J. O. F. Melo

Chemical recycling of cell phone Li-ion batteries: Application in environmental remediation.

This paper presents, for the first time, the recycling and use of spent Li-ion battery cathode tape as a catalyst in the degradation of an organic dye. In our proposal, two major environmental problems can be solved: the secure disposal of cell phone batteries and the treatment of effluents with potentially toxic organic dyes. The spent Li-ion battery cathode investigated in this paper corresponds to 29% of the mass of Li-ion batteries and is made up of 83% LiCoO2, 14.5% C and less than 2.5% Al, Al2O3 and Co3O4. The use of spent Li-ion battery cathode tape increased the degradation velocity constant of methylene blue in the absence of light by about 200 times in relation to pure H2O2. This increase can be explained by a reduction in the activation energy from 83 kJ mol(-1) to 26 kJ mol(-1). The mechanism of degradation promoted by LiCoO2 is probably related to the generation of superoxide radical (O2(-)). The rupture of the aromatic rings of methylene blue was analyzed by ESI-MS.

Application of Spent Li-Ion Batteries Cathode in Methylene Blue Dye Discoloration

This paper aims to present the mechanism study of methylene blue (MB) discoloration using spent Li-ion battery cathode tape and hydrogen peroxide. The recycled cathode used in this work is composed of 72% of LiCoO2, 18% of carbon, and 10% of Al. The value found for surface area is 8.9 m2/g and the ZCP value occurs in pH = 2.95. Different from what is proposed in the literature, the most likely mechanism of methylene blue discoloration is the oxidation/delitiation of LiCoO2 and the reduction of H2O2 forming . Thus, in this paper, an important and promising alternative for discoloration of textile industry dyes using spent Li-ion battery cathode is presented.

Electrochemical recycling of Zn from spent Zn-MnO 2 batteries

Scientific scene has increased the environmental studies about battery recycling. Following this tendency, this paper aims to study the electrochemical recycling of zinc from Zn–MnO2 batteries. The electrodeposition of zinc was performed on carbon steel. In pH = 4.6, the zinc electrodeposition occurs via chemistry and electrochemistry steps. For determinant step reaction, the order was (∂lnip/lnCH+)≈0 and (∂lnip/lnCZn+2)≈1.

Seasonal Water Evaluation of Main Lagoons in the City of Sete Lagoas-MG

The city of Sete Lagoas is set in a karst system and has the presence of lagoons, which, in some cases, are interconnected to the regime of free aquifers. The objective of this work was to evaluate the water quality of the lagoons of Boa Vista, Brejao, Catarina, Cercadinho, Jose Felix, Mucuri and Paulino, situated in the city, over a period of 12 months, through physical and chemical analyzes. Conductivity, pH, turbidity, chloride, calcium, magnesium, sodium and potassium parameters were determined. The results showed that the Paulino and Mucuri lagoons presented higher sodium and conductivity index and, since they are located in the central area of Sete Lagoas, may have been influenced by anthropic actions. In addition to these, the Brejao lagoon presented high values of potassium, which may be related to the agricultural activity developed in its environment. In this sense, the study of the water quality is of fundamental importance so that the county can develop specific measures to improve the quality of the waters of each pond and improve evaluating the basic sanitation of the city.

MINERALS AND PHENOLIC COMPOUNDS OF CAGAITA FRUITS AT DIFFERENT MATURATION STAGES (Eugenia dysenterica)

O Cerrado e o maior bioma no Estado de Minas Gerais-Brasil, representado uma biodiversidade de especies frutiferas, destacando a cagaiteira (Eugenia dysenterica). Frutos de cagaiteira sao considerados uma opcao importante para fruticultura, por apresentarem fonte de compostos fenolicos com propriedades antioxidantes e teores de minerais que podem contribuir com efeitos beneficos a saude. Neste estudo, caracterizaram-se os compostos fenolicos por cromatografia liquida de alta eficiencia e avaliaram-se os teores de minerais presentes em frutos de cagaiteira em estadio de maturacao maduros e verdes. Em relacao aos minerais, frutos maduros e verdes destacam-se por serem ricos em potassio. Os frutos verdes sao ricos em boro, enquanto os frutos maduros sao fonte desse mineral. Nos frutos de cagaiteira maduros e verdes, foram identificados os compostos fenolicos: os acidos galico, cafeico, vanilico, p-cumarico, siringico, ferulico e salicilico, epicatequina, quercetina e rutina, sendo os maiores teores dos compostos os acidos cafeico, p-cumarico, siringico e ferulico, epicatequina e rutina identificados nos frutos verdes, enquanto para frutos maduros o destaque foi para os acidos galico, vanilico esalicilico e quercetina. Assim, frutos de cagaita podem apresentar grande potencial para aplicacoes alimentares, terapeuticas e medicinais, trazendo beneficios a saude.

An Appraisal on the Source-to-Sink Relationship in Plants: an Application of Desorption Electrospray Ionization Mass Spectrometry Imaging

Amino acids/ureides and carbohydrates are the main nutrients for the plants growth. These metabolites are continuously translocated through the plant organism via well-known transportation mechanisms. The well-established source-to-sink relationship involves the transfer of these nutrients from mature (source) to young (sink) leaves. Desorption electrospray ionization mass spectrometry imaging (DESI-MSI) is used herein to determine the spatial distribution of amino acids/ureides and carbohydrates in the imprintings of Mentha × piperita L. leaves at three distinct maturation stages: young, expanding, and mature. Hence, chemical images of some typical carbohydrates (glucose, sucrose, sorbitol/mannitol) and free amino acids/ureides (phenylalanine, leucine, histidine, aspartate, asparagine, tyrosine, glutamate, allantoic acid) clearly point to a source-tosink relationship, as the young leaves are the final destination for some of these key metabolites. These results therefore reveal the high potential of DESI-MSI to investigate biochemical processes in plants, a still underexplored area.