scholarly journals Synthesis of molybdenum and tungsten modified composite systems based on bisorbent from rice husk

Author(s):  
Duisek Kamysbaev ◽  
Bazarbai Serikbaev ◽  
Galina Arbuz

The article presents results of the synthesis of a new composite material modified with polyvalent metals. Rice husk was chosen as a raw material for obtaining a carrier – a bisorbent consisting of carbon and amorphous silicon oxide. The sorption material was obtained from the products of thermal decomposition of rice husks. Further it was modified with ammonium salts of molybdenum and tungsten: (NH4)6Mo7O24·4H2O and (NH4)2O·12WO3·5H2O in Mo/W ratios: 5/5 wt. %, 10/5 wt. % and reducted by heating in a stream of hydrogen. The registration of the voltammetric curves in the medium of 1-methyl-4-piperidone was carried out in various background electrolytes: 0.2 M Li2SO4, pH = 6.36 and 0.1 M KOH, pH = 13, 2,5·10–2 M K2HPO4 + 2,5·10–2 M NaH2PO4, pH = 6.86. Differential voltammetric curves were analyzed. The electrochemical activity of the obtained modified composites in the potential range from -1.2 V to 0.5 V was determinated. The mechanism of the proceeding electrochemical processes on these modified electrode materials has been studied. The possibility of further use of synthesized composite systems based on bisorbents from the rice husk for the electrochemical reduction of 1-methyl-4-piperidone was shown.

Author(s):  
Bazarbai Serikbaev ◽  
Duisek Kamysbaev ◽  
Galina Arbuz ◽  
Dinara Alimbai ◽  
Akbayan Arin

The article studies the synthesis of carbon-based and amorphous silicon dioxide bisorbents. Sorption characteristics of new bases for producing modified systems to use them in electrocatalysis are presented. For preparation of SiO2/C baseas rice husk (RH) was chosen as the raw material. A series of experiments was performed to optimize parameters of the RH carbonization by varying temperature and time of the process. The material obtained from the RH thermal destruction products was modified by the heteropoly compound (NH4)3[Co3O6Mo6O18H6] · nH2O and thermally reduced by hydrogen. The registration of the voltammetric curves was carried out at pH = 6.22 in the background electrolyte of 0.1 M Na2SO4 and pH = 4.45 in 0.1 M KC8H5O4.The potential ranges were -1.2В – 1.2 V and -1.0 V – 0.2 respectively. The mechanism of the electrochemical processes on these materials has been studied. It is shown that the obtained composite electrode materials exhibit electrochemical activity in the investigated potential regions, and they are characterized by the stability of redox properties. The main ways of using the obtained composites are outlined.


2014 ◽  
Vol 1 (1) ◽  
pp. 37-44
Author(s):  
Laita Nurjanah ◽  
Syamsul Falah ◽  
Azmi Azhari ◽  
Suryani Suryani ◽  
I Made Artika

Rice husks contains 33.71% w/w lignocelluloses, the most abundantly available raw material on the earth for the production of biofuels and other valuable products. It is comprised of the carbohydrate polymers, cellulose, hemicellulose, and an aromatic polymer, lignin. One of the methods for removing the lignin component of rice husks is by delignification using white-rot-fungi. The aim of the study was to carry out delignification of rice husks using white-rot-fungi. The white-rot-fungi used here were Trametes versicolor and Phanerochaete chrysosporium. The study consisted of a biomass and microbial preparation, chemical assay of the rice husk, ligninase enzyme tests, and delignification of rice husks. Results showed that T. versicolor and P. chrysosporium have ligninase enzyme. The precentage of lignin from the total biomass rice husks was 23.61% w/w, and following the delignification process by T. versicolor for 20 days, the remaining lignin was 16.20% w/w, making the percentage of rice husks lignin degraded as 7.41% w/w. The biodelignification process also decreased the percentage of holocellullose, cellulose, and other extracted substances, and accordingly this increased the percentage of hemicellulose. Based on the ability of T. versicolor to degrade lignin of the rice husk at room temperature (28 ºC) as mentioned above, it can be concluded that T. versicolor has potential to be used for delignification process.


