Study of cytotoxicity performance of carbon nanohorns by method of spin probes

The effects of as-produced and treated by HNO3(3M) carbon nanohorns on the microviscosity of rat erythrocyte membranes and the viscosity of the water-containing plasma protein matrix were investigated by the method of spin probes. Addition of nanohorns at the concentration of 100 μg/ml to a suspension of erythrocytes led to an increase in membrane microviscosity during 4 h (about 60% effect). In addition, it was shown that nanohorns also induced an increased polarity of the microenvironment for lipophilic probes in the outer layer of membrane phospholipids, as well as disorders in erythrocytes membranes. Addition of nanohorns to plasma led to a little decrease in the viscosity of water and protein matrix, apparently, due to its partial destruction, impacting especially albumin. Pristine and treated by HNO3(3M) acid nanohorns was found more cytotoxic than nanoparticles of oxidized graphene, and significantly less than carbon nanotubes, which are known to dramatically increase the microviscosity of the membranes of erythrocytes and disrupt their integrity

Оптимизация технологии получения комбинированных целлюлозно-неорганических сорбентов для концентрирования радиоактивного цезия

Статтю присвячено оптимізації умов синтезу селективних до радіоактивного цезію комбінованих поглинальних матеріалів на основі целюлозного волокна і фероціаніду міді. Досліджено вплив параметрів модифікування волокна на вміст модифікатора в об’ємі органічного носія і на сорбційні характеристики продуктів. За результатами математичної обробки отриманих експериментальних даних одержано адекватні статистичні моделі процесу модифікування вибіленого бавовняного волокна розчинами фероціаніду міді за різних значень рН середовища та температури процесу. Визначено оптимальні значення технологічних параметрів процесу з використанням функції бажаності Харрінгтона. Показано, що оптимальними параметрами процесу модифікування, що забезпечують одержання ефективних сорбентів з вмістом фероціаніду міді в об’ємі носія 4,37 %, які характеризуються ступенем вилучення цезію з водних розчинів 95,14 % та коефіцієнтом розподілення 7501 мл/г, є рН середовища 5,4 та температура 90 °С. Однак оптимальні питомі сорбційні властивості сорбентів (питомі ступінь вилучення цезію 35,76 %/г та коефіцієнт розподілення 2236 (мл/г)/г) досягаються при вмісті модифікатора в сорбенті 2,71 %, який одержують при рН 7,8 та температурі 90 °С.In this article the optimization of the synthesis conditions of combined sorption materials based on cellulose fiber and copper ferrocyanide selective toward radioactive cesium. The influence of the parameters of modification process on the modifier in the bulk of organic carrier content and sorption characteristics of products was investigated. According to the results of mathematical processing of the experimental data the adequate statistical model of the modification of bleached cotton fiber with the solutions of copper ferrocyanide at different values of pH and temperature of the process were obtained. The optimal values of the technological parameters were determined using Harrington's desirability function. It was shown that the optimum parameters of the modification process allowing to obtain an effective sorbents with the content of copper ferrocyanide 4.37 % in the volume of the carrier, which are characterized by a recovery rate of cesium from aqueous solutions of 95.14 % and the distribution coefficient of 7501 ml/g, are pH 5.4 and temperature 90 °C. However, the optimal specific sorption properties (specific recovery rate of cesium 35.76 %/g and a distribution coefficient 2236 (ml/g)/g) is achieved when the modifier content is 2.71 % in a sorbent which is prepared at pH 7.8 and 90 °C.Статья посвящена оптимизированию условий синтеза селективных к радиоактивному цезию комбинированных поглощающих материалов на основе целлюлозного волокна и ферроцианида меди. Исследовано влияние параметров модифицирования волокна на содержание модификатора в объеме органического носителя и на сорбционные характеристики продуктов. По результатам математической обработки экспериментальных данных получены адекватные статистические модели процесса модифицирования беленого хлопкового волокна растворами ферроцианида меди при разных значениях рН среды и температуры процесса. Определены оптимальные значения технологических параметров процесса с использованием функции желательности Харрингтона. Показано, что оптимальными параметрами процесса модифицирования, обеспечивающими получение эффективных сорбентов с содержанием ферроцианида меди в объеме носителя 4,37 %, которые характеризуются степенью извлечения цезия из водных растворов 95,14 % и коэффициентом распределения 7501 мл/г, является рН среды 5,4 и температура 90 °С. Однако оптимальные удельные сорбционные свойства материалов (удельные степень извлечения цезия 35,76 %/г и коэффициент распределения 2236 (мл/г)/г) достигаются при содержании модификатора в сорбенте 2,71 %, который получают при рН 7,8 и температуре 90 °С

New Composite Sorbents for Caesium and Strontium Ions Sorption

Composite lignocellulose-inorganic sorbents derived from plant residues of agriculture and food industry, modified with ferrocyanides of d-metals and hydrated antimony pentoxide were prepared. Caesium and strontium ions removal from water was tested by radiotracer method. Sorption of heavy metal ions, methylene blue, gelatin, vitamin B12 was also studied

Combined and hybrid adsorbents: fundamentals and applications

Proceedings of the NATO Advanced Research Workshop on Combined and Hybrid Adsorbents: Fundamentals and Applications, Kiev, Ukraine, 15-17 September 2005

Thermal Transformation of Caffeic Acid on the Nanoceria Surface Studied by Temperature Programmed Desorption Mass-Spectrometry, Thermogravimetric Analysis and FT–IR Spectroscopy

