Studying electric double layer under sorption of gold on activated carbons from thiocarbamide solutions

The purpose of the article is to research the mechanism of gold-thiocarbamide complex sorption by activated carbons by studying the properties of the resulting electric double layer. The study of the electric double layer of coal sorption surface is conducted using a polar conductometric method based on the simultaneous use of polarization dependences on direct current and conductometric measurements on alternating current. It is shown that the sorption of thiocarbamide complexes of gold occurs more intensively at the cathodic values of sorbent potentials. Dependence of the adsorption value on the potential is actually linear in the negative region from 0.05 to 0.2 V. The absolute value of goldthiocarbamide sorption at the negative sorbent potential of 0.2 V coincides with the maximum values of the polarization current for direct current and conductivity for alternating current. The electrochemical reduction reaction of thiocarbamide compounds results in the formation of neutral thiocarbamide molecules, it might be the reason for gold deposition in a metallic form on the surface of the carbon sorbent. Neutralization of active compounds in the electric double layer creates conditions for the activation of positively charged gold ions directing to the negatively charged sorbent surface. The anodic region of sorbent polarization is characterized by the maximum values of gold ion sorption at the positive potential of 0.2 V. In this case the sorbent surface should be recharged, since in the same region of the potential the maximum AC conductivity is observed. Such conditions should lead to the destruction of the thick part of the electric double layer and, consequently, create favorable sorption conditions. The conducted studies allowed to derive a conclusion that the sor ption of gold-thiocarbamide complexes by activated carbons is significantly influenced by the sorbent potential. The use of the polar conductometric method for studying the electric double layer makes it possible to explain the features of given compound sorption on activated carbons.

Synthesis of olephilic aminoester from the triglyceride of soybean oil and methyldyethanolamine

The aminoester of the mixture of soybean oil’s fatty acids has been obtained through the interaction of methyldyethanolamine with triglycerides. The composition and structure of obtained aminoester have been identified via the IR-spectroscopy. High surface activity of aminoester on the water-air boundary has been revealed with the strain measuring and its colloid-chemical parameters calculated as well. The electrical conductivity of aminoester in various concentrations of agent’s water solutions has been studied via conductometric method. The laboratory researches justified that the aminoester and its 5 % water solutions have high oil-collecting property in the waters of different mineralization degree.

Thermodynamic Studies of Complexes of Amlodipine Besylate with Ni2+, Mg2+, Co2+ and Ca2+ cations in pure and in mixed binary solvent systems at 303.15, 313.15 and 323.15 K by Conductometric Method

The present work relates to the complexation reaction between Amlodipine Besylate[AML] with Ni2+, Mg2+, Co2+ and Ca2+ cation in dimethylsulfoxide (DMSO), pure methanol (MeOH) and their binary mixtures(DMSO-MeOH and DMSO-Water) by conductometric method. The conductance data show that the stoichiometry of the complexes formed between AML with Ni2+, Mg2+, Co2+ and Ca2+ cation in pure DMSO, pure MeOHas well as in the binary solvent mixtures was 1:1. The stability of AML complexes with Ni2+ , Mg2+, Co2+ and Ca2+ metal ion was observed to be sensitive to the nature of the solvent system. In case of DMSO-Water binary solvent systems there was a linear change in LogKf values but in case of DMSO-MeOH binary solvent systems non linear change in LogKf values observed.The negative values of ΔG0 show that the reaction is spontaneous and ability of the AML ligand to form stable complexes. However, the result shows positive value of ΔH0 which indicates that enthalpy is not driving force for the formation of the complexes. Furthermore, the positive value of ΔS0 indicates that entropy is a driving force for the complexation. The values of ΔH0 and ΔS0 for formation of the complexes were obtained from temperature dependence of the stability constants.

Conductometric comparative assessment of crop stress resistance to chemical pesticides

Using the conductometric method in field experiments, a positive correlation was established between the relative electrical conductivity of aqueous extracts of leaves and the yield of barley and soybeans: 0.833 and 0.994. Based on the regression equations, the threshold of stress resistance of plants to pesticides was calculated, which was 30% of the deviation of the electrical conductivity of aqueous extracts from the leaves of the treated plants from the control. A comparative assessment of 12 field crops to treatments with chemical pesticides was carried out.

Thermodynamic studies on metal complexes of Cd2+, Ni2+, Cu2+ AND Co2+ with pyridine-2,6-dicarboxylic acid in water, methanol and water-methanol binary solvent systems at 298.15 , 308.15 and 318.15 K by conductometric method

Stability constants are measured for complexes of Cd2+, Ni2+, Cu2+ and Co2+ with pyridine-2,6-dicarboxylic acid(PDA) in water, methanol and water-methanol binary solvent systems at 298.15, 308.15 and 318.15 K by conductometric method. The result shows that the stoichiometry of the complexes of PDA with all metals in all binary solvent systems is 1:2 [ML2]. The logKf values of PDA-M2+ complexes in H2O-MeOH binary solvent systems increase with increasing % of MeOH and temperature. The ΔH0 and ΔS0 of the complexation reaction in the different H2O-MeOH binary solvent systems were evaluated by the temperature dependence of the formation constants using a linear least square analysis according to van’t Hoff equation.