Natural waters and wastewaters often contain heavy metals, e.g., iron. Iron ore mining contaminates groundwater with iron up to 30 maximal permissible concentrations (MPC) as this element gets washed out from rock and soil. Adsorption is the most effective and economically feasible method of additional purification of natural and wastewater from iron. Its efficiency depends on the type of adsorbent. The research objective was to select the most efficient sorption material to eliminate water from iron, as well as to establish the adsorption patterns for different sorbents, thus creating sustainable and effective purification. The study featured carbonaceous sorbent of the SKD-515 grade, mineral sorption materials with aluminosilicate of the AC grade, and silicate-based sorbent of the ODM-2F grade. The porous structure was studied by porometry methods while the surface image was obtained using scanning electron microscopy. Other indicators included equilibrium, kinetics, and dynamics of iron adsorption by various sorbents. The Freundlich and Langmuir equations made it possible to calculate the key adsorption parameters. The Gibbs energy values were obtained from the Langmuir equation and equaled 11.93–20.66 kJ/mol, which indicated the physical nature of the adsorption process. Under static conditions, the sorbents demonstrated a high adsorption capacity with respect to iron, depending on the structure, and could be arranged as AC > SKD-515 > ODM-2F. In SKD-515, iron adsorption occurred in micropores; in AC and ODM-2F, it took place in mesopores. The kinetics of iron extraction showed that the adsorption process was limited by external mass transfer. The research provided a new understanding of iron adsorption by materials of various structures. The conclusions were supported by scanning electron microscopy images. Initial concentration, flow velocity, and loading layer height were studied in dynamics, i.e., during continuous operation of the adsorption column. The system proved extremely effective and reached 99.0% Fe3+ extraction under the following conditions: flow rate = 1 L/min, loading column height = 0.15 m, column diameter = 0.05 m, initial concentration = 0.5 mg/L (5 MPC). The column performance was tested at an initial concentration of iron ions of 50 MPC, which simulated the wastewater treatment at industrial enterprises. This comprehensive study of iron adsorption from wastewater proved the efficiency of the mineral sorption materials with aluminosilicate of AC grade.

The removal of carbon from wastewater by means of carbon adsorbents is experimentally studied. The kinetics of phenol adsorption from aqueous solutions simulating its content in industrial wastewater at mining enterprises and coke plants is investigated. The kinetic curves of phenol adsorption on AG-OV-1 and ABG active carbon differ from the classic form. The time to attain equilibrium in the phenol–water–sorbent system varies in the range 30–60 min. The adsorption process is found to be limited by external diffusion. The external diffusion coefficients are calculated. On the basis of the external mass-transfer coefficients, we may expect high phenol extraction from wastewater at moderate filtration rates through the dense immobile sorbent layer.

Сточные воды лакокрасочного производства представлены преимущественно хлор- и кислородсодержащими соединениями, в том числе фенолом, трихлорэтиленом, хлороформом, хлорфенолом и другими, извлечение которых возможно с применением адсорбционных методов. На адсорбцию органических соединений влияет не только пористая структура адсорбента, но и химическое состояние его поверхности. Изучена адсорбция загрязняющих веществ из водных растворов гранулированными активированными углями (хлороформ - 4,73-7,87, трихлорэтилен - 2,30-6,11, фенол - 2,6-2,82, хлорфенол - 4,04-6,87 ммоль/г сорбента). Оценено влияние рН исходных растворов и влияние предварительной термической обработки адсорбентов воздухом в инертной атмосфере на извлечение токсичных компонентов. Установлено, что влияние рН на адсорбцию загрязняющих веществ заметно только в сильнощелочной среде (рН от 9 до 12). Причиной снижения адсорбции может быть рост электростатического отталкивания между ионизированными при высоких значениях рН карбоксильными и фенольными группами на поверхности адсорбентов и атомами хлора адсорбата для хлороформа, трихлорэтилена и хлорфенола, а также ионизированной гидроксильной группой - для фенолов. Адсорбция хлороформа зависит только от объёма пор и их доступности. Присутствие поверхностных кислородных соединений приводит к увеличению электростатического отталкивания для трихлорэтилена и донорно-акцепторного взаимодействия для...

Проведено исследование кинетики адсорбции трихлорэтилена из водных растворов на активных углях (АУ) марок СКД-515, ПФС, КсАУ, Пуролат-Стандарт. Изучен механизм массопереноса при адсорбции трихлорэтилена на АУ исследуемых марок. Построены кинетические кривые, характеризующие изменение величины адсорбции во времени. Кинетические кривые проанализированы в координатах «степень достижения равновесия γ от времени τ». Данные зависимости позволили выяснить модель структуры гранул АУ. Для системы «активный уголь - водный раствор трихлорэтилена» определено, что в интервале 7-40 мин лимитирующей стадией процесса адсорбции, в зависимости от свойств АУ, является внешняя диффузия. Рассчитаны коэффициенты внешнего массопереноса для исследуемых углей, их величины близки и имеют достаточно высокие значения, что указывает на высокую скорость сорбционного процесса лимитируемого внешним массопереносом. Получены данные, необходимые для инженерных расчётов параметров адсорбционной...

Introduction. Whey drinks, fruit nectars, and reconstituted juices are usually based on domestic water. This water may contain various contaminants, which can interact with vitamins in fruit drinks. The research objective was to study the impact of trichloromethane, hydroxybenzene, chlorophenol, trichloroethylene, and ethylene chloride on the state of vitamins in juice products. Study objects and methods. The study featured aqueous fruit and berry concentrates, used in fruit nectar production. The control sample contained water without contaminants, while the test samples involved trichloromethane, trichloroethylene, ethylene chloride, hydroxybenzene, and chlorophenol. Capillary zone electrophoresis made it possible to determine bioactive substances (vitamins) in aqueous fruit and berry concentrates. Molecular absorption spectroscopy in visible spectrum was used to check the color intensity. Gas chromatography helped to analyze the content of contaminants. Results and discussion. The experiment tested vitamin preservation in fruit nectars based on water contaminated with trichloromethane, trichloroethylene, ethylene chloride, hydroxybenzene, and chlorophenol. Trichloromethane did not react with bioactive substances. Trichloroethylene, ethylene chloride, hydroxybenzene, and chlorophenol lowered the content of ascorbic acid, carotene, thiamine, riboflavin, choline, and pyridoxine. Depending on the organic matter, water contamination led to a decrease in carotene by 7–35%, vitamin B1 – by 10–100%, B2 – by 11–100%, B4 – by 8–45%, and B6 – by 8–100 in the finished product. The paper introduces a theoretic substantiation of the interaction between the contaminants and the bioactive substances. Conclusion. Water, contaminated with such organic substances as hydroxybenzene, chlorophenol, trichloroethylene, and ethylene chloride, proved to affect the vitamin preservation in juices, which was illustrated by chemical equations. Therefore, juice production requires preliminary water purification because toxic and cancerogenic substances can decrease the quality and food safety of the finished product.