Preparation and characterization of activated carbon from a new raw lignocellulosic material: flamboyant (Delonix regia) pods.

Activated carbons were prepared from flamboyant pods by NaOH activation at three different NaOH:char ratios: 1:1 (AC-1), 2:1 (AC-2), and 3:1 (AC-3). The properties of these carbons, including BET surface area, pore volume, pore size distribution, and pore diameter, were characterized from N(2) adsorption isotherms. The activated carbons obtained were essentially microporous and had BET surface area ranging from 303 to 2463 m(2) g(-1).(13)C (CP/MAS and MAS) solid-state NMR shows that the lignocellulosic structures were completely transformed into a polycyclic material after activation process, thermogravimetry shows a high thermal resistance, Boehm titration and Fourier-transform infrared spectroscopy allowed characterizing the presence of functional groups on the surface of activated carbons. Scanning electron microscopy images showed a high pore development. The experimental results indicated the potential use of flamboyant pods as a precursor material in the preparation of activated carbon.

Simultaneous determination of the textile dyes in industrial effluents by first-order derivative spectrophotometry.

A first-order derivative spectrophotometric method for the simultaneous determination of three textile dyes, Procion Yellow HE4R, Procion Red HE7B and Remazol Black 5 (RB5), has been developed. The effects of pH, heating and ionic strength of the solution on the absorption spectra of the dyes were investigated. The wavelengths selected for the measures of the derivative signals of HE4R (395 nm), HE7B (604 nm) and RB5 (659 nm) presented these coefficients of linear correlation: 0.9978, 0.9992 and 0.9999, and these detection limits: 0.180, 0.317 and 0.0233 mg L(-1), respectively. The reliability and reproducibility of the method were tested and showed recovery values of 95.7 to 109%. The proposed method was applied for the determination of dyes in binary and ternary mixtures of textile effluents and showed an estimate of the loss of dyes for the effluents between 6.67 and 28.9%.

Sulfate removal from waste chemicals by precipitation.

Chemical oxidation using Fenton's reagent has proven to be a viable alternative to the oxidative destruction of organic pollutants in mixed waste chemicals, but the sulfate concentration in the treated liquor was still above the acceptable limits for effluent discharge. In this paper, the feasibility of sulfate removal from complex laboratory wastewaters using barium and calcium precipitation was investigated. The process was applied to different wastewater cases (two composite samples generated in different periods) in order to study the effect of the wastewater composition on the sulfate precipitation. The experiments were performed with raw and oxidized wastewater samples, and carried out according to the following steps: (1) evaluate the pH effect upon sulfate precipitation on raw wastewaters at pH range of 2-8; (2) conduct sulfate precipitation experiments on raw and oxidized wastewaters; and (3) characterize the precipitate yielded. At a concentration of 80 g L(-1), barium precipitation achieved a sulfate removal up to 61.4% while calcium precipitation provided over 99% sulfate removal in raw and oxidized wastewaters and for both samples. Calcium precipitation was chosen to be performed after Fenton's oxidation; hence this process configuration favors the production of higher quality precipitates. The results showed that, when dried at 105 degrees C, the precipitate is composed of hemidrate and anhydrous calcium sulfate ( approximately 99.8%) and trace metals ( approximately 0.2%: Fe, Cr, Mn, Co, Ag, Mg, K, Na), what makes it suitable for reuse in innumerous processes.

Transition metal rates in latosol twice treated with sewage sludge

A reciclagem agrícola do lodo de esgoto tem provocado o acúmulo de metais pesados no solo e na água, podendo atingir níveis tóxicos e causar danos às plantas cultivadas, aos animais e ao homem, por meio da cadeia trófica. Neste intuito foi desenvolvido o presente experimento, em condições de campo, entre 2000 e 2002, onde foram avaliados os efeitos da aplicação de lodo de esgoto por dois anos, sobre a extração de metais de transição (essenciais e não) pelo extrator DTPA em um Latossolo Vermelho distrófico (LVd) de textura média. As concentrações dos elementos metálicos: Mn, Fe, Cd, Ni, Co, Pb e Cr não foram detectados pelo método da absorção atômica na solução obtida com o extrator DTPA. A aplicação de lodo de esgoto causou inicialmente pequena elevação no pH do solo, posteriormente a diminuição do mesmo, e manteve-se próximo ao original. Foi possível concluir que, com a aplicação consecutiva do lodo, os teores extraíveis de Fe e Mn nas amostras de solos aumentaram gradativamente nos dois anos agrícolas, com as doses do lodo de esgoto aplicado, época de amostragens, e foram superiores ao tratamento testemunha. O extrator apresentou capacidade restrita para avaliação da fitodisponibilidade dos metais pesados decorrentes das baixas concentrações nas amostras de solo.

