Determination of the Mass Concentration of PCDDs/PCDFs (Stationary - - PowerPoint PPT Presentation
Determination of the Mass Concentration of PCDDs/PCDFs (Stationary Source Emissions ) Department of Environment Islamic Republic of Iran (DoE) Outline: Department of Environment (DoE)- Iran Dioxin / Furans (an overview) Dioxins /
Department of Environment (DoE)- Iran Dioxin / Furans (an overview) Dioxins / Furans toxicity Sources of Dioxins /Furans Pathways of Human Exposures Principle of the sampling procedure (EPA 23 & EN
1948)
Sampling devices and materials Transportations and Storage, Sample Extraction and
Clean-up techniques
The DoE has established in 1971 and it’s responsible for matters related to protect the environment. The DoE is located in Pardisan Park, that is covering more than 270 hectares in the Northwest
Tehran. Currently, 66 Governmental Laboratories under the DoE and 285 the DOE-Trusted Laboratories are available in Iran.
Dioxins have two chlorinated benzene connected through
a central ring with two oxygen atoms.
Furans have two chlorinated benzene connected through
a central ring with one oxygen atom.
The chlorine atoms can be attached in 8 different places
75 pieces 135 pieces
Mono-, di-,tri- octa- chloro dioxins / furans show not really toxicity Most toxic of family are: 2,3,7,8-tetrachlorodibenzodioxin (TCDD) 2,3,7,8-tetrachlorodibenzofuran (TCDF) 1,2,3,7,8-pentachlorodibenzodioxin (PCDD) 2,3,4,7,8-pentachlorodibenzofuran (PCDF)
The toxicity of dioxins/ furans is calculated with the Toxicity Equivalence Factors (TEF). In the report, PCDDS/PCDFS are added together form the value Toxicity Equivalent (TEQ).
Cont.
PCCDs / PCDFs Toxic Equivalent Factors
PCDDs Congeners I-TEFs
Tetra-CDD 2,3,7,8 1.0 Penta-CDD 1,2,3,7,8 0.5 Hexa-CDD 1,2,3,4,7,8 0.1 1,2,3,6,7,8 0.1 1,2,3,7,8,9 0.1 Hepta-CDD 1,2,3,4,6,7,8 0.01 Octa-CDD 1,2,3,4,6,7,8,9 0.001
TEF is a number assigned based on potency of the TCDD (the most toxic dioxin) .
PCDFS Congener I-TEFs
Tetra-CDF 2,3,7,8 0.1 Penta-CDF 1,2,3,7,8 0.05 2,3,4,7,8 0.5 Hexa-CDF 1,2,3,4,7,8 0.1 1,2,3,6,7,8 0.1 1,2,3,7,8,9 0.1 2,3,4,6,7,8 0.1 Hepta-CDF 1,2,3,4,6,7,8 0.01 1,2,3,4,7,8,9 0.01 Octa-CDF 1,2,3,4,6,7,8,9 0.001
As example: coal / oil and wood combustors, chlorine bleaching of paper, waste incinerators of all kinds, vehicle traffic, chemical production processes, accidental fires, most metal industries, specially sintering processes Anthropogenic Sources:
Natural Sources: As example: forest fires and volcano activities.
Three general physicochemical pathways:
Cont.
The first process occurs when the feed material going to the incinerator contains PCDDS/PCDFS and a fraction of these compounds persist in thermal breakdown
volume of PCDDS/PCDFS released to the environment.
Cont.
The second process is the formation of PCDDS/PCDFS from the thermal breakdown and molecular rearrangement of precursor compounds. The precursor compounds are such as chlorinated benzenes, chlorinated phenols and PCBs, which are resemblances to the PCDDS/PCDFS molecules.
The
third process called De-Novo-Synthesis
PCDDS/PCDFS . In this mechanism , inorganic chloride compounds such as NaCI or HCI will form to chlorine (CI2) in the presence of oxygen and subsequently, Cl2 reacts with aromatic components. Therefore destruction
concentration. The De-Novo-Synthesis is most active in a temperature range of 200 - 500 °C with a maximum at approximately 350 ° C.
