Paul Su

Decontamination of surfaces exposed to carbon-based nanotubes and nanomaterials

Contamination of surfaces by nanomaterials can happen due to accidental spillage and release or gradual accumulation during processing or handling. Considering the increasingly wide use of nanomaterials in industry and research labs and also taking into account the diversity of physical and chemical properties of different nanomaterials (such as solubility, aggregation/agglomeration, and surface reactivity), there is a pressing need to define reliable nanomaterial-specific decontamination guidelines. In this paper, we propose and investigate a potential method for surface decontamination of carbon-based nanomaterials using solvent cleaning and wipes. The results show that the removal efficiency for single- and multiwalled carbon nanotubes from silicon wafers sprayed with water-surfactant solutions prior to mechanical wiping is greater than 90% and 95%, respectively. The need for further studies to understand the mechanisms of nanomaterial removal from surfaces and development of standard techniques for surface decontamination of nanomaterials is highlighted.

Smoke Characterization and Damage Potentials

Smoke is a mixture of (1) particulates consisting of soot, semi-volatile organic compounds (SVOC), and solid inorganic compounds; and (2) non-particulates consisting of very volatile organic compounds, volatile organic compounds, and liquid and gaseous inorganic compounds. Soot creates bridging between electrical conductors and conveys corrosive products, resulting in damage to electronics and electrical circuits through leakage current and corrosion, while SVOC and non-particulates stain and impart malodor to surfaces. Soot is also a very effective adsorbent and transport mechanism for SVOC, non-particulates and inorganic compounds.

Pilot testing of fire sprinkler system in extremely corrosive industrial duct environments

Due to the extremely corrosive environments inside many exhaust ducts fabricated from combustible materials, the mechanical integrity of fire sprinkler system components is often prematurely compromised, leaving the system unable to protect against fires originating within these ducts [FM Global Loss Prevention Data Sheet, 7–78, Industrial Exhaust System, 2011; Understanding the Hazard, Fire in Industrial Exhaust Systems, FM Global, Johnston, RI, 2006]. Pilot testing of a new fire sprinkler system was conducted to protect the fiber‐reinforced plastic duct at a nitric/hydrofluoric (HF/HNO3) mixed acid pickling operation. Based on previous laboratory and field tests [Su and Doerr, Process Saf Prog 29 (2010) 70–78], this fire sprinkler system was composed of corrosion resistant sprinkler nozzles, a linear heat detector, flexible mounting connections, sprinkler piping, and controls. Pilot testing results have led to development and recommendation of a new fire protection system capable of protecting combustible exhaust ducts from fire in extremely corrosive environments.

Fire Protection Sprinkler System for Extremely Corrosive Industrial Duct Environments

Because of the extremely corrosive environments inside many industrial exhaust ducts, sprinkler systems have not been successfully designed to protect against fires originating within these ducts. Damage to the exhaust ductwork system caused by fire can lead to interruption of the plant operations for an extended period of time with substantial financial losses. Research has been performed to evaluate the corrosion resistance properties of various materials and coatings such that corrosion resistant sprinklers and fire protection hardware can be developed for use in these flammable exhaust ducts and other corrosive industrial environments. Laboratory tests, including electrochemical techniques and crevice coupon immersion tests, were used to select suitable alloys and coatings for in‐situ field test rack studies. These results are providing the basis for the development of fire protection systems suitable for these industrial exhaust ducts. 1

Removal of Multi-Walled Carbon Nanotubes From Contaminated Surfaces With Microscale Topological Features

Experiments were performed to examine the ability of surfactants to remove multi-walled carbon nanotubes (MWCNTs) from silicon wafers with nano and micro scaled features. Well-defined microscale topological features on silicon wafers were induced using photo lithography and plasma etching. The etching time was varied to create variation in topological features with the size and height of ∼ 8±1 μm, and ∼2±1 μm, respectively. MWCNTs in the form of pristine liquid solution were deposited on the surface of silicon wafers using the spin coating process. During cleaning, the contaminated surfaces were first sprayed with one of the two surfactants, sodium dodecyl sulfate (SDS) and sodium dodecyl benzene sulfonate (SDBS), or water. MWCNTs were wiped off using a wiping mechanism. The area density of the MWCNTs was quantified prior to and after their removal using scanning electron microscopy (SEM) and post-image processing. The results show decreasing removal efficiency for all the surfactants as the topological features on the wafers deepen through increasing the etching time. Surfactants show better decontamination efficiency compared with water.Copyright