Separation of TiO2 particles from suspension using indigenous low-cost ceramic microfiltration membrane

Abstract

The increased use of TiO2 nanoparticles in manufacturing and commercial products has led to environmental contamination and health issues. This study aimed to apply tubular ceramic membrane fabricated using low-cost clays (kaolin, quartz) along with hydroxypropyl methylcellulose binder for the separation of TiO2 nanoparticles from water. The prepared tubular ceramic membrane exhibited excellent water permeability (1.4945 × 10−7 m3/m2s kPa) with an average pore size of 0.178 μm and porosity of 40 %. Cross flow microfiltration experiments using TiO2 nanoparticles suspension were performed by varying the applied pressure (138–414 kPa), cross flow velocity (2.41 × 10−3 - 5.63 × 10−3 m/s), pH (4–11) and feed concentration (0.05–1 wt%). The permeate flux increased linearly with an increase in the pressure as well as cross flow velocity with a maximum permeate flux of 4.24 × 10−5 m3/m2s at 414 kPa, whereas a reduction in permeate flux was observed with increasing feed concentration of TiO2. The membrane displayed 100 % separation efficiency at all the investigated pressures. Furthermore, the membrane fouling mechanism during the microfiltration process was analyzed using resistance-in-series model. Results demonstrated that filtration resistance (Rf) and total resistance (Rt) decreased with increasing cross flow velocity from 2.41 × 10−3 m/s to 5.63 × 10−3 m/s, whereas filtration resistance remained constant at high pressures. The estimated membrane cost is 253 USD/m2 based on raw materials, energy consumption, manpower and equipment cost. These promising results elucidated the suitability of tubular ceramic membrane towards the removal of TiO2 from wastewater.