Hydrophobic ceramic membrane for membrane distillation: A mini review on preparation, characterization, and applications

Membrane distillation (MD) is one of the emerging separation technologies with extremely high separation factor, especially in desalination application. MD utilizes the hydrophobic membrane which only allows the passage of vapor through the membrane pores. Recent years have witnessed great progress in the development of hydrophobic ceramic membranes for MD applications due to their superior properties over the polymeric counterparts. However, ceramic membranes are hydrophilic in nature; hence, membrane surface modification process is required to acquire hydrophobic properties for MD applications. Direct grafting using silane agents is the most widely used ceramic membrane hydrophobization method. Hence, this mini review provides a complete summary of the research progress on the preparation and characterization of the hydrophobic ceramic membranes through silane agent grafting, as well as their applications in MD. Finally, future research directions have also been addressed

Novel superhydrophobic and superoleophilic sugarcane green ceramic hollow fibre membrane as hybrid oil sorbent-separator of real oil and water mixture

The frequent oil spill accidents in nowadays has aroused great attention all over the world. Superhydrophobic and superoleophilic grafted on various substrates have attracted much attention to treat oil and water mixture because of their unique performance that can effectively separate oil and water mixture. At the same time, ceramic membrane also shows potential substrates to be used in treating oil and water mixture. However, conventional ceramic membrane that made from alumina show drawbacks in term of its high cost production. Herein, we report a new ceramic membrane that derived from agricultural-sugarcane bagasse waste and modified into superhydrophobic and superoleophilic to act as hybrid oil sorbent and separator. In this study, we successfully treat three types of real oil and water mixture from palm oil mill effluent (POME), restaurant and car wash with oil rejection and flux up to 99% and 134 L/m2h, respectively. In summary, this work demonstrates a facile, economic and effective method to fabricate superhydrophobic and superoleophilic substrates for oil and water separation

Permporometry: the determination of the size distribution of active pores in UF membranes

Permporometry is a method by which the characteristics of the interconnecting 'active' pores of an ultrafiltration membrane can be measured. It is these active' pores that are responsible for the actual membrane performence. Application of permporometry on different membrane types, including ceramic as well as polymeric membranes, shows that the method can provide objective information on the `active¿ pore size present

Characterization of amorphous silica and crystalline silica from rice husk ash on water filtration application

The presence of water pollution which consists of heavy metals, fecal and others has produced a major problem. These can lead the water to the toxicity and the impurity of water will be disrupted. Therefore, it would not be safe to drinks and could be threatening to live health. In addition, the current market now is dealing with high-cost production to develop ceramic membranes and has been using expensive material to make the filtration system works. In order to challenge the issue, the preparation of ceramic water filtration at low-cost production and using an effectively silica from natural waste rice husk was evaluated. Rice husk was fired at 700ºC and 1000ºC respectively and produced rice husk ash which mutated to amorphous and crystalline silica. Five samples were fabricated after been mixed with the compositions of rice husk ash, kaolin clay, and wheat flour, used at 40:40:20 ratios by weight respectively. The fabrications of the ceramic membrane were conducted by using dry pressing. The samples then were dried in the oven at 60ᵒC for 1 hour followed by sintering at 1000ᵒC respectively. These samples (OO, C1, C2, N1, and N2) were tagged based on unwashed and washed material with the chemical. The properties of silica which are the microstructure and pore size, from rice husk ash were obtained by using Scanning Electron Microscopy (SEM), X-Ray Fluorescence (XRF) and x-ray diffractometer (XRD). Effect of silica content in ceramic filtration membrane was investigated and characterized in term of porosity, density, water absorption, membrane hardness, pore size, flow rate, the turbidity of water (before and after filtration) and pH value. From the result, sample C2 was the best option to support the objective by 98.60% silica content, 64.82% of porosity, 1.1433 mg/cm3 of density, 40.59% of water absorption, 171.0 Hv of hardness, 0.177 l/hr of flowrate and pH of 7.62 of water after filtration. In general, the quality of the ceramic filter membrane is reliant on the raw material, while the flow rate and water clarity are dependent on the pore size of the filter membrane

