Preparation and characterization of hydrothermally engineered TiO2-fly ash composite membrane

This work targets the preparation and characterization of an inexpensive TiO2-fly ash composite membrane for oily wastewater treatment. The composite membrane was fabricated by depositing a hydrophilic TiO2 layer on a fly ash membrane via the hydrothermal method, and its structural, morphological and mechanical properties were evaluated. The separation potential of the composite membrane was evaluated for 100-200 mg.L-1 synthetic oily wastewater solutions. The results show that the composite membrane has excellent separation performance and can provide permeate stream with oil concentration of only 0.26-5.83 mg.L-1. Compared with the fly ash membrane in the average permeate flux and performance index (49.97 x 10(-4) m(3).m(-2).s(-1) and 0.4620%, respectively), the composite membrane exhibits better performance (51.63 x 10(-4) m(3).m(-2).s(-1) and 0.4974%). For the composite ash membrane, the response surface methodology based analysis inferred that the optimum process parameters to achieve maximum membrane flux and rejection are 207 kPa, 200 mg.L-1 and 0.1769 m.s(-1) for applied pressure, feed concentration and cross flow velocity, respectively. Under these conditions, predicted responses are 41.33 x 10(-4) m(3).m(-2).s(-1) permeate flux and 98.7% rejection, which are in good agreement with the values obtained from experimental investigations (42.84 x 10(-4) m(3).m(-2).s(-1) and 98.82%). Therefore, we have demonstrated that the TiO2-fly ash composite membrane as value added product is an efficient way to recycle fly ash and thus mitigate environmental hazards associated with the disposal of oily wastewaters.