OIL SOLUTIONS™ Technology Profile:
Oil Solutions has introduced a product line that pioneers in this area, has a patent on a revolutionary microencapsulation technology for hydrocarbons, chemicals or heavy metals. The process is a two-step microencapsulation system that encloses contaminants on a molecular level in an inert amorphous silica matrix as envisioned in Figure 1. The first step in this unique approach is to surround small quantities of the organic contaminant with an aqueous, silica-surfactant system to form a micelle with the Step 1 additive. The surfactant orients itself with the hydrophobic portion toward the hydrocarbon and the hydrophilic portion toward the polar sites of the hydrophilic silica (Figure 1). The second additive is a curing agent. Oil Solutions Step 2 curing additive is a slightly acidic, aqueous, polymeric material that reacts with the alkaline Step 1 silica to speed up the microencapsulation process. Within minutes, microencapsulation is observed to occur in the form of precipitated agglomerates of wet silica containing the contaminant species in the micelle trapped inside the silica matrix. The pH of the microencapsulated material is approximately neutral. Characterization results suggest the resulting silica matrix is not very permeable or leachable and is resistant to environmental or chemical reactions.
Research supports the conceptual use of the Oil Solutions microencapsulation technology to remediate hazardous waste to within most regulatory guidelines. Examples of supportive research experiments with the Oil Solution additive process are described below:
• Bulk Oil Samples – A sample of used 10W-30 motor oil was microencapsulated with the Oil Solutions additives and allowed to dry. A TCLP extraction (EPA 1311) followed by analysis for TPH (EPA 8015m) indicated less than 1 ppm extractable TPH from the microencapsulated sample. A similar experiment was conducted with standard Type F hydraulic oil. The TPH leachable portion of the microencapsulated hydraulic oil was 7 ppm using the same EPA test procedures. The concentrations of the neat oils were 20 percent by volume.
• Oil Contaminated Soil – Soil contaminated with 4015 ppm of crude oil was microencapsulated using the Oil Solutions additives. A TCLP extraction (EPA 1311) of the treated product, followed by analysis for TPH using EPA 8015m indicated the leachable TPH was reduced to 1.23 ppm. This suggests a high level of success is possible in remediating crude oil contaminated soil with Oil Solutions microencapsulation technology.
• Oil/Halocarbon/Lead Contaminated Soil – Soil contaminated with 1590 ppm crude oil, 115 ppm lead and 32 ppm 1,1,1-trichloroethane was treated with Oil Solutions additives. TCLP extraction (EPA 1311) of the treated product, followed by analysis for TPH using EPA 8015m, SW846-8010 for halocarbons and SW846-6010 for lead indicated leachable TPH was reduced to 154 ppm, 1,1,1-trichloroethane was reduced to ________________________________________
Morphological results from Optical Microscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDXA), X-Ray Diffraction and Mass Spectroscopy provide evidence that suggests microencapsulation has long-term stability associated with the micro silica cell matrix.
• Morphological Characterization – Fluorescence, Optical Microscopy Photos, Scanning Electron Microscopy (SEM), Energy Dispersive X- Ray Analysis (EDXA), X-Ray Diffraction and Mass Spectroscopy Research were used to characterize the morphology of the microencapsulation silica cell matrix. Twenty volume percent of a neat crude oil sample, known to fluoresce under ultra violet (UV) light, was microencapsulated and allowed to air dry. The sample was examined using several analytical procedures. The crude oil was observed to be present in the microencapsulated sample under plane polarized light due to the presence of an oil stain on the silica cells as shown in Figure 2.The same sample was then examined under UV light as shown in Figure 3. The sample did not fluoresce as expected attributed to the crude oil in the microencapsulated sample. The oil stain was absent in the control sample without crude oil.SEM, coupled with EDXA, shows the silica morphology has many cavernous chambers and pockets at 2,000-fold magnification as shown in Figure 4. X-Ray Diffraction indicates the silica cell is largely amorphous silicon dioxide (silica). Amorphous structures are random in nature, and are known to be very stable as opposed to a highly ordered crystalline structure. The crude oil is said to be microencapsulated, meaning it is molecularly bound by physical forces in the micelles and trapped in the fine pores of the silica matrix. The electron micrograph RS 970546 shown in Figure 5 indicates fine structure at the edge reflected by dark and light contrasting of the order of 0.05 to 1 m m or less (500 to 1000 Å or less). This suggests that the porosity and characteristics of the silica aggregates have dimensions over a very broad range (tens of Ås to m m size). The technology in Oil Solutions and its ability to microencapsulate a high volume of oil (10 – 30 %) on a gram of encapsued material per gram of silica basis is linked to a very small pore size (ca. 50 – 100 Å ) as indicated by the fine structure on the micrograph shown in Figure 5.
• Mass Spectroscopic Analysis – The mass spectroscopy (MS) procedure is a technique to study volatiles in fluid inclusions of ores and oil inclusions in rock core samples. In this example, it is used to demonstrate the stability of microencapsulated product. The MS parameters are 125C at 10-7 torr. The procedure involves crushing a rock sample in a mass spectrometer and observing all possible organic fragments between 60 and 120 atomic mass units resulting from the organic species released from the sample at these severe conditions. In the control experiment (Figure 6a), a background scan (without crushing) mass spectrum of a sample of crude oil included in rock was obtained. The spectrum shows isolated peaks of modest intensity. The sample was crushed internally in the mass spectrometer according to the procedure. Immediately, the spectra in Figure 6b shows a complete range of fragments with atomic mass units between 60 and 120 are detected, as the crude oil components are set free from inclusions in the core sample.Microencapsulated crude oil was placed in the mass spectrometer in a second experiment. The background scan (Figure 6c) shows isolated peaks of modest intensity as expected similar to the results shown in Figure 6a. The microencapsulated crude oil sample was subsequently crushed. Immediately, the spectra (Figure 6d) still showed only isolated peaks of modest intensity and not the substantial increase in amu and intensity found in Figure 6b. The crude oil is present in the microencapsulated sample, but under these aggressive conditions, it does not show appreciable release of the oil for detection in the mass spectrometer. The mass spectroscopy experiment suggests the microencapsulated crude oil sample is very stable to physical force as compared to the crude oil that is not irreversibly included in a rock.