Environmentally friendly acid carbon (CG) catalysts, containing a high amount of sulfonated and oxygenated groups, were prepared from glycerin, a biodiesel waste. CGs were produced by glycerin carbonization in the presence of H2SO4 at 1:3 m:m ratio in a closed autoclave at 180ºC for different times: 0.25; 1; 3 and 6 hours (CG-0.25h; CG-1h; CG-3h and CG-6h, respectively). The catalyst properties for all carbons were evaluated in the glycerol etherification reaction with tert-butyl alcohol (TBA). The yield for mono-tert-butyl glycerol (MTBG), di-tert-butyl glycerol (DTBG) and tri-tert-butyl-glycerol (TTBG) was high and very similar for all CGs, of about 43% and 20% for the MTBG and DTBG + TTBG, respectively. Furthermore, the activity of these catalysts were close to those obtained using a commercial resin, Amberlyst-15, of about 50% and 27% for MTBG and DTBG + TTBG, respectively.

CONTEXTO: A deficiência de zinco em crianças ou adolescentes acarreta danos ao crescimento, desenvolvimento e ao sistema imune dos indivíduos. OBJETIVO: Verificar a existência de deficiência de zinco plasmático e/ou leucocitário em adolescentes com hepatite autoimune. MÉTODOS:Participaram do estudo 23 pacientes com hepatite autoimune entre 10 e 18 anos, atendidos no Ambulatório de Hepatologia Pediátrica do Hospital de Clínicas da UNICAMP - Campinas, SP e 23 adolescentes com idade pareada com os pacientes formaram o grupo controle. Foi coletada amostra de sangue de todos os pacientes e grupo controle para as análises de zinco plasmático e zinco leucocitário por meio da espectrofotometria de absorção atômica, além de ter sido verificado o estado nutricional de cada adolescente. Os testes estatísticos empregados foram o de Mann-Whitney, correlação de Spearman e análise de concordância interclasses. RESULTADOS: O nível de significância adotado foi de 5%. A média de zinco plasmático nos pacientes foi de 71.91 ± 11.79 µg/dL e no grupo controle foi de 80.74 ± 10.92 µg/dL, essa diferença foi significante (P = 0.04). O nível de zinco leucocitário nos pacientes foi igual a 222.33 ± 166.13 pmol/10(6) células e no grupo controle foi de 226.64 ± 217.81 pmol/10(6) células, não ocorrendo diferença estatisticamente significante entre estes (P = 0.45). CONCLUSÃO: A avaliação do estado nutricional mostrou que a eutrofia é prevalente nos pacientes e estes possuem maior valor de gordura corporal que o grupo controle com diferença significativa. São necessárias mais pesquisas com adolescentes com hepatite autoimune em relação aos níveis de micronutrientes essenciais, como o zinco, pois um bom estado nutricional pode melhorar o prognóstico da doença hepática.

CONTEXT: Zinc deficiency in children and adolescents impairs their growing, development and immune system. OBJECTIVE: To verify the existence of plasma and leukocyte zinc deficiency in adolescents with autoimmune hepatitis. METHODS: The study comprised 23 patients with autoimmune hepatitis, aged 10-18 years, assisted at the Ambulatory Service of Pediatric Hepatology of the University of Campinas Teaching Hospital, Campinas, SP, Brazil, and adolescents with ages compatible with the patients' ages comprised the control group. Sample of blood in both groups was collected for the analyses of plasma zinc and leukocyte zinc by atomic absorption spectrophotometry, beyond the nutritional status was evaluated in each adolescent. The following statistical tests were used: Mann-Whitney, Spearman's correlation and interclass concordance analysis. RESULTS:The significance level adopted was 5%. The average zinc level in plasma in patients was 71.91 ± 11.79 µg/dL and, in the control group, it was 80.74 ± 10.92 µg/dL, showing a significant difference (P = 0.04). The leukocyte zinc level in patients was 222.33 ± 166.13 pmol/10(6) cells and, in the control group, it was 226.64 ± 217.81 pmol/10(6) cells; there was no statistical significance between them (P = 0.45). CONCLUSION:The evaluation of the nutritional status showed that eutrophy is prevalent in patients, and they presented a higher body fat value than the control group, with a significant difference. More research is needed with adolescents with autoimmune hepatitis regarding levels of essential micronutrients, such as zinc, because a good nutritional status can improve the prognostic of liver disease.

Fixed-bed column studies were undertaken to evaluate the performance of a commercial Brazilian activated carbon in removing Pb(II) from aqueous environment. Breakthrough points were found out for the metal adsorption by varying different operating parameters like feed concentrations (10 and 20 mg L-1) and bed heights (0.5, 1.5 and 2.8 cm). A good agreement was observed between the experimental data and the values predicted by the bed depth service time (BDST) model. Regeneration of the exhausted columns was possible with HCl, and the adsorption capacity was maintained after three adsorption-desorption cycles.

Adsorption of heavy metal cations by activated carbon is dependent on the capacity of the material in promoting adsorption and the time needed to reach equilibrium. Carbon samples were previously activated either by phosphoric acid treatment at 400 ºC or by steam at 800 ºC. The results of Pb(II) adsorption by these activated carbons have shown that equilibrium was typically reached within the first 5 min of contact between carbon and metal solution, with a maximum adsorption capacity higher than 69 mg g-1 for the vapor-activated sample. Temperature influences the sorption capacity, which corresponds to an endothermic process. Lead(II) retention is more pronounced at high temperature and low pH.

Cation exchange capabilities of a Brazilian natural zeolite, identified as scolecite, were evaluated for application in wastewater control. We investigated the process of sorption of chromium(III), nickel(II), cadmium(II) and manganese(II) in synthetic aqueous effluents, including adsorption isotherms of single-metal solutions. The natural zeolite showed the ability to take up the tested heavy metals in the order Cr(III) > Cd(II) > Ni(II) > Mn(II), and this could be related to the valence and the hydration radius of the metal cations. The influence of temperature (25, 40 and 60 ºC) and initial pH value (from 4 to 6) was also evaluated. It was found that the adsorption increased substantially when the temperature was raised to 60 ºC and that maximum adsorption capacity was observed at pH 6. These results demonstrate that scolecite can be used for removal of heavy metals from aqueous effluents, under optimized conditions.

Argilas pilarizadas formadas pela intercalação de óxidos de metais de transição, capazes de prevenir o colapso da estrutura, constituem materiais micro- e mesoporosos com diferentes atividades catalíticas e estabilidades. Argilas pilarizadas com cromo e com ferro foram utilizadas como catalisadores em reações de oxidação do cicloexano em fase gasosa. Os resultados indicam que os catalisadores são ativos e seletivos na produção de cicloexanona e cicloexanol. Entretanto, especial atenção deve ser dada à acidez superficial dos sólidos, responsável pela formação de cicloexeno no meio reacional, com conseqüente redução dos produtos de interesse.

Pillared clays formed by intercalation of transition metal oxides, capable of preventing the collapse of the structure, gives micro- and mesoporous materials with different catalytic activities and stabilities. Chromium and iron pillared clays were tested as catalysts in the gas phase ciclohexane oxidation. The results showed that the catalysts are active and selective in the oxidation reaction to produce ciclohexanone and ciclohexanol, but special attention must be done to the surface acidity of this materials, responsible by ciclohexene formation.