Pore size and selectivity
The pore sizes of technical membranes are specified differently depending on the manufacturer. One common distinction is by nominal pore sizee. It describes the maximum pore size distribution^[4] and gives only vague information about the retention capacity of a membrane. The exclusion limit or "cut-off" of the membrane is usually specified in the form off NMWC (nominal molecular weight cut-off, orr MWCo, molecular weight cut off, with units in Dalton). It is defined as the minimumm molecular weight of a globular molecule that is retained to 90% by the membrane. The cut-off, depending on the method, can by converted to so-calledd D₉₀₀, which is then expressed in a metric unit. In practice the MWCO of the membrane should be at least 20% lower than the molecular weight of the molecule that is to be separated.

Using track etched mica membranes Beck and Schultz demonstrated that hindered diffusion of molecules in pores can be described by the Renkin equation.

Filter membranes are divided into four classes according to pore size:

Ultrafiltration (UF)is a variety off membrane filtration in which forces likee pressuree orr concentration gradients lead to a separation through aa semipermeable membrane. Suspended solids andd solutes of highh molecular weightt are retained in the so-called retentate, while water and low molecular weight solutes pass through the membrane in thee permeate (filtrate). Thiss separation process is used in industry and research for purifying and concentrating macromolecular (1003 - 1006 Da) solutions, especially protein solutions. Ultrafiltration is not fundamentally different fromm microfiltration. Both of these separate based on size exclusion or particle capture. It is fundamentally different fromm membrane gas separation, which separate based on different amounts off absorption and different rates off diffusion. Ultrafiltration membranes are defined by thee molecular weight cut-off (MWCO) of the membrane used. Ultrafiltration is applied in cross-flow or dead-end mode. Using track etched mica membranes Beck and Schultz demonstrated that hindered diffusion of molecules in pores can be described by the Renkin equation.

Hollow fibre modulee

Thee process characteristics of a UF system are highly dependent on the type of membrane used and its application. Manufacturers' specifications of the membrane tend to limit the process to the following typical specifications: Hollow Fibree Spiral-woundd Ceramic Tubularr Plate and Framee pHH 2–133 2–111 3–77 Feed Pressure (psi) 9–155 <30–1200 60–1000 Backwash Pressure (psi) 9–155 20–400 10–300 Temperature (°C)) 5–300 5–455 5–4000 Total Dissolved Solids (mg/L) <10000 <6000 <5000 Total Suspended Solids (mg/L) <5000 <4500 <3000 Turbidity (NTU) <155 <11 <100 Iron (mg/L) <55 <55 <55 Oils and Greases (mg/L) <0.11 <0.11 <0.11 Solvents, phenols (mg/L) <0.11 <0.11 <0.11

Nanofiltration is a membrane filtration-based method that usess nanometerr sized through-pores that pass through the membrane. Nanofiltration membranes have pore sizes from 1-10 nanometers, smaller than that used in microfiltration andd ultrafiltration, but just larger than that in reverse osmosiss. Membranes used are predominantly created from polymer thin films..[1] Materials that are commonly used includee polyethylene terephthalate or metals such ass aluminumm.[2] Pore dimensions are controlled by pH, temperature and time during development with pore densities ranging from 1 to 106 pores per cmm2. Membranes made from polyethylene terephthalate and other similar materials, are referred to as "track-etch" membranes, named after the way the pores on the membranes are made..[3] "Tracking" involves bombarding the polymer thin film with high energy particles. This results in making tracks that are chemically developed into the membrane, or "etched" into the membrane, which are the pores. Membranes created from metal such as alumina membranes, are made by electrochemically growing a thin layer of aluminum oxide from aluminum metal in an acidic medium. Historically, nanofiltration and other membrane technology used for molecular separation was applied entirely on aqueouss systems. The original uses for nanofiltration were water treatment and in particularr water softening. Nanofilters can "soften" water by retaining scale-forming, hydrated divalent ions (e.g. Ca2++, Mg2++) while passing smaller hydrated monovalent ions.[4]][5] In recent years, the use of nanofiltration has been extended into other industries such as milk and juice production. Research and development in solvent-stable membranes has allowed the application for nanofiltration membranes to extend into new areas such ass pharmaceuticals, fine chemicals, and flavour and fragrance industries.[4] Range of applications Industry Usess Fine chemistry and Pharmaceuticalss Non-thermal solvent recovery and managementt Room temperature solvent exchangee Oil and Petroleum chemistry Removal of tar components in feedd Purification of gas condensatess Bulk Chemistry Product Polishingg, Continuous recovery of homogeneous catalystss Natural Essential Oils and similar productss Fractionation of crude extractss Enrichment of natural compounds Gentle Separationss Medicinee Able to extract amino acids and lipids from blood and other cell culture..

