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<article article-type="research-article" dtd-version="1.3" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xml:lang="en"><front><journal-meta><journal-id journal-id-type="publisher-id">chemicallytech</journal-id><journal-title-group><journal-title xml:lang="en">Fine Chemical Technologies</journal-title><trans-title-group xml:lang="ru"><trans-title>Тонкие химические технологии</trans-title></trans-title-group></journal-title-group><issn pub-type="ppub">2410-6593</issn><issn pub-type="epub">2686-7575</issn><publisher><publisher-name>MIREA – Russian Technological University (RTU MIREA).</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="doi">10.32362/2410-6593-2020-15-4-59-70</article-id><article-id custom-type="elpub" pub-id-type="custom">chemicallytech-1633</article-id><article-categories><subj-group subj-group-type="heading"><subject>Research Article</subject></subj-group><subj-group subj-group-type="section-heading" xml:lang="en"><subject>ANALYTICAL METHODS IN CHEMISTRY AND CHEMICAL TECHNOLOGY</subject></subj-group><subj-group subj-group-type="section-heading" xml:lang="ru"><subject>АНАЛИТИЧЕСКИЕ МЕТОДЫ В ХИМИИ И ХИМИЧЕСКОЙ ТЕХНОЛОГИИ</subject></subj-group></article-categories><title-group><article-title>Shifts in the pKa value of acid–base indicators caused by immobilization on solid substrates via water-soluble polycationic polymers: a case study of Congo Red</article-title><trans-title-group xml:lang="ru"><trans-title>Смещение величины pKa  кислотно-основных индикаторов, вызванное иммобилизацией на твердой подложке за счет водорастворимого поликатионного полимера, на примере Конго Красного</trans-title></trans-title-group></title-group><contrib-group><contrib contrib-type="author" corresp="yes"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0001-8021-4591</contrib-id><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Наумова</surname><given-names>А. О.</given-names></name><name name-style="western" xml:lang="en"><surname>Naumova</surname><given-names>A. O.</given-names></name></name-alternatives><bio xml:lang="ru"><p>Наумова Алина Олеговна, аспирантка. Scopus Author ID 57191089401</p><p>119571, Россия, Москва, пр-т Вернадского, д. 86</p></bio><bio xml:lang="en"><p>Alina O. Naumova, Postgraduate Student. Scopus Author ID 57191089401</p><p>86, Vernadskogo pr., Moscow, 119571</p></bio><email xlink:type="simple">alina.naumova.92@bk.ru</email><xref ref-type="aff" rid="aff-1"/></contrib><contrib contrib-type="author" corresp="yes"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0001-8438-1952</contrib-id><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Мельников</surname><given-names>П. В.</given-names></name><name name-style="western" xml:lang="en"><surname>Melnikov</surname><given-names>P. V.</given-names></name></name-alternatives><bio xml:lang="ru"><p>Мельников Павел Валентинович, кандидат физико-математических наук, доцент. Scopus Author ID 18042368100, ResearcherID D-9773-2014</p><p>119571, Россия, Москва, пр-т Вернадского, д. 86</p></bio><bio xml:lang="en"><p>Pavel V. Melnikov, Cand. of Sci. (Physics and Mathematics), Assistant Professor. Scopus Author ID 18042368100, ResearcherID D-9773-2014</p><p>86, Vernadskogo pr., Moscow, 119571</p></bio><xref ref-type="aff" rid="aff-1"/></contrib><contrib contrib-type="author" corresp="yes"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0001-5196-5919</contrib-id><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Долганова</surname><given-names>Е. В.</given-names></name><name name-style="western" xml:lang="en"><surname>Dolganova</surname><given-names>E. V.