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CHEMICAL SCIENCES
Hybrid extraction-amperometric determination of Cu (II) by solution in water, mixed and nonwater mediums Yakhshieva Z. , Kutlimuratova N. (Republic of Uzbekistan) Гибридное экстракционно-амперометрическое определение Cu (II) в водной, смешанной и неводной среде Яхшиева З. З.1, Кутлимуратова Н. Х.2 (Республика Узбекистан)
2Яхшиева Зухра Зиятовна / Yakhshieva Zukhra - кандидат химических наук, старший научный сотрудник, соискатель;
2Кутлимуратова Нигора Хакимовна / Kutlimuratova Nigora - кандидат химических наук,
старший преподаватель, химический факультет,
Национальный университет Узбекистана им. М. Улугбека, г. Ташкент, Республика Узбекистан
Abstract: methods of hybrid extraction amperometric determination Cu (II) by solution of thionalidc and tioacetamide in water, mixed and non-water mediums have been elaborated. These methods were used at caring out of analysis of binary, triple and more complex model mixtures imitated some industrial materials and natural objects.
Аннотация: разработаны методики гибридного экстракционно-
амперометрического определения Cu(II) раствором тионалида и тиоацетамида в водной, смешанной и неводной среде. Предложенные методики применены к анализу бинарных, тройных и более сложных модельных смесей, имитирующих промышленные материалы и природные объекты.
Keywords: amperometrical, titration, thionalid, tioacetamid.
Ключевые слова: амперометрия, титрование, тионалид, тиоацетамид.
In practical relation electroanalytical chemistry has promoted to solution of such problem as extraction-amperometric titration of ions of different metals directly in extracts excluding reextraction; increasing a sensibility, selectivity and also expression of caring out of determinations [1-3].
Titration in water, mixed and non-water mediums in principle must be an fundament or ground for metals determination in extracts obtained at extraction division or concentration elements and also in organic materials which badly solute in water.
New variant of amperometrical titration of ions of different metals after extraction separation of them as diethylditiocarbaminates or ditizonates has been elaborated. This method consists from following stages: to aliquate part of extract an angydrons acetic acid, little quantity of nonwater solution of suitable strong oxidizer (Cr2O3, KMnO4, H2O2 or O3) was added and then the mixture was heated for full destruction of complexe and extraction reagent. After cooling analysed solution phone electrolyte (CH3COOK or LiClO4) was added and after this titration solution was carried out.
The base stage of analysis is destruction of extracted complex and surphlus of reagent by strong oxidiber satisfied to fob lowing demands: at first it must fast and fully to destruct of the extracted complex and secondly neither itself non its products of reduction must not interact with titrator (TAA-tioacetamid, TA-thionalide) and titrating ions and also don’t participate in electrode processes. It was determined that the best oxidizers corresponded to above mentioned demands are solutions of Cr2O3, KMnO4, H2O2 in prolytical solvents with concentration neither more 0,001M because at this demands titrants practically don’t undergo to oxidation and also amperometrical titration of ions of different metals has carried out smoothly as well in absence of oxidizers. But it is necessary to avoid more high
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concentrations of oxidizers because at these the curvers of titration are less cleare and results of titration are overstated.
Titration of diethylditiocarbaminated complex es of Cu (II) by solution of tioacetamide in acetic acid was carried out. Some artificial mixtures containing 0,1-0,2% of Cu(II) different amounts of such ions as Fe(III), Al(III), Zn(II), Cd(II), Ni(II) and Pb(II) were analyzed on the content of Cu(II). Obtained results are presented in table 1.
Table 1. Determination of Cu (II) by solution of tioacetamide on the phone of 0,25 M CH3COOK
in artificial mixtures
Content of metals ions in analyzed mixture, % Founded of Me (Р=0,95; х ± AX) n S Sr
Cu(0,135) + Co(3,01) + Zn (56,86) 0,133 ± 0,002 8 0,002 0,015
Cu(0,145) + Fe(56,87) + Al(42,98) 0,144 ± 0,001 6 0,001 0,007
Cu(0,169) + Cd(84,62) + Pb(15,04) 0,167 ± 0,003 5 0,002 0,012
Titration was carried out by following method: to analysed probe counting Cu (II) 5 ml of 20 % solution of titrant previously purified from traces of heavy metals by extraction of them as diethylditiocarbaminates chloroform; 15 ml of 10% solution of tioacetamide solution of ammoniate pH 8,5 were added. Obtained mixture was diluted by water to 70 ml and 5ml 0,2 % solution of DDTNa was added and then was extracted twice by chloroform or CCl4 portions of 10 ml. Extracts were collected in different dividing fannels containing 25 ml 0,5 of sulfer acid and were washed by acid acidanikan were poured out in measured flashs on 25 ml which were completed to mark by chlorophorm. For determination of Cu (II) extracts were placed in glasses in quantity 5 ml.
