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Yi-Tang Chang

Publications and source records attributed to Yi-Tang Chang.

2 recordsLinked to original sources

A method for controlling hydrogen sulfide in water by adding solid phase oxygen.

This work evaluates the addition of solid phase oxygen, a magnesium peroxide (MgO(2)) formulation manufactured by Regenesis (oxygen-releasing compounds, ORC), to inhibit the production of hydrogen sulfide (H(2)S) in an SRB-enriched environment. The initial rate of release of oxygen by the ORC was determined over a short period by adding sodium sulfite (Na(2)SO(3)), which was a novel approach developed for this study. The ability of ORCs to control H(2)S by releasing oxygen was evaluated in a bench-scale column containing cultured sulfate reducing bacteria (SRB). After a series of batch tests, 0.4% ORC was found to be able to inhibit the formation of H(2)S for more than 40 days. In comparison, the concentration of H(2)S dropped from 20 mg S/L to 0.05 mg S/L immediately after 0.1% hydrogen peroxide (H(2)O(2)) was added, but began to recover just four days later. Thus, H(2)O(2) does not seem to be able to inhibit the production of sulfide for an extended period of time. By providing long-term inhibition of the SRB population, ORC provides a good alternative means of controlling the production of H(2)S in water.

Hydrogen Peroxide↗

Organic compound distribution between nonionic surfactant solution and natural solids: applicability of a solution property parameter.

A solution property parameter phi was defined to examine the distribution characteristics of organic compounds between the solids and four nonionic surfactant solutions. The studied compounds consisted of BTEX (benzene, toluene, ethylbenzene, and p-xylene) and chlorinated pesticides (lindane, alpha-BHC, and heptachlor epoxide), which span several orders of magnitude in terms of water solubility (Sw). The solid samples were composed of a very low organic matter clay (Ca-montmorillonite), and a high organic matter natural soil (Shamou Mountain soil). The surfactants tested included two alkyl chain surfactants and two containing aromatic group surfactants with added concentrations both below and above their critical micelle concentration (CMC). By observing the Kom or Ksf variation, the result indicates, besides the Sw of the organic compounds, the distribution coefficient is regarded as a function of the soil organic matter (SOM) constituents, and the chemical structure of the organic compounds. Also, it can be found the greater phi values represent the higher releasing ratios of the organic compounds from the contaminated soil to groundwater. For the relatively higher Sw compounds, such as BTEX, all of the phi values are close to 1. The phi values for the relatively lower Sw compounds are far greater than 1, and increase with the increasing affinity of the compounds to the surfactants.

Benzene↗