</given-names></name></name-alternatives><bio xml:lang="ru"><p>Долганова Елена Вячеславовна, инженер</p><p>119571, Россия, Москва, пр-т Вернадского, д. 86</p></bio><bio xml:lang="en"><p>Elena V. Dolganova, Engineer</p><p>86, Vernadskogo pr., Moscow, 119571</p></bio><xref ref-type="aff" rid="aff-1"/></contrib><contrib contrib-type="author" corresp="yes"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0002-7709-4186</contrib-id><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Яштулов</surname><given-names>Н. А.</given-names></name><name name-style="western" xml:lang="en"><surname>Yashtulov</surname><given-names>N. A.</given-names></name></name-alternatives><bio xml:lang="ru"><p>Яштулов Николай Андреевич, доктор химических наук, профессор. Scopus Author ID 6507694451</p><p>119571, Россия, Москва, пр-т Вернадского, д. 86</p></bio><bio xml:lang="en"><p>Nikolai A. Yashtulov, Dr. of Sci. (Chemistry), Professor. Scopus Author ID 6507694451</p><p>86, Vernadskogo pr., Moscow, 119571</p></bio><xref ref-type="aff" rid="aff-1"/></contrib><contrib contrib-type="author" corresp="yes"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0003-4132-0097</contrib-id><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Зайцев</surname><given-names>Н. К.</given-names></name><name name-style="western" xml:lang="en"><surname>Zaitsev</surname><given-names>N. K.</given-names></name></name-alternatives><bio xml:lang="ru"><p>Зайцев Николай Конкордиевич, доктор химических наук, профессор, заведующий кафедрой.Scopus Author ID 57193485921</p><p>119571, Россия, Москва, пр-т Вернадского, д. 86</p></bio><bio xml:lang="en"><p>Nikolai K. Zaitsev, Dr. of Sci. (Chemistry), Professor. Scopus Author ID 5719348592</p><p>86, Vernadskogo pr., Moscow, 119571</p></bio><xref ref-type="aff" rid="aff-1"/></contrib></contrib-group><aff-alternatives id="aff-1"><aff xml:lang="ru"><institution>МИРЭА – Российский технологический университет (Институт тонких химических технологий имени М.В. Ломоносова)</institution><country>Россия</country></aff><aff xml:lang="en"><institution>MIREA – Russian Technological University (M.V. Lomonosov Institute of Fine Chemical Technologies)</institution><country>Russian Federation</country></aff></aff-alternatives><pub-date pub-type="collection"><year>2020</year></pub-date><pub-date pub-type="epub"><day>12</day><month>09</month><year>2020</year></pub-date><volume>15</volume><issue>4</issue><fpage>59</fpage><lpage>70</lpage><permissions><copyright-statement>Copyright &amp;#x00A9; Naumova A.O., Melnikov P.V., Dolganova E.V., Yashtulov N.A., Zaitsev N.K., 2020</copyright-statement><copyright-year>2020</copyright-year><copyright-holder xml:lang="ru">Наумова А.О., Мельников П.В., Долганова Е.В., Яштулов Н.А., Зайцев Н.К.</copyright-holder><copyright-holder xml:lang="en">Naumova A.O., Melnikov P.V., Dolganova E.V., Yashtulov N.A., Zaitsev N.K.</copyright-holder><license xml:lang="ru" license-type="creative-commons-attribution" xlink:href="https://creativecommons.org/licenses/by/4.0/" xlink:type="simple"><license-p>Данная работа распространяется под лицензией Creative Commons Attribution 4.0.</license-p></license><license xml:lang="en" license-type="creative-commons-attribution" xlink:href="https://creativecommons.org/licenses/by/4.0/" xlink:type="simple"><license-p>This work is licensed under a Creative Commons Attribution 4.0 License.</license-p></license></permissions><self-uri xlink:href="https://www.finechem-mirea.ru/jour/article/view/1633">https://www.finechem-mirea.ru/jour/article/view/1633</self-uri><abstract><sec><title>Objectives</title><p>Objectives. Herein, the effects of cationic polyelectrolytes on the properties of solid substrate immobilized acid–base indicators are investigated to predict shifts in their spectral patterns and characteristics.</p></sec><sec><title>Methods</title><p> Methods. The properties of the silica gel immobilized indicator dye in a solution of the cationic polyelectrolyte were studied using automatic photometric titration in the visible region and spectrophotometry using a specialized computerized setup.