Sugar and organic matter stored inside are consumed by respiration, and water is released to the outside. This causes the taste and nutritional qualities of fruits and vegetables to deteriorate over time.

Thus, if fruits and vegetables are stored with reduced respiration, it can delay the deterioration of their quality and keep them fresh longer.

The speed of ripening with respiration of fruits and vegetables is slowed by an increase in the concentration of carbon dioxide in the air in storage.

However, too high a concentration of carbon dioxide will adversely affect the appearance, flavor, and nutritional value of the fruit and demote its quality. In other words, to maintain the freshness, the amount of carbon dioxide in storage must be kept constant within a certain range.

To remove carbon dioxide from storage, slaked lime has often been used as an adsorbent.However, when lime (calcium oxide, CaO) absorbs carbon dioxide, it changes into calcium carbonate (limestone, CaCO3) and is unable to absorb any more carbon dioxide.

NAGASEP separation membranes have the advantage of allowing a very large amount of carbon dioxide to permeate through the atmospheric components (nitrogen and oxygen).

This ability allows NAGASEP to remove excess carbon dioxide from storage.

Unlike adsorbents, NAGASEP can repeatedly adjust the concentration of carbon dioxide in storage over long periods of transportation, such as when they’re inside containers.

NAGASEP reduces the deterioration of fruits and vegetables during long-distance transport and extends their life. We provide you this option to keep your products fresh on their way to the new market.

The post Extend Freshness of Fruits and Vegetables by Controlling Gas Concentration to Optimal Levels  appeared first on NAGASEP.

Many industrial processes such as printing, metal cleaning or painting produce waste air streams containing low concentrations of organic solvents, such as acetone, toluene, perchloroethane, xylene, etc. The total value of the solvent lost with the waste air is considerable. In addition, these solvents represent a significant pollution problem, and in recent years several procedures for recovering solvents from air, such as carbon adsorption, incineration, etc. have been introduced in the industry. All of them show some draw-backs in terms of efficiency, reliability and costs. In this paper a membrane process is described, which provides an attractive alternative to the conventional methods. In a basic study the permeabilities of acetone, toluene, xylene, dichloroethane and dichloromethane through a homogeneous polydimethylsiloxane (PDMS) membrane have been determined using a pressure difference between 400 and 1000 mbar as driving force. The selectivity of the membrane for the various solvents and their dependence on the solvent concentration in a mixture with nitrogen were studied.

The selectivities of the PDMS membrane for the solvent/nitrogen mixtures were in the range of S = 70-160, depending on the solvent and its concentration in the feed mixture. Based on these data a pilot plant process has been designed in which a solvent is recovered from a waste air stream and the depleted air is recycled into the waste air producing process. The solvent which has permeated the membrane is recovered as a liquid by condensation. Thus, complete recycling of air and solvents is possible. In a cost analysis it has been demonstrated that the membrane process is indeed an attractive alternative to conventional air cleaning techniques.

Read the full research of Removal of organic vapors from air

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In mass culture of animal cells, it is important to keep the oxygen concentration in the liquid high in order to maximize the biological function. However, animal cells can be easily killed by the bursting bubbles, so a static oxygen supply method is in need.

The silicone membrane has good oxygen permeability, the oxygen supply area can be increased by using ultra-fine hollow fibers. The homogeneous membrane is free of germs, and oxygen can be supplied without bubbles regardless of the supply pressure. It has good heat resistance so it’s available for autoclave.

In addition, since the hollow fiber membrane of NAGASEP is a soft thread, it can be combined with various materials. For example, hollow fibers can be woven into a cloth shape. Also, when the housing changes, modules of various forms such as flat shape and tubular shape can be used. It is highly designable.

Today, NAGASEP gas exchangers are used by many pharmaceutical manufacturers as part of the core for cell culture equipment.

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“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

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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?
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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

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