Membrane Separation PDF

MEMBRANES ENOC | DEL ROSARIO | DUARTE | DUMDUM  Learning Points Define a Identify the Classification Advantages & membrane Driving force of Membranes D...

MEMBRANES ENOC | DEL ROSARIO | DUARTE | DUMDUM  Learning Points Define a Identify the Classification Advantages & membrane Driving force of Membranes Disadvantages for MSP Desired Properties  What is a Membrane? -Is a thin barrier, placed between two phases or mediums -It allows one or more species to selectively pass from one or more species to selectively pass from one medium to the other while retaining the rest. -It is done by driving force -Membranes used for separation of mixtures are called semi-permeable Classification of Membranes 1. Polymeric Membrane 2. Liquid Membrane 3. Inorganic Membrane  Polymeric membrane Polymeric membranes are made from synthetic polymers and are used in various separation processes due to their versatility and low cost. They are categorized into two different groups: Natural Polymers and Synthetic Polymers  Natural Polymers (naturally-occuring Polymer for in nature) Membrane Preparation Synthetic Polymers (Lab-grown synthetics) Natural Polymers Natural Polymers occur in nature and can be extracted from plants and animals and they are often water- based Natural polymers are essential to daily life as our human forms are based on them Examples of naturally occurring polymers are silk, wool, DNA , cellulose, and proteins.  Synthetic Polymers Synthetic polymers are derived from petroleum oil, and made by scientists and engineers. They can be classified into four main categories: thermoplastics, thermosets, elastomers, and synthetic fibers. They are commonly found in a variety of consumer products. Applications of polymeric membranes in separation process desalination processes drug manufacturing gas separations  Liquid Membranes Liquid membranes are made up of two homogeneous miscible liquids (a feed solution and an acceptor solution), which are spatially separated by a third immiscible liquid, which acts as a membrane between the two liquids. Applications of liquid membranes in separation process water and wastewater treatment: separation of organic acids separation of gas through absorption Inorganic Membrane Inorganic membranes are made from materials like ceramics, metals, or zeolites. They are highly stable under extreme conditions (temperature, pH, pressure) and are used in applications requiring robust performance, such as gas separation and catalytic processes. Applications of inorganic membranes in separation process gas separation food industry desalination in chemical processing What is the Driving force for MSP? Pressure difference Concentration difference  Pressure Driven Process 1. Reverse osmosis 2. Nanofiltration 3. Ultrafiltration 4. Microfiltration  Reverse osmosis The process of movement of solvent through a semipermeable membrane from the solution to the pure solvent by applying excess pressure on the solution side In reverse osmosis, a reverse pressure difference is imposed that causes the flow of solvent to reverse, as in the desalination of seawater. This process is also used to separate other low-molecular-weight solutes, such as salts, sugars, and simple acids from a solvent (usually water). RO offers high removal efficiency for salts and contaminants, producing high-quality purified water. Reverse osmosis is used extensively in both residential and industrial settings. In homes, it is often employed in water filtration systems to provide clean drinking water. Industrially, RO systems are used in manufacturing processes, food and beverage production, pharmaceuticals, and even in power generation. It is energy-efficient compared to thermal desalination processes like distillation.  Nanofiltration Nanofiltration membranes have intermediate pore sizes between those of RO and UF membranes. Typically, the pore size ranges from about 1 to 10 nanometers. NF selectively separates ions and molecules based on size and charge. It can remove divalent ions (e.g., calcium, magnesium) and certain larger organic molecules while allowing smaller ions (e.g., sodium, chloride) to pass through. Nanofiltration operates at lower pressures compared to reverse osmosis but higher than microfiltration and ultrafiltration. Typically, NF requires pressures in the range of 100 to 600 psi (pounds per square inch). Like other membrane processes, NF requires pressure to push the solution through the membrane. The separation efficiency depends on factors such as membrane pore size, operating pressure, and the characteristics of the feed solution. NF is advantageous because it can selectively remove ions and molecules without completely desalinating water like RO, and it operates at lower pressures compared to RO, thus consuming less energy.  Nanofiltration Applications Softening water by removing calcium and magnesium ions (often referred to as 'nanofiltration softening'). Color and organics removal in water treatment processes. Partial desalination of water where only certain ions need to be removed, such as in drinking water production. Industrial applications such as in the food and beverage industry for concentration and purification processes.  