Ervim Lenzi’s research while affiliated with Universidade Estadual de Maringá and other places

Copper behavior and bioavailability in a red Latosol treated with Cu-enriched sewage sludge were investigated. Results showed that sewage sludge increases nutrient and organic matter concentration in the soil. In sludge-amended treatments, bioavailability to lettuce plants was reduced due formation of organic complexes. In this case, plant productivity was affected only by soil acidity. Phytotoxicity was noticed in treatments without sludge and with high amounts of copper. Metal levels in roots, instead of in plant shoots, show a good fit with bioavailable copper estimated using the Mehlich-1 solution, commonly used in routine analyses, even at high metal levels.

A greenhouse experiment was conducted to evaluate phytotoxicity and distribution of Cu in a tropical soil amended with sewage sludge (Sw) and copper sulfate (CuSO4 center dot 5H(2)O). Samples of a clay soil from the State of Parana, Brazil were collected at depth of 0-20; 20-40 and 40-60 cm, and brought to the laboratory to be properly accommodated in experimental units (PVC tubes). The Cu treatments were performed by the application of Sw (10 t ha(-1)) amended with Cu (SB-T), and by CuSO4. H2O (WB-T). Lettuce plants were cultivated in the amended soil in order to predict the toxicity of the Cu. The experiment was conducted for 70 days, and then the lettuce plants and soil samples were collected for analysis. A sequential method was used to separate soil Cu into following fractions: exchangeable, amorphous iron oxide bound, crystalline iron oxide bound, organic matter bound and residual bound. The experimental results showed that Fe, Zn, K, P, Cu and organic matter amounts of the soil increased with the treatment SB-T. The toxic phyto-available Cu content in the soil for the lettuce plants was 80.00 mg kg(-1). A percolation study showed that the Cu contents were larger for the first 20 cm of depth, indicating that the metal was not transported down the soil profile. The Cu content of different fractions declined in an order residual > amorphous iron oxide > crystalline iron oxide > organic matter > exchangeable, regardless of treatment performed. Additionally, the Cu contents added from treatments were determined mainly in amorphous iron oxide fraction.

O estudo abordou o tratamento do efluente gerado num Espectrômetro de Absorção Atômica - EAA, no tocante ao metal pesado zinco, utilizando a propriedade do cátion formar o precipitado Zn(OH)2(ppt). O assunto foi tratado teórica e praticamente. Teoricamente foram levantados parâmetros termodinâmicos e analisada matematicamente a solubilidade do Zn(OH) 2(ppt) com a variação do pH. Experimentalmente foi analisado o comportamento da solução aquosa do Zn(OH) 2(ppt) e da solução in natura do efluente descartado com o pH. As medidas da concentração de zinco nas diversas situações foram realizadas pelo método da EAA, com limite de detecção (LD) de 0,030 mg L-1. Os resultados nas diferentes situações de solução e pH do meio, para a solubilidade mínima do Zn(OH) (ppt), SMínima, em mg L-1, foram: valor teórico = 2,3; valor experimental para solução de Zn(OH) (ppt) = 0,92; valor para solução in natura = 0,092, respectivamente. Estes valores estão de conformidade com BRASIL-Resolução Conama n. 397/2008.This work analyzed the treatment of effluent produced by an Atomic Absorption Spectrometer (AAS) containing the heavy metal zinc, utilizing the capacity of Zn2+ to react with hydroxide ion (HO-), forming Zn(OH) 2(ppt). The content was treated theoretically and experimentally. Theoretically, the thermodynamic parameters were assessed and the solubility of Zn(OH) 2(ppt) with pH variation was analyzed mathematically. Experimentally, the study analyzed the behavior of the Zn(OH) 2(ppt) aqueous solution and in natura solution of discarded effluent with the medium pH. The values of zinc concentration in the different situations were measured using AAS, flame modality, with detection limit (DL) 0.030 mg L-1. The results in the different situations of solution and medium pH for the minimum solubility of Zn(OH) 2(ppt), in mg L-1, were: theoretical value = 2.3; experimental value for the Zn(OH) 2(ppt) solution = 0.92; in natural effluent = 0.092, respectively. These values are in compliance with BRAZIL-Conama Resolution number 397/2008.

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.

The conditions for the preparation of activated carbon from flamboyant pods treated with NaOH were optimized through response surface methodology (RSM) and central composite rotatable design (CCRD). The effects of the activation temperature, activation time, and impregnation ratio were studied from the BET surface area, micropore volume, and yield results. The results showed that the activation temperature and the impregnation ratio are the factors that most influence the activated carbon production. Activation temperature of 761.70 °C, activation time of 0.86 h, and impregnation ratio (NaOH:char) of 3.46 led to BET surface area, micropore volume, and yield values of 2854 m2 g−1, 1.44 cm3 g−1, and 10.80%, respectively. Porosity parameters and scanning electron microscopy were used to investigate the activated carbon obtained under optimal conditions.

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%.

The evaluation of micronutrient availability in agricultural soil treated with sewage sludge was developed in field with maize cultivation on a Dystrophic Red Latosol. The experiment used a randomized complete block design, with the treatments in a split-plot scheme, in time, with six doses of sewage sludge (main-plot treatment) in relation to the five sampling periods for the soil (subplot treatment), with four replications. The sewage sludge was applied in the superficial layer (0-20 cm). The micronutrients Fe, Cu, Mn and Zn were extracted from the soils using a DTPA (diethylenetriaminepentaacetic acid) solution. The same micronutrients were analyzed in the plant tissue after the nitric-perchloric decomposition of the maize samples by spectrometric atomic absorption. The results showed an increasing amount of Fe, Mn, Zn, Cu, Cation Exchange Capacity (CEC) and a decreasing pH in the soil. The increasing doses of sewage sludge increased the Fe, Mn, Cu and Zn availability in the soil solution, and the uptake amount by maize plants were always greater than the control values.

The evaluation of micronutrient availability in agricultural soil treated with sewage sludge was developed in field with maize cultivation on a Dystrophic Red Latosol. The experiment used a randomized complete block design, with the treatments in a split-plot scheme, in time, with six doses of sewage sludge (main-plot treatment) in relation to the five sampling periods for the soil (subplot treatment), with four replications. The sewage sludge was applied in the superficial layer (0-20 cm). The micronutrients Fe, Cu, Mn and Zn were extracted from the soils using a DTPA (diethylenetriaminepentaacetic acid) solution. The same micronutrients were analyzed in the plant tissue after the nitric-perchloric decomposition of the maize samples by spectrometric atomic absorption. The results showed an increasing amount of Fe, Mn, Zn, Cu, Cation Exchange Capacity (CEC) and a decreasing pH in the soil. The increasing doses of sewage sludge increased the Fe, Mn, Cu and Zn availability in the soil solution, and the uptake amount by maize plants were always greater than the control values.