scholarly journals New Electrodes Prepared from Mineral and Plant Raw Materials of Kazakhstan

2016 ◽  
Vol 18 (2) ◽  
pp. 141 ◽  
Author(s):  
A.A. Atchabarova ◽  
R.R. Tokpayev ◽  
A.T. Kabulov ◽  
S.V. Nechipurenko ◽  
R.A. Nurmanova ◽  
...  

<p>Electrode materials were prepared from activated carbonizates of walnut shell, apricot pits and shungite rock from “Bakyrchik” deposit, East Kazakhstan. Physicochemical characteristics of the obtained samples were studied by the Brunauer-Emett-Taylor method, scanning electron microscopy, Raman spectroscopy and other methods. Electrochemical properties of the obtained materials were studied by the method of cyclic voltammetry. It was found that the samples have an amorphous structure. Samples based on plant raw materials after hydrothermal carbonization at 240 °С during 24 h, have more homogeneous and developed surface. Specific surface area of carbon containing materials based on apricot pits is 1300 m<sup>2</sup>/g, for those on the based on mineral raw material, it is 153 m<sup>2</sup>/g. It was shown that materials after hydrothermal carbonization can be used for catalytic purposes and electrodes after thermal carbonization for analytical and electrocatalytic purposes. Electrode obtained by HTC have electrocatalytic activity. CSC 240 has high background current (slope i/Е is 43 mА V<sup>–1</sup> cm<sup>–2</sup>), low potential of the hydrogen electroreduction (more positive by ~ 0.5 V than samples based on plant raw materials). The reaction of DA determination is more pronounced on the electrodes obtained by HTC 240 °C, 24 h, due to the nature, carbon structure and high specific surface area of obtained samples.</p>

2020 ◽  
pp. 17-24
Author(s):  
Dmitriy Aleksandrovich Yelatontsev ◽  
Elena Vladimirovna Ivanyuk

The paper presents the of influence peroxide ammonium, alkali, nitric acid, organosolvent and "aqueous ammonia soaking" (AAS) delignification methods on the degree of removal of lignin from non-wood lignocellulosic waste walnut shell Juglans Regia L. and apricot seed Prunus Armeniaca L. It is shown that the maximum degree of delignification (94%) is achieved when processing raw materials with 42 wt% HNO3 and 20 wt% NaOH; the minimum is at peroxide-ammonia treatment (80%). We found that the greatest specific surface area (202 m2∙g-1) provided by the application 42 wt% HNO3, and a maximum iodine number (32 mg∙g-1) when using 25 wt% NH4OH. Delignification significantly increases the specific surface area (5 m2∙g-1 to 120–200 m2∙g-1) iodine number (6.35 mg∙g-1 to 25 to 32 mg∙g-1) of biomass, however, at 45–55% reduced exchange capacity of the material. The obtained cellulose intermediates having acceptable physical and chemical characteristics can be used for further preparation of available sorbents or ion exchange materials. In accordance with the principles of "green chemistry", it is proposed to dispose the spent delignification solutions from AAS and nitric acid methods in liquid nitrogen fertilizers producing.


2021 ◽  
Vol 104 (4) ◽  
pp. 95-103
Author(s):  
S. Abdimomyn ◽  
◽  
D. Abduakhytova ◽  
A. Atchabarova ◽  
G.L. Turdean ◽  
...  

Nowadays, a strategy for the utilization of secondary resources to obtain valuable components is actual. It will lead to the most rational use of natural resources and environmental protection. Electrochemical methods are perfectly applicable to solve this problem. Electrochemical methods allow concentrating of the target components without preliminary preparation of the raw material. Carbon materials (CM) based on plant and carbon-mineral raw materials are an excellent option as a matrix for obtaining the electrodes, due to their availability, low cost, high specific surface area, and the presence of different functional groups. The lack of theoretical substantiation of the adsorption phenomena on carbon electrodes served as an incentive for the study and development of a method for obtaining a mechanically strong electrode based on modified carbon and polyethylene. The design and mechanical strength of carbon electrodes (CE) are of great importance for the efficiency of purification and extraction of valuable components. In this article, we obtained carbon mate- rial from walnut shells by hydrothermal carbonization with further steam-gas activation (the specific surface area is 754.0 m2/g). The structural, physicochemical characteristics of the carbon material, binder, and carrier material were studied by the following methods: scanning electron microscope (SEM), Brunauer–Emmett–Teller (BET), thermogravimetric analysis and differential scanning calorymetry (TGA-DSC). The method of hot-pressing is applied for obtaining the carbon electrodes. Using the method of full-factor experiment and steepest ascent, the values of pressure and temperature during pressing and the ratio of carbon material: binder was optimized: P = 226 atm; T = 90.8 °C; carbon material: binder ratio = 67.5:32.5 %, respectively


Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 173
Author(s):  
Velma Beri Kimbi Yaah ◽  
Satu Ojala ◽  
Hamza Khallok ◽  
Tiina Laitinen ◽  
Marcin Selent ◽  
...  

