Annelise Engel Gerbase

Collection and recycling of electronic scrap: A worldwide overview and comparison with the Brazilian situation

Recycling and the related issue of sustainable development are increasing in importance around the world. In Brazil, the new National Policy on Solid Wastes has prompted discussion on the future of electronic waste (e-waste). Over the last 10 years, different e-waste collection systems and recycling processes have been applied globally. This paper presents the systems used in different countries and compares the world situation to the current Brazilian reality. To establish a recycling process, it is necessary to organize efficient collection management. The main difficulty associated with the implementation of e-waste recycling processes in Brazil is the collection system, as its efficiency depends not only on the education and cooperation of the people but also on cooperation among industrial waste generators, distributors and the government. Over half a million waste pickers have been reported in Brazil and they are responsible for the success of metal scrap collection in the country. The country also has close to 2400 companies and cooperatives involved in recycling and scrap trading. On the other hand, the collection and recycling of e-waste is still incipient because e-wastes are not seen as valuable in the informal sector. The Brazilian challenge is therefore to organize a system of e-waste management including the informal sector without neglecting environmentally sound management principles.

PREPARATION, CHARACTERIZATION AND ELECTROCHEMICAL STUDIES OF 1,1'-BIS( DIPHENYLPHOSPHINO)FERROCENE (DPPF) DERIVATIVES. CRYSTAL STRUCTURE OF DPPFCO(NO) 2 SBF6

Abstract The neutral dppfFe(NO)2 (1), the novel cationic [dppfCo(NO)2][SbF6] (2), as well as the dppfFe(CO)3 (3) dppf = 1,1′-bis-(diphenylphosphino)ferrocene) complexes were prepared and characterized. The interaction between the two metallic centers through the dppf ligand was studied in the solid state by 57Fe Mossbauer spectroscopy and in solution by cyclic voltammetry. The Mossbauer parameters are compared with those of other dppfMLn, complexes. Electrochemical studies performed on these complexes show the great influence of the MLn moiety on the redox processes of the dppf iron center. The crystal structure of complex 2 was determined (C34H28CoF6FeN2O2P2Sb). The compound crystallizes in the triclinic, space group P 1 , a = 10.441(2), b = 10.755(2), c = 17.320(5) A , α = 104.10(2), β = 0.504(10), γ = 111.504(10)°, U = 1744.7(7) A 3 , Z = 2, R = 0.0765, wR2 = 0.1878 . In this complex, the cobalt atom is coordinated to two nitrosyl ligands and to phosphorus atoms of the dppf ligand, providing a distorted tetrahedral geometry.

Polymers oxidation with VO(acac)2 complex

Abstract The introduction of epoxy groups in the polymer backbone is one of the most promising methods of modifying polydienes. In this work the performance of the classical catalytic system VO(acac) 2 / tert -butylhydroperoxide was evaluated for the epoxidation of polydienes. The polymers investigated were a hydroxylated poly(butadiene), two polybutadienes with high and with low 1,4-content, a poly(isoprene), and a styrene–butadiene copolymer. The epoxidized polymers were characterized by IR, 1 H and 13 C NMR and GPC techniques. The vanadium system was active for the epoxidation reaction and the reactivity decreases in the order HTPB>PI>1,4-PB>1,2-PB∼SBR. The occurrence of secondary reactions to low extension could be detected by the presence of hydroxyl, carbonyl and alcohol signals in the spectra of epoxidized polymers. Incomplete mass recovery (70–90%) was observed probably due to the chain degradation or modification of the polymer polarity.

Reciclagem do lixo de informática: uma oportunidade para a química

Recycling and sustainable development are increasing in importance around the world. In Brazil, the new National Policy on Solid Wastes has prompted discussion on the future of electronic waste (e-waste). Brazil generates the greatest amount of e-waste among Latin American countries. Nevertheless complete recycling, including end processing of e-waste, does not occur in Brazil. This paper discusses the physical and chemical technologies currently used worldwide and in Brazil for printed circuit board recycling, with emphasis on metal recovery and plastic processing. The goal is to put in evidence the important role that chemistry can play in developing cheaper processes to recycle e-waste.

Very efficient epoxidation of 1,4-polybutadiene with the biphasic system methyltrioxorhenium (MTO)-CH2Cl2/H2O2

The biphasic system methyltrioxorhenium (MTO)-H2O2/CH2Cl2 was studied in the epoxidation of polybutadiene and the results showed that this system presents a high selectivity and the extension of epoxidation (10–50%) can be modulated by the amount of oxidant added, without significant change in the molecular weight of the polymer.

