Mixed-Matrix Membrane for Humic Acid Removal: Influence of Different Types of TiO2 on Membrane Morphology and Performance

Abstract

Different types of titanium dioxide (TiO 2) nanoparticles (NPs) (PC-20, P25 and X500), with various particle sizes in coagulation bath were incorporated as an nanofiller into membrane matrix. The NPs were added to the polyvinylidene (PVDF) ultrafiltration (UF) membranes via phase inversion and colloidal precipitation method. A series of test, such as surface field emission scanning electron microscopy (FESEM) images, energy-dispersive X-ray spectroscopy (EDX) mapping and pore size measurement were performed to characterize the modified mixed-matrix membranes. FESEM was applied to observe the distribution pattern of TiO 2 NPs in the membrane matrix and its distribution was examined using (EDX). The size and distribution of TiO 2 NPs on the membrane surface was affected to a very great extent by the size of TiO 2 prepared in the coagulation bath. Conversely, the presence of TiO 2 on membrane surface does not provide any significant changes on the membrane pore size distribution, suggesting that in situ precipitation method is suitable to prepare mixed-matrix membrane without scarifying the membrane rejection ability. The performance of the UF membranes fabricated from the nano-sized TiO 2 particles were evaluated by measuring the membrane permeates flux and humic acid (HA) rejection. The experiment demonstrated that the flux improvements of the membranes were improved due to the pore enlargement (defect) as well as increasing membrane hydrophilicity. The flux of the mixed-matrix membrane prepared by adding X500 nanofiller was the greatest (44.06 L/m 2 • h), which was determine as the optimum TiO 2 type without scarified the membrane rejection (98.44%) compared to PC-20 and P25. This is due to the relatively small size of X500 which provides better dispersibility in the membrane matrix whereby flux was enhanced due to improve of hydrophilicity without the expense of poor humic acid rejection.

Titanium dioxide nanotubes embedded mixed matrix PES membranes characterization and membrane performance

“…Temperature polarization coefficient (θ) is the ratio between the temperature close to the membrane surface calculated by simulations using equation (11) and the experimental temperature measured at the feed side [48][49]. It indicates the durable contribution of the boundary layer on the total heat transfer resistance of the VMD system.…”

“…The non-linear equation (9) A c c e p t e d M a n u s c r i p t 11 The temperature polarization phenomenon occurs as a result of a temperature difference between the bulk feed temperature (T b ), interfacial temperature (T im ), and the temperature in the vacuum membrane side (T v ). This temperature gradient is due to the heat flux through the liquid layer, which is needed to provide the required heat for evaporation at the membrane interface.…”

“…However, there are no detailed studies for utilizing titanium dioxide nanotubes TiO 2 NTs to modify the membrane properties and performances, which could solve the problems of fouling and increase the lifetime of the membrane [7][8][9][10][11][12][13]. In addition, TiO 2 NTs could be used to produce M a n u s c r i p t 3 the next generation of membranes with high selectivity, reasonable flux, low fouling, and enhanced mechanical properties due to remarkable physical and chemical properties.…”

“…Titanium dioxide (TiO 2 ) is one of the most important semiconductors in our daily life for its unique properties including superior photo-reactivity, superhydrophilicity, nontoxicity, longterm stability, and low cost [8,9]. In the recent years, many researchers focused on the preparation of TiO 2 nano-inorganic mixed matrix membranes to improve membrane performance by reducing fouling and increasing hydrophilicity [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24].…”

Study on PVDF-TiO2 mixed-matrix membrane behaviour towards humic acid adsorption

“…In order to produce PVDF-TiO 2 MMMs, PVDF solution layers were immersed into the coagulation bath with TiO 2 colloidal suspension as described in our previous report [8][9][10][11][12]. The preparation conditions of the membranes were summarized in Table 1.…”