Heavy metals are toxic elements that can accumulate in wastewater from various sources, such as industrial activities, mining, agriculture, and household products. They can pose serious health and environmental risks if they are not properly removed or treated before discharge. In this article, you will learn how to test wastewater for heavy metals using some common methods and equipment.
The first step to test wastewater for heavy metals is to collect representative samples from the source or the treatment plant. You need to use clean and suitable containers, such as glass or plastic bottles, and avoid metal caps or lids that can contaminate the samples. You also need to label the samples with the date, time, location, and other relevant information. Depending on the type of analysis you want to perform, you may need to preserve the samples by adding acid, refrigerating them, or filtering them to remove solids and organic matter.
Necessário: 01 - Identificar Fontes e Locais de Descarga: - Identificar as fontes de águas residuárias que contêm metais pesados, como processos industriais, atividades agrícolas, descargas urbanas, entre outros; - Mapear os locais de descarga para determinar os pontos de coleta das amostras; 02 - Sele??o dos SQI's (Metais Pesados de Interesse): - Identificar os metais pesados de interesse com base nas atividades e processos específicos da fonte de contamina??o; -Priorizar os metais pesados mais relevantes para a avalia??o da qualidade da água.
One of the most widely used methods to test wastewater for heavy metals is atomic absorption spectroscopy (AAS). This technique measures the amount of light that is absorbed by the atoms of a specific metal when they are vaporized in a flame or a furnace. The higher the concentration of the metal in the sample, the more light is absorbed. AAS can detect a variety of metals, such as lead, mercury, copper, zinc, and cadmium, with high sensitivity and accuracy. However, it requires expensive and sophisticated equipment, skilled operators, and careful calibration.
A Espectroscopia de Absor??o At?mica (EAA) é uma técnica analítica amplamente utilizada para a determina??o quantitativa de metais pesados em amostras de águas residuais. O processo envolve várias etapas, desde a prepara??o das amostras até a interpreta??o dos resultados.
Another method to test wastewater for heavy metals is to use colorimetric methods, which rely on the change of color of a solution when a metal reacts with a specific reagent. For example, you can use a test kit that contains a strip of paper or a plastic device that is coated with a reagent that changes color in the presence of a metal. You can then compare the color with a chart or a meter that indicates the concentration of the metal. Colorimetric methods are simple, quick, and inexpensive, but they are less sensitive and accurate than AAS, and they can be affected by interferences from other substances in the sample.
O método colorimétrico é uma técnica analítica amplamente utilizada para a determina??o de metais pesados em águas residuais. Ele se baseia na forma??o de complexos coloridos entre os metais pesados e reagentes específicos, cuja intensidade de cor é proporcional à concentra??o do metal na amostra.
A third method to test wastewater for heavy metals is to use electrochemical methods, which involve applying an electric current or a voltage to a sample and measuring the resulting electrical signal. The signal depends on the concentration of the metal and its ability to transfer electrons. Electrochemical methods can be divided into two categories: potentiometric methods, which measure the voltage difference between two electrodes; and amperometric methods, which measure the current that flows between two electrodes. Electrochemical methods can be sensitive, selective, and portable, but they also require calibration, maintenance, and quality control.
Os métodos eletroquímicos s?o técnicas analíticas que se baseiam na intera??o entre os metais presentes na amostra eletrolítica e um eletrodo, gerando correntes elétricas ou potenciais elétricos mensuráveis. Existem várias técnicas eletroquímicas utilizadas na análise de metais pesados em águas residuais
There are also other methods to test wastewater for heavy metals, such as X-ray fluorescence (XRF), inductively coupled plasma (ICP), and mass spectrometry (MS). These methods are based on the emission or detection of electromagnetic radiation by the metal atoms or ions. They can provide fast, accurate, and comprehensive results, but they are also expensive, complex, and require special sample preparation and handling.
Atomic fluorescence spectrometry Atomic fluorescence spectrometry is an emission spectrometry analysis method based on atomic radiation energy analysis. The characteristic emission light emitted by the excitation light source is used to irradiate the atomic vapor of a certain concentration of the element to be measured to produce atomic fluorescence. Under certain conditions, the relationship between the fluorescence intensity and the concentration of the element to be measured in the measured solution follows Lambert-Beer's law. Measuring the intensity of fluorescence can determine the content of the element in the sample to be tested.
Cromatografia de Troca I?nica (IC); Espectrometria de Absor??o At?mica com Forno de Grafite (GFAAS); Espectrometria de Massa com Plasma Indutivamente Acoplado (ICP-MS); Microscopia Eletr?nica de Varredura com EDS (EDS-SEM); Espectrometria de Emiss?o At?mica com Fonte de Arco Elétrico (AES);