Papers by Keyword: Ceramic Membrane

Abstract: The scarcity of drinking water is currently a critical issue in many parts of the world. Providing clean/urgent longer limited to natural sources. Wastewater treatment has become an urgent necessity in many countries, particularly in the Middle East and North African regions characterized by a desert climate. Hence, the development of effective methods for wastewater treatment is vital to overcome this water shortage. The present study attempts to explore the use of local clay from the United Arab Emirates (UAE) to prepare porous ceramic membranes (flat disk shape) for the purpose of removing toxic heavy metals from contaminated water. Two types of ceramic membranes were prepared by powder metallurgy method; the first type was prepared by uniaxial compression of the clay powder with particle size ≤ 250 μm, followed by sintering. The second type of membrane was composed of an activated carbon/clay powder mixture at different ratios (0.5%, 3% w/w). The activated carbon was used as an agent to form porosity in the plain clay membrane. The activated carbon was found to affect the final characteristics of the flat disk membranes sintered at 1000°C. 3% w/w activated carbon/clay powder was found to induce 19% porosity in the flat disc. The flat disc membranes were also characterized by X-ray diffraction, and scanning electron microscopy, X-ray fluorescence. The plain clay and 3% w/w activated carbon membranes were tested for their efficiency for water permeation. The results proved that the UAE clay could be considered as a promising material for the fabrication of ceramic membranes for prospective use in the removal of water contaminated with heavy metals.

Abstract: In biodiesel industries, the removal of glycerol from biodiesel is very important in the downstream process of the biodiesel production since the presence of glycerol in biodiesel causes diesel engine problems. Glycerol is commonly separated from biodiesel by extraction method using water, however, this method results in a vast amount of wastewater and requires a high energy consumption. In this work, a ceramic microfiltration membrane made of α-alumina was applied to remove glycerol from biodiesel. The microfiltration experiment was carried out using biodiesel containing various glycerol concentrations as the feed. For all investigated glycerol concentrations from 1000 ppm until 10,000 ppm in the feed, the membrane showed an excellent separation performance with rejection values of 91 to 99%. The profile of the permeate flux against the permeation time showed a flux decline because of the fouling phenomenon during the crossflow microfiltration experiment, and stable permeate fluxes were obtained after 2 h of permeation time. The result of this work showed that the separation process using the microfiltration membrane is a promising method to purify biodiesel instead of the conventional water washing method.

Abstract: The growing concern with the environment has driven the development of new technologies for the treatment of produced water. In this context, the filtering hydrocyclone appears as an interesting alternative for the treatment of these waters contaminated with oil from the petroleum industry. This research addresses the flow of fluids inside a hydrocyclone equipped with a porous wall (membrane) containing two tangential inlets and two concentric outlets, with the aim of study the impact of the formation of the polarization layer by concentration on the oily water separation process using CFD. Concentration fields and transmembrane pressure, concentration, and permeate flux profiles are presented and analyzed. The results show that the proposed filtering cyclonic separator concentrates the oil in the central region of the equipment, however, for high oil concentrations; the core expands and approaches the porous wall. Furthermore, the increase in the oil volume fraction causes a decline in the permeate flux, and an increase in feed velocity causes a decrease in the polarization layer.

Abstract: A ceramic membrane has been produced from a natural zeolite. A series of samples has been sintered at range temperature from room temperaure to 900°C. The influence of the sintering temperature on the specific surface area, pore diameter, and surface roughness has been investigated. It has been found that a decrease for value of the specific surface area and average pore diameter from 300°C to 900°C was attributed to a change of the crystalline structure of tridimite from partially to fully crystallized samples. The fabricated membrane has been used successfully to evaluate the separation performance during the treatment of coconut sap. The membranes have a steady state flux from 0.12 to 0.22 mL/min.cm² at an applied pressure of 1 bar.

Abstract: One of the main challenges related to the oil industry is the conscious disposal of effluents from the stages of oil exploration and production. The treatment of the water produced originated these processes has become a challenge for the sector. The membrane filtration technique emerges as an important tool in the treatment of these oily waters, due to their good characteristics, such as uniformity in permeate quality and long shelf life. In this work, a 2D mathematical model was developed, using computational fluid dynamics (CFD) as tool for the evaluation of the water-oil separation process in a tubular ceramic membrane. Linear momentum, energy, and mass conservation equations were used, which were solved using the commercial package ANSYS CFX® 15. The results obtained demonstrate that the developed model was able to predict the behavior of the water/oil separation process through the membrane, evidencing the influence of the oil particle size under the formation of the polarization layer by concentration, as well as, allowed to verify the importance of the temperature and the retention index of the solute under the permeation velocity and system performance.

