title: Influence of calcium hydroxide on the fate of perfluorooctanesulfonate under thermal conditions.
abstract: To explore the potential fate and transport of perfluorochemicals in the thermal treatment of sludge, perfluorooctanesulfonate (PFOS), a perfluorochemical species commonly dominant in wastewater sludge, was mixed with hydrated lime (Ca(OH)(2)) to quantitatively observe their interaction under different temperatures. The phase compositions of the mixtures after the reactions were qualitatively identified and quantitatively determined using X-ray diffraction technique. The results of the thermogravimetry and differential scanning calorimetry analyses indicate that PFOS gasified directly during the thermal treatment process when the temperature was increased to around 425 °C. However, the formation of CaF(2) at 350 °C suggests that the presence of Ca(OH)(2) in the mixture can lead to the decomposition of PFOS at 350 °C, which is lower than the decomposition temperature of PFOS alone (425 °C). The increase of temperature promoted a solid state reaction between PFOS and Ca(OH)(2), and also enhanced the interaction between the gaseous products of PFOS and CaO (or Ca(OH)(2)). The preferred Ca/F molar ratio to achieve fluorine stabilization by Ca(OH)(2) was above 1:1 in the experiment involving 400 °C and 600 °C treatment. It also showed that equilibrium efficiency is achieved within 5 min at 400 °C and within 1 min above 600°C.
authors: Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, Hong Kong SAR, China.
authors: Fei
authors: F
authors: Wang
authors: Xingwen
authors: X
authors: Lu
authors: Kaimin
authors: K
authors: Shih
authors: Chengshuai
authors: C
authors: Liu
mesh_terms: D017738:Alkanesulfonic Acids / Q000737:chemistry*; D002118:Calcium / Q000032:analysis / Q000737:chemistry; D002126:Calcium Hydroxide / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning / Q000379:methods; D005461:Fluorine / Q000737:chemistry; D005466:Fluorocarbons / Q000737:chemistry*; D008956:Models, Chemical; D015233:Models, Statistical; D012722:Sewage; D013696:Temperature; D013818:Thermogravimetry; D014874:Water Pollutants, Chemical / Q000032:analysis; D018508:Water Purification / Q000379:methods*; D014961:X-Ray Diffraction
chemical_list: D017738:Alkanesulfonic Acids; D005466:Fluorocarbons; D012722:Sewage; D014874:Water Pollutants, Chemical; D005461:Fluorine; C076994:perfluorooctane sulfonic acid; D002126:Calcium Hydroxide; D002118:Calcium