Вилучення іонів міді лігніфікованою багасою із водних витяжок грунтів

Abstract

Analysis of soil contamination with heavy metals has been carried out, which leads to a reduction, and in some cases, to loss of species composition of plants. It is determined that about 20% of the territory of Ukraine is contaminated with heavy metals. The widespread use of copper and its compounds in industry inevitably leads to the entry of Cu (II) into the water and soil environment. The maximum permissible concentration of copper ions in soils is 100 mg / kg (total content) and 3 mg / kg (content of moving forms). Therefore, today, the removal of copper (II), which belongs to heavy metals of the first class of danger, is an important scientific, technical and environmental task. The expediency of increasing the requirements to the quality of soils is substantiated, it makes it necessary to search for new, environmentally friendly and economically viable ways of extracting heavy metal ions, in particular copper (II) from them. This is possible, when using sorbents in soil purification, from plant wastes, chemically or biologically modified. One of the most promising waste for the production of sorbents is the bulk of sugar sorghum (the weight of technical stems of sugar sorghum, which is obtained by mechanical pressing, is discarded). Native (untreated) sorghum waste, as a rule, has low sorption-kinetic characteristics and sorption capacity. Therefore, an urgent problem is the search for methods of treatment of plant polymers in order to reduce the duration of the sorption process and increase their sorption capacity. The purpose of the study is to develop a method for obtaining a sorbent by chemical modification of lignocellulose waste from sugar sorghum and identifying possible directions for its further practical use in agroecology. A method for lignifying the bagasse from sorghum sugar for soil purification is proposed hydrolysis of the crushed plant material with an aqueous solution of mineral (organic) acid, washing with water, activating lignin with an aqueous solution of alkali metal hydroxide, filtering, washing with water, neutralizing the residual alkalinity of the resulting material with an aqueous solution of acid, dehydration (pressing) and drying. The luggage proposed by us can destroy the esters, the free saturated and unsaturated organic acids, the various macromolecular alcohols and some part of the carbohydrates (hemicellulose and pectin), improve the sorption and porous structure by loosening the plant fibers and increase the number of available functional groups capable of joining reactions, complex formation and ion exchange with heavy metal ions. The growth of the sorption capacity of the lignified bagasse is due to an increase in the number of sorption-active centers on which the sorption of heavy metal ions (in particular, copper) may occur due to the formation of cationic and neutral solvate complexes. The sorption properties of untreated and lignified cadavers with respect to copper (II) ions have been studied. It has been established that lignified bagasse can be used in agrotechnologies as a sorbent for soil purification from contamination by copper ions.