Loss of macronutrients (N, P, K) in the hydrographic basin of the River Ivaí, an affluent of the River Paraná

Neste estudo foram analisadas algumas variáveis ambientais que influenciam a perda de macronutrientes (N, P e K) na bacia hidrográfica do rio Ivaí, afluente do rio Paraná. As amostras compostas de água foram coletadas mensalmente, em 5 dias consecutivos, durante um ano. No ato da coleta foram medidos, o pH, a temperatura, o O2(dissolvido) e os níveis fluviométricos. O N total foi determinado pelo método de Kjeldahl. Após a digestão das amostras com redução de volume foram determinados, o P total, pelo método espectrofotométrico do UV-Vis com ácido ascórbico e o K total pela técnica da espectrometria da absorção atômica. O DQO foi determinado pelo método da oxidação da matéria orgânica pelo K2Cr2O7, em excesso, em ácido sulfúrico concentrado. Em termos de intervalos das médias mensais, média global, os resultados experimentais foram os seguintes, em mg L-1: N (0,32-3,22 e 1,65); K (0,73-2,69 e 1,38); P (não detectado-0,39 e 0,076); COD (0,21-36,0 e 12,8); O2(diss) (1,89-8,40 e 5,43); e, temperatura (0C) (16,0-30,8 e 24,6); pH (5,18-8,50 e 7,15). A análise estatística dos dados mostrou que a quantidade de cada macronutriente levada pelas águas do rio Ivaí é diretamente correlacionada aos níveis fluviométricos do rio, em nível de 5% de confiança. As quantidades perdidas em t a-1 foram: N = 25.136,0; K = 21,010,0 e P = 1,161,2, respectivamente.

Lead behavior in soil treated with contaminated sewage sludge and cultivated with maize

Lead (Pb) behavior was studied in soil treated twice with sewage sludge contaminated with lead at interval of 18 months. Soil samples received five different treatments: three with lead [0 (reference); 2,500; 5,000 mug g-1] and two with a mixture of lead and cadmium (interferer) (2,500 + 2,500 and 5,000 + 5,000 mug g-1, respectively). Vases containing treated soil were cultivated with maize in a greenhouse for 75 days. Pb was extracted using nitric perchloric digestion and analyzed by atomic absorption spectroscopy. The soil, containing sewage sludge contaminated by lead presented a higher concentration of Pb. The metal concentration remained constant in all treatments at 20-60 cm depth. No absorption of Pb by the plants was detected

Estudo da fitodisponibilidade do cobre em alguns solos do Estado do Paraná / Study of copper phytodisponibility in some soils of Paraná state, Brazil

The phytodisponibility of copper as a micronutrient was evaluated on soils from the third plateau of Parana State. The experiment was developed in greenhouse, using polyethylene pots of 2,5 L and samples of seven soils. The experimental design was a completely randomized, with three replications. The treatments were three doses of copper (0,0 - 2,5 and 5,0 mg dm-3 soil), using a solution of CuSO4 5H2O after liming and a corrective fertilization according to the rotine analysis. Soybean (Glycine max (L.) Merril) and corn (Zea mays L.) were used as test plants. After 45 days of seeding, the shoots of the plants were cut, dried in stove at 70§C until constant weight, then they were weighted, grounded and submitted to nitro-perchloric digestion. The copper contents in these plants were determinated by atomic absorption spectrometry. Copper addition didn't show a significant effects to the dry matter production of soybean and corn plants, but copper concentration increased in this dry matter, without significant differences betweeen the 2,5 and 5,0 mg dm-3 doses. Copper contents in soybean dry matter ranged from 1,5 to 7,3 mg.kg-1, while in the corn dry matter they ranged from 3,1 to 9,4 mg.kg-1

Determinaçäo do cádmio em materiais consumidos pelo ser humano / Determination of cadmium in materials consumed by human

With the Dithizon espectrophotometric method, the concentration of cadmium in materials consumed by mankind were determined. The sample were collected by about Maringá. The materials analysed were: water, rice, bean, corn, wheat, soybean, lettuce, coffe, several kinds of tobacco and tea. the cadmium found in water and food samples is below the critic levels suggested by the National regulation. The concentration of cadmium in almost all of the tobacco samples are in the level of 1.35 pp,