2021 ◽  
Vol 9 (2) ◽  
pp. 193
Author(s):  
I Putu Dharma Putra Ritzada ◽  
Ni Luh Yulianti ◽  
Ida Bagus Putu Gunadnya

ABSTRAK Penelitian ini bertujuan untuk menganalisa karakteristik briket biomassa dengan variasi geometri dan jenis bahan baku briket biomassa yang berbeda  dan menentukan perlakuan manakah yang menghasilkan briket dengan kualitas yang paling baik. Penelitian ini menggunakan RAK (Rancangan Acak Kelompok) Faktorial menggunakan 2 faktorial dan 3 kali ulangan. Faktor pertama adalah jenis bahan baku (A) yang terdiri dari tiga taraf yaitu bambu tabah (A1), sekam padi (A2) dan campuran bambu tabah sekam padi (A3). Faktor kedua yaitu bentuk geometri briket (B) yang terdiri dari dua taraf yaitu balok (B1) dan silinder (B2). Seluruh perlakuan diulang sebanyak 3 kali ulangan sehingga didapatkan 18  data pengamatan. Data yang diperoleh dianalisis dengan sidik ragam dan apabila terdapat pengaruh perlakuan yang signifikan, maka dilanjutkan dengan uji BNT terhadap rata-rata perlakuan. Hasil penelitian menunjukan bahwa Interaksi antar perlakuan jenis bahan baku dan  bentuk geometri memberikan pengaruh yang signifikan terhadap  parameter mutu briket yang dihasilkan, Perlakuan briket yang dibuat dari sekam padi dengan bentuk silinder (A2B2) merupakan perlakuan yang menghasilkan briket dengan kualitas paling baik dengan nilai kadar air sebesar 2,64% bb, kadar abu sebesar 6,60%,  laju pembakaran sebesar 73,16 (gr/menit) dan volatille matter sebesar 13,86 %. ABSTRACT This study aims to analyze the characteristics of biomass briquettes with different geometry variations and types of biomass briquette raw materials and determine which treatment produces the best quality briquettes.This research uses block design (RAK) using 2 factorials and 3 replications.The first factor is the type of raw material (A) which consists of three levels, namely tabah bamboo (A1), rice husk (A2) and a mixture of tabah bamboo rice husk  (A3). The second factor is the geometric shape of the briquette (B) which consists of two levels, namely beams (B1) and cylinders (B2). All treatments were repeated 3 times in order to obtain 18 observational data. The data obtained were analyzed by means of variance and if there was a significant treatment effect, then it was followed by the BNT test on the average treatment.The results showed that the interaction between treatments. Types of raw materials and geometric shapes had a significant effect on the quality parameters of the resulting briquettes.The treatment of briquettes made from rice husks in a cylindrical shape (A2B2) is a treatment that produces the best quality briquettes with a moisture content value of 2.64% bb.ash content was 6.60%, combustion rate was 73.16 (gr / minute) and volatile matter was 13.86%.


Author(s):  
А.В. Вураско ◽  
Е.И. Симонова ◽  
А.Р. Минакова

Целлюлоза из плодовых оболочек злаковых культур обладает высокой сорбционной емкостью. Однако относительно короткие волокна затрудняют получение прочного бумажного материала. В то же время целлюлоза из соломы, наоборот, обладает относительно большой длиной волокна и приемлемыми сорбционными свойствами. Для разработки эффективных целлюлозосодержащих сорбентов интерес представляет композиционный материал из целлюлозы шелухи и целлюлозы соломы. Цель исследования – получение сорбционного материала на основе технической целлюлозы из соломы и шелухи риса. Техническая целлюлоза из соломы и шелухи риса получена окислительно-органосольвентным способом с предварительной щелочной обработкой растительного сырья (зольность ее 0,05 % от абсолютно сухой целлюлозы). При этом целлюлозу из соломы риса применяли в качестве целлюлозы-основы, а целлюлозу из шелухи риса – как целлюлозу- адсорбент. При постоянном содержании целлюлозы-основы в композиции независимо от степени ее помола капиллярная впитываемость изменяется в пределах погрешности измерений. При постоянном содержании целлюлозы- основы в композиции и добавлении к ней целлюлозы-адсорбента с возрастающей степенью помола капиллярная впитываемость снижается незначительно (на 1…2,5 мм). Сорбционная способность по йоду зависит от степени помола как целлюлозы-адсорбента, так и целлюлозы-основы. С увеличением степени помола сорбционная способность по йоду возрастает. Адсорбционная способность по метиленовому голубому при постоянном содержании 50% целлюлозы-основы в композиции и добавлении к ней целлюлозы-адсорбента с увеличивающейся степенью помола (35, 39, 43,5, 47,5 оШР) возрастает. Установлено, что количественная оценка эффективности композиции подтвердила наличие эффекта синергизма, который характерен для адсорбционной способности по метиленовому голубому и возрастает с увеличением степени помола целлюлозы- адсорбента с 1,07 до 1,12 с учетом погрешности эксперимента. Cellulose from the fruit shells of cereals has a high sorption capacity. However, relatively short fibers make it difficult to obtain durable paper material. At the same time, straw cellulose, on the contrary, has a relatively long fiber length and acceptable sorption properties. For the development of effective cellulose sorbents of interest is a composite material of cellulose husks and cellulose straw. The aim of the work is to obtain sorption materials on the basis of technical cellulose from straw and rice husks obtained by oxidation-organosolvent method with pre-alkaline treatment of vegetable raw materials. In the course of work, technical cellulose from straw and rice husks with ash content of 0.05% of completely dry cellulose was obtained. Upon receipt of the sorption material, cellulose from rice straw is used as a base cellulose, and cellulose from rice husk as cellulose is an adsorbent. With a constant content of cellulose base in the composition, regardless of its degree of grinding, capillary absorbency varies within the measurement error. With a constant content of cellulose-base in the composition and the addition of cellulose-adsorbent with an increasing degree of grinding capillary absorbency decreases slightly (1...2,5 mm). The sorption capacity of iodine depends on the degree of grinding, as cellulose-adsorbent, and the degree of grinding of cellulose-base. With increasing degree of grinding sorption capacity of iodine increases. Adsorption capacity of methylene blue at a constant content of cellulose-base 50 % in the composition and the addition of cellulose- adsorbent with an increasing degree of grinding (35, 39, 43.5, 47.5 0SHR) increases. It was found that the quantitative evaluation of the composition efficiency confirmed the presence of synergism effect, which is typical for the adsorption capacity of methylene blue and increases with increasing the degree of cellulose-adsorbent grinding from 1.07 to 1.12, taking into account the experimental error.