Gerenciamento dos resíduos da disciplina química inorgânica II do curso de química da Universidade Federal do Rio Grande do Sul

Beginning students in chemistry usually do not realize that wastes generated in their experimental classes constitute an environmental problem and that residues must be treated or disposed of in a suitable way. In this manuscript we describe the work that we have been doing in the inorganic chemistry course of the Federal University of Rio Grande do Sul with the objective of creating a critical consciousness in the students about the chemical wastes they generate. With this policy, students are required to take into account the nature of the residues they generate, how they can treat or segregate them, and how they can keep them in a suitable way for final destination, instead of simply throwing them away.

Antimicrobial activity of 1,4-naphthoquinones by metal complexation

O efeito da complexacao com metais sobre a atividade antimicrobiana de 1,4-naftoquinonas foi investigado. Complexos contendo niquel, cromo, ferro, cobre e cobalto da 5-amino-8-hidroxi-1,4-naftoquinona (2) e seus acil-derivados (3-8) foram sintetizados e caracterizados e sua atividade antimicrobiana foi avaliada. Dados de espectroscopia de infravermelho indicaram que as naftoquinonas coordenam os metais atraves dos atomos de oxigenio e nitrogenio para 2 e atraves de atomos de oxigenio, quando os ligantes sao os acil-derivados 3-8. Testes de sensibilidade antimicrobiana demonstraram que 2 e seus derivados foram efetivos na inibicao do crescimento de bacterias patogenicas como Staphylococcus aureus, Streptococcus uberis e Bacillus cereus, mas nao apresentaram efeito contra bacterias Gram-negativas. A complexacao de metais geralmente causou diminuicao da atividade biologica. O complexo de niquel de 2 foi o mais eficaz contra bacterias Gram-positivas, apresentando valores de MIC de, 375 a 1400 µg/mL. Os complexos metalicos podem ser ferramentas uteis para o estudo do mecanismo antimicrobiano de 1,4-naftoquinonas nestas bacterias.

Mössbauer and infrared study of the thermal decomposition of iron and nickel compounds impregnated in alumina

Abstract In this work, studies of Fe 3 (CO) 12 and a mixture of Fe 3 (CO) 12 and Ni (acac) 2 impregnated in Al 2 O 3 were undertaken using Mossbauer and i.r. spectroscopies. In freshly prepared samples, low oxidation species were shown to be present. After thermal decomposition, the data indicate the appearance of aluminum compounds of Fe II and Fe III plus superparamagnetic Fe III . No Fe° species were detected, even under H 2 atmosphere.

Investigação da cinética de cura por calorimetria diferencial exploratória (DSC) de resinas epóxi preparadas a partir de óleo de soja epoxidado com diferentes anidridos e aminas terciárias

In the present work, differential scanning calorimetry (DSC) was used to investigate the curing reaction kinetics of epoxy resins produced from reaction of epoxidized soybean oil (ESO) with cyclic anhydrides dodecenylsuccinic (DDS), maleic (MAL), phthalic (PA), succinic (SUC) and hexahydrophthalic (CH), in the presence of tertiary amines such as triethylamine (TEA), N,N-dimethylaniline (ARO) and 1,4-diazabicyclo [2,2,2] octane (DABCO). The heating rate, the nature and structure of anhydrides and amines were found to affect the curing reaction. The dynamic methods of Kissinger, Ozawa and Barrett were used to calculate the activation energy of the reactions where different anhydrides were used. DDS and maleic anhydrides were more reactive than the others. In studying the influence from the catalyst, we used the Barrets method to determine the activation energy of the reactions. The 1,4-diazabicyclo [2,2,2] octane amine (DABCO) was the most reactive, showing the lowest activation energy (Ea= 51 kJ.mol-1) and pre-exponential factor (ln A0 = 9 s-1).

Comparative Sites for Coordination of Naphthoquinones and its Derivatives: Studies on the Synthesis of a Series of 1,4-Naphthoquinone Derivatives and Their Ni(II) Complexes

Abstract New derivatives (5–8) of 5-amino-8-hydroxy-1,4-naphthoquinone (1) have been synthesized and characterized by IR, UV-Vis, 1H NMR, mass spectra and CNH. These new ligands and the 5-amino-8-hydroxy-l,4-naphthoquinone (1), the 5-amino-6-bromo-8-hydroxy-1,4-naphtho-quinone (2), the 5-acetylamino-8-hydroxy-1,4-naphthoquinone (3) and the 5-dodecanoylamino-8-hydroxy-1,4-naphthoquinone (4), were complexed with Ni(II) giving the chelates (1a–8a). The structure and site of coordination of these complexes are discussed in relation to their spectroscopic data and thermal analysis.