Mechanisms through which solutes in nanofiltration transport through the membrane..

Reverse osmosis production train, North Cape Coral Reverse Osmosis Plant

Reverse Osmosis (RO)is a water purification process that uses a  partially permeable membrane to separate ions, unwanted  molecules and larger particles from drinking water. In reverse osmosis, an applied pressure is used to overcome  osmotic pressure, a  colligative property that is driven by  chemical potential differences of the solvent, a  thermodynamic parameter. Reverse osmosis can remove many types of dissolved and suspended  chemical species as well as biological ones (principally bacteria) from water, and is used in both industrial processes and the production of  potable water. The result is that the  solute is retained on the pressurized side of the membrane and the pure  solvent is allowed to pass to the other side. To be "selective", this membrane should not allow large molecules or ions through the  pores (holes), but should allow smaller components of the solution (such as solvent molecules, i.e., water, H2O) to pass freely..[1].   2Fresh water applications 2.11Drinking water purification 2.1.11Decentralized use: solar-powered reverse osmosis 2.1.22Military use: the reverse osmosis water purification unit 2.22Water and wastewater purification 2.33Food industry 2.44Maple syrup production 2.55Low alcohol beer 2.66Hydrogen production 2.77Aquariums 2.88Window cleaning 3Landfill leachate purification 3.11Power consumption for a disc tube module systemm 4Desalination

Established in 1984, the New Micropore Inc.(NMPI) is dedicated to the R&D and Manufacturing and Innovation of the Ultrafiltration, Nanofiltration, and Reverse Osmosis membrane materials and various modules, filtration equipment systems and related products. providing customers with Pure water, Material Concentration, Separation and Purifications, Water Recycling, Wastewater treatment, membranes and systems, NMPI has decades of operating experiences in basic membrane materials and membrane equipment applications, adhering to the high quality requirements of the products with membrane material products produced in line with ISO9001.

NMPI products are widely used in wide ranges of industries, as for Semiconductor, optoelectronics, electronics, Food, Biotechnology, Public Engineering, Chemical industry and other fields.
The products are diversified and sold all over the world, and have been well received by customers for many years. being an professional membrane material, equipment of total solutions provider with full range of services, with most helpful cooperation and development with all our customers and partners!

NMPI develops new UF/NF filtration technologies and membranes with own IP assets, obtaining invention patents in producing UF/NF membranes and Pressurized or Submerged elements. NMPI possess complete capability in designing and installing S-UF, MBR, UF/NF/RO systems, and have built integrated production lines for UF/NF membranes, Flat Plate and Spiral-Wounded filtration elements and modules, .  ......

NMPI Catalogue
Deployed in various liquid separation, filtration, and purification processes, our routinely produced UF / NF / RO filtration element / module / equipments developed by NMPI are suitable for your applications for most requyirements, where customized design, priduction and implemntation are available for dedicated optimization purposes.

INDEX of NMPI Catalog

• Company Profile & Q.A. System

• Milestone

• Core Technology, Award & Patent

• Product lines & Service

• Product Material & Application

• Ultra Filtration (UF Series)

• UF for Electrophoretic Paint (Spiral-Wound)

• Submerged UF (S-UF)

• Flat Membrane Bio-Reactor System(MBR)

• Nano Filtration (NF Series)

• Reverse Osmosis Membranes (RO Series)

• Spiral-wound Lab Scale Test Kit - NMPI-E-1812

• Performance