Abstract: Innovative technologies are needed to attend the increasingly strict requirements for produced water treatment, since most of the separation processes are limited to particles larger than 10 μm. Separation processes using ceramic membranes are attracting great interest from academic and industrial community. Nevertheless, few studies, especially numerical, regarding the inorganic membrane’s application for the polluted water separation have been reported. In the present work, therefore, a study of fluid-flow dynamics for a laminar regime in porous tubes (tubular porous ceramic membrane) has been performed. The mass, momentum and mass transport conservation equations were solved with the aid of a structured mesh using ANSYS CFX commercial package. The velocity of local permeation was determined using the resistance in series model. The specific resistance of the polarized layer was obtained by Carman-Kozeny equation. The numerical results were evaluated and compared with the results available in the literature, where by a good agreement with each other was found. The numerical results, obtained by the proposed shell and tubular membrane separation module, indicate that there is facilitation of mass transfer and hence a reduction in the thickness of the polarized boundary layer occurs.

Abstract: This work deals with preparation and characterization of asymmetric ceramic membranes using the residue as a precursor of granite, for use in the treatment of effluents. For this, were prepared ceramic supports of alumina coated with a layer of residue of granite and sintered at temperatures of 800, 850 and 900° C for 1h for each temperature. The characterization of the membranes was accomplished through the technique of scanning electron microscopy (SEM), flow measurements with deionized water and analysis of rejection of indigo blue in a synthetic effluent. SEM images revealed that the membrane sintered at 900°C was completely covered with a uniform layer of residue. Flow analysis with deionized water showed that the calcined membrane at 800oC presented the largest flow. Rejection tests showed that the membranes were efficient in removing indigo blue from effluent.

Abstract: Ceramic membranes have received significant attention from both academia and industry, as they show the great potential in several important applications such as H₂ separation, recovery of CO₂ from natural gas and reduction of green-house gas emission from flue gas. The aim of the present study was to evaluate the effect of peptizing agent concentration on morphology of unsupported alumina membranes that are suitable for gas separation. The unsupported alumina membranes were prepared by the sol-gel method using aluminum-tri-sec-butoxide as a precursor and acetic acid as a peptizing agent. The particle size distributions of produced boehmite sols, as measured by dynamic light scattering technique, range from 10 to 600 nm. The increase in the concentration of acetic acid results in formation of particles of smaller median diameter. The pore volume and size distribution of unsupported alumina membranes were characterized by the Brunauer–Emmett–Teller (BET) method of adsorption of nitrogen gas. The pore size distributions of membranes were rather narrow in the range of 3 to 6 nm. The average diameter and volume of pores increase and the surface area decreases while the concentration of acetic acid increased.

Abstract: Alumina membrane for microfiltration has been studied by introduction of carbon fiber as porogenic agent. Ceramic membranes have advantages due to its inert chemical and resistance to relatively high temperatures, however, being porous, tend not to withstand high pressures. This work investigates the possibility of introducing carbon fibers so, after firing, rest communication channels and owing to the increased probability of contact between fibers, achieve high permeability with maintaining the mechanical strength. Formulations were proposed with variations of fiber length, concentration and burn at two temperatures. They were characterized by linear shrinkage, porosity, density, permeability, 3 points flexural strength, SEM and MicroCT. The Taguchi method correlated the parameters: fiber length, fiber concentration and burn temperature and validated by ANOVA. The combination that best met the commitment was 3% v/v of 1mm fibers and burnt at 1500°C, with Darcyana permeability of 3.44 10^-15m2 and fracture stress of 56.27MPa.

Abstract: Industrial wastes reuse becomes attractive to raw materials economy and to avoid environmental problems. The aim of this study is to develop and characterize tubular ceramic membranes using in their composition inorganic residues generated in the industries, such as, granite, alumina residue from calcination process and kaolin. Initially, it was performed the physical chemical and mineralogical characterization of the residues. Different formulations of ceramic masses have been studied with incorporation of residue, clay and additives for producing tubular membranes through the extrusion process. The membranes were characterized by SEM and flow measurements with distilled water. The membranes were applied to effluent treatment from textile and oil industry. The granite residue showed a high content of SiO₂ and Al₂O₃ in its chemical composition and significant amount of iron and calcium oxides resulting from the granite processing. The granite residue presented average particle size of 13.98 µm. The residue from alumina process contain gibbsite and α-alumina, and average particles size of 15.68 µm. The residue from kaolin processing presented high content of quartz and alumina and average particles size of 29.0 µm. The tubular membrane produced with granite residue presented porosity from 17 to 30%, pores size in the range of 0.06 to 0.14µm and water flow from 10 (at 2 Bar) to 24 L/h.m² (at 4 Bar). These membranes retained 100% of indigo particles and was effective in the separation of indigo. The membrane prepared with alumina residue presented porosity close to 58% , pore size of 0.96 µm and water flow from 68 to 80 L/h.m² (at 2 Bar). These membranes were applied with successes in the separation of water from emulsion (100 ppm oil/water) with rejection above 96%. The membrane prepared with kaolin residue presented pore size from 0.16 to 0.22 µm, porosity from 41 to 44% and water flow from 53 to 70 L/h.m². The ceramic membranes with industrial residues were successfully produced and applied in the treatment of industrial effluents.