Ultrafiltration In this process, pressure is used to obtain a separation of molecules by means of a semipermeable polymeric membrane (M2). The membrane discriminates on the basis of molecular size, shape, or chemical structure and separates relatively high- molecular weight solutes such as proteins, polymers, colloidal materials such as minerals, and so on. The osmotic pressure is usually negligible because of the high molecular weights. UF offers efficient removal of suspended solids, colloids, and large molecular weight solutes while allowing smaller molecules and solvents to pass through. It is energy-efficient and can be operated at lower pressures compared to RO.  Ultrafiltration Applications Water Treatment: UF is widely used in water and wastewater treatment for the removal of suspended solids, colloids, bacteria, and some viruses. It is effective in producing high-quality water for drinking purposes or as pretreatment before further purification steps. Food and Beverage Industry: UF is utilized for clarification and concentration processes in industries such as dairy, juice production, and brewing, where it helps remove particles and bacteria while preserving flavor and nutrients. Pharmaceutical and Biotechnology: UF plays a critical role in protein purification, virus removal, and concentration of pharmaceutical products. Industrial Processes: UF is employed in various industrial applications for separating and concentrating liquids, recovering valuable substances, and treating process streams.  Microfiltration In microfiltration, a pressure-driven flow through the membrane is used to separate micron-size particles from fluids. The particles are usually larger than those in ultrafiltration. MF offers efficient removal of larger particles, bacteria, and suspended solids while allowing smaller molecules and solutes to pass through. It is relatively energy-efficient and cost-effective for applications that require clarification and particle removal. Examples are separation of bacteria, paint pigment, yeast cells, and so on from solutions.  Microfiltration Applications Water and Wastewater Treatment: Microfiltration is used for the removal of suspended solids, turbidity, and bacteria from water. It is commonly employed in drinking water treatment, as well as in industrial and municipal wastewater treatment processes. Food and Beverage Industry: MF is utilized for clarification and sterilization processes in the production of beverages (e.g., beer, wine, juice) and dairy products. Biotechnology and Pharmaceuticals: Microfiltration plays a role in biopharmaceutical production for separating cells, proteins, and other biomolecules. Industrial Processes: MF is applied in various industrial sectors for separating solids from liquids, recovering valuable particles or compounds, and purifying process streams. Concentration Gradient Driven Membrane Process 1. Dialysis 2. Membrane Extraction 3. Electrodialysis 4. Pervaporation In this case, because of concentration Dialysis differences, the small solutes in one liquid phase diffuse readily through a porous membrane to the second liquid (or vapor) phase. Passage of large molecules through the membrane is more difficult. This membrane process has been applied in chemical processing separations such as the separation of H2SO4 from nickel and copper sulfates in aqueous solutions, food processing, and artificial kidneys. Dialysis is primarily used in medical settings to manage and treat kidney failure. It allows patients with impaired kidney function to maintain proper fluid and electrolyte balance, remove metabolic waste products, and control blood pressure.  Membrane Extraction Involves using a membrane to separate components based on their solubility and diffusivity. A liquid membrane selectively allows certain solutes to pass through while retaining others. This process is often used in chemical and pharmaceutical industries for separating and purifying substances. Membrane extraction is applied in the extraction of valuable components from fermentation broths and in the removal of pollutants from wastewater.  Membrane Extraction Applications Environmental Remediation: Membrane extraction is used for the removal of pollutants, heavy metals, and toxic substances from wastewater or contaminated soil. Analytical Chemistry: It is employed for preconcentration and extraction of trace analytes from complex matrices in analytical chemistry. Metallurgical Processes: Membrane extraction can be utilized in the extraction and separation of metals from ores or industrial effluents. Biotechnology and Pharmaceuticals: It has applications in bioprocessing and pharmaceutical industries for the separation and purification of biomolecules and pharmaceutical compounds.  