Ceramic Hollow Fiber Membranes As New Filter Media And Their Application In Oil/Water Separation Processes

Citation: Steffen Schütz, Frank Ehlen, Ina Unger, Sreenath Kariveti, Can Wang, Mehrdad Ebrahimi, Steffen Kerker, Peter Czermak: CERAMIC HOLLOW FIBER MEMBRANES AS NEW FILTER MEDIA AND THEIR APPLICATION IN OIL/WATER SEPARATION PROCESSES, in Proceedings FILTECH 2015, 24-25. February 2015, CologneCeramic membranes become continuously attractive for separation applications with fluids at increased temperatures, at high or low pH levels and in contact with critical chemical species as solvents or other organic components when polymeric membranes often fail due to high fouling or material instability. A ceramic hollow fiber membrane was developed at MANN+HUMMEL, see Figure 1. This ceramic hollow fiber membrane shows the advantages of a high volumetric filtration area and low material volumes compared to ceramic membranes with other geometries. The specific design of this membrane comprises a microfiltration ceramic support layer and an ultrafiltration ceramic functional separation layer with a pore size d90 = 40 nm. This two layer structure leads to high membrane fluxes and low pressure drop during operation. The membrane operation in cross flow mode allows the control of fouling layers due to the applied cross flow velocity. Figure 1: Cross-section of a ceramic hollow fiber membrane (MANN+HUMMEL). The operation behavior of this ceramic hollow fiber membrane was investigated for oil/water separation applications in close cooperation with a research partner and in application tests with customers. It was shown that the membrane can be operated with high oil loads up to 5000 ppm in the waste water without requiring a pretreatment. The oil contents in the permeate water were reduced to 1 ppm. Pure mechanical backflushing with permeate water was sufficient to clean the membrane in place and to reach nearly the initial flux values of the new membrane during operation. The robustness of the membrane operation in industrial applications was shown by running the membranes for several weeks in water treatment processes with industrial waste water. The waste water treatment was also promising when additional high solid loads contaminated oily waste water to be cleaned

Use of nanoporous ceramic membranes for carbon dioxide separation

Natural gas processes accounts for about 5.3 billion tonnes per year of carbon dioxide (CO2) emission to the atmosphere. At this rate of emission, the expectation will drastically rise if not curtailed. In order to achieve this, a cost-effective and environmental friendly technology is required. In recent times, membrane technology has been widely applied for CO2 removal from raw natural gas components. This article examines CO2 separation from natural gas, mainly methane (CH4), through a mesoporous composite membrane. A laboratory scale tubular silica membrane with a permeable length of 348 mm, I.D and O.D of 7 and 10 mm, respectively, was used in this experiment. Scanning electron microscopy (SEM) was used to analyze the morphology of the membrane. Single gas permeation of helium (He), CH4, nitrogen (N2), argon (Ar) and CO2 were determined at permeation temperature range between 25 and 100°C and feed gauge pressure of 0.05 to 5.0 barg. Before silica modification, He recorded the highest flow rate (0.3745 l/min) while CO2 recorded the least flow rate (0.1351 l/min) at 0.4 barg and 25°C. After silica modification, CO2 flow enhances significantly (3.1180 l/min at 1.0 barg) compared to CH4 (2.1200 l/min at the same gauge pressure) due to the influence of surface flow mechanism. Temperature variation described the applicability of Knudsen diffusion for He. A combination of viscous, surface and Knudsen diffusion transport mechanisms were obtained throughout the experiment. Membrane thickness was also calculated to be 2.5 × 10−4 m

Preparation and characterisation of inexpensive porous kaolin hollow fibre as ceramic membrane supports for gas separation application

