Os principais atributos edáficos relacionados com a lixiviação de naftaleno nos solos consistem na granulometria, no teor de matéria orgânica e na composição mineralógica das frações silte e argila. Este trabalho objetivou determinar os valores da dispersão e do retardamento do naftaleno em amostras de solos coletadas nas proximidades de tanques de armazenamento de combustíveis localizados em Recife, PE. Os experimentos de lixiviação foram realizados em colunas contendo amostras deformadas e foram modelados usando a equação de convecção-dispersão, que foi ajustada aos dados experimentais com o emprego do software CXTFIT 2.0. Os resultados indicaram que solos arenosos oferecem menor resistência à lixiviação de naftaleno e que a presença de goethita, juntamente com a matéria orgânica, é possivelmente o principal fator responsável pelo retardamento do transporte desse composto no conjunto de amostras estudadas.

The main soil properties related to the leaching of naphthalene in soils are particle size, organic matter content and the mineralogical composition of silt and clay fractions. The aim of this study was to evaluate naphtalene reactive transfer in soil columns determinated by the dispersion and retardation of naphthalene in soil samples collected from the surroundings of fuel storage tanks in Recife, Brazil. Leaching experiments were carried out in columns containing disturbed soils and were modeled using the convection-dispersion equation, which was adjusted to the experimental data with the CXTFIT software 2.0. The results indicated that sandy soils offer less resistance to leaching of naphthalene and that the presence of goethite, together with organic matter appeared to be the main factors responsible for the retardation of naphtalene transport in the studied samples.

This work used green coconut mesocarp as a bioadsorbent to remove Reactive Gray BF-2R dye. A 2³ factorial design was used to evaluate the influence of the variables adsorbent mass, particle size and stirring speed on the adsorptive process. Kinetic and adsorption equilibrium studies were performed. Results showed that the kinetic equilibrium was reached after 150 min. Using the Langmuir model, a q max of 21.9 mg g-1 and k of 0.30 L g-1 was obtained. The mesocarp of coconut, a residue of agribusiness, proved to be an effective alternative technique for the removal of dye in this study.

Neste trabalho foi proposto um método de análise em fluxo por multicomutação para a determinação de amoxicilina em formulações farmacêuticas. O método proposto é baseado na reação de diazotização da o-nitroanilina com amoxicilina em meio alcalino, produzindo um composto amarelo que foi monitorado em 435 nm. As características do método foram: faixa linear de 25 até 400 mg L-1 de amoxicilina, limite de detecção de 5,1 mg L-1, frequência analítica de 50 determinações por hora e desvio padrão relativo inferior a 3,9% (n = 10) para uma amostra típica de 100 mg L-1 amoxicilina. Para verificar a exatidão do método, as amostras foram analisadas empregando um método independente e aplicando-se o teste-t pareado não houve diferença significativa no nível de confiança de 95%.

A multicommuted flow analysis method for the spectrophotometric determination of amoxicillin in pharmaceutical formulations is reported. The proposed method is based on the reaction of diazotised o-nitroaniline with amoxicillin in an alkaline medium, producing a yellow compound that was monitored at 435 nm. The main features of the method were: a linear relationship with amoxicillin concentration ranging from 25 to 400 mg L-1; a detection limit of 5.1 mg L-1; an analytical throughput of 50 determinations per hour; and a relative standard deviation lower than 3.9% for a typical amoxicillin sample with concentration of 100 mg L-1 (n = 10). To verify the accuracy of the method, samples were also analyzed employing an independent method, and applying the paired t-test to the results no significant difference at the 95% confidence level was observed.

The decomposition of detergent powder samples in a microwave oven and autoclave was evaluated. To establish the best experimental conditions a 2(5) factorial design was performed, varying the conditions in autoclave and microwave digestion and flow system parameters for the determination of phosphorus. The best composition was: 0.2 mL sulfuric acid; 500 W power and a 2 min time interval; 6 mmol L-1 of ascorbic acid and 16 mmol L-1 of molybdate to flow system. This factor levels use less reagents than the reference method. No statistically significant differences were found between the autoclave and microwave oven responses at the 95% confidence level.

Hidrocarbonetos policíclicos aromáticos (HPA) estão presentes no óleo diesel, sendo considerados perigosos devido à sua toxicidade. Neste estudo relatamos a degradação de 16 HPA em dois solos diferentes (S1 e S2) contaminados artificialmente com óleo diesel, usando processos foto-Fenton e pseudo-foto-Fenton. Planejamentos fatoriais foram usados para obter condições de tratamento mais eficientes e econômicas. Para a reação foto-Fenton, as condições mais favoráveis resultaram 94,6% e 95,6% de degradação dos HPA para os solos S1 e S2, respectivamente. O processo pseudo-foto-Fenton também apresentou um nível satisfatório de degradação, obtido em condições econômicas, com ferro endógeno, baixa concentração de peróxido, curto tempo de exposição à radiação e sem ajuste do pH do solo. Os resultados demonstram a eficiência do processo pseudo-foto-Fenton para tratar áreas contaminadas por HPA.

Polycyclic aromatic hydrocarbon (PAH) components of diesel fuel are considered hazardous, due to their toxicity. We report the degradation of 16 PAHs using photo-Fenton and photo-Fenton-like processes in two different soil samples (S1 and S2) artificially contaminated with diesel oil. Experimental factorial designs were used to determine the most effective treatment conditions, with a view to achieving economical feasibility. For photo-Fenton reactions, the best degradation conditions resulted in an overall PAH concentration reduction of 94.6% and 95.6% for soils S1 and S2, respectively. The photo-Fenton-like processes also led to satisfactory degradation levels, obtained with only endogenous iron, low hydrogen peroxide concentration, short exposure time and no soil pH adjustment. These results demonstrate the viability of photo-Fenton-like processes to treat PAH contaminated areas.

The plating process generates solid waste rich in heavy metals and aiming to reduce environmental impact of such waste, this work suggests a methodology for zinc reduction, through a 2(4) factorial planning, studying the influence of the following variables: acid concentration (15, 20 or 30% v/v), acid type (sulfuric or hydrochloric), acid volume (15, 20 or 25 mL) and extraction time (12, 24 or 36 h). Through this methodology it is possible to establish the optimal conditions (15 mL of a 30% hydrochloric acid concentration during 12 h) to get a 100% efficiency in zinc extraction.