Electrodialysis Uses electrically charged membranes and an electric field to separate ions from a solution. Positive and negative ions migrate towards oppositely charged electrodes, passing through selective ion-exchange membranes. This process is typically used for desalination and water treatment, such as the removal of salts and other charged species from brackish water or seawater.  Electrodialysis Applications Desalination: Electrodialysis is used for the desalination of brackish water and seawater by selectively removing ions, particularly useful in regions where freshwater is scarce. Food and Beverage Industry: It is employed for the demineralization of whey, fruit juices, and other food processing streams. Industrial Processes: Electrodialysis finds applications in various industrial processes for the separation and concentration of electrolytes, such as in metal finishing, pharmaceuticals, and chemical manufacturing. Wastewater Treatment: ED can be used for the recovery of valuable components from wastewater streams and for concentrating streams prior to disposal.  Pervaporation Pervaporation is a membrane- based process that separates mixtures of liquids by partial vaporization through a selective membrane. The membrane allows specific components of the liquid mixture to vaporize and pass through, while retaining others. This technique is commonly used for separating organic solvents from water, such as in the dehydration of ethanol or the separation of volatile organic compounds from aqueous solutions.  Pervaporation Dead-End Filtration Cross-Flow Filtration  Pervaporation PERMEATION + VAPORIZATION Permeation involves the diffusion of molecules through a membrane. Diffusion moves from high concentration to low concentration across the membrane. Permeate means “to pass” through a membrane. Pervaporation EXAMPLE  Vapor Permeation vs Pervaporation Vapor Permeation Vapor Permeation denotes the transport of matter through a membrane from a vapor feed mixture to a vapor permeate.  Vapor Permeation vs Pervaporation Pervaporation Methods for the separation of mixtures of liquids by partial vaporization. A feed liquid mixture is brought into contact with a membrane which allows the removal of components into a vapor stream on the permeate. NOTE: The vapor phase is achieved by maintaining low pressure on the permeate or by applying a vacuum.  Pervaporation Applications Dehydration of Organic Solvents: Pervaporation removes water from alcohols like ethanol, isopropanol, and methanol. Wastewater Treatment: Pervaporation removes volatile organic compounds from industrial wastewater, ensuring compliance with environmental regulations. Biofuel Production: Pervaporation is crucial in bioethanol production, particularly in the dehydration step to achieve fuel- grade ethanol. Oil and Petrochemical Industry: Pervaporation can separate hydrocarbons based on molecular size and polarity, useful in refining and petrochemical processes.  Advantages of MSP Lower Energy Consumption: Compared to thermal separation processes like distillation, membrane processes often require less energy, especially in the case of processes like reverse osmosis and ultrafiltration. High Selectivity: Membranes can be highly selective for specific molecules, allowing for the efficient separation of components with similar boiling points or molecular sizes. (semi-permeable) Space Efficiency: Membrane systems are typically more compact than other separation processes, requiring less space for installation. Reduced Chemical Usage: Membrane processes often require fewer chemicals for operation compared to other methods, resulting in less chemical waste. Wide Range of Applications: Membrane processes can be applied in various industries, including water and wastewater treatment, food and beverage processing, pharmaceuticals, and biotechnology.  Disadvantages of MSP Clogging and Scaling: Membranes can become fouled by particulates, biological matter, or scaling, leading to reduced performance and the need for frequent cleaning or replacement. High Initial Investment: The initial cost of membrane systems and replacement membranes can be high. Limited Chemical Compatibility: Not all membranes are compatible with all chemicals. Exposure to certain solvents, acids, or bases can degrade the membrane material, limiting its use in certain applications. Reduced Efficiency: Concentration polarization, where solute concentration builds up near the membrane surface, can reduce the efficiency of separation and permeate flux.  Desired Properties of a Membrane 1. Good permeability: passes through easily, facilitating efficient separation. 2. High selectivity: allowing certain substances to pass while blocking others. 3. Chemical Stability: The membrane must resist degradation from chemicals to ensure long-term performance. 4. Mechanical strength: It should withstand physical stresses without tearing or breaking. 5. Resistance to fouling and adsorption: The membrane must prevent buildup and surface binding to maintain efficiency and reduce cleaning. MEMBRANES