Preparation and Adsorption Properties of Rod MgNiAl-LDH

2019 ◽  
Vol 956 ◽  
pp. 294-304
Author(s):  
Guo Jun Ke ◽  
Hong Jun Tan ◽  
Peng Fei Yang ◽  
Pin Yu Zou

Using magnesium nitrate, nickel nitrate and aluminum nitrate as raw materials and urea as precipitant, magnesium nickel aluminum ternary hydrotalcites with large specific surface area were prepared by hydrothermal method. The prepared samples were characterized by SEM、XRD、BET and EDS etc., respectively. The adsorption properties of MgNiAl-LDHs, MgAl-LDHs and their calcined products (MgNiAl-LDOs, MgAl-LDOs) for chloride ions in solution were investigated. The results show that MgNiAl-LDHs are cubic with rod-like structure, with a specific surface area of 197.62 m2/g, which is much larger than that of MgAl-LDHs (102.82 m2/g). Under the same adsorption conditions, the saturated adsorption capacities of MgNiAl-LDHs and MgAl-LDHs for chloride ions are 130.06mg/g and 110.02 mg/g respectively. MgNiAl-LDOs showed better adsorption ability for chloride ions. By simulating the adsorption data, the results show that the adsorption kinetics and the adsorption isotherm are in accordance with the quasi-second-order kinetic model and the Langmuir isotherm model, respectively.

2019 ◽  
Vol 956 ◽  
pp. 305-313
Author(s):  
Guo Jun Ke ◽  
Zhou Zhou ◽  
Peng Fei Yang ◽  
Bai Xing Song

Magnesium-aluminum hydrotalcite and carbon nanotube composites (CNTs/MgAl-LDHs) were prepared by one-step hydrothermal method using magnesium nitrate, aluminum nitrate and carbon nanotubes as raw materials and urea as precipitant. The samples were characterized by SEM, XRD, BET and other methods. The adsorption properties of CNTs/MgAl-LDHs on chloride ions and the factors affecting the adsorption of chloride ions were studied. The results show that the prepared CNTs/MgAl-LDHs exhibit a three-dimensional honeycomb structure with a specific surface area of 103.019 m2/g, which is larger than the specific surface area of MgAl-LDHs of 84.344 m2/g. The results showed that the optimal adsorption conditions were: adsorption temperature was 45°C, the pH value was 8, the adsorption time was 100 min, the Cl- concentration was 0.01 M (584 mg/L), and the adsorbent concentration was 1.0 g/L. CNTs/MgAl-LDHs has the best adsorption performance for chloride ions. The maximum adsorption capacity is 75.58 mg/g. The adsorption isotherms and adsorption kinetics are consistent with the Langmuir isotherm model and the quasi-secondary kinetic model.


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.


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>


2019 ◽  
Vol 72 (9) ◽  
pp. 717
Author(s):  
Junying Song ◽  
Zhanbin Huang ◽  
Fengzhi Yang

Excess pentavalent vanadium(v) has severely degraded water quality and posed a huge threat to human health over the past several decades. Hence, it’s urgent and significant to explore a novel adsorbent which is low cost and efficient to treat vanadium pollution. In this work, a novel iron-manganese oxide@diatomite (MnFe2O4@DE) adsorbent with superior removal performance for simulated vanadium(v) wastewater was synthesised via a facile hydrothermal method. The as-prepared MnFe2O4@DE composite was characterised through different characterisation techniques. The results indicated that the MnFe2O4 nanoparticles were uniformly deposited on the surface of diatomite, resulting in a larger specific surface area and pore volume of the composite. In addition, the MnFe2O4@DE adsorbent exhibited the highest adsorption capacity for vanadium(v) (18.37mgg−1±0.5%), which was up to around 13.24 and 1.33 times as much as that of pure diatomite and MnFe2O4, respectively. This is mainly attributed to the enhanced specific surface area and pore volume. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis demonstrated vanadium(v) could be reduced to low valence vanadium with low toxicity by the MnFe2O4@DE composite which could exist as VO2+ and VO+ cations in solution. The adsorption process was better fitted with a pseudo-second-order kinetic model and Langmuir model, which is spontaneous and endothermic. Overall, the novel MnFe2O4@DE composite could be applied as a promising adsorbent in addressing vanadium pollution issues due to its properties of low cost, effectiveness, and environmental friendliness.