This paper presents results related to the development of a carbon composite intended for water purification. The aim was to develop an adsorbent that could be regenerated using light leading to complete degradation of pollutants and avoiding the secondary pollution caused by regeneration. The composites were prepared by hydrothermal carbonization of palm kernel shells, TiO2, and W followed by activation at 400 °C under N2 flow. To evaluate the regeneration using light, photocatalytic experiments were carried out under UV-A, UV-B, and visible lights. The materials were thoroughly characterized, and their performance was evaluated for diclofenac removal. A maximum of 74% removal was observed with the composite containing TiO2, carbon, and W (HCP25W) under UV-B irradiation and non-adjusted pH (~5). Almost similar results were observed for the material that did not contain tungsten. The best results using visible light were achieved with HCP25W providing 24% removal of diclofenac, demonstrating the effect of W in the composite. Both the composites had significant amounts of oxygen-containing functional groups. The specific surface area of HCP25W was about 3 m2g−1, while for HCP25, it was 160 m2g−1. Increasing the specific surface area using a higher activation temperature (600 °C) adversely affected diclofenac removal due to the loss of the surface functional groups. Regeneration of the composite under UV-B light led to a complete recovery of the adsorption capacity. These results show that TiO2- and W-containing carbon composites are interesting materials for water treatment and they could be regenerated using photocatalysis.


Author(s):  
Т.В. САВЕНКОВА ◽  
М.А. ТАЛЕЙСНИК ◽  
Н.А. ЩЕРБАКОВА ◽  
С.Ю. МИСТЕНЕВА ◽  
И.И. МИЗИНЧИКОВА

Описаны и теоретически обоснованы разработанные технологические приемы производства мучных кондитерских изделий при сохранении влаги на всех стадиях производства. В рамках исследования решали следующие задачи: увеличение удельной поверхности частиц дисперсной фазы эмульсии за счет моделирования рецептурного состава; дезагрегирование муки, повышение равномерности распределения дисперсионной среды (эмульсии) с образованием оболочек вокруг максимально возможного количества частиц муки различных фракций. Объектом для моделирования рецептурного состава было сахарное печенье. Установлено, что замена рецептурных компонентов с повышенной влажностью на сырье с высоким содержанием сухих веществ позволяет высвободить влагу и использовать новые виды сырья с повышенными нативными свойствами. Предложенные приемы подготовки сырьевых компонентов: снижение вязкости солодового экстракта, используемого для снижения количества сахара-песка, осмотическое набухание яичного порошка, пластикация жира со стабилизацией его структуры лецитином, инверсия сахарозы в условиях совмещения гидродинамического и акустического кавитационных воздействий при получении инвертного сиропа – обеспечивают благоприятные условия получения эмульсии с повышенной удельной поверхностью. Отличительной особенностью предлагаемой технологии является получение эмульсии в две стадии: приготовление суспензии без жира и собственно получение эмульсии. Раздельная подача сахара в два приема: 40–60% его рецептурного количества вносится на стадии приготовления суспензии, оставшаяся часть – при приготовлении эмульсии – и кавитационная обработка суспензии при температуре 36–38°С и частоте колебаний волновода 24 кГц позволяют повысить частичную концентрацию частиц сахара в 8–12 раз. При приготовлении эмульсии пластицированный жир и лецитин предварительно смешивают с оставшейся частью сахара-песка, а затем с суспензией. Дезагрегированную путем аэрации муку и эмульсию одновременно и параллельно подают в месильную машину для достижения их заданного соотношения до начала процесса тестообразования. Разработанный комплекс технологических приемов позволил создать технологический поток производства сахарного печенья с улучшенными показателями качества – намокаемостью до 230% (по классической технологии 180–200%), сниженной на 20% плотностью, повышенными пористостью и рассыпчатостью и сохраняющего до 92% влажности, что на 18% выше, чем в изделиях, полученных по классической технологии. The developed technological techniques for the production of flour confectionery products while maintaining moisture at all stages of production are described and theoretically justified. The following tasks were solved in the framework of the study: increasing the specific surface area of the particles of the dispersed phase of the emulsion by modeling the recipe composition; disaggregating flour, increasing the uniformity of the distribution of the dispersion medium (emulsion) with the formation of shells around the maximum possible number of flour particles of various fractions. The object for modeling the formulation composition was sugar cookies. It is established that the replacement of prescription components with high humidity with raw materials with a high content of dry substances allows you to release moisture and use new types of raw materials with increased native properties. The proposed methods of preparation of raw materials: reducing the viscosity of malt extract used to reduce the amount of granulated sugar, osmotic swelling of egg powder, fat plasticization with the stabilization of its structure with lecithin, sucrose inversion under conditions of combining hydrodynamic and acoustic cavitation effects in the production of invert syrup – provide favorable conditions for obtaining an emulsion with an increased specific surface area. The production of an emulsion in two stages is a distinctive feature of the proposed technology: the preparation of a suspension without fat and the actual production of the emulsion. Separate supply of sugar in two steps: 40–60% of its prescription amount is introduced at the stage of preparation of the suspension, the remaining part – during the preparation of the emulsion – and cavitation treatment of the suspension at a temperature of 36–38°С and the waveguide oscillation frequency of 24 kHz, it is possible to increase the partial concentration of sugar particles by 8–12 times. When preparing the emulsion, the plasticized fat and lecithin are pre-mixed with the remaining part of the granulated sugar, and then with the suspension. The aeration-disaggregated flour and emulsion are fed simultaneously and in parallel to the kneading machine to achieve their desired ratio before the dough-forming process begins. The developed complex of technological techniques allowed to create a technological flow for the production of sugar cookies with improved quality indicators – wetting up to 230% (according to the classical technology 180–200%), reduced density by 20%, increased porosity and friability, and preserving up to 92% humidity, which is 18% higher than in products obtained by the classical technology.


