Influence of cellulose-containing sorbent preparation method based on linen fiber on its functional properties

The creation of biosorbents based on modified flax fiber is aimed at solving the problem of water pollution from heavy metal ions. A method for obtaining a sorbent on the basis of linen fiber including sequential treatment of polysaccharide material with sodium metaperiodate and sodium bisulfite has been developed. Modification conditions for obtaining an effective sorbent have been selected. Equilibrium and kinetics of copper ions sorption with the use of native and modified linen fiber in comparison with Lewatit S100 cationic exchange resin have been studied. It is established that the time of achieving sorption equilibrium in the heterophase system 'aqueous solution of copper sulfate - a modified sorbent' is reduced by 1.5-2 times while the degree of extraction of copper ions is increased by about 1.5 times as compared to the initial fiber. The influence of solution pH on the sorption of copper ions by native flax fiber has been studied. It has been found that in the pH range of the medium 1-7, along with the sorption of Cu ions, the sorption of H ions is observed, which indicates a competitive mechanism of sorption of heavy metal cations and protons with the participation of the cellulose-containing sorbent. Experimental isotherms of copper ions sorption have been processed in linear coordinates of Langmuir's equation that made it possible to determine the values of maximum sorption capacity of sorbents under study which increase in a series: native flax fiber (0.86 mol/kg) < flax fiber, oxidized and treated with sodium bisulfite (1.69 mol/kg) < Lewatit S100 cationite (1.89 mol/kg). Data from infrared spectroscopy and elemental analysis indicate the appearance of new sorption-active groups in the sorbent structure. The sorbent has been tested for purification of aqueous solutions and beverages from heavy metal ions under laboratory conditions. Peculiarities of the sorption of copper (II) ions from juice and white wine have been revealed. It has been found that the obtained modified sorbent on the basis of flax fiber in the purification of beverages is not inferior to the industrial cationic exchange resins in its sorption properties.