| Summary: | 碩士 === 國立高雄第一科技大學 === 環境與安全衛生工程研究所 === 104 === In this study, NF270 and NF90 were modified using in-situ surface modification method to investigate the antifouling abilities of different foulants including humic acid, sodium alginate, calcium chloride and their complex as well as the removal of six pharmaceuticals and personal care products (PPCPs) including carbamazapine (CBZ), ibuprofen (IBU), triclosan (TRI), sulfadiazine (DIA), sulfamethoxazole (SMX) and sulfamethazine (SMZ) in the aqueous environment. Membranes were modified using 3-sulfopropyl methacrylate potassium salt (SPM) and 2-hydroxyethyl methacrylate (HEMA) with concentrations of 0.005 - 0.2 M and used in the PPCP rejection and fouling experiments. The modified membranes before and after fouling experiments were characterized for their hydrophobicity (using contact angle measurement), surface morphology (using scanning electron microscope), surface functional groups (using Fourier Transform InfraRed spectroscopy) and PPCP adsorption (using surface extraction) to validate the rejection mechanisms of PPCPs. Moreover, modified Hermia model was used to simulate premate flux decline so as to validiate membrane fouling mechanisms.
The permeate flux increased for NF270 but slightly decreased for NF90 after being modified using SPM or HEMA. After fouling experiments using humic acid, sodium alginate, calcium chloride or their complex, less flux decline but higher flux recovery was observed for the modified membranes compared to the virgin ones. The hydrophilicity of the modified membranes was increased, which can validate the high flux recovery and antifouling ability.
PPCP rejection increased using the clean or fouled modified membranes due to the extra structural barrier of the grafted layer. The rejection of CBZ increased the most using the modified NF270 while each PPCP rejection was over 99% using the modified NF90.
The surface adsorption of the highly hydrophobic TRI and IBU increased on the modified membranes but their rejection was also increased, which indicates the grafted modification layer can effectively prevent the solution-diffusion of TRI and IBU through membranes. NF270 modified using SPM showed more TRI adsorption than using HEMA, but NF90 modified using HEMA showed more TRI adsorption than using SPM. TRI adsorption onto the modified membranes using SPM or HEMA followed second-order kinetics, and can be fitted well using the Freundlich model, with chemical adsorption (n< 1) and Langmuir model for SPM and HEMA modified membranes, respectively.
Using the modified Hermia model to simulate the premate flux decline in the fouling experiments showed that complete blocking and intermediate blocking were the dominant mechanisms of HA, SA and HA+SA fouling while gel layer formation was the dominant mechanism of Ca+HA+SA fouling. Because the sizes of PPCP and foulants are bigger than the memberanes pore radii, the foulants will partially or completely block membranes pores at the beginng of filtration and then aggregate and pile up to form the gel layer on the membrane surface.
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