</p></sec><sec><title>Results</title><p> Results. The measured pKa value of the immobilized dye, which had shifted by three units to the acidic region, was very similar to the pKa value observed for the indicator in the modifying polymer solution. The observed change in pKa of the immobilized dye and the influence of the solution’s ionic strength were attributed to the local electric potential of the polymer globule. In contrast to the processes associated with covalent immobilization, the effect exerted by the solution’s ionic strength on the indicator reaction diminishes, which, in turn, affects the measured values obtained.</p></sec><sec><title>Conclusions</title><p>Conclusions. The creation of a sensor for continuous visualization of pH levels based on Congo Red immobilized on silica gel was described. Here, a color transition was noted between pH 1 and 4. These materials can be used to monitor metal extraction processes from industrial effluents or to optimize the extraction of valuable actinides. The approach demonstrated in this work can be applied to immobilize other indicators for pH level monitoring purposes or the production of sensors for other analytes.</p></sec></abstract><trans-abstract xml:lang="ru"><sec><title>Цели</title><p>Цели. Целью настоящей работы было изучение влияния катионного полиэлектролита на свойства кислотно-основных индикаторов при их иммобилизации на твёрдой подложке и установление закономерностей сдвига их спектральных и кислотно-основных характеристик.</p></sec><sec><title>Методы</title><p> Методы. Свойства индикатора в растворе катионного полиэлектролита и иммобилизованного на поверхности силикагеля изучали методами автоматизированного фотометрического титрования в видимой области, спектрофотометрии и с помощью специализированного компьютеризированного стенда.</p></sec><sec><title>Результаты</title><p> Результаты. Измеренное значение рКа красителя при закреплении на силикагеле смещается на 3 единицы в кислую область и близко к значению рКа для индикатора в растворе модифицирующего полимера. Наблюдаемое изменение величины рКа при иммобилизации и влияние ионной силы раствора объясняются с точки зрения влияния локального электрического потенциала полимерной глобулы. В отличие от ковалентной иммобилизации, уменьшается влияние ионной силы раствора на индикаторную реакцию, и оно может быть легко учтено при измерениях.</p></sec><sec><title>Выводы</title><p>Выводы. Показана принципиальная возможность создания датчика для непрерывного визуального контроля рН на основе Конго Красного, иммобилизованного на силикагеле с переходом цвета в интервале 1–4 pH. Такой материал может использоваться для контроля в процессах извлечения металлов из промышленных стоков или для оптимизации извлечения ценных актинидов. Продемонстрированный в настоящей работе подход может быть применен для иммобилизации других индикаторов, как для обеспечения измерения в других диапазонах pH, так и для создания сенсоров на другие аналиты.</p></sec></trans-abstract><kwd-group xml:lang="ru"><kwd>иммобилизация индикаторов</kwd><kwd>кислотно-основные индикаторы</kwd><kwd>оптические сенсоры pH</kwd><kwd>Конго Красный</kwd><kwd>органические красители</kwd></kwd-group><kwd-group xml:lang="en"><kwd>immobilization of indicators</kwd><kwd>acid–base indicators</kwd><kwd>optical pH sensors</kwd><kwd>Congo Red</kwd><kwd>organic dyes</kwd></kwd-group><funding-group><funding-statement xml:lang="ru">Работа выполнена в рамках государственного задания Российской Федерации № 13.3140.2017 / ПЧ</funding-statement><funding-statement xml:lang="en">This study was supported by the Russian Federation under grant no. 13.3140.2017/PCh. This article has been translated from Russian into English by N. 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