Pilot scale testing composite swellable organosilica nanoscale zero‐valent iron—Iron‐Osorb®—for in situ remediation of trichloroethylene

Abstract

Iron-Osorb ® is a solid composite material of swellable organosilica with embedded nanoscale zero-valent iron that was formulated to extract and dechlorinate solvents in groundwater. The unique feature of the highly porous organosilica is its strong affinity for chlorinated solvents, such as trichloroethylene (TCE), while being impervious to dissolved solids. The swellable matrix is able to release ethane after dechlorination and return to the initial state. Iron-Osorb ® was determined to be highly effective in reducing TCE concentrations in bench-scale experiments. The material was tested in a series of three pilot scale tests for in situ remediation of TCE in conjunction with the Ohio Environmental Protection Agency at a site in central Ohio. Results of these tests indicate that TCE levels were reduced for a period of time after injection, then leveled out or bounced back, presumably due to depletion of zero-valent iron. Use of tracer materials and soil corings indicate that Iron-Osorb ® traveled distances of at least 20 feet from the injection point during soil augmentation. The material appears to remain in place once the injection fluid is diluted into the surrounding groundwater. Overall, the technology is promising as a remediation method to treat dilute plumes or create diffuse permeable reactive barriers. Keys to future implementation include developing injection mechanisms that optimize soil distribution of the material and making the system long-lasting to allow for continual treatment of contaminants emanating from the soil matrix. O

Continuum-based models and concepts for the transport of nanoparticles in saturated porous media: A state-of-the-science review

“…In engineered filtration systems such physical straining results in a continuous compressible cake [208,209] or a mat with holes on it [209]. But although observed in experimental micromodel by the aid of pore visualization [210] this is not considered common in natural aquifers unless it is encountered at the upper area of porous media [53,211] or in the case of injecting engineered NP into subsurface media, in the near vicinity of the injection well [e.g., 212,[213][214][215]. Occasionally straining has been further subdivided into two mechanisms of wedging and bridging.…”

“…In addition to this difficulty in upscaling the depth-dependent model of Bradford et al, it is also unclear whether this model can be valid in the real condition of flow in larger scales where the effect of preferential flow paths is considerable [153,199,210,244,245]. To date, relatively very few studies have discussed the occurrence of straining, clogging or pore plugging in the porous medium during NP transport in multi-dimensional domains [96,157,213,214], some of which even tried to rule out these phenomena. Therefore, there is a crucial need to develop more rigorous conceptual models that can consider the concurrent effect of various phenomena occurring with straining of NP during transport in porous media.…”

“…In spite of large number of NP transport studies in 1-D column experiments, multidimensional transport reports are scarce [214,244,245,379]. Likewise, multidimensional modeling tools are…”

Indoor Air Purification of Volatile Organic Compounds (VOCs) Using Activated Carbon, Zeolite, and Organosilica Sorbents

“…Organosilica has also been demonstrated to be effective at removing butanol, methyl t-butyl ether (MTBE), tetrachloroethylene, trichloroethylene, ethanol, and toluene from fresh water and salt water. 43 Iron-Osorb was determined to be highly effective in reducing TCE concentrations in bench-scale experiments. 43 Organosilica has also been shown to strongly sorb hydrophobic forms of the organic ligand diethylenetriaminepentaacetic acid (DTPA), even in the presence of large volumes of water 44−46 Although many commercial air purifiers are available, most are specifically designed to benefit allergy sufferers and asthmatics by removing airborne particles (e.g., pet dander, dust, mold tobacco smoke particles).…”

“…43 Iron-Osorb was determined to be highly effective in reducing TCE concentrations in bench-scale experiments. 43 Organosilica has also been shown to strongly sorb hydrophobic forms of the organic ligand diethylenetriaminepentaacetic acid (DTPA), even in the presence of large volumes of water 44−46 Although many commercial air purifiers are available, most are specifically designed to benefit allergy sufferers and asthmatics by removing airborne particles (e.g., pet dander, dust, mold tobacco smoke particles). These purifiers are specific to certain pollutants and most air purifiers should not be expected to remove all gaseous pollutants found in a typical home.…”