Ingestion Inhalation of vapors and particulates Dermal contact
Acute symptoms/short term
Chronic symptoms/long term
Iran signed the Stockholm Convention in May 2001 and ratified it in February 2006. Iran as well as other countries agree to reduce or eliminate the production, use or release
the 12 persistent
pollutants (POPs) and PCDDS/PCDFS are in the list of POPs chemicals.
Commonly used devices for controlling Air Pollution:
Dry Scrubbers Cyclones, Electrostatic Precipitators (ESP), Fabric Filters (bag houses), Wet Scrubbers
To perform isokinetic sampling, it is necessary that the velocity and direction of the gas entering the nozzle is the same as the velocity and direction of the stack gas at the sampling point. 𝑗𝑡𝑝𝑙𝑗𝑜𝑓𝑢𝑗𝑑 𝑠𝑏𝑢𝑗𝑝 % = (Velocity at the nozzle / Velocity of the stack gas) ∗100
Isokinetic ratio during the sampling differs by more than 5% to +15% the measurement is not valid.
Isokinetic Sampling
V = stack gas velocity (m/s) K = pitot tube velocity constant (34.97) C = velocity pressure coefficient (for S-type pitot=0.84) (dimensionless) ΔP = square root of differential pressure of stack gas (mmH20) T stack = stack temperature (ºC) M = molecular weight of stack gas, wet basis (g/g mole) P = absolute stack gas pressure (mm.Hg)
The dry weight component (CO2, O2, N2) of the stack gas is calculated by: Molecular Weight
M dry = dry molecular weight of stack gas (g/g mole) %CO2 = percentage CO2 in gas stream %O2 = percentage O2 in gas stream % N2= 100 – ( % CO2+ % O2 + % CO ) 44(g/g mole) = MW carbon dioxide 32(g/g mole) = MW oxygen 28(g/g mole) = MW carbon monoxide 28(g/g mole) = MW nitrogen
M= 0.44 (%CO2) + 0.32 (%O2) + 0.28 (%N2)
Minimum required number of traverse points for sampling sites which meet specified criteria Traverse Points 2- Volumetric flow rate in the stack
Volumetric flow rate (m3/s)= Duct area (m2) x average velocity of stack gases (m/s)
Platform access shall be safe and easy access to the work platform and provided via caged ladder, stairway, or other suitable ways. Location of Sampling Port Sampling ports shall be located at least 8 times stack diameter down stream (B) and 2 times up stream (A) from any flow disturbance.
It’s possible to choose between three different methods:
Filter/Condenser Method Dilution Method Cooled Probe Method Gas is sampled isokinetically in the duct. The PCDDs/PCDFs, both adsorbed on particles and in the gas phase, are collected in the sampling train. The collecting parts can be
Filter/Condenser Method (Sampling train) The sample gas is sucked through the nozzle, probe and filter (< 125 °C). Then the gas passes the condenser and the condensate flask and adsorbent by suction device. Initial Checks before Sampling
Power Supply Safe Platform Sampling Ports (Correct Positions) Gas Velocity
Temperature Profiles Nozzle Selection Gas Oxygen Moisture Contents
1) Cleaning of the sampling equipment in the laboratory. Normally rinsing with water and detergent, followed by rinsing with solvent and/or treatment in a muffle oven for several hour (around 400 C). 2) Rinsing with solvent prior to sampling (can be done either in the laboratory or at sampling site). 3) Rinsing the equipment being in contact with the stack gas with solvents after the sampling. This rinsing solution is an important part
dichloromethane
Cleaning Sampling Devices:
Record keeping (at least every 15 min)
Leakage Test
A leak check shall be carried out before and after every sampling
flow rate shall be less than 5 % of the normal flow rate.
Field Blank
A field blank procedure shall be performed at least before each measurement series.
The field blank is taken at the operator’s site according the following procedure:
The value of this field blank shall not exceed 10 % of the emission limit value and shall be reported with the corresponding measured values
each of acetone and dichloromethane
After Sampling Sample Storage The samples shall be stored in the dark not higher than room temperature (approx. 25°C).
PCDDs/ PCDFs Sampling Train (EPA 23)
Front Half Back Half Front Half Probe Nozzle FH Filter Holder Back Half Filter Support BH filter Holder Condenser Transfer Line
Cont.
