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

Abstract

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 × 10^–4 m³·m^–2·s^–1 and 0.4620%, respectively), the composite membrane exhibits better performance (51.63 × 10⁻⁴ m³·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 × 10^–4 m³·m⁻²·s⁻¹ permeate flux and 98.7% rejection, which are in good agreement with the values obtained from experimental investigations (42.84 × 10⁻⁴ m³·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.

Key words： TiO₂-fly ash membrane; oily wastewater; fouling; microfiltration

Acknowledgment

We would like to express our sincere gratitude to the Central Instruments Facility of IIT Guwahati for providing facilities to conduct FESEM analysis. Contact angle instrument used in this work was financially supported by a grant for Center of Excellence for Sustainable Polymers at IIT Guwahati from Department of Chemicals & Petrochemicals, Ministry of Chemicals and Fertilizers, Government of India. We sincerely acknowledge the support of Dr. S. Senthilkumar, Department of Biosciences and Bioengineering, IIT Guwahati for his valuable suggestions to improve data collection and RSM model analysis at critical operating conditions.

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