The studies of pyrolysis of caffeic acid (CA) and its surface complexes is important for the development of technologies of heterogeneous catalytic pyrolysis of plant- and wood- based renewable biomass components. In this work, the structure and thermal transformations of the surface complexes of CA on the surface of nanoceria were investigated using Fourier transform–infrared (FT–IR) spectroscopy, thermogravimetric analysis (TGA) and temperature-programmed desorption mass spectrometry (TPD MS). It was found that CA on the surface of cerium dioxide forms several types of complexes: bidentate carboxylates, monodentate carboxylates and complexes formed as a result of interaction with phenolic hydroxyl groups. This is due to the ability of nanosized cerium dioxide to generate basic hydroxyl groups that can deprotonate phenolic groups to form phenolates on the surface. The main pyrolysis products were identified. The possible ways of forming 3,4-dihydroxyphenylethylene, acetylene carboxylic acid, pyrocatechol and phenol from surface complexes of CA were suggested. It was established that on the nanoceria surface effectively occur the decarboxylation, decarbonylation, and dehydration reactions of the CA, which are the desirable processes in biomass conversion technologies

BENZOYL PEROXIDE DECOMPOSITION BY NITROGEN-CONTAINING CARBON NANOMATERIALS

The catalytic activities of nanoporous carbon materials, their modified forms and enzyme catalase was determined by calculation of Michaelis constants according to the kinetics of substrate decomposition. It is found that the catalytic activity of studied samples correlated with surface basicity and presence of quaternary nitrogen groups in structure

Decarboxylation of <i>p</i>-Coumaric Acid during Pyrolysis on the Nanoceria Surface

Temperature-programmed desorption mass spectrometry (TPD MS) was used to study the pyrolysis of p-coumaric acid (pCmA) on the nanoceria surface. The interaction of pCmA with the CeO2 surface was investigated by FT-IR spectroscopy. The obtained data indicated the formation on the nanoceria surface of bidentate carboxylate complexes with chelate (Δν = 62 cm−1) and bridge structure (Δν = 146 cm−1). The thermal decomposition of pCmA over nanoceria occurred in several stages, mainly by decarboxylation. The main decomposition product is 4-vinylphenol (m/z 120). The obtained data can be useful for studying the mechanisms of catalytic thermal transformations of lignin-containing raw materials using catalysts containing cerium oxide and the development of effective technologies for the isolation of pCmA from lignin

Catalytic Pyrolysis of Lignin Model Compounds (Pyrocatechol, Guaiacol, Vanillic and Ferulic Acids) over Nanoceria Catalyst for Biomass Conversion

Understanding the mechanisms of thermal transformations of model lignin compounds (MLC) over nanoscale catalysts is important for improving the technologic processes occurring in the pyrolytic conversion of lignocellulose biomass into biofuels and value-added chemicals. Herein, we investigate catalytic pyrolysis of MLC (pyrocatechol (P), guaiacol (G), ferulic (FA), and vanillic acids (VA)) over nanoceria using FT-IR spectroscopy, temperature-programmed desorption mass spectrometry (TPD MS), and thermogravimetric analysis (DTG/DTA/TG). FT-IR spectroscopic studies indicate that the active groups of aromatic rings of P, G, VA, and FA as well as carboxylate groups of VA and FA are involved in the interaction with nanoceria surface. We explore the general transformation mechanisms of different surface complexes and identify their decomposition products. We demonstrate that decomposition of carboxylate acid complexes occurs by decarboxylation. When FA is used as a precursor, this reaction generates 4-vinylguaiacol. Complexes of VA and FA formed through both active groups of the aromatic ring and decompose on the CeO2 surface to generate hydroxybenzene. The formation of alkylated products accompanies catalytic pyrolysis of acids due to processes of transalkylation on the surface

Secondary structure of muramyl dipeptide glycoside in pristine state and immobilized on nanosilica surface

Fourier transform infrared spectroscopy (FT-IR) and temperature programmed desorption mass spectrometry (TPD-MS) data of O-glycoside MDP in pristine and immobilized on silica surface states indicate that O-glycoside MDP binds to the silica surface by means of carboxylic and NH moieties of isoglutamine. Moreover, pyrolysis of O-glycoside MDP on the silica surface proceeds through formation of additional product 3-iminopyridine-2(3H)-one, which identified in mass spectra as molecular ion with m/z 108 and its fragment ions with m/z 79, 77, 51. FTIR and TPD-MS data confirm existence of a MDP first β-turn on the silica surface resulting from the formation of a hydrogen bond between the NAc carbonyl and the L-Ala NH for MDP and its analogs, as reported previously

The Influence of Carbon Nanotubes on the Physical and Chemical Properties of Nanocomposites Based on Unsaturated Polyester Resin

The new actual scientific direction is in the development of different nanocomposites and the study of their medical–biological, physicochemical, and physicomechanical properties. One way to expand the functionality of nanocomposites and nanomaterials is to introduce carbon nanostructures into the polymer matrix. This study presents the properties of unsaturated polyester resins (Estromal, LERG S.A.) based on PET recyclate with multi-walled carbon nanotubes (MWCNTs): their mechanical and thermomechanical characteristics, resistance to ultraviolet radiation (UV-vis), and chemical resistance properties. The properties of the obtained materials were characterized using physical–chemical research methods. The changes in the properties of the composites for MWCNT content of 0.1, 0.3, and 0.5 wt % were determined. The results showed positive influences on the thermomechanical and mechanical properties of nanocomposites without significant deterioration of their gloss. Too much CNT added to the resin leads to heterogeneity of the composite structure