Leonardo Strey

Biosorption and removal of chromium from water by using moringa seed cake (Moringa oleifera Lam.)

This study evaluated the adsorption capacity of chromium from contaminated aqueous solutions by using Moringa oleifera Lam. seeds. Parameters such as solution pH, adsorbent mass, contact time between solution and adsorbent, isotherms, thermodynamic, kinetics, and desorption were evaluated. The maximum adsorption capacity (Qm) calculated to be 3.191 mg g-1 for the biosorbent. Activated carbon was used for comparison purposes in addition to the biosorbent. The best fit was obtained by the Langmuir model for both adsorbents. The average desorption value indicated that both the biosorbent and activated carbon have a strong interaction with the metal. The results showed that the biosorbent has advantages owing to its low cost and efficiency in Cr3+ removal from contaminated waters.

The use of Crambe abyssinica seeds as adsorbent in the removal of metals from waters

This study aimed to evaluate the efficacy of crambe seeds (Crambe abyssinica Hochst) as adsorbent material in the removal of the toxic metals cadmium, lead and chromium from contaminated solutions. The byproduct was obtained from oil extraction of crambe seeds in a Soxhlet system. In kinetic tests, the adsorbent masses had varied in solutions containing the metals under pH 5.0 and 7.0. Metal concentrations were determined by flame atomic absorption spectrometry (FAAS). According to optimal conditions found, the adsorption assays were performed for obtaining the isotherms of each metal, which were linearized in agreement with the mathematical models of Langmuir and Freundlich. According to the obtained results, the adsorbent was effective in removing the assessed metals in aqueous solutions, being feasible its employment as an alternative material for the adsorption of metals, besides being a byproduct, which has undergone no prior treatment.

Applicability of Crambe abyssinica Hochst. byproduct as biosorbent in the removal of chromium from water

espanolEl objetivo de este estudio fue evaluar la eficacia del uso de subproducto de semillas de crambe como biosorbente en la eliminacion del metal pesado cromo a partir de soluciones contaminadas. Por medio de microscopia electronica de barrido, espectroscopia infrarroja y determinacion del punto de carga cero se realizo la caracterizacion del biosorbente. Se analizo la influencia de diferentes condiciones en la adsorcion de iones, tales como soluciones a diferentes condiciones de pH, variacion de las masas de biosorbente, tiempo de contacto y temperatura, y las concentraciones de metal se determinaron por espectrometria de absorcion atomica de llama. En los ensayos para obtener las isotermas, los modelos matematicos de Freundlich y Dubinin-Radushkevich fueron los que mejor ajustaron los datos experimentales. El estudio de desorcion demostro una intensa interaccion entre el metal y el adsorbente, lo que confirma los datos del modelo de pseudo-segundo orden y energia media de Dubinin-Radushkevich para quimisorcion. La maxima capacidad de adsorcion del biosorbente se estimo en 6,807 mg.g-1. Para el estudio comparativo con un adsorbente comercial se utilizo carbon activado en pruebas de adsorcion y desorcion. Basandose en estos resultados, se concluyo que el subproducto fue eficaz en la eliminacion de cromo de soluciones acuosas, y su uso como un material alternativo viable para la eliminacion de este metal, ademas de ser un subproducto, que no ha sufrido tratamiento previo. EnglishThe aim of this study was to evaluate the efficacy of using crambe seeds byproduct as biosorbent in the removal of chromium heavy metal from contaminated solutions. By means of scanning electron microscopy, infrared spectroscopy and the determination of the point of zero charge was performed the biosorbent characterization. The influence of various conditions on the ions adsorption, such as solutions at different pH conditions, variation of the biosorbent masses, contact time and temperature were investigated, and the metal concentrations determined by atomic absorption spectrometry flame mode. In trials to obtain the isotherms, the mathematical models of Freundlich and Dubinin-Radushkevich best fitted the experimental data. The desorption study demonstrated intense interaction between the metal and adsorbent, which confirms the data from the pseudosecond order model and mean energy of Dubinin-Radushkevich model for chemiosorption. The maximum adsorption capacity of biosorbent was estimated at 6.807 mg.g-1. To comparative study with a commercial adsorbent, activated carbon was used for tests of adsorption and desorption. Based on these results, it was concluded that the byproduct was effective in removing chromium from aqueous solutions, and its use as a viable alternative material for this metal removal, in addition to being a byproduct, which has not suffered pretreatment.

