Comparison of extruded and pressed low cost ceramic supports for microfiltration membranes

Abstract

A comparison has been made between ceramic microfiltration membranes of the same composition obtained by pressing and by extrusion in terms of microstructure and properties.The extruded membranes displayed lower porosity and smaller pore size than pressed membranes. The higher the clay content in the starting composition, the clearer this tendency became. In contrast, the difference tended to disappear when starch was added to the initial composition. The mechanical strength values followed a decreasing exponential variation with porosity, which was influenced by the starting composition and the shaping method.Water permeability reflected the strong effect of the mean pore size. The membranes synthesised from the composition with the higher clay content showed the lowest permeability, while those obtained from the composition including starch showed the highest value. A model derived from the Hagen-Poiseuille equation enabled the tortuosity values to be calculated.

Influence of starch content on the properties of low-cost microfiltration ceramic membranes

“…Figure 13. Relation between tortuosity factor (τ) and starch content of the membrane composition, following the model set out in [37][38][39]. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 23 Tables Table 1. Chemical compositions of the raw materials used (wt%).…”

“…3] and the pore size distributions determined by mercury intrusion. This model has been successfully used in previous research with other low-cost ceramic membrane compositions [37][38][39]. The data have been collected from the previous sections and plotted in figure 7.…”

Caracterização Morfológica E Parâmetros Funcionais De Membrana Cerâmica Multitubular

“…A maioria das membranas comerciais são produzidas por alumina, sílica, zircônio, titânio ou uma combinação destes óxidos (Lorente-Ayza et al, 2015). Os materiais TiO2 e ZrO2 conferem a membrana características hidrofílica, proporcionando redução na formação de incrustações, resistência química em soluções ácidas e básicas (Zhang et al, 2013;Vinoth Kumar et al, 2015).…”

On the underestimated effect of the starch ash on the characteristics of low cost ceramic membranes

“…The proportions of the different composition ingredients were fixed from previous experience by the authors with low cost ceramic membranes formulations [23,38,40]. Table 3.…”

“…Cylindrical test specimens of 50 mm diameter and 7 mm thickness were formed by uniaxial dry pressing at 250 kg•cm -2 in a laboratory unidirectional press (Model Mignon, Nannetti, S.r.l., Italy) and dried in an oven at 110ºC. The dry specimens were then sintered in a laboratory electric kiln (Model Rapido, Pirometrol S.L., Spain) with a thermal cycle characterised by a slow firing cycle up to 500ºC (to complete starch burnout) and a soaking time of 6, 60 and 120 minutes at maximum [40,46].…”