Water purification from hydroxo com pounds of iron on wood membranes

Abstract

The work is devoted to the development of wood membranes, which can be an effective alternative to membranes made of traditional materials — polymers and ceramics. Wood membranes are made from natural environmentally friendly, inexpensive, renewable and affordable raw materials that are easily recycled. It is established that the pore size of wood corresponds to the average pore size of the microfiltration membrane. We investigate the process of purification of water from Fe(III) hydroxo compounds with a wood membrane and show its high efficiency when filtering water through the outer surface of a microfiltration tubular wood membrane, which is due to the steric mechanism of its action and the formation on its surface of an additional retention layer in the form of a dynamic membrane of Fe(III) hydroxo compounds. The influence of various physicochemical factors on the retention capacity of the membrane is studied, and its technological parameters are established. It is shown that the membrane (99.9%) had the highest retention coefficient for Fe(III), when the initial concentration of Fe(III) showed up to 340.2 mg/dm³, pH 7.0-8.0, working pressure 1.0 MPa and specific membrane performance 0.05-0.08 m³/(m² · h). Under these conditions, the permeate Fe(III) concentration values were lower than the MPC of Fe(III) in drinking water. Adding, the mixtures of Cl^–, HCO₃ ^– and SO₄ ^2– ions (200 mg/dm3 each) to the solution containing Fe(III) hydroxo complexes had practically no effect on the separation properties of the membrane. It is noted that, during the filtration of the solution through the inner surface of the tubular tree membrane, the value of its specific productivity increases sharply, but its retention capacity decreases.