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This work proposes the use of agro-industrial wastes, specifically peanut hull (HP) and orange peel (OP), as adsorbents for dyes, such as Remazol Golden Yellow RNL-150% (RYG), Gray Reactive BF-2R (RG) and Reactive Turquoise Q-G125 (RT). Characterization by Brunauer-Emmett-Teller indicates that the adsorbents are mesoporous, with pHzpc values of 5.0 for HP and 4.0 for OP. Fourier transform-infrared spectroscopy identified carbonyl and sulphonic groups. The initial pH of the best-adsorbing solution of the three colours was 2.0. Increasing the concentration of the adsorbent promoted an increase in the percentage of removal until saturation of the adsorbent. In a factorial design, the largest value of q was obtained with 0.25 g of the adsorbent, with a particle size of < 0.4 mm and a stirring speed of 300 rpm. Such conditions were used in kinetic studies and studies of adsorption equilibrium. The evolution kinetics were rapid in the first few minutes, and after 180 min the system reached equilibrium. The kinetic model that best fit the experimental data to a 95% confidence level for the F test was the pseudo-second-order model for RYG/HP, RG/OP and RT/OP. There was no significant difference between the kinetic models as evaluated by the F test for RYG/OP, RG/HP and RT/HP. The experimental results indicated favourable dye adsorption characteristics for the adsorbents studied. The results of the F test showed that for RYG and RG, there was no significant difference between the two evaluated models. This study suggests that HP and OP are viable alternatives for the treatment of effluents containing RYG, RG and RT dyes.

This study proposes the use of activated charcoal made from Umba uba wood as an adsorbent for the removal of naphthenic acid in an aviation kerosene model mixture. The activated charcoal was characterised as mesoporous with a carbon graphite profile and presented pH pzc equal to 10.5. The best working conditions were obtained for activated charcoal levels of <0.09 mm and 300 r min À1. The system reached the equilibrium after 360 min, without significant statistical difference for the pseudo-first-and pseudo-second-order kinetic models. The Weber-Morris and Boyd models corroborated the conclusion that adsorption is not controlled only by the intraparticle diffusion step. For the equilibrium study, the adsorptive capacity obtained was of 1.1 g g À1 , with the Brunauer-Emmett-Teller model better correlating with the experimental data. Given the results obtained, the activated charcoal demonstrated to have a remarkable potential for removing naphthenic acid in an aviation kerosene model mixture.

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RESUMO A Biologia pode ser uma das disciplinas escolares mais interessantes ou mais enfadonhas para os estudantes, dependendo do modo como ela for abordada. Articulando aspectos do consenso construtivista com os eixos da Alfabetização Científica, este artigo pretende mostrar as potencialidades do ensino por investigação para o ensino de Biologia, de forma a torná-lo mais significativo aos estudantes. Sequências didáticas baseadas no ensino por investigação podem ampliar os objetivos do ensino de Biologia na perspectiva da Alfabetização Científica, permitindo situar os estudantes no centro do processo de ensino e aprendizagem de modo que desenvolvam compreensões sobre conceitos e teorias, sobre o processo de produção de conhecimento e sobre as relações entre ciência, tecnologia, sociedade e ambiente.

Neste estudo, apresentamos as concepções que estudantes de Ciências Biológicas expressam em escritos reflexivos sobre as possibilidades e desafios do Ensino de Ciências por Investigação (EnCI), após os primeiros contatos com essa abordagem em uma disciplina do curso de licenciatura. Conhecimentos, crenças e concepções dos professores influenciam sua prática profissional. Conhecer as concepções dos licenciandos sobre EnCI é importante para compreendermos o que pode inibi-los de adotar essa abordagem, trazendo implicações para os processos de formação docente. Foi realizada a análise de conteúdo de escritos reflexivos de 46 licenciandos. Os dados apontam que os licenciandos reconheceram satisfatoriamente as principais qualidades do EnCI relacionadas ao conhecimento pedagógico e ao conhecimento do tema. Os desafios citados relacionam-se principalmente ao conhecimento pedagógico. Foi possível identificar concepções limitantes ao uso do EnCI que se relacionam em parte à falta de experiência em ensino, esperada para esse estágio de formação e, em parte, a mitos culturais e tensões entre uma visão de ensino tradicional, centrada no professor, e uma visão de ensino centrada no estudante. Tornar as concepções explícitas e analisá-las profundamente junto aos professores em formação pode ser um passo inicial na desconstrução das concepções limitantes.

A B S T R A C TAdsorption of the reactive gray BF-2R dye from an aqueous solution using orange peel as the adsorbent was investigated by the batch method. Experiments characterizing the chemical and physical properties of the adsorbent found that orange peel is a microporous material with a pH zpc 3.9 and containing carboxylic and sulfonic groups. The greatest adsorption capacity was obtained using a 2 3 factorial design for 0.25 g of adsorbent, particle size < 0.419 mm and at 300 rpm. The pseudo-second-order model provided the best fit of the experimental data. The Weber-Morris model indicated that two or more mechanisms control the process. Statistical analysis of the equilibrium studies indicated that there was not a significant difference between the Langmuir and the Fritz-Schlunder models according to an F-test. The results showed that orange peel can remove the reactive gray BF-2R dye.

C.M.B.M. Barbosa), marta.duarte@ufpe.br (M.M.M.B. Duarte) A B S T R A C TBanana peel (BP) and green coconut mesocarp (GCM) were evaluated as adsorbents for the removal of the dyes reactive gray BF-2R (RG), reactive turquoise Q-G125 and remazol golden yellow RNL-150% (RGY). Adsorbents were classified as mesoporous materials, with the pHzpc of 5 for BP and 7 for GCM. The initial pH of the best-adsorbing solution of the dyes was 2.0. There was no significant difference between the kinetic models evaluated by the F test at a 95% level of confidence, except for the RGY/GCM system. The adsorption process is not merely a function of an intraparticle diffusion step. The Freundlich model was the best fit for RGY/GCM, and no significant difference was evident between the two models evaluated for the other systems by the F test. For RG/BP, the models did not fit the experimental data. The adsorbents evaluated may be useful for the treatment of effluents that contain dyes.