Removal of cadmium from water using by-product Crambe abyssinica Hochst seeds as biosorbent material.

The effectiveness of Crambe abyssinica Hochst seeds by-product as a biosorbent for the removal of cadmium ions from wastewater was analyzed. The biomass of crambe was characterized by scanning electron microscopy, infrared spectroscopy and determining the point of zero charge. The optimum adsorption conditions obtained were 400 mg of biomass in a solution of pH 6.0 and contact time of 60 min to remove 19.342 mg g(-1) cadmium ions. The isotherms of adsorption were constructed and, according to the mathematical linearization, the best fitting followed the Freundlich and Dubinin-Radushkevich models, describing a multilayer adsorption and chemical interaction, also confirmed by the pseudo-second order model and enthalpy value. In the desorption process, about 79% of cadmium ions that had been adsorbed were recovered. The same conditions applied for studying the isotherms of adsorption and desorption were used for comparative study with activated carbon. It was concluded that the use of crambe by-product as biosorbent for cadmium removal in wastewaters was not only a viable alternative to activated carbon, but also required no previous treatment, so it represents a sustainable material with high applicability and low environmental impact.

Produtividade e componentes de produção da soja adubada com diferentes doses de fósforo, potássio e zinco / Yield and production components of soybean fertilized with different doses of phosphorus, potassium and zinc

O correto incremento da produtividade agrícola deve estar aliado ao avanço tecnológico no conhecimento das exigências nutricionais de cada cultura, proporcionando, dessa forma, o correto uso de insumos na propriedade agrícola. Com o objetivo de estudar a resposta de plantas de soja ao zinco (Zn) em relação a diferentes doses de fósforo (P) e potássio (K), foi realizado este experimento no município de Palotina-PR. O solo foi classificado como Argissolo Vermelho-Amarelo eutrófico. Os tratamentos foram arranjados em esquema fatorial 3x3, constituindo três formas de adubação com P2O5 e K2O: sem adubação, uma vez e duas vezes a recomendação de adubação pela análise de solo e três doses de Zn (0; 2 e 4 kg ha-1). Como fonte de nutrientes, foram utilizados fosfato bicálcico para P, cloreto de potássio para K e sulfato de zinco para Zn. As doses de Zn aplicadas não influenciaram, significativamente, a produtividade, não sendo justificada a sua suplementação na forma de adubação de base. Já a adubação com P2O5 e K2O provocou significativo aumento da produtividade e aumento do número de legumes por planta, com aumento das doses desses nutrientes no solo.

The correct productivity increment must be allied to the technological advance in the knowledge of the nutritional requirements of each culture, thus allowing for the correct use of the inputs in the agricultural property. With the objective of studying the plants of soybean reply to zinc (Zn) in relation to the different doses of phosphorus (P) and potassium (K), this experiment was performed in the municipality of Palotina-PR. The soil was classified as typic hapludalf. The treatments were arranged in a 3x3 factorial scheme, constituting three fertilization forms with P2O5 e K2O: without fertilization, recommended dose and twice the recommended fertilization dose by the soil analysis and three Zn doses (0; 2 and 4 kg ha-1). Nutrient sources used were bicalcic phosphate for P, potassium chloride for K and zinc sulphate for Zn. The applied Zn doses did not significantly influence productivity, so supplementing the base fertilization form is not justified. On other hand, fertilization with P2O5 e K2O resulted in a significant increase in productivity and an increase in the number of legumes per plant, with an increase of the doses of these nutrients in the soil.