Obtenção de micro e nanocelulose para preparação de membranas poliméricas como barreira seletiva

Abstract

The use of polymeric membranes has been extensively studied for separation processes. The study of materials and methodologies for development of such membranes for cost reduction and improvement in their properties are necessary to face this scenario. In the preparation of membranes, organic materials such as polymers and elastomers are employed with the possibility of incorporation of reinforcement materials and to modify the characteristics to favor certain processes. These membranes are called composite, they are obtained by dispersing a physical component in the polymer matrix, where the size of the dispersed phase varies from micrometer to nanometer scale and the interface between the phases must be well defined. Natural fibers has highlighted as a reinforcing material due to their renewable nature and vast source of raw materials, in addition having good mechanical properties and low cost. The plant cell wall cellulose can be purified, isolated and incorporated into membranes acting as reinforcing agent. The hydrolysis techniques are employed methodologies for isolating crystals of cellulose, using different acids resulting in different properties. In this work we used Kraft pulp from Eucalyptus ssp following two methods for isolation (acids HCl and H2SO4) of micro (MCC) and nanocrystals (NCC) of cellulose. Incorporating these materials into membranes of polysulfone (PSf) were evaluated for permeate flux, rejection protein, contact angle and scanning and transmission electron microscopy. Nanocelulose presented diameter and length defined and favorable aspect ratio for incorporation into polymeric membranes. The solution obtained after hydrolysis with H2SO4 can be consider more stable as it presented less agglomerations. The addition of microcellulose and cellulose nanocrystals to membranes proved satisfactory for the preparation of polymeric membranes. There was an increase in rejection of the proteins, selectivity and hydrophilicity for the reinforced membranes, especially with nanocelulose obtained by hydrolysis with H2SO4.