Active ceramic sheet formed by papermaking method and using a natural binder

S.A. LEONARDI; C. SCHNELL; M.A. ZANUTTINI; MILT, VIVIANA G.; MIRÓ, EDUARDO E.

Congreso; IX Iberoamerican Congress on Pulp and Paper; 2016

A papermaking process is used for preparingceramic fiber sheets that can be used as filters, absorbent or catalyst. Ceramic fiber (SiO2-Al2O3)(diameter of 3 µm and a 600 µm long) is obtained by disintegration a ceramic insulationbed in water. Softwood cellulosic fibers are added to help the consolidation ofthe wet bed and the binder material is a native mineral (natural ulexite). Itis obtained from quarries and is purified in the laboratory by elutriation inan aqueous medium for separating high density material. Its purity iscontrolled by XRD and X-ray fluorescence. Ulexite meets the necessary featuressuch as: no toxic, almost insoluble, low density (1.96 g /cm3) and aslender shape of the crystals that helps obtaining a uniform distribution ofthem during the bed formation. Furthermore, ulexite sinterizes at low temperaturesand is inert to fibers and adsorbent or catalyst up to 700 °C. For papermakingformation, the system requires retention agents. Two linear polymers are used:a cationic (PVAm, 4 x 105 Da, 4.5 meq /g) and an anionic (A-PAM, 2 x106 Da, 1.9 meq/g). In the preparation recipient, the addition ofPVAm makes colloidal system cationic (335 meq/ l) with no major changes due tothe addition of ceramic fibers. Later, colloidal charge is reduced by 60% byadding the ulexite. Charge is further reduced somewhat with the addition of thecellulosic pulp. The final addition of A-PAM is such that further reduces thecationic charge without canceling (60 meq /l). Figure 1-a shows ulexitecrystals which are deposited on ceramic fibers. During the calcination stage,cellulosic fibers are removed and ulexite sintered joining ceramic fibers (Figure1-b). The strength reached (0.9 Nm/g) are low relative to a cellulosic paperbut are sufficient to allow manipulation of bed (Figure c) since it has someflexibility (elastic modulus 68 MPa) and strain to break is 0, 8%.The incorporation of absorbent elements(zeolites) or oxidation catalysts for environmental use (La-Ba or Co) do not greatlyaffects the mechanical properties.