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The international research group and RUDN University chemists proposed new reagents for the removal of lead from wastewater
The international research group and RUDN University chemists proposed new reagents for the removal of lead from wastewater
RUDN University chemists together with colleagues from other countries synthesized new compounds that effectively bind lead ions and can be used to remove it from wastewater and even from the living organism, that is, to play the role of an antidote for lead poisoning. The article is published in the journal Crystals.

Complex compounds of lead are widely used for the synthesis of polymers and compounds necessary for the production of semiconductors, materials for nonlinear optics and ferroelectrics. The large radius of the divalent lead ion Pb (II) allows you to change the number of bound atoms, ions or molecules (ligands) from 4 to 9. Thus, it is possible to obtain a wide range of substances based on lead, that combine organic and inorganic components in a single molecule. The widespread use of lead compounds in production leads to the accumulation of toxic waste, what stimulates the solution to the problem of removing lead from wastewater.

Fedor Zubkov, an employee of the Organic Chemistry Department of RUDN University, together with colleagues from Iran, Spain, Italy, and Croatia have obtained compounds that can effectively bind lead in wastewater, as well as in human and animal body. Chemists have created it on the basis of nicotinic and picolinic acids hydrazides. Nitrate, chloride, and perchlorate-anions serve as counterions to positively charged lead ions and stabilize the complex due to strong electrostatic interactions.

To study the obtained complexes, chemists had to design a special device for the synthesis and simultaneous selective crystallization of reaction products. To do this, alcohol solution of a mixture of lead nitrate (II), the corresponding ligand, and sodium perchlorate was placed in the main part of the tube as a donor of counterions. The mixture was heated at 60 °C so that the side branch of the tube, also filled with alcohol, remained at room temperature. The crystals of the complex formed in the side vessel after several days of synthesis were filtered, washed with ether and dried in air. The yield of metal complex ranged from 67 to 87 % of the theoretically possible.

According to x-ray diffraction analysis, one of the complexes turned out to be binuclear, that is, it contains two lead ions bound by a common ligand. Using computer simulations, it was shown that all complexes form supramolecular ensembles with different types of intermolecular interactions. In the formation of such structures, anions of inorganic acids play an important role, which experiences a strong electrostatic attraction to the internal coordination sphere of the lead complex. As a result, metal organic coordination polymers (metal organic frameworks, MOFs) are formed, which are promising metal organic catalysts and selective acceptors of heavy-metal ions.

The resulted substances — supramolecular ensembles — allow to bound and precipitate even trace amounts of lead in wastewater. They can be used for drinking water treatment and even as an antidote for lead poisoning.

The article is published in the journal Crystals.

International scientific cooperation View all
03 Nov 2017
The main goal of the RUDN University and UNISDR Office for Northeast Asia and Global Education and Training Institute for Disaster Risk Reduction at Incheon (UNISDR ONEA-GETI) cooperation is to obtain knowledge about disaster risk reduction and international experience in this area for creating training courses for basic and additional professional education in RUDN
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RUDN soil scientists have revealed a direct correlation between the rate of soil formation of carbon dioxide, called CO2 emissions, and the content of microbial biomass in it. It is known that CO2 emission from soil is mainly conditioned by respiration of soil microorganisms and plant roots. The more CO2 soil emits, the more microbial biomass it usually contains. It was shown that CO2 emission by chernozem of different ecosystems (or different types of land use) correlates with the content of microbial biomass, and most closely with the rate of its microbial respiration. And the soil with good microbial properties has the “best quality”, is more fertile, provides the highest yield of crops and other plant biomass.

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RUDN University chemists proposed a way to reduce three times the temperature for the oxidation of alkanes

RUDN University chemists and their colleagues from the Russian Academy of Sciences have proposed new catalysts that allow to reduce the temperature of the oxidation reaction of alkanes three times — from 150 to 50 degrees. This significantly reduces the cost of synthesizing alcohols, aldehydes and other compounds needed, in particular, for the production of nylon and capron.

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