“VOC” (volatile organic compounds) is a general term for organic compounds that are volatile and become gases in the atmosphere. It includes various substances such as gasoline, toluene, and chlorofluorocarbons. These substances are known to cause air pollution related to photochemical oxidants and are related to ozone layer depletion and global warming. Emission regulations have been taking shape in Europe and the United States. The emission regulations have been started in Japan on April 1, 2006.

No need to mention the petroleum through vents, most VOCs are contained as solvents in adhesives, paints, inks, etc., they are discharged from chemical product manufacturers and printing-related facilities. Also, electronic parts and metal processing manufacturers use VOCs as cleaning agents.

There are two types of VOC emission countermeasures: combustion treatment and separation / recovery treatment. The separation / recovery method includes adsorption by activated carbon and membrane separation operation with selective permeable membrane.

NAGASEP is a separation membrane module made of a single material of silicone rubber and has excellent properties for separating and concentrating VOCs. Membrane separation is a process that takes advantage of specific selective permeability of silicone membrane to the target component.

The device has a simple structure in which a vacuum pump and a steam recovery container are installed besides the membrane module, and VOCs can be continuously concentrated and recovered by depressurizing the permeation side of the membrane at atmospheric pressure on the gas supply side.

NAGASEP is a separation membrane module made of a single material of silicone rubber and has excellent properties for separating and concentrating VOCs. Membrane separation is a process that takes advantage of specific selective permeability of silicone membrane to the target component.

The device has a simple structure in which a vacuum pump and a steam recovery container are installed besides the membrane module, and VOCs can be continuously concentrated and recovered by depressurizing the permeation side of the membrane at atmospheric pressure on the gas supply side.

In the picture below you could see the permeability of VOCs in NAGASEP.

The post Separation, concentration and recovery of volatile organic compounds appeared first on NAGASEP.

Silicone rubber has very different properties from general synthetic rubber.

Physical properties

It has properties such as heat resistance and high electrical insulation. It does not harden even at low temperatures. It is resistant to ultraviolet rays, and physiologically inactive. These characteristics are due to the difference in silicone rubber’s molecular structure from general rubber.

Chemical properties

General rubber is a bond of carbon and carbon, but silicone rubber is a bond of silicon and oxygen. This bond is called a siloxane bond, and the characteristic properties of silicone rubber are due to this siloxane bond.
The binding energy of Si—O in silicone rubber is considerably larger than that of CC and CO bonds, so it is chemically stable. In addition, the Si—O bond has about 50% ionic bond property compared to the CC bond, which consists of 100% covalent bond, and can be said to be located between organic and inorganic. It is thought that the presence of this ionic bond strengthens the bond between CH of the methyl group which directly bonded to silicon and contributes to stabilization.

The post Characteristics of Physical and chemical properties of silicone rubber appeared first on NAGASEP.

Nagasep has excellent permeability of VOC (volatile organic solvent) as well as gas molecules, so the target component can be separated and recovered from the atmosphere or water. The standard size of the hollow fiber membrane and the permeability of various gases are displayed below.

Read the full research of GAS Permeability

The post Gas permeability of NAGASEP appeared first on NAGASEP.

In biochemical analyzers such as blood analyzers, components are quantitatively analyzed by colorimetric analysis.

Colorimetric analysis is an analysis method in which the solution is exposed to light and the concentration of the component is measured by the intensity of the transmitted light. In the analyzer, the blood sample is diluted with pure water in the cell, then the solution is exposed to light for analysis.

If air bubbles are mixed in the cell, they would become detection noise when exposed to the transmitted light.

By degassing the diluted water of the sample and the washing water of the cell using NAGASEP, detection noise in the analysis can be reduced and more accurate analysis results can be obtained.

The post Degassing helps improve accuracy of analytical instruments appeared first on NAGASEP.

The amount of oxygen dissolved in water under atmospheric pressure is approximately 8 ppm at 25 ° C.

Metals will get rusted by water and oxygen. The reaction of iron rusting process happens like this : When iron comes into contact with water, it dissolves in water as iron ions, and at the same time, dissolved oxygen produces hydroxide ions. Iron (II) hydroxide is formed by the reaction of iron ions and hydroxide ions. This is oxidized by dissolved oxygen, thus produces ferric hydroxide containing hydroxide called red rust.

