Recently, contaminated site is an important source of anthropogenic volatile organic compounds (VOCs). In order to clarify the contaminated site VOCs concentration level, species, and sources, air samples were collected with Summa Canisters in the atmosphere of a closed plant during the in situ thermal desorption remediation process. According to the United States Environmental Protection Agency TO-15 method, 57 kinds of VOCs were detected, using gas chromatography-mass spectrometry method. The results showed that the concentration of total volatile organic compounds (TVOCs) ranged from 99.49 μg•m −3 to 849.63 μg•m −3 , with a mean value of 460.93 μg•m −3 . The detected VOCs could be categorized as olefins, halogenated hydrocarbons, alcohols, ketones, sulfur compounds, ethers, esters, alkanes, and aromatics. Halogenated hydrocarbons and aromatics were the predominant compounds, whose concentration accounted for 40.27% and 39.73% of TVOCs, respectively. The principal component analysis results showed that the production of glyphosates, raw pesticide materials, and exhaust emissions during plant production process and site remediation were the probable sources of detected ambient VOCs. This study is significant to assess human health risk during the site remediation and make VOCs controlling policy.
This work describes the use of a novel palygorskite, a type of magnesium aluminium silicate clay possessing a high specific surface area and pore surface activity, as a low cost and highly efficient adsorbent for hydrogen sulfide (H(2)S) removal. Adsorption of H(2)S on palygorskite pretreated with acid or base was investigated in a fixed bed adsorber. The samples after base pretreatment had better dynamic adsorption performances than raw material and samples pretreated with acid. The H(2)S adsorption capacity decreased with an increase in inlet H(2)S concentration. This can be interpreted by the fact that H(2)S adsorption on the surface of palygorskite is chemisorption. The adsorption capacity increased from 25 to 50 °C, then decreased from 50 to 100 °C, which indicates that chemisorption took place and its better reaction temperature was around 50 °C.
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