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567 results on '"Langford, Cooper H."'

121. Mineralisation of sulfolane by UV/O3/H2O2in a tubular reactor

Author

Mehrabani-Zeinabad, Mitra, Yu, Linlong, Achari, Gopal, and Langford, Cooper H.

Abstract

Degradation of sulfolane in contaminated groundwater was studied in a flow-through photoreactor with recirculation, using various oxidative methods, including ozone (O3)/hydrogen peroxide (H2O2), ultraviolet (UV)/ozone, UV/hydrogen peroxide and UV/ozone/hydrogen peroxide. Total organic carbon as an indicator of the extent of mineralisation and sulfate as a byproduct produced during degradation were measured. The effects of several operating conditions, including flow rate, initial concentration of sulfolane and ratio of different oxidants, were investigated. It was noted that although the loss of sulfolane was similar for the UV/ozone/hydrogen peroxide and the UV/hydrogen peroxide process, the overall mineralisation rates were significantly different, indicating that the combination of oxidants offers a significantly more efficient system. The results show that in water containing 100 mg/l sulfolane, more than 99·5% can be mineralised to carbon dioxide (CO2), water (H2O) and sulfate (SO42−) by the UV/ozone/hydrogen peroxide process (the most efficient process) within 4 h (13·2 kJ energy from UV irradiation transferred). The UV/ozone/hydrogen peroxide process mineralised sulfolane in contaminated groundwater, but with a longer reaction time.

Published
2016
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128. Modeling sorption behavior of atrazine on intact soil columns

Author

Li, Jinhe, Prasher, Shiv O., Clemente, S., Reynolds, William D., Smith, Ward N., Gamble, Donald S., Topp, Edward, Langford, Cooper H., and Salehi, Farhad

Subjects
Atrazine -- Research, Soil absorption and adsorption -- Research, Soil permeability -- Research, Engineering and manufacturing industries, Science and technology
Abstract

The sorption behavior of atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine), a commonly used herbicide for corn, on intact soil columns was studied by incorporating a new two-stage sorption mechanism into PESTFADE, a pesticide fate and transport model. This mechanism takes into account intraparticle diffusion of pesticide into the soil matrix (also sometimes known as bound residues), the sorption capacity of soil, and a variable pesticide distribution coefficient [K.sub.d]. The modified model's performance was verified by comparing simulated values with those obtained from an intact column study in the laboratory. The two-stage mechanism was also compared and contrasted with the conventional adsorption approach based on a constant [K.sub.d]. Simulations with the two-stage mechanism indicated a closer agreement with measured values (deviations in the range of 5-65%) than that of the conventional adsorption approach (deviations in the range of 10-700%). Furthermore, it was found that simulated values were particularly sensitive to soil tortuosity [Tau], soil bulk density [Rho], soil moisture content [[Theta].sub.w], labile sorption capacity [[Theta].sub.c], and intraparticle diffusion parameters.

Published
1999

139. Metal to Ligand Charge-Transfer Photochemistry of Metal-Metal-Bonded Complexes. 12. The Primary Photoprocess of (CO)5ReMn(CO)3(.alpha.-diimine) Complexes Studied by Temperature- and Pressure-Dependent Photochemistry and Pico- and Nanosecond Flash Photolysis

Author

Rossenaar, Brenda D., primary, van der Graaf, Tim, additional, van Eldik, Rudi, additional, Langford, Cooper H., additional, Stufkens, Derk J., additional, and Vlcek, Antonin, additional

Published
1994
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141. Application of Photocatalysts and LED Light Sources in Drinking Water Treatment.

Author

Izadifard, Maryam, Achari, Gopal, and Langford, Cooper H.

Subjects
PHOTOCATALYSTS, DRINKING water purification, WATER pollution, ORGANIC compounds, EMERGING contaminants, LIGHT emitting diodes, IRRADIATION
Abstract

This study investigates a cross-section of TiO2 compositions for which existing evidence suggests the prospect of improved performance compared to standard Degussa P25. In the context of a program aimed toward a 365 nm LED based photo-reactor, the question is whether a distinctly superior photocatalyst composition for drinking water treatment is now available that would shape design choices. An answer was sought by synthesizing several photocatalysts with reported high reactivity in some context in the literature, and by performing photocatalysts reactivity tests using common pollutants of water system including Natural Organic Matter (NOM) and Emerging Contaminants (ECs) from the pesticide and pharmaceutical classes. 365 nm Light Emitting Diodes (LEDs) were used as the irradiation source. Since LEDs are now available in the UV, we did not examine the TiO2 modifications that bring band gap excitation into the region beyond 400 nm. The results suggest that the choice of the photocatalyst should be best made to fit the reactor design and photocatalyst mounting constraints such as mass transport, reactive surface, and light field. No photocatalyst composition overall, superior for all classes emerged. [ABSTRACT FROM AUTHOR]

Published
2013
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