Adsorption purification of liquid flows applied to no-waste chemical fibre technologies. Review

Abstract

The basic premises of the scientific-technical conception of perfection of traditional methods of adsorption purification based on the use of granulated and ground sorbents were analyzed. The expediency and efficiency of using cyclic regimes in tray-contact adsorbers was justified as a priority direction of the idea. Tasks for the further progressive introduction of the leading technology and equipment in adsorption purification practice were formulated. However, the number of sorption processes in chemical fibre technologies is comparatively small and is usually limited to traditional sorption filters with a stationary bed. Attempts to utilize adsorption for purification of WW and process solutions have usually been unsuccessful. These failures were due to the incorrect selectiou of the physicochemical conditions for adsorption of dissolved substances or regeneration of absorbers and imperfect equipment and technological formulation of the processes.The basic requirements for low-waste sorption processes for decontaminating emissions were formulated in [6] based on the general principles of no-waste technology:-ensuring the maximum possible degree of saturation of file adsorbent and consequently decreasing the amount of sorbent required for conducting the process; increasing the time between regenerations; -decreasing the required amount of absorbers while preserving the overall efficiency of the mass exchange process; -converting to process schemes with regeneration of the absorber and possible separation of desorbed products. In the general case, in selecting methods of regenerating sorbents, it is necessary to consider the physicochemical properties of the desorbed substance and the specific features of the plant in which WW and process solutions are formed. As a function of the type of purification (regenerative or destructive), regeneration of the sorbent is either associated with extracting absorbed substances from the sorbent and returning them to the production cycle or destroying them during desorption. Regenerative purification is usually used in local adsorption installations, since the wastewaters contain one or two substances which can be returned to basic production or utilized in the form of a commercial by-product. However, in local purification of low-concentration WW (100-150 rag/liter), the cost of the extracted product frequently cmmot colnpensate for the specific costs of decontaminating the wastes. For this reason, file selection of a scheme and consequently a method of desorption is determined not only by the physicochemical properties and value of the separated product, cost of the sorbent and outlays for regeneration, but also by the concentration of extractable substances in file WW sent for purification.All-Russian Scientific-Research Institute of Synthetic Fibres, Tver'.