Investigation of the quality of water in the process of its purification using ultrafiltration by the method of differential scanning calorimetry

Abstract

The increased interest in ultrafiltration technology in the last decade is caused by the search for new purification methods that allow obtaining high-quality drinking water that meets modern regulatory requirements. Modern water purification schemes use an ultrafiltration unit before reverse osmosis in softening, desalination and demineralization of water for food production. The pore size of ultrafiltration membranes ranges from 5 nm to 0.05-0.1 microns. Using ultrafiltration instead of the traditional water treatment scheme, makes it possible to obtain water with a low content of suspended and colloidal substances, increase the productivity and serviceability of reverse osmosis membranes. The water treatment scheme may contain the following modules: coarse filter; ultrafiltration unit, buffer tank; mixer; water container; reverse osmosis installation; pumps. The method of differential scanning microscopy is used to assess the quality of water during its purification. Water samples were cooled with liquid nitrogen to -30 ? and then heated to 30 ?. Crystals melting peaks were recorded on the DSC curves, and the thermal effect was calculated. During the water purification process, the value of the thermal effect of frozen water samples melting declines (from 515.1 to 261.2 J / g), the value of the temperatures at the onset (from 0.7 to -0.13 ?) and at the peak of crystal melting (from 7.45 up to 4.27 ?). The difference between the heat effect data for water samples after coarse filtration and ultrafiltration is small, which indicates that the ultrafiltration unit allows cations and anions to pass through, which preserves the salt balance of water.