Abstract Hydrogen sulfide (H2S) is an environmentally hazardous, corrosive, and toxic gas, mostly generated in gas and oil industry. For small-scale natural gas processing sites (less than 10 tonne S/day), the use of regenerable iron oxide adsorbent to adsorb H2S from natural gas is still an economical and effective method. The objective of this research project was to understand the performance of an iron oxide adsorbent, recently emerging in the Canadian market, in removing H2S from gas streams. To accomplish this, the breakthrough behaviors of H2S adsorption in a fixed-bed reactor under elevated pressures were studied. The effects of variations in superficial velocity from 0.09 m/s to 0.26 m/s, operating pressure from 4 to 50 atm absolute, and the height of the fixed-bed from 11.7 cm to 24.5 cm on breakthrough curves and sulfur loading were investigated. In all the experiments, the H2S concentration profiles of the exiting gas from the reactor were measured until the bed was saturated. It was found that the shape of the breakthrough curves depend on the superficial velocity and the inlet H2S concentration in gas streams. Under both higher superficial velocity and higher inlet H2S concentration, the shape of the breakthrough curve becomes steeper. The sulfur loading of the adsorbent depends on the superficial velocity, the inlet H2S concentration in gas streams, and the bed height. The sulfur loading decreases as the superficial velocity and the inlet H2S concentration increase, but increases as the bed height increases. The change of operating pressure does not have a significant effect on the shape of the breakthrough curve or sulfur loading of the adsorbent. The investigation was also extended using the regenerated adsorbents. A mathematical formula was developed to describe the breakthrough curves.

Abstract Hydrogen sulfide (H2S) is an environmentally hazardous, corrosive, and toxic gas, mostly generated in gas and oil industry. For small-scale natural gas processing sites (less than 10 tonne S/day), the use of regenerable iron oxide adsorbent to adsorb H2S from natural gas is still an economical and effective method. The objective of this research project was to understand the performance of an iron oxide adsorbent, recently emerging in the Canadian market, in removing H2S from gas streams. To accomplish this, the breakthrough behaviors of H2S adsorption in a fixed-bed reactor under elevated pressures were studied. The effects of variations in superficial velocity from 0.09 m/s to 0.26 m/s, operating pressure from 4 to 50 atm absolute, and the height of the fixed-bed from 11.7 cm to 24.5 cm on breakthrough curves and sulfur loading were investigated. In all the experiments, the H2S concentration profiles of the exiting gas from the reactor were measured until the bed was saturated. It was found that the shape of the breakthrough curves depend on the superficial velocity and the inlet H2S concentration in gas streams. Under both higher superficial velocity and higher inlet H2S concentration, the shape of the breakthrough curve becomes steeper. The sulfur loading of the adsorbent depends on the superficial velocity, the inlet H2S concentration in gas streams, and the bed height. The sulfur loading decreases as the superficial velocity and the inlet H2S concentration increase, but increases as the bed height increases. The change of operating pressure does not have a significant effect on the shape of the breakthrough curve or sulfur loading of the adsorbent. The investigation was also extended using the regenerated adsorbents. A mathematical formula was developed to describe the breakthrough curves.

The investigation of the atmospheric fate and transport of semi-volatile organic compounds (SOCs) often requires the sampling of large volumes of air (>100 m3) in a relatively short period of time. Conventionally high-volume pumps are not suitable for remote areas without access to reliable network power. We have developed a flow through sampler for such situations. It consists of a horizontally-oriented flow-tube, that can collect gaseous and particle-bound SOCs from large volumes of air by turning into the wind and having the wind blow through a porous sampling medium such as polyurethane foam. Through both indoor and outdoor experiments, we quantified its air sampling rate (through battery operated anemometers inside and outside of the flow tube), its sampling efficiency (by theoretical plate number analysis of the break-though curves for PCBs, PAHs, OCPs and PBDEs), and its accuracy (by comparison of concentrations, time trends, temperature dependences and isomer ratios with those obtained by conventional high-volume sampling) under conditions of constant and variable meteorological conditions (wind speed, temperature). The flow-through sampler was deployed to monitor SOC concentrations at a remote Chinese research station located close to Nam Co Lake, Tibet. During the campaign, fifteen 1 month-long samples were taken, corresponding to sample volumes between 5,000 and 20,000 m3. Despite those large sample volumes, only HCB and HCHs experienced break-through, but application of frontal chromatograph theory allows the estimation of breakthrough-corrected air concentrations even for those relatively volatile SOCs. The pesticide levels at Nam Co are generally very low. Most pesticides had higher levels during summer, resulting in a strong temperature dependence. This is correlated with air mass origin across the Himalayas in the Gangetic plains of India and Bangladesh. The flow through sampler constitutes a feasible method for reliably and quantitatively collecting SOCs from large air volumes.

The investigation of the atmospheric fate and transport of semi-volatile organic compounds (SOCs) often requires the sampling of large volumes of air (>100 m3) in a relatively short period of time. Conventionally high-volume pumps are not suitable for remote areas without access to reliable network power. We have developed a flow through sampler for such situations. It consists of a horizontally-oriented flow-tube, that can collect gaseous and particle-bound SOCs from large volumes of air by turning into the wind and having the wind blow through a porous sampling medium such as polyurethane foam. Through both indoor and outdoor experiments, we quantified its air sampling rate (through battery operated anemometers inside and outside of the flow tube), its sampling efficiency (by theoretical plate number analysis of the break-though curves for PCBs, PAHs, OCPs and PBDEs), and its accuracy (by comparison of concentrations, time trends, temperature dependences and isomer ratios with those obtained by conventional high-volume sampling) under conditions of constant and variable meteorological conditions (wind speed, temperature). The flow-through sampler was deployed to monitor SOC concentrations at a remote Chinese research station located close to Nam Co Lake, Tibet. During the campaign, fifteen 1 month-long samples were taken, corresponding to sample volumes between 5,000 and 20,000 m3. Despite those large sample volumes, only HCB and HCHs experienced break-through, but application of frontal chromatograph theory allows the estimation of breakthrough-corrected air concentrations even for those relatively volatile SOCs. The pesticide levels at Nam Co are generally very low. Most pesticides had higher levels during summer, resulting in a strong temperature dependence. This is correlated with air mass origin across the Himalayas in the Gangetic plains of India and Bangladesh. The flow through sampler constitutes a feasible method for reliably and quantitatively collecting SOCs from large air volumes.