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.


2014 ◽  
Vol 12 (4) ◽  
pp. 715-721 ◽  
Author(s):  
Ying Duan ◽  
Chenchen Wang ◽  
Xuede Li ◽  
Wei Xu

The study describes the removal of fluoride from drinking water using activated alumina (AA). AA was modified with H2SO4, FeCl3 and a combination of the two to enhance fluoride adsorption. The AA adsorbents were characterized using Brunauer–Emmett–Teller surface area analysis and X-ray fluorescence. The maximum adsorption capacity of H2SO4- and FeCl3-modified AA adsorbents was 4.98 mg/g, which is 3.4 times higher compared with that of normal AA. The results showed that the surface area of AA increased when modified with H2SO4. AA modified with FeCl3 enhanced fluoride adsorption ability through ion-exchange between chlorine ions and fluoride ions. The fluoride adsorption properties of AA modified with both H2SO4 and FeCl3 were consistent with the Langmuir model. The fluoride adsorption kinetics of the adsorbents were well described by the pseudo-second-order kinetic model.


2021 ◽  
Vol 9 ◽  
Author(s):  
Yongmei Wang ◽  
Tiantian Chen ◽  
Xiaolin Zhang ◽  
Teza Mwamulima

Zero valent iron (ZVI) particles were embedded into porous materials to avoid aggregation and separation problems in the controlled synthesis process. To investigate the adsorption mechanism of crystal violet and methylene blue, activated carbon (AC) and AC-based ZVI extraction by solid-phase and liquid-phase reduced approaches was conducted. Characterization methods of specific surface area, scanning electron microscopy (SEM), and x-ray diffractograms (XRD) were used to elucidate the structure of adsorbents, and the adsorption capacities of crystal violet and methylene blue were obtained under experimental conditions of various pH values (2.0–10.0), adsorption times (0–72 h), and temperatures (30–50°C). The adsorption of crystal violet/methylene blue was controlled by both chemisorption and reduction. The adsorption processes were fitted to a pseudo-second-order kinetic model, and that of reduction kinetics was suitable to pseudo-first-order kinetic model. The thermodynamic study revealed that the adsorption of crystal violet and methylene blue was endothermic and spontaneous, and the adsorption isotherms fitted well to the Langmuir model. Different adsorption capacities of crystal violet and methylene blue on various adsorbents were found, indicating that both the properties of adsorbents (pore size, specific surface area, and chemical functional groups) and the structures of adsorbates had significant effect on the removal of dye molecules.


2012 ◽  
Vol 600 ◽  
pp. 178-181 ◽  
Author(s):  
Kun Wang ◽  
Qiao Wen Yang ◽  
Chuan Liu ◽  
Hui Zhao ◽  
Gan Chen ◽  
...  

Coke fines and semi-cokes have high ash content, low specific surface area and pore volume. In order to increase the properties of the sample and make the activated composite materials, it must be deashed and activated. In this research, the deashing experiment of the raw materials by different concentration of HNO3 and KOH was tested, then the material was activated in high temperature steam. From the FTIR test, we can acquire the content of the surface functional groups, such as carboxyl and hydroxyl. The specific surface area, pore size, volume of the material were determinated by using the N2 isothermal adsorption. From the experiments of acid and alkali treatment, we can conclude that the optimal technological condition of the material: the concentration 20% of alkali and acid treatment processing. The ash content is decreased to 8%. The acid functional groups increased rapidly after HNO3 treatment. The activated coke fines have mainly mesopores and its proportion of microspore is low. The specific surface area of the activated material reached 80m2/g and increased about 5 times than that of raw materials.


2015 ◽  
Vol 44 (16) ◽  
pp. 7419-7427 ◽  
Author(s):  
Wanjun Mu ◽  
Mei Li ◽  
Xingliang Li ◽  
Zongping Ma ◽  
Rui Zhang ◽  
...  

The hexagonal WO3 nanowires prepared with the assistance of C2H10N·H2SO4 possess a large specific surface area and numerous adsorption functional groups, consequently improving the Sr2+ adsorption capacity considerably.


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