As shown from table 1 results of determination of Cu (II) by solution of tioacetamide in artificial mixtures by the elaborated method are characterized by sufficient reproduction and rightness.
Titration of the Cu (II) after it’s extraction separation was carried out bv solution of tioacetamide. For titration of Cu (II) ions in the presence of large quantities of ions of different metals usually acompaned them in minarals, allowes and some other objects the method was proposed based on the preliminary extraction separation of Cu (II) ions and following their titration in obtained extracts by solution of tioacetamide.
Method of caring out of analysis: aliquates of analyzed solution containing about 200 mkg of Cu (II) were placed in fannel, acidified by 0,2 M solution of HCl, than 5 ml of 0,1 M solution of EDTA and 2 ml of 1,0 % water solution of sodium salt of dimethylglioxime were added and obtained mixtures were mixed and after 10 min Cu(II) was extracted by two portion (5,0 ml) of chloroform during 1 minute. United extracts were transfered in glass for titration than 5 ml acetic acid was added and obtained mixture was heated to beginning of boiling and dimethylglioxime of Cu (II) was destructed by addition of 30-40 drops of saturated solution of KMnO4 in acetic acid before appearing of yellow-brown colouring. Probe containing Cu (II) cooled to room temperature was titrated by 0,01 M solution of tioacetamide by above mentioned method.
Results of Cu (II) determination are presented in table 2 and they have witnessed about rightness and reproduction of the proposed methods.
Titration of the Cu (II) after it’s extraction separation was carried out by solution of thionalide. Thus new extraction-amperometrical method of Cu(II) determination in mixture with noble metals based on the extraction of Cu(II) in chloroform at pH=8-9 by mezithelen oxide, destruction of extracting reagent and complex of Cu(II) by strong oxidizer (Cr2O3, O3, H2O2) with following titration by thionalide, was elaborated.
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Method of carring out of analysis: to aliquate of analyzed solution containing 5-75 mg Cu(II) mezithelen oxide (0,2 g) was added then with help of KOH or HCl the pH was established in range 4,5-5,0. Then mixture was diluted to volume 50 ml and was extracted during 1,0 min by 10 ml of phases extract was destroyed at heating by chromic or hydrogen peroxide after which collected in flash (25 ml). Aliquate of obtained solution was placed and optimal condition, were carried out for amperometrical titration of Cu (II) (2,0 ml 0,5 M CH3COOH and necessary quantity of DMCO or n-propanol) and then Cu (II) was titrated by thionalide.
Table 2. Results of extraction amperometrical determination of Cu (II) by solutions tioacetamide
and thionalide in artificial mixtures
Nature and quantity of metals, % Reagent Founded of Me (Р=0,95; х ± AX) n Sr
Cu(0,102) + Pt(4,88) + Fe(10,09) + +Os(0,03) TAA (Cu) 0,101 ± 0,019 4 0,118
Cu(0,102) + Ag(10,73) + Au(1,51) + +Os(0,06) (Cu) 0,104 ± 0,022 5 0,170
Cu(0,353) + Au(0,907) + Ni(21,54)+ +Fe(47,63) TA (Cu) 0,350 ± 0,211 3 0,249
Cu(0,306) + Ag(0,813) + Bi(0,129)+ +Th (0,071) (Cu) 0,301 ± 0,101 5 0,269
As shown from data of table 2 the elaborated methods of amperometrical titration of Cu (II) by solutions of tioacetamide and thionalide in different artificial mixtures of salts after extraction separation are characterized by high selectivity.
References
1. Korenman Ya. I. Praktikum po analiticheskoy ximii. Elektroximichiskiye metodi analiza.// M. Kolos. 2005. P. 232-235.
2. KoritaI., DvorjakI., Bogachkova V. Elektroximiya.// M.: Mir. 1977. 472 p.
3. Xaritonov Yu. Ya. Analiticheskiye (instrumentalniye) metodi analiza. M.: Visshaya shkola. 2008. 559 p.
Standard enthalpy of combustion and formation of 2,5-dimercapto-1,3,4-thiadiazole Koval I. , Volkov A. (Russian Federation)
Стандартные энтальпии сгорания и образования 2,5-димеркапто-1,3,4-тиадиазола Коваль И. С. , Волков А. В. (Российская Федерация)
1Коваль Илья Сергеевич /Koval Ilya - аспирант;
2Волков Алексей Владимирович / Volkov Alexey - кандидат химических наук, доцент, кафедра аналитической химии,
Ивановский государственный химико-технологический университет, г. Иваново
Аннотация: методом бомбовой калориметрии в среде кислорода определена энергия сгорания 2,5-димеркапто-1,3,4-тиадиазола. Рассчитаны стандартные энтальпии сгорания и образования: АсН = -1930,1 ± 3,3 кДж/моль, AfH° = 32,6 ± 3,3 кДж/моль; Величины приведены для исследуемого вещества в кристаллическом состоянии при температуре 298,15 К.
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