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We present here applications of the nanoscale metal particles for transformation of carbon tetrachloride (CT). CT is one of the most prevalent contaminants in soils and aquifers. It has been listed as priority pollutants by the U.S. Environmental Protection Agency, and also appeared on the Superfund National Priority List. There is an urgent need to develop effective control and treatment methods. The purpose of this study was aimed to measure the rate and extent of dechlorination, characterize and quantify reaction intermediates and final products. EXPERIMENTAL METHODS Synthesis of nanoscale iron particles. Nanoscale iron particles were synthesized by adding 1:1 volume ratio of FeCI3*6H20 (0.045M) into NaBH4 (0.25M) solution and mixed vigorously under room temperature (22±1 °С) for a few minutes. Ferric iron (Fe3+) was reduced to zero-valent iron (Fe°) by borohydride, a strong reductant. Metal particles from this reaction have sized mostly in the range between 1 to 100 nanometers [1,2]. BET analysis gave a specific surface area of 35 m2/g. Batch experiments. Batch experiments were conducted with 50 mL serum bottles. In each batch bottle, 20 mL deionized water was mixed with 0.25 g of the nanoscale metal particles. Then, 10 pL stock solution of CT dissolved in methanol was spiked into the solution. Initial organic concentration was about 0.1 mM. The serum bottles were capped with Teflon Mininert valves and mixed on a rotary shaker (30 rpm) at room temperature (22±1°C). Parallel experiments were also performed without the metal particles (control) and with a commercial grade iron (Aldrich, 99%, <10 pm, BET surface area 0.9m2/g ). Methods of Analyses. Organic concentrations were measured by the static headspace gas chromatograph (GC) method. At selected time intervals, 20 pL headspace aliquot was withdrawn from the batch bottle for GC analyses. Concentrations of chlorinated methanes were measured using a HP5890 GC equipped with a DB-624 capillary column (30mx0.32mm) and an electron capture detector (ECD). The detection limit of this method was less than 5 pg/L. Hydrocarbon products in the headspace were qualitatively identified with a Shimadzu QP5000 GC-MS and further quantified with GC analysis by comparing retention times and peak areas with standard gas samples (ethane, ethylene, acetylene, methane and carbon dioxide).
DOI link for We present here applications of the nanoscale metal particles for transformation of carbon tetrachloride (CT). CT is one of the most prevalent contaminants in soils and aquifers. It has been listed as priority pollutants by the U.S. Environmental Protection Agency, and also appeared on the Superfund National Priority List. There is an urgent need to develop effective control and treatment methods. The purpose of this study was aimed to measure the rate and extent of dechlorination, characterize and quantify reaction intermediates and final products. EXPERIMENTAL METHODS Synthesis of nanoscale iron particles. Nanoscale iron particles were synthesized by adding 1:1 volume ratio of FeCI3*6H20 (0.045M) into NaBH4 (0.25M) solution and mixed vigorously under room temperature (22±1 °С) for a few minutes. Ferric iron (Fe3+) was reduced to zero-valent iron (Fe°) by borohydride, a strong reductant. Metal particles from this reaction have sized mostly in the range between 1 to 100 nanometers [1,2]. BET analysis gave a specific surface area of 35 m2/g. Batch experiments. Batch experiments were conducted with 50 mL serum bottles. In each batch bottle, 20 mL deionized water was mixed with 0.25 g of the nanoscale metal particles. Then, 10 pL stock solution of CT dissolved in methanol was spiked into the solution. Initial organic concentration was about 0.1 mM. The serum bottles were capped with Teflon Mininert valves and mixed on a rotary shaker (30 rpm) at room temperature (22±1°C). Parallel experiments were also performed without the metal particles (control) and with a commercial grade iron (Aldrich, 99%, <10 pm, BET surface area 0.9m2/g ). Methods of Analyses. Organic concentrations were measured by the static headspace gas chromatograph (GC) method. At selected time intervals, 20 pL headspace aliquot was withdrawn from the batch bottle for GC analyses. Concentrations of chlorinated methanes were measured using a HP5890 GC equipped with a DB-624 capillary column (30mx0.32mm) and an electron capture detector (ECD). The detection limit of this method was less than 5 pg/L. Hydrocarbon products in the headspace were qualitatively identified with a Shimadzu QP5000 GC-MS and further quantified with GC analysis by comparing retention times and peak areas with standard gas samples (ethane, ethylene, acetylene, methane and carbon dioxide).
We present here applications of the nanoscale metal particles for transformation of carbon tetrachloride (CT). CT is one of the most prevalent contaminants in soils and aquifers. It has been listed as priority pollutants by the U.S. Environmental Protection Agency, and also appeared on the Superfund National Priority List. There is an urgent need to develop effective control and treatment methods. The purpose of this study was aimed to measure the rate and extent of dechlorination, characterize and quantify reaction intermediates and final products. EXPERIMENTAL METHODS Synthesis of nanoscale iron particles. Nanoscale iron particles were synthesized by adding 1:1 volume ratio of FeCI3*6H20 (0.045M) into NaBH4 (0.25M) solution and mixed vigorously under room temperature (22±1 °С) for a few minutes. Ferric iron (Fe3+) was reduced to zero-valent iron (Fe°) by borohydride, a strong reductant. Metal particles from this reaction have sized mostly in the range between 1 to 100 nanometers [1,2]. BET analysis gave a specific surface area of 35 m2/g. Batch experiments. Batch experiments were conducted with 50 mL serum bottles. In each batch bottle, 20 mL deionized water was mixed with 0.25 g of the nanoscale metal particles. Then, 10 pL stock solution of CT dissolved in methanol was spiked into the solution. Initial organic concentration was about 0.1 mM. The serum bottles were capped with Teflon Mininert valves and mixed on a rotary shaker (30 rpm) at room temperature (22±1°C). Parallel experiments were also performed without the metal particles (control) and with a commercial grade iron (Aldrich, 99%, <10 pm, BET surface area 0.9m2/g ). Methods of Analyses. Organic concentrations were measured by the static headspace gas chromatograph (GC) method. At selected time intervals, 20 pL headspace aliquot was withdrawn from the batch bottle for GC analyses. Concentrations of chlorinated methanes were measured using a HP5890 GC equipped with a DB-624 capillary column (30mx0.32mm) and an electron capture detector (ECD). The detection limit of this method was less than 5 pg/L. Hydrocarbon products in the headspace were qualitatively identified with a Shimadzu QP5000 GC-MS and further quantified with GC analysis by comparing retention times and peak areas with standard gas samples (ethane, ethylene, acetylene, methane and carbon dioxide).
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ABSTRACT
We present here applications of the nanoscale metal particles for transformation of carbon tetrachloride (CT). CT is one of the most prevalent contaminants in soils and aquifers. It has been listed as priority pollutants by the U.S. Environmental Protection Agency, and also appeared on the Superfund National Priority List. There is an urgent need to develop effective control and treatment methods. The purpose of this study was aimed to measure the rate and extent of dechlorination, characterize and quantify reaction intermediates and final products.