respectively, was determined by aqua regia digestion, followed by atomic absorption spectrometry. The results obtained from the sequential extraction procedure indicated that about 10% of Cu(II) and Cd(II) were present in the easily mobilized fraction. All the metal species under investigation showed a predominance of reducible fraction, i.e., more than 50%, while the metal content in the third fraction (oxidizable) varied from 12 to 35%. The metal recovery rate was good, with no significant difference between the amount of metals recovered through the extractant steps and the extractable metals (aqua regia). The results indicate that the sediment poses a risk to aquatic organisms, since a slight change in physical chemical parameters such as pH can mobilize this species to the water column.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Banana Peel Applied to the Solid Phase Extraction of Copper and Lead from River Water: Preconcentration of Metal Ions with a Fruit Waste

This article reports on an investigation into the ability of minced banana peel to extract lead and copper ions from water and the parameters involved in this process. The kinetics of copper and lead uptake reached equilibrium in 10 min and the extraction of metals ions was favorable above pH 3. The medium was characterized by FTIR, which showed absorption bands of carboxylic and amine groups at 1730 and 889 cm(1), respectively. The adsorption isotherm fitted by Langmuir's model showed maximum adsorption capacities of 0.33 and 0.20 mmol g(-1) (or 20.97 and 41.44 mg g(-1)) for Cu(II) and Pb(II), respectively. Minced banana peel was applied in the preconcentration system and showed approximately 20-fold enrichment factor and the column was I reused for 11 cycles without loss in the percentage of recovery. The proposed method was applied in the determination of Cu(II) and Pb(II) in a sample of raw river water and was validated by comparison with a standard reference material.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Avaliação sazonal de alguns parâmetros indicadores da qualidade de água no reservatório da usina hidrelétrica de Ilha Solteira-SP, Brasil

The present work reports on a evaluation of some water quality indicator parameters from Catarina and Marina beach, located at Ilha Solteira town, SP, Brazil. The dissolved oxygen (DO), conductivity and temperature measures were performed on-site through the use of portable equipments and the measures of other parameters such as chlorine (Cl- ) and pH were performed on the laboratory. These parameters were monitored from october/2007 to october 2008 in order to investigate the seasonal influence on the water quality. According to the results the parameters investigated are above critical levels except the DO, which attained 16 mg L-1 in october/2008. The present investigation showed that all parameters are in acceptable levels despite the anthropic influence.O presente trabalho apresenta o resultado da avaliação de alguns parâmetros indicadores da qualidade de água nas praias Catarina e Marina, localizadas no município de Ilha Solteira-SP, Brasil. As medidas de oxigênio dissolvido (OD), condutividade e temperatura foram efetuadas on-site através de equipamentos portáteis e as medidas dos outros parâmetros estudados, cloreto (Cl- ) e pH, foram efetuadas no laboratório. Estes parâmetros foram estudados durante o período de outubro/2007 a outubro/2008 para avaliar a influência sazonal na qualidade da água. De acordo com os resultados os valores dos parâmetros encontram-se abaixo do valor máximo permitido, exceto a concentração de oxigênio dissolvido no período de outubro/2008, a qual atingiu 16 mg L-1. A presente investigação mostra que apesar de todos os parâmetros se encontrarem em níveis aceitáveis algumas variações podem ser atribuídas a influencia antrópica.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Concentration of Cu(II) and Cd(II) from natural river water by Adsorption on a Modified Silica Surface

A high surface area silica gel (737 ± m2 g-1) was synthesized modified through a two-step reaction with a 4-amino-2-mercaptopyrimidine ligand and applied to Cu(II) and Cd(II) adsorption from an aqueous medium. The modified material was characterized by FTIR, which showed that attachment of the molecule occurred via thiol groups at 2547 and 2600 cm-1, and by elemental analysis that indicated the presence of 0.0102 mmol of ligand. The data from adsorption experiments were adjusted to a modified Langmuir equation and the maximum adsorption capacity was 6.6 and 3.8 μmol g-1 for Cu(II) and Cd(II), respectively. After adjusting several parameters, the material was applied in the preconcentration of natural river water using a continuous flow system before and after sample mineralization, and the results showed a 10-fold enrichment factor. The proposed method was validated through preconcentration and analysis of certified standard reference material (1643e), whose results were in agreement with the values provided by the manufacturer

Zinc and lead content and availability in Brazilian soil contaminated with residue of a secondary smelting lead recycling plant

The sequential extraction procedure of Zinc and lead performed in a Brazilian soil showed that it presents high pollution potential once over 90% of total lead is present in fractions where the metals can be easily mobilized. The fraction contents are as follow: F1 = 174 and 15 mg kg-1; F2 = 3155 and 9.7 mg kg -1; F3 = 99 and 1.6 mg kg -1; Residual fraction = 38 and 5.5 mg kg -1 for lead and zinc, respectively. The comparison with non contaminated soil only Pb 2+ concentration is above its intervention reference concentration, 900 mg kg -1