Comportamento de zinco e manganês de pilhas alcalinas em uma coluna de solo

The aim of this study was to evaluate the behavior of Zn and Mn in a soil column. Two soil columns were sampled, and four opened alkaline batteries were placed at the top of one soil column. An acid-rainwater solution (HNO3 and H2SO4; pH 4) was percolated through the battery contaminated column during one year. The results showed that the leaching of alkaline batteries caused enrichment of 70 and 11 times in the Zn and Mn concentration of the topsoil, respectively. Additionally, leaching of electrolyte (KOH) from the batteries increased the soil pH in the contaminated column.

Recuperação de cádmio de baterias níquel-cádmio via extração seletiva com tributilfosfato (TBP)

This work describes a recovery process of cadmium from spent nickel-cadmium batteries by a new hydrometallurgical route based on the selective extraction in hydrochloric acid medium with tributylphosphate (TBP), alone or dissolved in kerosene. The best results were obtained when TBP concentration was at least 75 vol%. Nickel extraction was negligible under these conditions. It was isolated after processing the rafinate through an anionic ion-exchange column. Final wastes generated are basically sodium chloride solutions, with no turbidity, color or heavy metals present in significant amounts.

Processamento de pilhas Li/MnO2 usadas

This work presents two recycling processes for spent Li/MnO2 batteries. After removal of the solvent under vacuum the cathode + anode + electrolyte was submitted to one of the following procedures: (a) it was calcined (500 ºC, 5 h) and the calcined solid was submitted to solvent extraction with water in order to recover lithium salts. The residual solid was treated with sulfuric acid containing hydrogen peroxide. Manganese was recovered as sulfate; (b) the solid was treated with potassium hydrogeno sulfate (500 ºC, 5 h). The solid was dissolved in water and the resulting solution was added dropwise to sodium hydroxide. Manganese was recovered as dioxide. The residual solution was treated with potassium fluoride in order to precipitate lithium fluoride.

Recuperação de cobalto e de lítio de baterias íon-lítio usadas

The "active mass" (cathode + anode + electrolyte) of spent Li-ion batteries was submitted to one of the following procedures: (a) it was calcined (500 ºC) and submitted to extraction with water to recover lithium salts. The residual solid was treated with sulfuric acid containing hydrogen peroxide. Cobalt was recovered as sulfate; (b) the "active mass" was treated with potassium hydrogen sulfate (500 ºC) and dissolved in water. Cobalt was precipitated together with copper after addition of sodium hydroxide. Lithium was partially recovered as lithium fluoride. Co-processing of other battery components (aluminum and copper foils) affected negatively the behavior of the recovery procedures. Previous segregation of battery components is essential for an efficient and economical processing of the "active mass".

Pilhas alcalinas: um dispositivo útil para o ensino de Química

This paper presents the alkaline battery (MnO2/Zn) as a useful device in the teaching of chemistry. The preparation of the battery, the materials used in the preparation of the MnO2 electrode, the mechanism of energy storage and the parameters often used in the understanding of general batteries are discussed in detail. In addition, a schedule and a questionnaire that can be applied in an experimental class have been developed, which allow the assembly of an alkaline battery, its discharge using a galvanostatic or a load-resistance procedure, and the elaboration of a report based on the main text. This experimental class has been offered in the chemistry course of FFCLRP.

Reaproveitamento de óxidos de manganês de pilhas descartadas para eletrocatálise da reação de redução de oxigênio em meio básico

The oxygen reduction reaction was studied in alkaline media using manganese oxides obtained from spent batteries as electrocatalysts. Three processes were used to recover manganese oxides from spent batteries. The particles obtained were in the range from 8 to 11 nm. The electrochemical experiments indicated a good electrocatalytic activity toward oxygen reduction using the different samples and showing approximately a direct transference of 4 electrons during the process. Even though all the processes were efficient, the best result was observed for the prepared sample using reactants of low cost.

Desenvolvimento de conjunto membrana-eletrodos para célula a combustível de metanol direto passiva

Direct methanol fuel cells (DMFCs) without external pumps or other ancillary devices for fuel and oxidant supply are known as passive DMFCs and are potential candidates to replace lithium-ion batteries in powering portable electronic devices. This paper presents the results obtained from a membrane electrode assembly (MEA) specifically designed for passive DMFCs. Appropriated electrocatalysts were prepared and the effect of their loadings was investigated. Two types of gas diffusion layers (GDL) were also tested. The influence of the methanol concentration was analyzed in each case. The best MEA performance presented a maximum power density of 11.94 mW cm-2.

Eletrodos modificados por hidróxido de níquel: um estudo de revisão sobre suas propriedades estruturais e eletroquímicas visando suas aplicações em eletrocatálise, eletrocromismo e baterias secundárias

The present review paper describes the main features of nickel hydroxide modified electrodes covering its structural and electrochemical behavior and the newest advances promoted by nanostructured architectures. Important aspects such as synthetic procedures and characterization techniques such as X-Ray diffraction, Raman and Infrared spectroscopy, Electronic Microscopy and many others are detailed herein. The most important aspect concerning nickel hydroxide is related to its great versatility covering different fields in electrochemical-based devices such as batteries, electrocatalytic systems and electrochromic electrodes, the fundamental issues of these devices are also commented. Finally, some of the newest advances achieved in each field by the incorporation of nanomaterials will be shown.