Applicability of Moringa oleifera Lam. pie as an adsorbent for removal of heavy metals from waters

This study evaluated the efficacy of moringa seeds (Moringa oleifera Lam.) as an adsorbent material for removing toxic heavy metals such as cadmium, lead, and chromium from contaminated solutions. The effect of the adsorbent mass was investigated at two pH conditions (5.0 and 7.0). The optimized conditions were 0.300 g of adsorbent at pH 5.0, used for the isotherms construction, and linearized according to Langmuir and Freundlich models. Results showed that cadmium adsorption was similar in both the models used. For lead, the Freundlich model had the best adjustment and chromium was better adjusted by the Langmuir model. It was concluded that the adsorbent was effective in the remediation of solutions containing cadmium, lead and chromium, thus, its use as sustainable alternative material is feasible, since it has low cost, does not need a previous treatment and it is a byproduct.

Teores de nutrientes e metais pesados em plantas de estragão submetidas a diferentes fertilizações

The cultivation and use of medicinal plants has accompanied the evolution of mankind since antiquity, together with the development of techniques for their cultivation and management. In the search for sustainability of agroecosystems, the use of sources for fertiliser that provide the necessary nutrients for crops should be handled so as to cause the least possible environmental impact. The aim of this study was to evaluate the availability of N, P, K, Ca, Mg, Cu, Zn, Fe and Mn, and the heavy metals Cd, Pb and Cr, in tarragon plants (Artemisia dracunculus) subjected to different fertilisers, organic (swine-manure based compost) and mineral, in a dystrophic Red Argisol (PVd). The experimental design was completely randomised (DIC) in a 2 x 3 factorial scheme, comprising two sources and three levels of fertilisation (no fertilisation, recommended dose and double the recommended dose), giving a total of six treatments with four replications. The results showed that the source as well as the level of fertiliser influenced availability of the elements under evaluation in the plants. The organic fertilizer provided higher concentrations of Cu and Mn. Mineral fertilisation provided higher levels of the nutrients N and K. The heavy metals Cd and Cr showed no concentrations within the limits of detection for the method used.

Methods of extraction and bioavailability of zinc for the soybean culture fertilized with NPK+Zn

This work aims to evaluate the extractors Mehlich-1 and diethylene triamine pentaacetic acid (DTPA) and their extraction capacity for zinc (Zn) correlating them with the bioavailability of this nutrient in the soybean culture [Glycine max (L.) Merril] cultivated in a Eutrophic Red oxisol, in order to find better correlation between fertilization doses and plant absorption of zinc in conditions of the Parana Western region. The experiment was performed in 2008, in the city of Marechal Candido Rondon – Brazil, in completely randomized design. The treatments were arranged in 3×3 factorial scheme, consisting of three fertilization doses (N:P2O5:K2O in kg ha-1): without fertilization; recommended dose (4:40:40) and twice the recommended dose (8:80:80); and three Zn doses: 0.00; 1.00 and 2.00 kg ha-1. Between the evaluated extractors, Mehlich-1 presented higher capacity of Zn extraction in the studied soil. Concerning fertilization with Zn, though the doses show increment in the soil, no increase was found in the Zn concentration in leaf tissue. Key words: Micronutrients extraction, diethylene triamine pentaacetic acid (DTPA), Mehlich-1.

Production and nutrient accumulation in Tifton 85 (Cynodon dactylon (L.) Pers.) fertilized with swine manure in clayey soil

The aim of this study was to determine the production and nutrient content of Tifton 85 (Cynodon dactylon (L.) Pers.) fertilized with doses of swine manure and biofertilizer. The soil used in this study was a Rhodic Eutrudox. The treatments consisted of two forms of manure (in natura and biofertilizer), with four doses and four replications. Mean production of the grass in the first cutting based on fresh matter (FM) was 6,572 kg ha-1 and for dry matter (DM) 3,511 kg ha-1. The different types of manure had an effect on the Mg contents, and the doses had an effect on the contents of N, P, K, Mg, Cu, and Fe. In the second cutting, the mean production for FM was 7,590 kg ha-1 and for DM 3,632 kg ha-1; the sources had an effect on the P and Cu contents and the doses had an effect on the contents of N, P, K, Fe, Mn, Cu and Zn. By the obtained results, it was possible to conclude that the application of natural manure led to greater production of Tifton 85 when compared to the biofertilizer, and, furthermore, the leaf content of the nutrients N, P and K and of the micronutrients Fe, Cu and Zn increased according to the doses applied and sources used.