jmst
|
|
Abstract: In this article, synthesis and characterization of nanocomposite hydroxy sodalite (H-SOD)/α-alumina membrane via the so-called “pore-plugging” hydrothermal synthesis (PPH) protocol is reported for the first time. In nanocomposite architecture membranes, zeolite crystals are embedded within the pores of the supports instead of forming thin-film layers of the zeolite crystals on the surface of the supports. The as-prepared membranes were characterized with SEM and FTIR for morphology and purity of the H-SOD crystals. Compared to the conventional in-situ direct hydrothermal synthesis, membranes obtained from PPH possess higher mechanical and thermal stability. In addition, defect control with nanocomposite architecture membrane is possible because the zeolite crystals are embedded within the support pores of the membrane, thereby limiting the maximum defect size to the pore sizes of support. The nanocomposite architecture nature of the membranes safeguards the membrane from shocks or abrasion that could promote defects/inter-crystalline pores formation. These advantages could be helpful in the scale-up process of the preparation procedure of membranes at the commercial level with less-demanding conditions. Keywords: Hydroxy sodalite, Nanocomposites, Membranes, Ceramics, Porous materials, Thin films.Download Full Article |
|
|
Abstract: Desalination applications based on reverse osmosis (RO) technology today comprise over 50% of the capacity of all desalination systems worldwide and represent 75-85% of new desalination projects being implemented. The major reason for the shift in desalination projects to RO technology is the high energy efficiency of the RO process. There are three major application categories of large capacity, RO-based desalination projects: brackish RO; advanced municipal wastewater reclamation; and seawater RO. In the two first categories (brackish RO and wastewater reclamation), the systems’ configuration and equipment components are well defined. Therefore, project costs and operating expenses are fairly predictable. In seawater RO desalination systems, the RO process configuration is also very similar; however, some variability exists regarding the configuration of seawater water delivery and feed water pretreatment. The rest of the system’s components and system operation methods are very uniform. However, an evaluation of published cost data of medium- to large-scale water RO desalination projects illustrates significant variability in costs of desalination systems. This paper will analyze current economic conditions of seawater desalination, and highlight the limitations and possibilities of additional improvements of the economics of the SWRO desalination process. Keywords: Desalination, Reverse osmosis, energy, investment, cost. Download Full Article |
|
|
Abstract: A self-standing membrane was obtained from renewable polymers, such as agarose and sericin. Differential scanning calorimetric study revealed that there were two states of water in the membrane, such as bound water and free water. The membrane preferentially transported water from aqueous ethanol mixture by vapor permeation. Preliminary study revealed that the present membrane was applicable to forward osmosis.. Keywords: Agarose, Melting Point Depression, Membranes, Vapor Permeation, Sericin.Download Full Article |
|
|
Abstract: In this study, the effects of different sludge retention times (SRTs) on membrane fouling control with the addition of powdered activated carbon (PAC) were investigated for the anaerobic membrane bioreactors (AnMBRs). Chemical oxygen demand (COD), mixed liquor volatile suspended solids (MLVSS), food to microorganisms (F/M) ratio, particle size distribution, extracellular polymeric substances (EPS) and their relationships with membrane fouling were studied for AnMBR added with PAC at different SRTs. As SRT of the AnMBR increased to higher days, MLVSS concentration would increase and F/M ratio decreased and it was found to have a better membrane fouling control. It was also noticed that PAC addition would decrease EPS concentration and increased the floc size of the biomass which would help to reduce membrane fouling rate of AnMBRs. Keywords: Palm Oil Mill Effluent (POME), Anaerobic membrane bioreactor (AnMBR), membrane fouling, powdered activated carbon (PAC), sludge retention times (SRTs), F/M ratio. Download Full Article |
|
|
Abstract: This work describes the modification of zeolite Na-LTA membranes supported on macroporous carbon materials, prepared by a combination of secondary hydrothermal treatment followed by different alternative post-synthesis procedures, which aim at improving the permeance properties of the as-synthesized Na-LTA membranes with a simulated reformer mixture (H2, CO, CO2 and H2O) towards their use in a hydrogen purification device.These post-synthetic treatments include the deposition of a thin layer of amorphous silica formed by the hydrolysis of a silicon alcoxide, the coating with a thin metallic film by electroless plating, and the deposition of noble metal nanoparticles. Our results indicate that some of these treatments, which may be performed very quickly compared to other treatments which are generally used in order to improve the quality of the membranes, result in membranes which may effectively separate H2 from CO under simulated reformer conditions. Considering the simple approach employed in some of the cases described in this study, the potential benefits should be considered highly interesting in fields such as membrane recovery and membrane selectivity control. Keywords: Zeolite, membranes, hydrogen purification, fuel cells.Download Full Article |