Eletrodos positivos tubulares para baterias chumbo ácidas produzidas com material ativo nanométrico

Conventional stationary lead acid batteries positive tubular plates have a specific capacity of about 120 Ah/kg. This value represents an active material utilization coefficient of 50%. The production of these plates includes some initial processes to generate the active PbO2 from a precursor material. In the present work it will be presented a proper and novel methodology to assemble tubular plates directely with nanometric powder of PbO2 particles. The utilization coefficient of these plates was about 80%, and they were able to endure more than 130 severe duty cycles. This high utilization coefficient is a higly desirable feature for electric vehicles batteries.

Série histórica da composição química de pilhas alcalinas e zinco-carbono fabricadas entre 1991 e 2009

Mn, Zn, Fe, Cd, Pb and Hg were determined in Zn-C and alkaline batteries manufactured along almost 20 years. After samples disassembly the electroactive components were treated with aqua regia in bath ice for 24 h. Metals were analyzed by ICP-OES. Zn and Mn amounts did not vary significantly. Fe amount decreased, specially after 2000. Hg, Cd and Pb amounts dramatically decreased along time, being virtually absent in alkaline batteries manufactured after 2005. Pb still remains in Zn-C samples. Scanning electron microscopy of batteries manufactured in 1997 and 1998 showed the presence of Bi, In and Cr in the plastic/paper anode-cathode separator.

A gestão do conhecimento aplicada à reciclagem de componentes automotivos através do tratamento das informações contidas em documentos de patentes

This article evaluates the technologies adopted for recycling and reuse of automobile components, through the analysis of patents documents. The automobile batteries recycling is the main topic, followed by the automatic disassembly of vehicles, tires recycling and polyurethane recycling. None document approached recycling of steel and aluminum or ceramics products. The reduced number of technologies for the recycling of the polymeric compounds (including polyurethane) indicates that a bigger number of research and inventions must be elaborated in the next years, aiming at to the reduction of costs of processes and adequacy to the more restricted environmental legislation.

Simulação do intemperismo natural de pilhas zinco-carbono e alcalinas

Spent alkaline and Zn-C batteries were placed in seawater, rainwater or landfill leachate at room temperature for up 30 days in order to simulate natural weathering. After the experiments pH and electrical conductivity of the liquid were measured. The precipitate formed and the filtrate were submitted to metal analysis by ICP-OES. Seawater is the most corrosive medium, followed by landfill leachate. Pb, Cd and Hg were mainly in the filtrate. Fe, Mn and Zn were generally dominant in the precipitate. Na and K account for the electrical conductivity and are good indicators of the corrosion stage of the batteries.

Remoção de íons Pb2+ de solução de bateria automotiva por caulinita modificada com óxido de manganês

Nine absorbents were prepared using a mixture of Amazonian kaolinite and MnO2 at three temperatures (600, 700 and 900 ºC) in order to retain Pb2+ ions contained in the battery solutions. The batch experiments carried out with the batteries used water for 3 h and the kinetic isotherm was fitted with the pseudo-second order Lagergren equation. Findings show that synthesized adsorbents AD4, AD5 and AD7 performed well in reducing the Pb2+ ion content from 0.36 to 0.00 mg g-1. The better performance for removing the Pb2+ ions occurred for adsorbents synthesized in the temperature range from 600 to 700 ºC.

Método hidrometalúrgico para reciclagem de metais terras raras, cobalto, níquel, ferro e manganês de eletrodos negativos de baterias exauridas de Ni-MH de telefone celular

A hydrometallurgical method for the recovery of rare earth metals, cobalt, nickel, iron, and manganese from the negative electrodes of spent Ni - MH mobile phone batteries was developed. The rare earth compounds were obtained by chemical precipitation at pH 1.5, with sodium cerium sulfate (NaCe(SO4)2.H2O) and lanthanum sulfate (La2(SO4)3.H2O) as the major recovered components. Iron was recovered as Fe(OH)3 and FeO. Manganese was obtained as Mn3O4.The recovered Ni(OH)2 and Co(OH)2 were subsequently used to synthesize LiCoO2, LiNiO2 and CoO, for use as cathodes in ion-Li batteries. The anodes and recycled materials were characterized by analytical techniques.

Avaliação da lixiviação do cádmio e níquel provenientes da degradação de baterias níquel-cádmio em uma coluna de solo

Spent nickel-cadmium (Ni-Cd) batteries and salts of nickel and cadmium were placed in two different columns of soil for a period of two years. A leaching solution was passed through them at ambient temperature in this period. The behavior of metals in each column was then evaluated. Under the conditions of the experiment, cadmium and nickel demonstrated the potential to contaminate and affect the natural cycles of soil. The disposal of Ni-Cd batteries directly to the soil also increased the concentration of nickel (349 mg kg-1) and cadmium (2890 mg kg-1), sometimes exceeding the intervention values defined in CONAMA resolution 420/09.