In many rice producing countries of the world, including in Vietnam, various research aimed at using rice husk ash (RHA) as a finely dispersed active mineral additive in cements, concrete and mortars are being conducted. The effect of the duration of the mechanoactivation of the RHA, produced under laboratory conditions in Vietnam, on its pozzolanic activity were investigated in this study. The composition of ash was investigated by laser granulometry and the values of indicators characterizing the dispersion of its particles before and after mechanical activation were established. The content of soluble amorphous silicon oxide in rice husk ash samples was determined by photocolorimetric analysis. The pizzolanic activity of the RHA, fly ash and the silica fume was also compared according to the method of absorption of the solution of the active mineral additive. It is established that the duration of the mechanical activation of rice husk ash by grinding in a vibratory mill is optimal for increasing its pozzolanic activity, since it simultaneously results in the production of the most dispersed ash particles with the highest specific surface area and maximum solubility of the amorphous silica contained in it. Longer grinding does not lead to further reduction in the size of ash particles, which can be explained by their aggregation, and also reduces the solubility of amorphous silica in an aqueous alkaline medium.


Author(s):  
N. A. Bulychev

In this paper, the plasma discharge in a high-pressure fluid stream in order to produce gaseous hydrogen was studied. Methods and equipment have been developed for the excitation of a plasma discharge in a stream of liquid medium. The fluid flow under excessive pressure is directed to a hydrodynamic emitter located at the reactor inlet where a supersonic two-phase vapor-liquid flow under reduced pressure is formed in the liquid due to the pressure drop and decrease in the flow enthalpy. Electrodes are located in the reactor where an electric field is created using an external power source (the strength of the field exceeds the breakdown threshold of this two-phase medium) leading to theinitiation of a low-temperature glow quasi-stationary plasma discharge.A theoretical estimation of the parameters of this type of discharge has been carried out. It is shown that the lowtemperature plasma initiated under the flow conditions of a liquid-phase medium in the discharge gap between the electrodes can effectively decompose the hydrogen-containing molecules of organic compounds in a liquid with the formation of gaseous products where the content of hydrogen is more than 90%. In the process simulation, theoretical calculations of the voltage and discharge current were also made which are in good agreement with the experimental data. The reaction unit used in the experiments was of a volume of 50 ml and reaction capacity appeared to be about 1.5 liters of hydrogen per minute when using a mixture of oxygen-containing organic compounds as a raw material. During their decomposition in plasma, solid-phase products are also formed in insignificant amounts: carbon nanoparticles and oxide nanoparticles of discharge electrode materials.


Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1233
Author(s):  
Yuchao Zhao ◽  
Nan Ye ◽  
Haiou Zhuo ◽  
Chaolong Wei ◽  
Weiwei Zhou ◽  
...  

