Study of the filtering properties of fabrics derived from cotton and synthetic fibres

For the dehydration of various solutions and suspensions in the chemical industry, different types of filters are applied, including disk, cartridge, bag, press filters and others, with the main element consisting of a filtering membrane made of cotton or synthetic fibres. In this case, the main requirement for the membrane involves high retention ability with respect to the dispersed phase of solutions and suspensions. For application in forming a membrane, filter fabrics characterised by low clogging are advisable. In the present paper, the filtering properties of fabrics made of synthetic and cotton fibres are evaluated on the basis of experimental data along with a determination of indices of efficiency, turbidity, clogging and service life. The kinetics of the suspension dehydration was studied in a wide range of dispersed phase concentrations (3-500 g/dm(3)). The results of the studies revealed all tested samples of synthetic fabrics to exibit less clogging than the widely-used cotton ones (filter-diagonal and calico). The adhesion value of dispersed particles to the fibres of the membrane is established to allow the selection of appropriate fabrics for a particular filter type taking the acting direction of the driving force and gravity during the filtration process into account. The main phases of sediment formation on the membrane surface were established. The initial filter layer is shown to form during the first period, with the structure of this layer being determined by the density of the suspension. Filtration modes were investigated with the transition from sludge filtration to clogging observed in the range of 50-100 g/dm(3), which corresponds to the transition mode.