Imobilização de fontes de nitrogênio em grânulos de PVA e alginato de sódio e estudo da influência de ciclos de congelamento/descongelamento na caracterização e imobilização de nitrogênio

Abstract

In this work two nitrogen sources (urea and urea intercalated kaolinite) were immobilized in the PVA polymer matrix and sodium alginate in the ratio of 3:1, using the drip methodology in CaCl2. The granules were subjected to freezing and subsequent thawing in order to improve the structure and thermal resistance of the polymer matrix. The granules were analyzed for water removal with the increase of cycles of freeze/thaw (CC/D), and characterized by CHN, SEM, FTIR, XRD, TG and DTG. The granules that showed the best formulations were those of PVA+AS+U (PVA+sodium alginate+urea), because they present efficiency of immobilization near the granules PVA+AS+CI (PVA+sodium alginate+kaolinite intercalated with urea), but with greater thermal stability, about 200 °C. The granules were further subjected to leaching tests to verify the elimination of nitrogen, but no conclusive results of detection by the Kjeldahl method.