Tungsten-copper (W–Cu) composites are widely used as electrical contact materials, resistance welding, electrical discharge machining (EDM), and plasma electrode materials due to their excellent arc erosion resistance, fusion welding resistance, high strength, and superior hardness. However, the traditional preparation methods pay little attention to the compactness and microstructural uniformity of W–Cu composites. Herein, W–Cu composite coatings are prepared by pulse electroplating using nano-W powder as raw material and the influence of forward-reverse duty cycle of pulse current on the structure and mechanical properties is systematically investigated. Moreover, the densification mechanism of the W–Cu composite coating is analyzed from the viewpoints of forward-pulse plating and reverse-pulse plating. At the current density (J) of 2 A/dm2, frequency (f) of 1500 Hz, forward duty cycle (df) of 40% and reverse duty cycle (dr) of 10%, the W–Cu composite coating rendered a uniform microstructure and compact structure, resulting in a hardness of 127 HV and electrical conductivity of 53.7 MS/m.


2014 ◽  
Vol 1010-1012 ◽  
pp. 1015-1019
Author(s):  
Ze Xin Yang ◽  
Lin Dong ◽  
Meng Wang ◽  
Huan Li

The main purpose of this article is to develop an environmentally friendly and economically effective process to produce silica from rice husk ash. Sodium silicate solution was prepared by the reaction of rice husk ash and sodium hydroxide solution, and then the sodium silicate solution was used as the raw material for the preparation of silica with sodium bicarbonate. During the reaction, the by-product can be passed into CO2 to prepare sodium bicarbonate what can be reutilized. Experimental route achieved resource recycling and environment-friendly, low energy consumption, zero emissions and so on. Meanwhile the microstructures of the silica powders were characterized by Transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Thermo gravimetric/Differential thermal analyzer (TG-DTA).The purity of silicon was up to 99.43% and the particle size was 200-300nm.


2014 ◽  
Vol 699 ◽  
pp. 221-226
Author(s):  
Nurul Hanim Razak ◽  
Md. Razali Ayob ◽  
M.A.M. Zainin ◽  
M.Z. Hilwa

Eggshells and rice husk, two types of notable agricultural waste were used as bioadsorbent to remove Methylene Blue dye (MBD) in aqueous solution. This study was to investigate the performance of these two bioadsorbents in removing MBD. The removal percentage, adsorption capacity, and porosity characterization were examined. The method applied was a physical filtration. UV-VIS Spectrophotometer was used to determine the efficiency of the bioadsorbents in MBD adsorption. The highest removal percentage at the most concentrated MBD were 51% and 98% for eggshells and rice husks respectively. Meanwhile the characterization of rice husks pore size and volume proves that higher adsorptivity towards dye compares to eggshells porosity. It was concluded that the eggshells and rice husks bioadsorbents was successful to treat industrial textile wastewater with rice husks as the most efficient bioadsorbent in removing MBD.


2015 ◽  
Vol 1113 ◽  
pp. 198-203 ◽  
Author(s):  
Farrah Zuhaira Ismail ◽  
Mohamad Nidzam Rahmat ◽  
Norishahaini M. Ishak

Noise has detrimental effects on human lives and it is a nuisance to the environment. As many of the available sound reduction materials in the current market are hazardous, there are demands for alternative sustainable materials to reduce the noise problem. Therefore, the aim of this research is to study the potential of using an agricultural waste as sound absorption panel. For the purpose of this study, the combination of two materials was under studied; rice husks and sugarcane baggase. There were two main objective of the research; first is to develop absorption panels from the combination of rice husks and sugarcane baggase at different percentage of mixture. Second objective is to identify the absorption rate of the panels. The study encompasses the fabrication of the sustainable sound panels using the rice husk and sugarcane fibre and bond using Phenol formaldehyde (PF). Five panels of sized 12 inch x 12 inch and 12 mm thick were fabricated. The absorption coefficient of the samples was done at the acoustic lab, Faculty of Engineering & Build Environment, Universiti Kebangsaan Malaysia (UKM), Bangi. The panels were tested using an impedance tube. The procedure of the test was carried out in accordance with ISO 10534-2:1998 standards. Based on the results, sample 1 gave the highest absorption coefficient compared to sample 2, 3, 4 and 5. It can be concluded that the acoustic panel made from a mixture of 100% rice husks had higher absorption co-efficient compared to the performance of the other samples given the fact that the characteristic of the rice husks which has air gap in every single piece of rice husk. The spongy properties of the sample 1 panel has created many void spaces which encouraged more sound absorption capability due to the porous surface of the panel. Sound absorption is very much affected by the availability of porosity level of the panel. Thus, further studies on other potential materials from waste should be conducted.Keywords. Noise, Agriculture waste, sound, absorption panels, absorption co-efficient


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