Chinese Drywall --- Absorption Capacities

Re:  Adsorptive Capacities of the Interceptor Coating System:            

Interceptor OC - Water-based Coating System Interceptor EX - Powder Coating System

 The Interceptor coating system is designed specifically to address the issues of odor and off-gassing presented by “tainted” Chinese & domestic drywall. 

 â–  Case Summary   The “tainted” Chinese drywall has been tested by accredited labs in the US noting that the odor related to the Chinese drywall is in fact in the form of di-hydrogen sulfide, carbonyl sulfide, and carbon disulfide, among others. Given these facts among unknown rates of off-gassing and the varying life cycles of odorous effects, the Interceptor coating system is specifically formulated to address off-gassing and related odors by providing a coatings matrix to promote absorption and neutralization of these effects by various techniques of chemical adsorption and use of ion exchange affinities at the molecular level. The Interceptor coating system is formulated with an absorptive / adsorptive capacity to exceed the documented emissions expectancy of sulfur gas emitting drywall, and in particular, “tainted” Chinese drywall. 

â–  Theory for Adsorption Capacity   The gases and odors emitted from the tainted Chinese drywall will follow the laws of diffusion meaning they will migrate from areas of higher concentration to that of lower concentration.  The sulfur gases from the drywall are migrating toward the interior of the building structure (living quarters) as well as into the stud cavities.   For a specific sheet of drywall, the area associated with the living quarters versus the stud cavities would have a near equal amount of sulfur based gasses emitted into it, but would show less concentrated effects due to a larger volume of air spaced that is replenished.  The corresponding stud cavity area, in theory, would have a higher concentration of the sulfur based gases due to limited space and replenishment of air. Migration of the sulfur based gases from the interior of the tainted Chinese drywall occurs at any seasonable temperature and humidity level, but is most active at temperatures above 80F and relative humidity readings above 50%. 

In calculating adsorptive capacities:  

The laboratory determination of adsorption capacities is performed by the following method.  Adsorption capacities of the Interceptor coating system were calculated in terms of adsorption by % weight.  The mechanism(s) by which adsorption of the sulfur based gases occurs is proprietary information.  Once the sulfur based species are chemically bound to the adsorptive materials, the chemical reaction will not reverse itself to re-release the sulfur gases back into the atmosphere under any expected variation of conditions, including temperature, barometric pressure, humidity, etc. A 1% concentration of H2S gas (10,000 ppm) stream in 85% RH air is pumped through a 9” x 1” diameter column of adsorptive material.  The air flow rate is 1450 cc / min.  The air flow is continued until a 50 ppm out-flow of concentration of H2S gas is measured. 

Adsorption capacity = (H2S) x F x TBT / VC                          

 (H2S)  =  Concentration, in g/ml        

 F =  Flow, in cc / min     

 TBT =  Break through time, in minutes     

 VC  =  Volume of adsorptive material, in cc 

â–  Interceptor OC - Adsorptivity  

 The Interceptor OC when applied to drywall in two (2) coats at a spread rate of 400 sq ft per gallon, the adsorptive material present in the dry coating film matrix is approximately 2.90 g/sf with an average capacity for H2S gas adsorption of 30% by weight or approximately 0.87 g/sf. “Tainted” H2S gas emitting Chinese drywall averages near 1 microgram / kg which equates to 1 microgram per square foot of drywall averaging 2.2 lbs (1 kg) per square foot for 5/8” material.  In some of the most extreme cases, 5 micrograms / kg has been measured.  Taking this extreme example into account, the adsorptive potential of the Interceptor OC can be calculated per square foot: (0.87 grams / sf adsorptive capacity of Interceptor OC)         (5 micrograms / sf emission of H2S gas) Yields…  174,000 X for Interceptor OC on the face of the board, assuming all gases are emitted into the living space  

 â–  Interceptor EX Adsorptivity For concealed spaces behind the drywall, the Interceptor EX is electro-statically charged promoting adherence to all surfaces inside the confined space of the wall cavities.  Through a static discharge unit, the Interceptor EX is injected into the stud cavities and is activated to adhere by an electrostatic dipole formed during the injection process.  This electrostatic charge helps overcome the forces of gravity keeping these powder coatings in place once adhered to a surface within the stud cavity. By injection, the Interceptor EX is thoroughly dispersed throughout the stud cavity to maximize coverage within that space.  In instances where dispersion is limited, the coating is designed to take advantage of concentration gradients within the stud cavity adsorbing the sulfur based gases and related odors.  The concentration of the sulfur based gasses and related odors emitted into the stud cavity are reduced over time as they are absorbed into the molecular matrix of the powder coatings.  As this absorption occurs and results in chemical adsorption, the concentration with the stud cavity is reduced causing remaining odor and gas molecules to spread and even the concentration gradient within the confined space.   As a result, additional gas and odor molecules are absorbed into the powder coating and then adsorbed.   The Interceptor EX when injected into drywall confined spaces at an injection rate of 2 cc per average stud bay fronted by an 8 ft x 16 in drywall section, the adsorptive material present in the dry powder coating matrix is approximately 1.58 g/stud bay with an average capacity for H2S gas adsorption of 32% by weight or approximately 0.51 g/stud bay.   Using 5 micrograms / sq ft of H2S emissions from the drywall, this would equate to 53.3 micrograms of H2S emissions per stud bay.   The adsorptive potential of the Interceptor EX can be calculated per square foot as: (0.51 grams / sf adsorptive capacity of Interceptor EX)          (0.0000533 grams / stud bay emissions of H2S gas) Yields…  9568 X for Interceptor EX in an average size stud bay, assuming all gas emissions migrate into the confined space