Low-cost, porous ceramic kaolin-based hollow fibre membrane support (HFMS) for gas separation application was developed via phase inversion technique. The ceramic suspensions with various ratios of kaolin to polyethersulfone (PESf) binder (5:1 to 9:1) were extruded and then sintered at 1200 to 1500 °C. The HFMSs were characterised by several analyses to investigate the effects of kaolin/PESf ratio and sintering temperature on the sample properties. The results showed that the kaolin/PES ratio and sintering temperature affected the considerable structure and physical properties of the kaolin membrane. It is observed that with increasing sintering temperature, the porosity and gas permeation of the HFMS decreased, while the bending strength and density of the HFMS increased. As a result, a porous HFMS with sufficient mechanical strength and high gas permeation characteristics is achievable if the appropriate kaolin/PESf ratio and sintering temperature are chosen

CVD of solid oxides in porous substrates for ceramic membrane modification

The deposition of yttria-doped zirconia has been experimented systematically in various types of porous ceramic substrates by a modified chemical vapor deposition (CVD) process operating in an opposing reactant geometry using water vapor and corresponding metal chloride vapors as reactants. The effects of substrate pore dimension and structure, bulk-phase reactant concentration, reactant diffusivity in substrate pores and deposition temperature are experimentally studied and explained qualitatively by a theoretical modeling analysis. The experimental and theoretical results suggest a reaction mechanism which depends on water vapor and chloride vapor concentrations. Consequently, the diffusivity, bulk-phase reactant concentration, and substrate pore dimension are important in the CVD process. Effects of deposition temperature on the deposition results and narrow deposition zone compared to the substrate thickness also suggest a Langmuir-Hinshelwood reaction mechanism involved in the CVD process with a very fast CVD reaction rate. Gas permeation data indicate that whether deposition of solid in substrate pores could result in the pore-size reduction depends strongly on the initial pore-size distribution of the substrate

Mixed Ionic-Electronic Conducting Membranes (MIEC) for Their Application in Membrane Reactors: A Review

Mixed ionic-electronic conducting membranes have seen significant progress over the last 25 years as efficient ways to obtain oxygen separation from air and for their integration in chemical production systems where pure oxygen in small amounts is needed. Perovskite materials are the most employed materials for membrane preparation. However, they have poor phase stability and are prone to poisoning when subjected to CO2 and SO2, which limits their industrial application. To solve this, the so-called dual-phase membranes are attracting greater attention. In this review, recent advances on self-supported and supported oxygen membranes and factors that affect the oxygen permeation and membrane stability are presented. Possible ways for further improvements that can be pursued to increase the oxygen permeation rate are also indicated. Lastly, an overview of the most relevant examples of membrane reactors in which oxygen membranes have been integrated are provided.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 679933. The present publication reflects only the author’s views and the European Union is not liable for any use that may be made of the information contained therein

Removal of As(III) and As(V) from water using green, silica-based ceramic hollow fibre membranes via direct contact membrane distillation

Arsenite [As(III)] and arsenate [As(V)] removal by direct contact membrane distillation (DCMD) using novel hydrophobic green, silica-based ceramic hollow fibre membranes derived from agricultural rice husk was investigated in this work. The green ceramic hollow fibre membranes were prepared from amorphous (ASHFM) and crystalline (CSHFM) silica-based rice husk ash and modified to be hydrophobic via immersion fluoroalkylsilane (FAS) grafting of 1H,1H,2H,2H-perfluorodecyltriethoxysilane. Superhydrophobic contact angle values up to 157° and 161° were obtained for ASHFM and CSHFM, respectively. Remarkably, the membrane surface morphology mimicked a look-alike lotus-leaf structure with decrement in pore size after grafting via the silane agent for both membranes. The effect of arsenic pH (3–11), arsenic concentration (1–1000 ppm) and feed temperature (50–80 °C) were studied and it was found that feed temperature had a significant effect on the permeate flux. The hydrophobic CSHFM, with a flux of 50.4 kg m−2 h−1 for As(III) and 51.3 kg m−2 h−1 for As(V), was found to be the best of the tested membranes. In fact, this membrane can reject arsenic to the maximum contaminant level (MCL) limit of 10 ppb under any conditions, and no swelling mechanism of the membranes was observed after testing for 4 hours