| In this study, a novel hybrid system of suspened photocatalytsis reaction coupling with membrane process has been used in dealing with natural water which contains humic acid. One-dimensional T1O2 nanotubes(TNTs) were prepared and was used as photocatalyst. The researchs focused on the photocatalytic activity of the one-dimensional photocatalyst. Flat sheet ultrafiltration (UF) membrane made of polyacrylonitrile (PAN) was applied to separate TNTs from their suspension after photocatalysis. The photocatalysis process and its effect on the fouling of followed membrane process were mainly investigated.The effect of solution pH (4.0,6.0,8.0) on the photodegradation of HA was firstly studied. The best removal efficiency of HA was observed at pH=4.0, while the highest mineralization rate was observed at pH=6.0. Both removal rate and mineralization rate were observed increase with UV irradiation time, and were up to 97.0% and 70.6%, respectively, after UV irradiation 120 min. The degradation process obeyed the first order reaction kinetics. The catalyst in suspension mixture liquid after photocatalytic was separated by flat sheet ultrafiltration (UF) membrane. The coupling of membrane and photocatalysis process not only separated the TNTs form their suspention, but also prevented the fouling of followed membrane due to the photodegradation of HA. The attenuation of membrane flux was significant during no illumination.Irradiation can reduce the pollution from humic acid, increase the membrane flux and delay the attenuation of membrane flux. The fouling mechanisms of membrane was analyzed by fitting flux data with cake filtration model, the results indicated that the flux decline behavior could be described by the cake filtration model very well. The structure of the cake layer, which was dependent on the degradation time of HA, the interaction between HA and TNTs and solution pH, dominated the flux behavior of membrane in the separating TNTs from reacted system. |
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