Сочетание современных методов элементного анализа с сорбционным концентрированием обеспечивает надежное определение металлов платиновой группы в объектах со сложным матричным составом.К настоящему времени для этих целей синтезировано большое количество сорбентов на основе различных полимеров, неорганических оксидов, углеродных и других материалов.Сорбенты должны отвечать требованиям высокой селективности, эффективности извлечения платиновых металлов и на стадии сорбции, и на стадии элюирования, устойчивости в кислых средах, а также многократности использования, предпочтительно в динамических условиях.Общепризнанно [1], что наилучшую селективность и эффективность извлечения ионов металлов из сложных по составу растворов обеспечивает так называемая технология молекулярного распознавания (ТМР), использующая сорбенты на основе кремнезема с химически привитыми органическими лигандами макроциклического и/или линейного строения [2].В настоящей работе мы описываем способ сорбционной пробоподготовки анализируемых технологических растворов, содержащих платину, палладий и родий, на основе ТМР.Разработанные нами сорбенты на основе кремнезема с химически привитыми замещенными алкиларилсульфидами [3] обеспечивают извлечение ионов палладия(II) из растворов 0.1 -4 М HCl, содержащих до 90 г/л хлорид-иона и 10 4 -10 5 -кратные избытки макрокомпонентов, и последующее количественное элюирование палладия аммиачным буферным раствором (pH 10).Сорбент на основе кремнезема с химически привитым полиэтиленимином [4] может быть использован для селективного выделения ионов платины(IV) и родия(III) из растворов 0.1 -6 М HCl и их разделения на стадии элюирования 5%-м раствором тиомочевины в 0.01 M HCl и 20%-м раствором хлорида аммония, соответственно.Разработан способ пробоподготовки сложных растворов с использованием хроматографических колонок диаметром 8 мм, наполненных синтезированными сорбентами, имеющими оптимальные фазово-структурные характеристики с точки зрения гидролитической стабильности, ненабухаемости и скорости сорбции.Высокая селективность выделения целевых компонентов подтверждена опытами на реальных растворах переработки медно-никелевых шламов.Показано, что стабильность работы предлагаемых сорбентов сохраняется в течение не менее 10 циклов сорбции-десорбции.

This works deals with isolation of chloro complexes of platinum metals, in particular [IrCl6]3– and [IrCl6]2–, from hydrochloric acid solutions with different content of chloride ions by sorption method. Sorbents used were modified silicas obtained by the chemical grafting of short-chain polyethyleneimines (PEI) to their surface followed by crosslinking and quaternization to form a thin layer of supported ionic liquids. A PEI with low molecular weight (MW 600, ~12 units) and preferably linear molecules was selected. Mobility of polyethyleneimine chains determines the possibility of its multipoint grafting to silica surface. Procedures for the synthesis of sorbents and their structural characteristics have been reported. Dependences of Ir(III) and Ir(IV) sorption on HCl, H+, and Cl– concentration have been revealed. Sorption equilibrium is reached over 2–5 min, which is typical for materials based on mesoporous silica and indicates anion-exchange mechanism of binding. A hot NH4Cl solution has been used for the quantitative desorption of Ir(IV) ions. The sorbents were tested for separation of Ir(IV) from Pt(IV) and Rh(III). Obtained results may be recommended for the recovery of platinum metal ions from chloride solutions of complex composition.

A quasi-chemical model of self-assembly among identical objects is proposed. The model rests on two main premises: (a) larger ensembles are more stable and (b) have slower rates of transformation, growth, and decomposition. These statements result from all paired interactions in the considered ensemble. This formulation of self-assembly is shown to be conducive to the formation of large ensembles with sizes distributed normally in a fairly narrow range, and with the concentrations of smaller ensembles being negligible. The existence of two critical points follows from the model. One is a critical concentration that initiates self-assembly in the system when exceeded. The other is a critical ensemble size that sets a threshold for the self-driven growth of ensembles in the system. The growth of ensembles nearly ceases at a point far from equilibrium, and the mean ensemble size and the ensemble’s size distribution are under kinetic control. Stable structures of this kind (with kinetic control of their organization) can serve as models for many natural self-organized systems.

Sorption of Pd(II), Ag(I) and Cu(II) from nitric acid solutions by silica chemically modified with γ-aminopropyltriethoxysilane was studied. Based on the research of solid phase by IR & X-ray photoelectron spectroscopy, as well as thermogravimetry, it was suggested that palladium sorption from nitric acid solutions includes the following processes: coordination of palladium ions to nitrogen atoms of the functional group, reaction of palladium ions with the silica matrix and formation of polynuclear complexes. It was also proposed to use 5 % thiourea solution in 0,1 M HCl as a palladium desorbent. It was determined that the time of constant sorption rate settling in static conditions was (min): for Ag(I) – 10, for Cu(II) – 20, Pd(II) – 30. The row of ion sorption (imbibition) from 2 M HNO 3 is as follows: А Ag(I) > А Pd(II) >> А Cu(II) . At the same time, silver ions are not adsorbed from solutions with a concentration of HNO 3 < 1 M thus creating prerequisites for separation of ions.

The goals of school education and the role of lessons in natural sciences, particularly chemistry, in intellectual development of school children are analyzed. The reasons for the negative attitude to chemistry from the young people and the society are determined. The problems arising from the forthcoming reform of school education are discussed. The structure of the chemistry course for modern general schools is presented.

The effect of some amino acids: cysteine, methionine, glycine, lysine, and aspartic acid, on the formation of nanoparticles of zinc sulfide in aqueous solutions at pH 5.5–10.0 was investigated. A method of obtaining stable sols of ZnS particles of 2–4 nm size with narrow distribution of the particle size was developed. The investigated nanoparticles are shown to be sphalerite, the cubic modification of zinc sulfide. The ZnS sols modified with methionine and glycine show intense luminescence at 415–425 nm.