2011 ◽  
Vol 356-360 ◽  
pp. 1900-1908 ◽  
Author(s):  
Juliana De Carvalho Izidoro ◽  
Denise Alves Fungaro ◽  
Shao Bin Wang

A Brazilian fly ash sample (CM1) was used to synthesize zeolites by hydrothermal treatment. Products and raw materials were characterized in terms of real density (Helium Pycnometry), specific surface area (BET method), morphological analysis (SEM), chemical composition (XRF) and mineralogical composition (XRD). The zeolites (ZM1) from fly ash were used for metal ion removal from water. Results indicated that hydroxy-sodalite zeolite could be synthesized from fly ash sample. The zeolite presented higher specific surface area and lower SiO2/Al2O3ratio than the ash precursor. The adsorption showed that cadmium is more preferentially adsorbed on ZM1 than zinc. The adsorption equilibrium time for both Zn2+and Cd2+was 20 hours in a batch process. The adsorption isotherms were better fitted by the Langmuir model and the highest percentages of removal using ZM1 were obtained at pH 6 and 5 and doses of 15 and 18 g L-1for Zn2+and Cd2+, respectively. Thermodynamic studies indicated that adsorption of Zn2+and Cd2+by ZM1 was a spontaneous, endothermic process and presented an increase of disorder at the interface solid/solution.


2010 ◽  
Vol 636-637 ◽  
pp. 124-129 ◽  
Author(s):  
D.G. Pinto ◽  
Abílio P. Silva ◽  
A.M. Segadaes ◽  
T.C. Devezas

Alumina, with high melting point (2050°C), high hardness and mechanical strength, and excellent abrasion resistance, is one of the most common raw materials used in self-flow refractory castables (SFRC) for monolithic linings and is commercially available in various fine to coarse size classes. However, the performance of the refractory lining depends not only on the properties of its ingredients but also on its easy installation (good flowability). The aim of this work was to evaluate the relationship between the flowability index (FI) of fresh castable and the specific surface area (SSA) of its particles, which is mostly determined by the finer particles content. The results obtained showed that, by controlling the proportion between matrix and aggregate, it is possible to control the SSA of the refractory castable and find a mathematical relationship between the specific surface area and the minimum flowability index required to obtain a self-flow refractory castable. It is, thus, possible to optimize the refractory castable size composition and obtain an estimate for FI as a function of SSA. Using a minimum 45 wt.% matrix content in the castable mixture, a SSA value above 2.215 m2/g is obtained, which leads to FI ≥ 80%, the recommended value for self-flow.


Author(s):  
N. P. Shabelskaya ◽  
M. A. Egorova ◽  
G. M. Chernysheva ◽  
A. N. Saliev ◽  
A. N. Yatsenko ◽  
...  

Scientific interest in the processes of forming the structure of magnetic spinels and composites based on them is due to the possibility of synthesis of materials with multifunctional properties. The process of formation of cobalt (II) nanocrystalline ferrite and CoFe2O4/C composite material is studied. The mechanism of formation of structure of materials including a stage of formation of hydroxides of transition elements, precursors on the basis of complex connections of cations of iron and cobalt with citric acid and their subsequent destruction at heating is offered. The synthesized materials were characterized by x-ray phase analysis, electron microscopy, low-temperature nitrogen adsorption, Debye-Scherrer methods. It is shown that cobalt (II) ferrite has a developed surface, the value of the surface area according to the BET method is 16 m2/g, the average size of the crystallites determined by the Debye-Scherrer equation is 4.0 nm. Activated carbon with a specific surface area of 685 m2/g was used to prepare the composite material. The resulting composite material has a surface area of 222 m2/g, the average crystallite size of 1.1 nm. Cobalt (II) ferrite, included in the composition of the composite material CoFe2O4/C, has a slightly higher value of the lattice parameter, compared with pure cobalt (II) ferrite, which is associated with a decrease in the degree of spinel inversion. The synthesized composite material was tested in the process of adsorption of copper (II) cations from an aqueous solution. It is shown that CoFe2O4/C exhibits an increased adsorption capacity for copper (II) cations in comparison with pure activated carbon, despite a decrease in the specific surface area. The result is explained by the involvement of cobalt (II) ferrite in the adsorption process. The obtained materials may be of interest as catalysts, adsorbents.


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