Selective determination of rhodium and iridium in the urban environment using the catalytic method

2021 ◽  
Vol 87 (12) ◽  
pp. 17-22
Author(s):  
E. G. Khomutova

The problem of studying the level of technogenic pollution of the environment with platinum group metals is attributed first to the release of platinum metals into the environment together with the exhaust gases of cars using afterburning catalysts containing Pt, Pd, Rh. The pharmaceutical, electronics and jewelry industries the waste of which contains PGMs also contribute to the pollution of the environment. A number of studies have shown the toxic effects of PGM on humans. The goal of the study is to obtain new information about the level of technogenic pollution of the environment with platinum group metals (such as water-washings from roads, bio-collector plants, roadside dust), which necessitates developing of the method for sample preparation and determination of rhodium and iridium. A technique of sample opening and determination of rhodium and iridium in environmental objects, water-washings from roads, bio-collector plants, roadside dust is proposed. To increase the selectivity of rhodium determination, the samples were treated with a mixture of concentrated perchloric acid and sodium periodate when heated to boiling, which provided more than 5-fold increase the rhodium signal. Moreover, the permissible excess of iridium and ruthenium was increased by 5 and 20 times, respectively, due to the conversion of other PGMs into catalytically inactive forms. The indicator reaction of sulfarsazen oxidation by periodate was used in the kinetic determination of rhodium and iridium. The correctness of the results obtained by the developed method was confirmed by the ETAAS method. The determined content of Rh and Ir: in roadside waters (μg/liter) up to 0.015 and 0.005; in collector plants (g/ton) up to 0.030 Rh and 0.022; in street dust (g/ton) up to 0.05 and 0.025, respectively. The standard deviation of the repeatability of the determination results does not exceed 0.07 (Rh) and 0.12 (Ir). The developed method of opening samples and determining rhodium and iridium in environmental objects provided a great bulk of information about the content of rhodium and iridium in water-flushes from Moscow roads, bio-collector plants, roadside dust, which correlate fairly well with the scarce data from other geographic regions available in the literature and our earlier results on rhodium content in dust. The developed technique made it possible to obtain data on the level of technical pollution of the environment with PGMs in places with different traffic density in Moscow.

1996 ◽  
Vol 334 (1-2) ◽  
pp. 167-175 ◽  
Author(s):  
I.V. Kubrakova ◽  
T.F. Kudinova ◽  
N.M. Kuźmin ◽  
I.A. Kovalev ◽  
G.I. Tsysin ◽  
...  

Sensors ◽  
2021 ◽  
Vol 21 (22) ◽  
pp. 7639
Author(s):  
Guzel Ziyatdinova ◽  
Liliya Gimadutdinova

A novel voltammetric sensor based on СеO2·Fe2O3 nanoparticles (NPs) has been developed for the determination of lipoic acid, playing an essential role in aerobic metabolism in the living organism. Sensor surface modification provides a 5.6-fold increase of the lipoic acid oxidation currents and a 20 mV anodic shift of the oxidation potential. The best voltammetric parameters have been obtained for the 0.5 mg mL−1 dispersion of СеO2·Fe2O3 NPs. Scanning electron microscopy (SEM) confirms the presence of spherical NPs of 25–60 nm, and their aggregates evenly distributed on the electrode surface and formed porous coverage. This leads to the 4.4-fold increase of the effective surface area vs. bare glassy carbon electrode (GCE). The sensor shows a significantly higher electron transfer rate. Electrooxidation of lipoic acid on СеO2·Fe2O3 NPs modified GCE is an irreversible diffusion-controlled pH-independent process occurring with the participation of two electrons. The sensor gives a linear response to lipoic acid in the ranges of 0.075–7.5 and 7.5–100 μM with the detection limit of 0.053 μM. The sensor is selective towards lipoic acid in the presence of inorganic ions, ascorbic acid, saccharides, and other S-containing compounds. The sensor developed has been tested on the pharmaceutical dosage forms of lipoic acid.


1984 ◽  
Vol 38 (5) ◽  
pp. 644-647 ◽  
Author(s):  
Roberta L. Fox

Direct-current plasma emission spectrometric analysis of platinum group metals in solutions from automobile catalyst shows significant enhancement of analyte values Addition of a lithium buffer does not remove the interference The only matrix constituents in these solutions were aluminum and magnesium, both of which were found to cause enhancement in the determination of platinum, palladium, and rhodium A buffer consisting of 3500 mg/L lithium and 2500 mg/L lanthanum removed the enhancement effect of both magnesium and aluminum on these metals 8-hydroxyquinoline also reduced the degree of interference due to aluminum, although not as efficiently as lanthanum, indicating that formation of compounds in the dc plasma is a possible source for the observed interference


Sign in / Sign up

Export Citation Format

Share Document