FH Acetone Rinse BH Acetone Rinse Impinger Acetone Rinse Combine contents for shipment to the Lab FH Toluene Rinse BH Toluene Rinse Impinger Toluene Rinse Combine contents for shipment to the Lab Glass fiber filter XAD-2 Shipment to the Lab
1 3 2
PCDDs/ PCDFs Sampling Train (EPA 23)
4 Cont.
Acetone Rinse Toluene Rinse Combine with condensate liquid Thimble filter XAD-2 Shipment to the Lab
PCDDs/ PCDFs Sampling Train (EN1948)
Cont.
Extraction is necessary to isolate the PCDDs/PCDFs from the sample and to collect them in an appropriate solvent volume. Extraction procedures are normally based on soxhlet extraction of filters and adsorbents, and liquid/ liquid extraction of condensates. Extraction method must be tested with a set of validation criteria. Sample Extraction
13C12-labelled 2,3,7,8-chlorine substituted PCDDs/PCDFs,, added before GC injection. Recovery Standard Sampling Standard 13C12-labelled 2,3,7,8-chlorine substituted PCDDs/PCDFs,, added before sampling Calibration Standard 13C12-labelled 2,3,7,8-chlorine substituted PCDDs/PCDFs, added before extraction. These standards are also used for calculation of results. Extraction Standard Unlabelled 2,3,7,8-chlorine substituted PCDDs/PCDFs, used for calibration curve.
Sample clean-up is usually carried
by multi-column chromatographic techniques using a range of adsorbents. The main purpose is to remove sample matrix components, which may disturb the quantification method
Sample clean-up Method Validation
Linearity Selectivity & Sensitivity (matrices without interference) Limit of Detection Limit of Quantification Limit of Quantification
Precision (Repeatability, Intermediate precision, Reproducibility)
Accuracy Robustness
PCDD/PCDF Analytical Schematic Diagram
Container (liquid) Clean up Concentrated 5 ml (Hexan) Add internal standard Liquid /liquid Extraction XAD2 & Filters Clean up Concentrated 5 ml (Hexan) Add internal standard Soxhlet Extract 16 h Analysis DB5 DFS-GCHRMS Silica aluminium oxide sodium sulphate Silica aluminium oxide sodium sulphate
Measured PCDDs/PCDFs conc. ng/Nm3 TEF TEQ 2,3,7,8-TCDD 2 1 2 1,2,3,6,7,8-HxCDD 10 0.1 1 2,3,4,7,8-PCDF 12 05 6 1,2,3,4,6,7,8,9-OCDD 100 0.001 0.1 Unit: ng TEQ/Nm3 9.1 TEQ= ∑[PCDDi × TEFi] + ∑ [PCDFi × TEFi] The limit value of PCDDs/PCDFs concentrations in stack emission: 0.2 ng TEQ/Nm3
This standard is based on the use of High Resolution Gas Chromatography Mass Spectrometry (GC/HRMS) for separation and detection, combined with isotope dilution of samples at different levels for quantification
PCDDs/PCDFs in emission samples. At present, GC/HRMS is the only analytical technique that can provide sufficient selectivity for the determination of amounts
PCDDs/ PCDFs in emission samples. GC/HRMS is designed for ultra low detection by advance mass spectrometer detector.
In mass spectrometer, ions are separated according to their mass-to-charge ratio (m/z) in magnetic sector and a slit is used to select which mass-to-charge ratio reaches the
(DFS) has two sectors (magnetic and electrostatic). GCHRMS- DFS
SCHEMATIC DIAGRAM OF DFS-GCHRMS
HR is
by decreasing the slit widths, and thereby decreasing the number of ions that reach the detector.
EN 13284-1:2002 - Determination of low range mass concentration of dust – Part 1: Manual gravimetric method ISO 9096:2003 - Stationary source emissions — Determination of concentration and mass flow rate of particulate material in gas-carrying ducts — Manual gravimetric method. EPA Method 2 Determination of stack gas velocity and volumetric flow rate. EPA method 5 Determination of particulate matter from stationary sources EPA method 17 Determination of particulate matter from stationary sources U.S EPA Method 23 (1998). Determination of polychlorinated Dibenzo-p-dioxins and polychlorinated Dibenzofurans from municipal waste combustors, US Environmental Protection Agency U.S EPA Method 1613B (1994). Tetra- through Octa Chlorinated Dioxins and Furans by Isotope Dilution HRGC/HRMS, US Environmental Protection