A visão de futuros professores acerca do desenvolvimento de uma atividade de ensino de geometria utilizando caleidoscópios

Este artigo apresenta uma análise dos relatos de futuros professores que cursaram a disciplina Instrumentalização para o Ensino de Matemática V – Geometria sobre uma experiência de ensino utilizando caleidoscópios de dois e três espelhos. O objetivo foi analisar a visão de futuros professores acerca da experiência de ensino com caleidoscópios. Esta experiência foi realizada durante duas aulas de 50 minutos em uma turma de 9º ano de uma escola pública da cidade de Feira de Santana/BA. Participaram todos os professorandos da disciplina que, em duplas, trabalharam com os alunos organizados em grupos utilizando caleidoscópios de 2 e 3 espelhos. Relatos dos futuros professores destacaram que ficaram encantados com a participação de todos os alunos na atividade; consideraram uma atividade muito interessante, a qual cativou tanto os futuros professores quanto aos alunos; e que, na experiência de ensino, desajustes foram percebidos e relatados, mas que estes geraram reflexões sobre as tarefas e algumas dificuldades manifestadas pelos alunos. Considerando esses relatos e compreendendo o professor como um profissional que tem por tarefa ensinar, e a formação como forma/ação, pode-se concluir que a experiência de ensino foi prazerosa para alunos e professorandos, mostrando que os caleidoscópios são recursos promissores no ensino dos conceitos de geometria, com fácil aderência e implementação em aulas futuras

Activated carbon obtained from amazonian biomass tailings (acai seed): Modification, characterization, and use for removal of metal ions from water

Federal University of Pará. Graduate Program of Chemistry. Laboratory of Amazon Oils. Laboratory of Catalysis and Oilchemistry. Belém, PA, Brazil.Federal University of Amazonas. Department of Chemistry. Manaus, AM, Brazil.Federal University of Pará. Graduate Program of Chemistry. Laboratory of Amazon Oils. Laboratory of Catalysis and Oilchemistry. Belém, PA, Brazil / Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Federal University of Pará. Graduate Program of Chemistry. Laboratory of Amazon Oils. Laboratory of Catalysis and Oilchemistry. Belém, PA, Brazil.Federal University of Pará. Graduate Program of Chemistry. Laboratory of Amazon Oils. Laboratory of Catalysis and Oilchemistry. Belém, PA, BrazilFederal University of Pará. Graduate Program of Chemistry. Laboratory of Amazon Oils. Laboratory of Catalysis and Oilchemistry. Belém, PA, BrazilFederal University of Pará. Graduate Program of Chemistry. Laboratory of Amazon Oils. Laboratory of Catalysis and Oilchemistry. Belém, PA, BrazilMinistério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Federal University of Pará. Graduate Program of Chemistry. Laboratory of Amazon Oils. Laboratory of Catalysis and Oilchemistry. Belém, PA, BrazilAcai seed was used herein as an Amazon biomass waste for the synthesis of activated and modified carbon in order to find a possible use for the large volume of residues generated during the processing of this fruit and to add value to this residue. Activated carbon materials were used to remove Pb2+, Fe2+, and Mg2+ metal ions from water. The efficiency of removal of these ions by the acai seed activated carbon was compared with that by commercial activated carbon. Activated carbon materials were prepared by carbonization and chemical activation using two KOH impregnation ratios, namely 1:1 (ACK1) and 5:1 (ACK5), by mass. These samples were modified by treatment with nitric acid under microwave heating (ACK1-M) and (ACK5-M), respectively. The result of the elemental analysis indicated that this biomass has carbon and sulfur contents of 43.29% and 0.10% wt, respectively. The textural parameters showed that the obtained activated carbon samples presented high surface areas between 1462 and 2774 m2 g−1. Raman analysis revealed the different degrees of graphitization of the activated carbon materials. Boehm titration identified the presence of phenolic, carboxylic, and lactonic groups in samples that were confirmed by Fourier transform infrared spectroscopy. In the metal adsorption tests, ACK5-M showed better removal efficiency, reaching 86% removal for Pb2+, 69% for Fe2+, and 8% for Mg2+in 1 h of contact time; these results were superior to those obtained for commercial carbon. The results indicated that acai seed can be used for the production of activated carbon and can also be used for metal removal