METIS Scientific

Surface Decontamination of Poly-Chlorinated Biphenyls (PCBs) using DeconGel® Formulations 1101 and 1102

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OBJECTIVE:  Surface decontamination determination of DeconGel® formulations 1101 and 1102 on aluminum, carbon steel, and concrete surfaces contaminated with PCB (Aroclor 1016) oil following a modified version of Environmental Protection Agency (EPA) SW-846 Method 8082A, “Determination of PCBs by Gas Chromatography”.

 

HAZARDOUS MATERIALS RELEVANCE:  PCBs were widely used additives in transformer and capacitor coolants and insulating fluids.  Due to undesirable carcinogenicity, PCB production has been banned since the 1970s.  PCBs are considered chemically inert and resist degradation, and as such remain environmentally persistent pollutants.

 

HIGHLIGHTS:

·   Excellent PCBs decontamination was achieved by brushing DeconGel® onto contaminated surfaces facilitating encapsulation/emulsification of contaminants by DeconGel® active components. 

·   Utilizing non-brushed (poured) DeconGel® application to contaminated surfaces, DeconGel® 1102 was found to possess superior PCB oil decontamination efficacy in comparison to DeconGel® 1101 for all surfaces investigated.

 

RESULTS: As seen in Table 1, the decontamination efficacies for both DeconGel® formulations 1101 and 1102 were determined on aluminum, carbon steel, and concrete surfaces contaminated with PCBs (suspended in mineral oil):

 

Table 1. Decontamination efficacy of DeconGel® on PCB oil on aluminum, carbon steel, and concrete

 

Swipe Testing (ppm)

Formulation (Application Method)

DeconGel® 1101

(non-brushed)

DeconGel® 1101

(brushed)

DeconGel® 1102

(non-brushed)

DeconGel® 1102

(brushed)

Aluminum1

    

Control

16.3 ± 0.1

16.3 ± 0.1

16.3 ± 0.1

16.3 ± 0.1

Residual

  2.1 ± 0.1

<0.8*

  1.0 ± 0.1

<0.8*

Decon. Efficacy (%)

87.1 ± 1.0

≥95.1

93.9 ± 1.0

≥95.1

Carbon Steel2

Control

26.6 ± 0.8

26.6 ± 0.8

26.6 ± 0.8

26.6 ± 0.8

Residual

  3.3 ± 0.2

<0.8*

<1.2*

<0.8*

Decon. Efficacy (%)

87.6 ± 0.8

≥97.0

≥95.5

≥97.0

Concrete3

 

Control

16.1 ± 1.4

16.1 ± 1.4

16.1 ±1.4

16.1 ± 1.4

Residual

  4.5 ± 0.1

<0.8*

     2.1 ± 0.02

<0.8*

Decon. Efficacy (%)

72.0 ± 1.0

≥95.0

  87.0 ± 1.0

≥95.0

1 1212x dilution factor for samples and controls

2 784x dilution factor for samples and controls

3 941x dilution factor for samples and controls

* lower detection limit of samples/control preparative method = 0.8 ppm

 

Decontamination Efficacy (Swipe Testing) =

[(PCBs (ppm) of Swipe Control) – (PCBs (ppm) of Residual Swipe)/PCBs (ppm) of Swipe Control] x 100%

 

MATERIALS AND METHODS:

Sample Method

In a typical procedure, PCB-contaminated mineral oil (approx. 33145 ppm (v/v)) was added to the surfaces of 1) aluminum (brushed, 56.3 cm2), 2) carbon steel (commercial grade, 100 cm2), or 3) concrete (industrial grade, 56.3 cm2) coupons and then the PCB oil was spread out throughout the surface with a clean brush to afford 33 mg (aluminum coupon), 39 mg (steel coupon), and 53 mg (concrete coupon), respectively.  Approximately 6.0 g of either DeconGel® 1101 or 1102 was poured onto the contaminated surface and either 1) let to dry for 24 h, or

2) brushed onto the contaminated surface, first in an up-and-down fashion, followed by a left-to-right fashion, and then let to dry for 24 h.  Dried DeconGel® samples were peeled off the contaminated surface, and the surface was swipe tested (ASTM method D6966-08) using an air-dried (24 h) GhostWipe™ swipe (Environmental Express; Mt. Pleasant, SC).  Swipe samples were suspended in 40 mL DMSO solvent for 24 h and analyzed via GC/MS following a modified version[1] of EPA SW-846 Method 8082A, “Determination of PCBs by Gas Chromatography” (see below).

Control Method

For Swipe Controls, PCB-contaminated mineral oil (approx. 33145 ppm (v/v)) was added to the surfaces of 1) aluminum (brushed, 56.3 cm2), 2) carbon steel (commercial grade, 100 cm2), or 3) concrete (industrial grade, 56.3 cm2) and then the PCB oil was spread out throughout the surface with a clean brush to afford 33 mg (aluminum coupon), 39 mg (steel coupon), and 53 mg (concrete coupon), respectively.  The surface was swipe tested (ASTM method D6966-08) using an air-dried GhostWipe ™ swipe (Environmental Express; Mt. Pleasant, SC).  Swipes were suspended in 40 mL DMSO solvent for 24 h and analyzed via GC/MS following a modified version1 of EPA SW-846 Method 8082A, “Determination of PCBs by Gas Chromatography” (see below).

Standard

PCB standard Aroclor 1016 (Ultra Scientific; Kingston, RI) was dissolved in DMSO solvent to prepare three five-point standard curves for 1) a di-chlorinated biphenyl (9.60 min; M+ = 222; equation (y = 653,791.68x + 787,941.99), coefficient of determination (r2 = 1.0); 2) a tri-chlorinated biphenyl (10.52 min; M+ = 256; equation (y = 512,089.30x + 620,529.58), coefficient of determination (r 2= 1.0); and 3) a tetra-chlorinated biphenyl (11.37 min; M+ = 290; equation (y = 428,869.22x + 484,744.73), coefficient of determination (r2 = 1.0).    

Sample

PCB-contaminated mineral oil was confirmed to be Aroclor 1016 by GC/MS analysis and was found to have an Aroclor 1016 concentration (v/v) of approximately 33145 ppm.  

Analytical Instrumentation.

A Thermo GC/MS tandem instrument model Trace DSQ II with autosampler was used to determine Aroclor 1016 area under curve (AUC); sample and control Aroclor 1016 concentrations were calculated using generated standard curves. 

GC Column: Thermo TR-5ms SQC (15 m x 0.25 mm x 0.25 um)

GC Temperature gradient: start at 100 oC, hold for 1 min, ramp to 15 oC/min to 320oC, hold for 5 min.

MS Ion chamber temperature: 300oC



[1] PCB controls, standards, and samples were solubilized in DMSO.   

 

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