Adsorção de micronutrientes e metais potencialmente tóxicos por torta de filtro da cana-de-açúcar: influência da matéria orgânica na interação desses elementos no ambiente

Abstract

The main objective this work was to study the adsorption of micronutrients (copper(II), nickel(II), chromium(III)) and potentially toxic metals (cadmium(II) and lead(II)) for residuo of the sugarcane industry (filter cake) and to evaluate the interaction of humic substances extracted from these waste micronutrients and potentially toxic metals by complexation ability. Thus was compared filter cakes collected at two localities: In the city of Maceio in Alagoas (TF/AL), and the city of Jaboticabal the state of São Paulo (TF/SP). The experimental methodology of the study was first, the physical-chemical characterization of the TF/AL and SP for determination of soil organic matter (OM), thermogravimetric analysis (TGA) and infrared absorption spectrometry with Fourier transform (FTIR). Subsequently, was evaluated the adsorption capacity for metal ions: Cd(II), Cu(II), Ni(II), Pb(II) and Cr(III), in mono and multimetálico system for the two arrays values in pH 4,0; 6,0 and 8,0. The time range for the study was 10 – 2880 min. According to the results of adsorption for all ions in solution monometálica, there was a retention of over 90 % at the initial time (up to 240 min) to its arrays of pH values evaluated. In multimetálica solution for both matrices, there was a decrease in retention behavior in earlier times due to competition between the ions adsorb to TF, increasing the adsorption time, except for the Pb2+ ion had a similar retention multimetálica solution for all times and pH evaluated. In general, for both solutions, the adsorption profile at pH 6,0 results presented above 90% when compared to similar matrices. According to the kinetic studies at pH 6,0 the adsorption of potentially toxic metals and micronutrients for the TF/AL and SP follows, preferably, the pseudosegunda order kinetic model. The kinetic adsorption data were best fitted with the model pseudosegunda order, which provided the best correlation coefficients (r) for all ions analyzed in TF/AL and SP with mono and multimetálica solutions . The adsorption of ions is due to the high content of organic matter (OM) and also to the functional groups present in the samples, such as carboxylic groups and esters, according characterizations. Extraction of humic substances filter cake Alagoas and São Paulo (SHTF/AL and SP) filter and characterized by E4/E6 ratio was made, indicating that the SHTF/SP exhibit more aromatic structures corroborating the results of FTIR. For SHTF/AL and SP studies of complexation capacity (CC) for micronutrients and potentially toxic metals were performed. The CC reviews of metals were similar, and the CC for the Pb2+ ion complexed in SHTF/AL showed a much higher percentage of complexing the SHTF/SP. In general, it was found that the TF/AL and SP and SHTF/AL and SHTF/SP have potential application in aquatic systems polluted for adsorption/complexation of metals.