Jaleh Mansouri

Strategies for controlling biofouling in membrane filtration systems: challenges and opportunities

Biofouling is a critical problem in many membrane filtration processes. This review highlights the emerging strategies for polymer membrane modifications using organic and inorganic additives and surface modification to mitigate foulant deposition and biofilm formation. Constraints and opportunities for future implementation in membrane systems are outlined from the perspectives of water and wastewater treatment applications.

Novel membranes from conducting polymers

Abstract The first part of this paper presents the preparation and morphological studies of high surface area polypyrrole with fibrillar morphology. Mode of fibre growth within host membrane pores has been examined by ultra-microtome techniques. The rate of fibre growth in different solvents has been determined. The second part of this paper describes the formation of conducting composite membranes of polypyrrole with in-house prepared and commercial (“Biotran”) microporous polyamides. The conducting polymer was chemically polymerized using several techniques in association with the membranes in these studies. Surface and cross-sectional membrane morphology was studied by high-resolution field emission scanning electron microscopy, optical microscopy and transmission electron microscopy. Environmental stability of composite membranes has been examined by measuring the conductivity as a function of time.

Electrochemical preparation of polypyrrole colloids using a flow cell

A flow-through electrochemical cell has been used for the production of conducting polymer colloids. The polypyrrole/nitrate system was selected to investigate the effect of electrochemical and hydrodynamic conditions on the amount and quality of the colloids produced. The colloids produced are stable and exhibit small and relatively uniform particles.

Characterization of PVDF-PPy composite membranes

The present work is concerned with preparation and characterization of conducting composite membranes and degradation studies in dry atmosphere, water and other environments similar to practical application media. Improvement of the stability, mainly by incorporation of sulfonic stabilizer is another aspect of this work. This work has focused upon chemical oxidation to form the conducting polymers onto host membranes. Development of preferred preparation conditions involves a factorial orthogonal approach, where conductivity and water flux data are pooled from the results of three variables (temperature, concentration and time) at three levels. Morphological changes of membranes surface and cross-section before and after treatment is undertaken using field emission scanning electron microscopy. Chemical structure changes upon degradation in different media is studied by X-ray photoelectron spectroscopy. These studies demonstrate that the incorporation of sulfonate dopants can improve the environmental stability of these membranes by modifying their chemical structure.

Structural studies of polypyrroles with fibrillar morphology

Fibrillar polypyrroles have been prepared by electrodeposition through honeycomb γ-alumina membranes. The morphology has been extensively studied using field-emission scanning electron microscopy. The rate of fibre growth in several solvents has been measured by direct length measurement. The occupation of the host membrane pores by polypyrrole has been examined by ultramicrotome techniques. In extended polymerizations, both solid rods and tubes are found.

Biofouling performance of silver-based PES ultrafiltration membranes

AbstractPolyethersulfone (PES) polymer is widely used in membrane fabrication due to its good mechanical and chemical stability. However, fouling and in particular biofouling leads to reduced efficiency due to the hydrophobic characteristics of the membrane. In this work, we report on the fabrication of antimicrobial ultrafiltration membranes from PES and a range of silver additives. Commercial silver additives in the form of silver zinc zeolites and silver zinc glasses as well as some common organic silver salts were used. The effect of silver additives on membrane biofouling was extensively studied by both static and dynamic methods using bacteria culture. These tests demonstrated the anti-biofouling properties of modified membranes in comparison with control membranes. The issue of silver leaching during membrane fabrication is of critical importance from both sustainability of membranes and environmental aspects. This was studied in detail for PES–silver zinc zeolite membranes. The treatment of membra...

Assembly of conducting polymer networks inside hydrogel structures

The development of novel conducting polymer hydrogel composites has been pursued in the course of this work. It has been found that conducting polymers can be formed electrochemically within hydrogel structures. This enables the dimensions and shape of conducting polymer based structures to be easily modified. The resulting composites retain the properties of the hydrogels and also are electroactive. Preliminary work suggests that these structures show enhanced performance when used as electromolecular or electromechanical actuators.

Gelled Graphene Oxide–Ionic Liquid Composite Membranes with Enriched Ionic Liquid Surfaces for Improved CO2 Separation

Blends containing ionic liquid (IL) 1-ethyl-3-methyimidazolium tetrafluoroborate [emim][BF4] gelled with Pebax 1657 block copolymers were modified by adding graphene oxide (GO) and fabricated in the form of thin film composite hollow fiber membranes. Their carbon dioxide (CO2) separation performance was evaluated using CO2 and N2 gas permeation and low-pressure adsorption measurements, and the morphology of films was characterized using scanning electron microscopy, atomic force microscopy, and transmission electron microscopy. Upon small addition of GO into the IL-dominated environment, the interaction between IL and GO facilitated the migration of IL to the surface while suppressing the interaction between IL and Pebax, which was confirmed using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Amplified migration of IL to the surface and better dispersion of GO stacks were further achieved under alkaline conditions. With the enriched IL on the surface, the gas permeation through the films at 0.5 wt % GO and approximately 80 wt % IL loading reached 1000 GPU for CO2 with their CO2/N2 selectivity (up to 44) approaching that of pure IL.