The article presents the results of electrochemical studies made on carbon paste electrode based on bisorbents powder modified by molybdenum. Bisorbent consists of carbon and SiO 2 . It was synthesized as a support structure obtained from rice husk thermal decomposition products. The obtained sorption material has surface with high specific area -200 m 2 /g. Bisorbent was further modified by (NH 4 ) 6 Mo 7 O 24 · 4H 2 O (10 wt.%). The elemental composition of used RH was also determined. The surface morphology of plain and modified BS samples was studied. Recording of voltammetric curves was carried out at рН = 3.80, рН = 6.40 in 0.2 М electrolyte solution of Li 2 SO 4 . Cathodic and anodic waves were obtained which related to oxidation and reduction processes of molebdenium compounds in the entire range of the potentials (0.8 ÷ -1.2 V). The range of changing molybdate ions concentrations in solution was 2·10 -4 ÷ 10 -2 M. The dependencies of kinetic and electrochemical parameters on paramolybdate ions concentration were studied for modified electrode. Nature of changes in molybdenum reduction currents and oxidation currents indicates that Mo +6 reduction may occur by different mechanisms depending on the composite electrode properties. Results showed the possibility of further the synthesized composite system use for voltammetric determination of low (10 -4 -10 -2 ) concentrations of ions in a solution.
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.
В данной работе приведены результаты синтеза нового модифицированного поливалентными металлами композитного материала. В качестве сырья для получения носителя -бисорбента, состоящего из углерода и аморфного окисида кремния, была выбрана рисовая шелуха. Полученный из продуктов термического разложения рисовой шелухи сорбционный материал был модифицирован аммонийными солями молибдена и вольфрама: (NH 4 ) 6 Mo 7 O 24 ·4H 2 O и (NH 4 ) 2 O·12WO 3 ·5H 2 O в соотношениях Mo/W: 5/5 масс. %, 10/5 масс. % и восстановлен при нагреве в токе водорода. Регистрация вольтамперометрических кривых в среде 1-метил-4-пиперидона проводилась в различных фоновых электролитах: 0,2 М Li 2 SO 4 , pH = 6,36 и в 0,1 М КОН, рН = 13, 2,5·10 -2 M K 2 HPO 4 + 2,5·10 -2 M NaH 2 PO 4 , pH = 6,86. Проанализированы дифференциальные вольтамперометрические кривые. Выявлена электрохимическая активность полученных модифицированных композитов в диапазоне потенциалов от -1,2 В до 0,5 В. Изучен механизм протекающих электрохимических процессов на данных модифицированных электродных материалах. Показана возможность дальнейшего применения синтезированных композиционных систем на основе бисорбента из рисовой шелухи для электрохимического восстановления 1-метил-4-пиперидона.Ключевые слова: рисовая шелуха; бисорбент; молибден; вольфрам; модифицированные электроды; 1-метил-4-пиперидон. 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: (NH 4 ) 6 Mo 7 O 24 ·4H 2 O and (NH 4 ) 2 O·12WO 3 ·5H 2 O 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 Li 2 SO 4 , pH = 6.36 and 0.1 M KOH, pH = 13, 2.5·10 -2 M K 2 HPO 4 + 2.5·10 -2 M NaH 2 PO 4 , 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. Synthesis of molybdenumKeywords: rice husk; bisorbent; molybdenum; tungsten; modified electrodes; 1-methyl-4-piperidone. Бұл жұмыста поливалентті металдармен модификацияланған жаңа композициялық электродтық материал синтезінің нәтижелері келтірілген. Көміртек және кремний оксидінен тұратын бисорбент-матрицасын алу үшін шикізат ретінде күріш қауызыны таңдалды. Күріш қауызының термиялық ыдырау өнімдерінен алынған сорбциялық материал молибден және вольфр...
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