Red rust on pipes can be prevented by removing dissolved oxygen using NAGASEP. In addition, the flow of degassed water through the pipe would naturally create a film of triiron tetroxide called black rust. This black rust is formed on the surface of the iron and won’t react with moisture or oxygen, which can suppress the occurrence of red rust.

The post Reduce rust inside pipes by degassing water – Part 1 appeared first on NAGASEP.

1. Degassing of recycled water Using NAGASEP (internal perfusion modules) for recycled water in buildings to prevent pipe rusting.

2. Degassing of tap water Using NAGASEP (external perfusion modules) for tap water, besides degassing, harmful chlorine compounds are also removed at the same time.

What makes NAGASEP exceptional?

NAGASEP can deal with the rusty water without rebuilding the whole pipe system. You only need to put one or several modules into the tank and it will start producing non-oxygenated water. We have a real case that NAGASEP is installed where tank water enters into pipe and turns the water into degassed water. The degassed water can be a natural cleaner for the rusty pipe and can prevent rust in the future.

Why degassed water can reduce the red rust to black rust?

In normal water, the chemical reaction goes like: 4Fe + 3O2 + 2H2O → 4FeOOH

In degassed water, the chemical reaction goes like: 6FeOOH + 2e- → 2Fe3O4　＋ 2H2O + 2OH

What is frequency for changing a new module?

Whenever there is leak in the old module you should change for a new one. The reason for the damage to silicone is mainly because of oganochloride. Thus, the expected changing frequency for the module will be determined by the water quality.

The post Reduce rust inside pipes by degassing water – Part 2 appeared first on NAGASEP.

This research has used our product NAGASEP.

What is chlorealla?
Watch on YouTube

A hollow fiber culture system has been proposed for supplying the carbon dioxide to the microalgae, to replace the conventional air bubbling system which has been adopted to supply carbon dioxide in most conventional microalgal culture. In order to examine the usefulness of hollow fiber membranes for the microalgal culture, the microalgal growth rate for Chlorella sp. and the effective mass transfer coefficient of carbon dioxide through the hollow fiber membranes have been measured using the proposed photobioreactor filled with hollow fibers.

The microalgal growth rate using hollow fiber membranes was found to be three times greater than that observed in the conventional non-membrane photobioreactor. An experimental investigation has been conducted so as to evaluate the effect of the volume flow rate of the carbon dioxide and its concentration of the feed air through the hollow fibers on the microalgal growth rate. The present study clearly indicates that the hollow fiber membrane is quite useful for the microalgae culture in terms of enhancing both microalgal growth rate and dissolution rate of the carbon dioxide.

See the whole research of Microalgal Culture for Chlorella

The post Microalgal Culture for Chlorella sp. using a Hollow Fiber Membrane Module appeared first on NAGASEP.

Resin: PVC, PC, ABS, PP
Metal: aluminum, stainless

Above are the optional material for the housing of module.

For test modules, resin housing is cheaper. However, the resins listed above are not highly resistant to organic solvents.

If your application is recycling of organic solvent from waste liquid or there will be organic solvent, we would recommend you to use metal-based housing.

Also, for autoclave sterilization (120 ℃), it is reasonable to choose metal or polycarbonate(PC), since PVC and ABS has a lower working temperature.

The post How to know which housing material suits you better? appeared first on NAGASEP.

The removal of dissolved oxygen (DO) from water was studied using a silicone rubber hollow-fiber membrane module. Dissolved oxygen in water was effectively reduced by the vacuum degassing or pervaporation process through a non-porous membrane. The controlling transport property, gas permeability through the membrane, was independently measured by a method using a differential transformer. A gas-phase driving force model was presented based on the permeabilities of the permeates through the hollow-fiber. Experimental results of the oxygen removal from water were compared with the model calculations. The present model proved to explain the effects of the pressure condition and the operation mode on the removal of oxygen from water. Although the liquid-phase mass transfer resistance was shown to have a large effect on the removal performance of the membrane module, the membrane permeation step controlled the mass transfer during vacuum degassing.

Ⓒ 1998 Elsevier Science B.V.

Keywords: Fiber membranes; Gas and vapor permeation; Pervaporation; Water treatment; Dissolved oxygen

To read the entire essay, please download this PDF file.

The post Removal of dissolved oxygen using non-porous hollow-fiber membranes appeared first on NAGASEP.