The Chemical Engineering Department at the College of Engineering, University of Baghdad, held a M.Sc. thesis examination titled:
“ Preparation and Characterization of a Filtration
Membrane Reinforced by a Green Photocatalyst
for Organic Pollutants Removal in a
Simultaneous Process“
By the student “Abdelmoneim Sahab Adday” and supervised by Prof. Dr. Sama M. Al-Jubouri. The examination committee consisted of Prof. Dr. Basma A. Abdul Majeed as Chairman and the membership of Ass. Prof. Samar Kareem Theydan and Ass. Prof. May Ali Alsaffar. The thesis was accepted after conducting a public discussion and listening to the student’s defense. The thesis was summarized as follows:
The aim of study:
The aim of this research work is developing a versatile photocatalytic membrane by reinforcing with metal oxides to boost its performance and antifouling properties when applied for organic pollutants.
Abstract:
Organic pollutants-contained wastewater represents a concerning array of poisonous chemicals that presuppose suitable treatment and elimination to safeguard human health and the environment. Neoteric self-cleaning polyvinylidene fluoride (18 wt.% PVDF) ultrafiltration membranes were successfully developed by inserting the Ag2O@CRA photocatalyst responsive to visible light irradiation. The renewed Ag2O@CRA photocatalyst was prepared from the extracted ash from common water reeds locally available in Iraq. The extracted ash, obtained at 600 ⁰C for 6 h, was a cost-effective silica source for single-step synthesis of the Ag2O@CRA photocatalyst containing 9.75% Ag2O and a surface area of 99.849 m2/g and average crystal size of the Ag2O@CRA nanocrystals approximately 34.5 nm. Initially, the photocatalysis activity of the Ag2O@CRA was examined in the removal of methylene blue (MB) dye degradation in a batch reactor at various conditions including light source, photocatalyst dose, initial MB dye concentration, solution pH, and the presence of scavengers. The MB dye was eliminated at an initial MB concentration of 20 mg/L, Ag2O@CRA dose of 0.1g/ 100 mL, pH of 7 after 60 min at visible light. This photocatalyst displayed excellent stability after five cycles with more than 91% removal of MB dye.
The photocatalytic membranes were made with 0.1-0.5 wt.% of the Ag2O@CRA photocatalyst and their performance was examined in the removal of MB dye. The superior compatibility of the Ag2O@CRA photocatalyst with PVDF in the casting solution resulted in upgrading the antifouling properties, morphology, structure, porosity, pure water flux, and separation performance of the embedded membranes. The synergistic effect of molecular separation and photodegradation for the PVDF membrane containing 0.3 wt.% Ag2O@CRA photocatalyst produced a relatively high pure water flux (PWF) of 109.05 L/m2.h and removed 99.05% of MB dye and 99% of COD at an initial dye concentration of 10 mg/L, a treated solution volume of 1000 mL, feed flowrate of 1 L/min, an initial pH of 10, transmembrane pressure of 1 bar during 90 min. The scavenger investigation revealed that •OH radical was the dominant species responsible for MB photodegradation by both Ag2O@CRA photocatalyst and PVDF/Ag2O@CRA photocatalytic membrane.
The results of kinetic study showed that the photocatalytic oxidation of the MB dye by the Ag2O@CRA photocatalyst and PVDF/Ag2O@CRA photocatalytic membrane followed the pseudo-first-order kinetic model, and the apparent rate constant (k1) value was 0.1231 min-1 and 0.0196 min-1, respectively. Also, the Langmuir-Hinshelwood model was used to model the kinetics of the MB photocatalytic degradation by the Ag2O@CRA photocatalyst for 10-40 mg/L inlet MB concentrations and the PVDF membrane with 0.3 wt.% Ag2O@CRA photocatalyst for 5-20 mg/L inlet MB concentrations. The intrinsic photocatalysis reaction rate constant (kr.) was 0.8286 mg/L.min for the Ag2O@CRA photocatalyst and 0.209 mg/L.min for the PVDF/Ag2O@CRA photocatalytic membrane. Also, the equilibrium adsorption constant (Kad.) was 0.3245 L/mg for the Ag2O@CRA photocatalyst and 0.218 L/mg for the PVDF/Ag2O@CRA photocatalytic membrane. The manufacturing cost was estimated for the Ag2O@CRA photocatalyst and PVDF/Ag2O@CRA photocatalytic membrane to be $2.45/10 g and $78/m2, respectively.
