A.F. BUCSA, S.M. VULPE, B.F. VENESCU, D. BADEAisinn.jinr.ru/past-isinns/isinn-26/0601AM_session...

A.F. BUCSA, S.M. VULPE, B.F. VENESCU, D. BADEA

[email protected]

INSTITUTE FOR NUCLEAR RESEARCH, MIOVENI, ROMANIA

May 28th - June 1st

26th International Seminar on Interactions of Neutrons with Nuclei, Xi'an, China

Elemental arsenic and arsenic compounds are classified as „toxic" and "dangerous for the

environment" in the European Union under Directive 67/548/EEC

The International Agency for Research on Cancer (IARC) recognizes arsenic and inorganic arsenic compounds as group 1 carcinogens, and the EU lists arsenic trioxide, arsenic pentoxide, and arsenate salts as category 1 carcinogens

Arsenic is known to cause arsenicosis when present in drinking water, "the most common species being arsenate [HAsO2−

4; As(V)] and arsenite [H3AsO3; As(III)]"

Arsenic concentrations in drinking water according to the standard of World Health Organization are 10 microgram per liter (ppb)

The arsenic in the groundwater is of natural origin and is released from the sediment into the groundwater, caused by the anoxic conditions of the subsurface


May 28th - June 1st

INTRODUCTION

The paper presents results of the determination of As (III) and As (V) content in drinking water

samples by using solid phase extraction and neutron activation analysis.

Because arsenic compounds are often present in water at low concentrations, analytical

methods of chemical separation with high sensitivity are required.

Chemical method involving APDC/MIBK (Ammonium Pyrrolidine - Dithio-Carbamate/Methyl

Isobutyl Ketone) compounds for solid phase extraction of arsenic species and furthermore -

NAA-k0 standardization (Neutron Activation Analysis) for determining the concentrations of

As(III) and As(V) in drinking water has been developed.

For irradiation purpose of this experiment, it was used the TRIGA ACPR (Annular Core Pulsed

Reactor) from Institute for Nuclear Research, Pitesti, Romania, which provided a fare enough

value of thermal neutron flux for activation of arsenic.


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IRRADIATION FACILITY


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TRIGA ACPR Core

Water sampling

(250 ml)

Water sampling for As (III) determination Water sampling for

As (V) determination

Arsenic extraction using APDC/MIBK (2 ml of solution)

Evaporation of the 2 ml of solution on IR lamp (will result a

dry residue)

TRIGA ACPR Reactor irradiation experiment

Arsenic concentration determination NAA-k0

standardization method


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The scheme of APDC/MIBK-NAA method for arsenic content determination in drinkable water

COLLECTING WATER SAMPLES

The samples of natural water analysed to determine the content of As(III) and As(V) were collected from 4 sources:

1) A sample of bottled drinkable water available in the commercial market;

2) A sample of fountain water collected from Urlueni, Arges county;

3) A sample of spring water collected from Stolnici, Arges county;

4) A sample of filtered tap water collected from ICN Pitesti facility.

The samples were filtered immediately after collecting, using a 0.45 μm Millipore membrane to

remove particulate matter.


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APDC/MIBK EXTRACTION OF ARSENIC

Extraction of arsenic content from the water samples was performed using APDC and MIBK. Figure 1 show a picture of the water content separation film (which will be extracted for IR evaporation).

After the extraction step, the water samples

were placed in polypropylene cartridges and

left to evaporate under infrared light, as

shown in Figure 2.


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Figure 2. Evaporation of water

samples under IR lamp

Figure 1. Separation film with

potential arsenic content

THE IRRADIATION EXPERIMENT

All the samples inserted in polypropylene cartridges (high temps resistant) were irradiated in

the pneumatic rabbit - D10 location of the TRIGA ACPR reactor core grid, at ICN Pitesti.

The irradiation time was 3 hours after which, depending on the dose rate at contact, the

samples were stored to calm down in the reactor pool for a predetermined time so that the

short lives isotopes completely decay.

The samples were measured by using a high resolution detection system for gamma

spectrometry (HPGe – High Purity Germanium crystal).

After the measurements, the energy spectra of the gamma rays were obtained, which were

processed with the GENIE2000 acquisition program.


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•


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Basic equation a – analyte m - monitor

Nuclear data library recommended k0’s

•


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•


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TRACEABILITY: Certified Al – 0.1 % Au alloy (IRMM - 530, IRMM - 530R, ERM - EB530)

UNCERTAINTY: taking into account all parameters and covariances

QC/QA OF IMPLEMENTATION: SMELS (Synthetic Multi-Elements Standards)

•


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RESULTS AND DISCUSSION

May 28th - June 1st 26th International Seminar on Interactions of

Neutrons with Nuclei, Xi'an, China

For gamma rays spectra acquisition it was used a HPGe detector provided by

Canberra

Its calibration has been made using certified Co-60, Am-241, Cs-137, Ba-133,

Eu-152 sources. Following are the shape of energy and efficiency calibration

curves.



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Thermal neutron flux measurement in TRIGA ACPR – (D10) – pneumatic rabbit using Al- 0.1%Au foil monitor

Irradiation date 04/11/2017

Start: 12:14:53

Stop: 15:17:31 Tirr(sec) 10958

Power: 100kW Φmonitor 4 mm

Monitor Au0,1%

M(g) 4.44E-03

σ0 (cm^2) 9.88E-23

Nr.crt Tr(h) R (dis/(nucl*s)) Rcd Thermal flux

(n/cm^2*s)

R(medie)

(dis/nuc/*s)

Dev std (n-1)

(rata)

Flux med

(n/cm^2*s) Devstd (n-1) (flux)

1 43.57 2.12E-10 1,695 8.80E+12

2.12E-10 1.14E-12 8.82E+12 4.67E+09

2 47.32 2.13E-10 1,695 8.85E+12

3 65.41 2.14E-10 1,695 8.89E+12

4 137.29 2.12E-10 1,695 8.79E+12

5 188.66 2.11E-10 1,695 8.75E+12


To reduce the arsenic content of water samples, Millipore filters with a grain size of less than 0.4μm can be used.

After neutron flux calculation, net peak area resulted after gamma rays spectra deconvolution, k0-standardization were employed.

The obtained results are presented in figure 3. Based on the data presented in this paper, it was concluded that the APDC/MIBK-NAA method for determining As(III) and As(V) species is a valid, reliable and effective method.

The importance of determining the concentration of arsenic species is due to the fact that the presence of this chemical in drinking water has a detrimental effect on human health.


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Figure 3. Arsenic speciation in drinkable water

REFERENCES

1. Zs. Molnár – „Neutron Activation Analysis”.

2. F. DeCorte – „The K0 standardization method”.

3. F. DeCorte et A.Simonits – „Vade mecum for K0 – users”.


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谢谢

Thank you!


May 28th - June 1st

A.F. BUCSA, S.M. VULPE, B.F. VENESCU, D. BADEAisinn.jinr.ru/past-isinns/isinn-26/0601AM_session...

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