Investigation of pilot scale manufacturing of polysulfone (PSf) membranes by wet phase inversion method

Membranes are used as a support layer for the fabrication of thin film composite membranes. Sup- port layer properties can affect many performance parameters of TFC membranes such as flux, rejection, morphology and stability against pressure. Although studies in lab scale fabrication exist, investigation the pilot scale polysulfone membrane fabrication has not been done. In this study, opti- mization of polysulfone support membranes fabrication was conducted in pilot scale. Coagulation bath temperature; casting speed and solution content were selected as main parameters for the opti- mization. Membrane surface properties were investigated in details with SEM and pore size dis- tribution. Membrane performance were determined with permeability experiments. Differences in pilot scale and lab scale membrane manufacturing were observed and compared with literature. On the contrary to literature it was found that, coagulation bath temperature has exact opposite effect in pilot scale membrane formation compared to lab scale studies. 10°C drop (from 25°C to 15°C) in coagulation bath temperature decreased mean pore size of membranes from 27 nm to 8 nm and per- meability from 464 l/m2h to 100 l/m2h while everything else was kept constant

Surface modification of reverse osmosis desalination membranes with zwitterionic silane compounds for enhanced organic fouling resistance

Three different zwitterionic functional trimethoxysilane compounds, 4-(diethyl(3-(trimethoxysilyl)propyl)ammonia)butane-1-sulfonate (EPBS), 4-(dimethyl(3-(trimethoxysilyl)propyl)ammonia)butane-1-sulfonate (MPBS), and 3-(dimethyl(3-(trimethoxysilyl)propyl)ammonia)propane-1-sulfonate (MPPS), were synthesized and used for the surface modification of commercial polyamide thin-film composite reverse osmosis membranes to enhance their salt rejection and antifouling performance. Commercial membrane surfaces were spray-coated using three different aqueous solution concentrations (1.0, 1.5, and 2.0%) of each zwitterionic silane compound. Surface characterization of coated membranes performed via X-ray photoelectron spectroscopy and water contact angle measurements confirmed the successful, permanent attachment of zwitterionic groups to membrane surfaces. Organic fouling studies accomplished through dead-end stirred cell filtration experiments using xanthan gum and bovine serum albumin revealed that all coated membranes had higher flux recovery rates upon cleaning with water and NaOH, demonstrating the easier cleanability provided by zwitterionic groups on the membrane surface. For example, in the case of xanthan gum fouling experiments, membranes coated with 2.0 wt % MPPS solution regained 100% of its initial flux after cleaning with deionized water, whereas the control membrane had 69% flux recovery

Mechanisms, diagnosis, and monitoring of biofouling in membrane processes: a review

Membrane systems have become one of the major technologies in water and wastewater treatment processes. In recent decades, membrane processes have made rapid progress owing to their advantageous properties over conventional systems. However, biofouling restricts their wide-spread application through irreversible deterioration of their structure, performance, and longevity. Any effort against biofouling either in the membrane synthesis step or in the process necessitates a well understanding of the underlying mechanisms causing this issue through employing various monitoring and diagnosis techniques. This paper mainly reviews the progress in the research and development of biofouling reduction in membrane processes. It first addresses the underlying biofouling mechanisms. Then, a critical overview of the state-of-the-art approaches in the membrane biofouling diagnosis and monitoring was provided to discuss the advantages and the limitations of the current techniques in the lab and large-scale applications. The last section of the review focuses on the future aspects. This paper could be served as a guide for the new entrants to the field of biofouling, as well as to the established researchers and academicians

High performance polyamide thin film composite (PA-TFC) desalination membranes modified by zwitterionic silanes

By: Ilter, Selda Erkoc; Sharabati, Jalal; Saffarimiandoab, Farzin; et al. Conference: 254th National Meeting and Exposition of the American-Chemical-Society (ACS) on Chemistry's Impact on the Global Economy Location: Washington, DC Date: AUG 20-24, 2017  Sponsor(s):  Volume: 254 Meeting Abstract: 57 Published: AUG 20 201

Evaluation of biofouling behavior of zwitterionic silane coated reverse osmosis membranes fouled by marine bacteria

Zwitterionic modification of membrane surfaces is a promising approach to decrease membrane biofouling. In this study, biofouling properties of two commercial polyamide (PA) reverse osmosis (RO) desalination membranes coated with zwitterionic sulfobetaine silane compounds including4-(diethyl(3-(trimethoxysilyl)propyl)ammonia)butane-1-sulfonate (EPBS) and 3-(dimethyl(3-(trimethoxysilyl)propyl)ammonia)propane-1-sulfonate (MPPS) were investigated using five different marine bacteria isolated from Bosphorus, Turkey. To mimic the real environment, new marine strains were isolated for the biofouling assay. The biofouling behavior was monitored at different maturation stages of biofouling bacteria on the surfaces of the membranes. In addition, the permeability variation of the coated membranes was analyzed by measuring the flux values before and after the biofouling process compared to the uncoated, control membrane. According to the results, while commercial control RO membranes were highly prone to biofouling, zwitterionic sulfobetaine silane coated membranes showed a strong anti-bacterial effect against the isolated marine biofouling bacteria with significant bio-film adhesion resistance. When the flux value of commercial uncoated control membrane decreased by 38% after biofouling, the flux reduction was 16% and 20% in the EPBS and MPPS coated membranes, respectively