English English

Keywords: polyacrylonitrile

Kinetics of Cu(II) removal from aqueous solution with the use of Fe3O4/C nanocomposite

,
 5-12 p.
Abstract
this work studied the sorption kinetics of the Fe3O4/C nanocomposite obtained by heating polyacrylonitrile (PAN) and FeCl2∙4H2O in air, the preparation procedure of which was described in the previous works [9, 10]. The main task was to calculate the sorption characteristics and check the practical application of this nanocomposite, that is the possibility of purification from heavy metals from water sources, verified on the example of modeling the sorption of copper ions from an aqueous solution of copper(II) acetate hexahydrate, hence the equations of diffusion (Morris-Weber model) and chemical kinetics (Lagergren's pseudo-first order, Ho and McKay's pseudo-second order), as well as the Elovich chemosorption model were applied. Analysis of the data illustrated that the diffusion of copper ions inside the pores of the nanocomposite and chemical interactions between copper ions and functional groups of the sorbent surface, such as hydroxyl, carboxyl, carbonyl, etc., which are typical of carbon sorbents, contribute to the total sorption rate. Experimentally, the capacity of this nanocomposite for copper sorption was 208.4 mg/g, however, modeling showed that this value could theoretically be higher by 37%.
PDF

ANALYSIS OF MAGNETITE IN THE FE3O4/C NANOCOMPOSITE

, , , ,
 30-41 p.
Abstract
This paper presents the magnetite study results of a Fe3O4/C nanocomposite obtained with air pyrolysis of a heterogeneous system which includes iron dichloride tetrahydrate – the source of magnetite nanoparticles (NPs) – and polyacrylonitrile (PAN) – the source of a carbon shell for nanoparticles protection from issues like aggregation. Methods such as Mössbauer spectroscopy and X-ray diffraction analysis are used for studying and determine the magnetite NP formation way. There are two types of NPs in the system studied: ferrimagnetic and superparamagnetic ones, the difference between which is clearly watched when taking Mössbauer spectra – sextets and doublets relatively. All magnetite NPs are established to be formed according to the reaction chain the inter-mediate elements of which is ferrous carbonate well-known for its decomposition into magnetite upon heating: FeCl2 → FeCO3 → Fe3O4. This transformation occurs in the temperature range from 200 oC to 400 oC above which an ability of the carbon shell to protect NPs is gradually reduced that leads to agglomeration and oxidation to hematite α-Fe2O3.
To study the magnetite obtained, size distribution of magnetite crystallites and the degree of nonstoichiometry are estimated. According to various calculations, the average crystallite size is 9-10 nm.
To preserve the NP properties, storage methods are important to be chosen properly, thence Mössbauer spec-troscopy of the Fe3O4/C nanocomposite is carried out after keeping it in air at room temperature for 1 year.
PDF