Abstract The aim of this study was to develop an adsorbent from coffee husk, residue from the coffee industry by different activation methods and to evaluate its application in the treatment of effluent containing synthetic Ponceau 4R dye. The activations were with phosphoric acid and zinc chloride, then the samples were characterized in terms of physical and chemical composition, structure and morphology, thermal behavior and kinetic and thermodynamic study. Regarding the characterization of the material, the activation with phosphoric acid showed porous morphology and a high surface area (429.7 m2 g-1) and with the kinetic study it was possible to obtain an equilibrium time of 60 min and dispersion according to Elovich kinetics (R2 = 0.96 and RMSE < 0.24). According to the experimental design, the adsorptive capacity can be evaluated with the significant result (qe = 19.87 mg g-1) under the conditions of 90 min of the adsorption process and at the concentration of 2 g L-1 of adsorbent. In relation to the equilibrium study the Langmuir model fit the data with coefficient of determination of R2 = 0.84. Finally, the Ponceau 4R dye adsorption process using coffee husks as an activated carbon was thermodynamically favorable through the negative Gibbs free energy and positive entropy (+0.022 kJ mol-1 K-1). Therefore, the use of coffee husk as activated carbon proved to be a favorable material for Ponceau 4R dye adsorption.

Abstract This work reports the study of the potential application of Zn/TiO2 catalysts, obtained by the sol-gel method, in processes of environmental decontamination through the reactions of photodegradation of textile dye, followed by electrospray mass spectrometry. The catalysts synthesis was performed according to a 2² factorial design with repetition at the central point. The characterization techniques used were: N2 adsorption measurements (BET method), scanning electron microscopy with energy dispersive X-ray (MEV/EDS), X-ray diffraction and point of zero charge (PZC). The photocatalytic tests were performed in batch in the presence of sunlight, and to evaluate the degradation kinetics study, a rapid direct injection electrospray mass spectrometry (DI-ESI-MS) method has been developed. By the photocatalytic tests, the calcination temperature of 400 °C has shown the best results of discoloration for the reactive Orange-122 dye (99.76%) in a reaction time of 2h. The discoloration kinetics were a pseudo-first order, and a statistical analysis was performed to investigate the effects of the variables and to optimize the conditions of discoloration to the dye. After the reactional time of 2 h, an ion of m/z 441.5 was detected by ESI-MS, indicating that the photocatalytic process was effective for the degradation of the dye to secondary compounds.

Foram utilizadas 800 larvas com 2 dias de idade com o objetivo de testar o uso de farelo de soja em rações para tilápias-do-nilo durante o período de reversão sexual (30 dias). O experimento foi conduzido segundo delineamento em blocos casualizados com quatro tratamentos e quatro repetições, no qual um tanque-rede com 50 larvas correspondeu a uma unidade experimental. Os tratamentos consistiram de rações isoprotéicas e isoenergéticas (38,6% de proteína digestível e 3.800 kcal/kg de energia digestível) com 0, 16, 34 ou 42% de farelo de soja. O aumento no nível de farelo de soja teve efeito linear positivo sobre os valores de peso e comprimento finais médios, mas não afetou a condição corporal e os índices de sobrevivência. Recomenda-se incluir o farelo de soja em níveis de até 42% na ração de tilápias-do-nilo na fase de reversão.

Eight hundred Nile tilapia larvae with two days old were used to evaluate the inclusion of soybean meal in diets fed Nile tilapia during the sex reversion period (30 days). The experiment was analyzed as a completely randomized blocks, with four treatments and four replications. A net tank with 50 larvae was considered an experimental unit. The treatments were formulated to be isoprotein and isonitrogenous (38.6% of digestible protein and 3,800 kcal/kg of digestible energy), with increasing levels of soybean meal inclusion 0, 16, 34 and 42%. Average final weight and length linearly increased as the dietary soybean meal levels increased. No treatment effect on survival and body condition was observed. It is recommend to include up to 42% of soybean meal in Nile tilapia diets in the sexual reversion phase.