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This dissertation, Behavior of Perfluorochemicals on Solid Surfaces: Sorption and Mineralization Processes by Fei, Wang, 王飞, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: The study evaluated the sorption behavior of PFOS and PFOA on γ-alumina and boehmite. The results of adsorption kinetics on γ-alumina and boehmite show that it takes 48 h to reach equilibrium. The adsorption isotherms reveal the maximum adsorption capacities of PFOS and PFOA are different due to their different functional groups. An increase in pH leads to a decrease in PFOS and PFOA adsorption on alumina, which may be attributed to the reduction in electrostatic interaction. The adsorption of both PFOS and PFOA decreases with an increase in ionic strength due to the compression of the electrical double layer. The different sorption level of PFC on γ-alumina and boehmite indicated that the crystal phase of mineral also affected the sorption process. The sorption of PFOS and PFBuS on boehmite was significantly retarded by the competitive sorption of humic acid (HA), implying that PFOS and PFBuS are likely more mobile in water and groundwater systems enriched with HA. The sorption behavior of PFOS and PFBuS on the HA-modified boehmite surface was also found to differ due to their different chain lengths. In addition, the results revealed that the sorption of PFOS and PFBuS on HA-modified boehmite is pH-dependent.The isotherm study of FOSA on three types of microplastics indicated that hydrophobic interaction plays a dominant role in the sorption process and the molecule structure of different microplastics can affect its sorption level. The PFOS sorption isotherm indicated that electrostatic interaction plays an important role in the PFOS sorption process on PE and PS while its sorption on PVC was electrostatic interaction independent. The effects of pH and ionic strength indicated that electrostatic interaction plays an important role in PFOS sorption process. The kinetic study showed that the PCMAs had a rapid sorption towards PFAS species and the isotherm study indicated that hydrophobic interaction played an important role in the sorption process. The sorption of PFOS by the PCMAs was not significantly affected by the pH and slightly decreased with an increase in ionic strength. Moreover, the sorbent had showed excellent regeneration performance. Two main fluorine mineralization mechanisms leading to the substantial formation of CaF2 and Ca5(PO4)3F phases were observed. They had a close relationship with the thermal treatment condition and the PFOS content of the sludge. At low temperatures (300C -600C), CaF2 dominated in the product and increases in treatment time and temperature generally enhanced the fluorine transformation. However, at higher temperatures (700C -900C), increases in treatment time and temperature had a negative effect on the overall efficiency of the fluorine crystallization. The results suggest that in the high temperature environment there were greater losses of gaseous products such as HF and SiF4 in the transformation of CaF2 to Ca5(PO4)3F, the hydrolysis of CaF2, and the reaction with SiO2. The quantitative analysis also showed that when treating sludge with low PFOS content at high temperatures, the formation of Ca5(PO4)3F may be the primary mechanism for the mineralization of the fluorine in PFOS. DOI: 10.5353/th_b5089989 Subjects: Fluorocarbons

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