RESUMO

Mercury is a metal present in the Earth's crust, but due to human contribution, its concentration can increase, causing environmental impacts to aquatic ecosystems, among others. The Reis Magos River Hydrographic Basin represents economic and socio-environmental importance for the state of Espírito Santo, Brazil. However, there are not many publications regarding the quality of water and sediments, so no data is reported concerning the total concentration of Hg. Thus, the present work aimed to evaluate the distribution of total Hg in water and sediments along this hydrographic basin. For a better inference, physicochemical parameters of the water were determined (temperature, pH, electrical conductivity, oxidation-reduction potential (ORP), turbidity, dissolved oxygen (DO), total dissolved solids (TDS), and salinity), and in the sediments, the contents of matter organic matter, pH, carbonates and granulometry. Mercury determination was performed by Thermodecomposition and Amalgamation Atomic Absorption Spectrometry (TDA AAS) with a DMA-80 spectrometer. The Hg determined in the water was lower than the limit of quantification, 0.14 µg∙L-1, which is lower than the maximum limits recommended by world reference environmental agencies. In the sediment samples, the Hg found were below 170 µg∙kg-1, values below which there is less possibility of an adverse effect on the biota. However, when the degree of anthropic contribution was evaluated using the Geoaccumulation index (IGeo), the contamination factor (CF), and the ecological risk potential index (EF), there was evidence of moderate pollution. Thus, this highlighted the need for monitoring the region since climatic variations and physical-chemical parameters influence the redistribution of Hg between the water/sediment interface.

Assuntos

Mercúrio , Metais Pesados , Poluentes Químicos da Água , Brasil , Ecossistema , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Humanos , Mercúrio/análise , Metais Pesados/análise , Oxigênio/análise , Rios/química , Água/análise , Poluentes Químicos da Água/análise

RESUMO

Spent Li-ion batteries (LIBs) despite being produced with valuable metals from non-renewable natural resources are considered hazardous solid wastes because they contain metals and organic solvents pollutants for the environment. Due to this, it becomes necessary to know the chemical composition of these spent batteries to assist in the proper disposal and/or recycling process. This study aimed to provide quantitative data regarding the chemical composition of the cathode active material (CAM) of eight different spent LIBs used in cell phones and propose relationship with their energy capacity, year of manufacture and brand. CAM powder was leached using an environmentally friendly process with citric acid (2.0 mol L-1) and H2O2 (0.25 mol L-1), and the metals concentrations were determined by inductively coupled plasma optical emission spectrometry (ICP OES). Co (43-67 wt%), Li (5.3-6.8 wt%), Mn (0.8-8.2 wt%), Ni (0.1-11.7 wt%) and Al (0.06-3.2 wt%) were present in higher concentrations, whereas Cr (0.0005-0.002 wt%), Cu (0.01-0.05 wt%), Mg (0.005-0.02 wt%), Ti (0.001-0.07 wt%), Ga (0.0009-0.03 wt%) and Zn (0.009-0.05 wt%) were present in lower concentrations. The result obtained showed a considerable variation between CAM elemental composition, which may be related to type of electrolyte, energy capacity and year of manufacture. Since this difference in chemical composition is not shown on product labels, this work using a green leaching process and a suitable analytical method may assist in the recycling processes and avoid the inappropriate disposal of the material.