Introduction
Nutsche filters are the simplest volume filters that operate both under vacuum and over-pressure. In these filters, the directions of the gravity action and the movement of the filtrate coincide. Nutsche filters are used in small-scale manufacturing and in laboratory conditions. This article will not mention the complex designs (with stirrers, drying and heating/cooling) of Nutsche filters that are used in manufactures due to their complexity and difficulty of maintenance.
The filter housing 1 (see Fig.1 and Fig.2) is made in the form of a cylindrical vertical container, open at the top (vacuum) or sealed (druk filter), with a false bottom-grid 2, on which a filter partition 3 (usually fabric) is placed on top. For vacuum filters, the cavity under the partition is connected to the vacuum pump through an intermediate container - a filtrate collector. Suspension in suction filters is fed into the cavity above the filter partition. The Druk filter is a Nutsche filter operating under excess pressure. In Druk filters, excess pressure above the filter partition is created by pumping the suspension with a pump or by pumping compressed gas with a compressor into the cavity above the filter partition. The sediment accumulates on the partition to a certain level (thickness), after which the supply of the suspension is stopped. The sediment is washed as necessary, blown, and then unloaded manually. After the filter partition is regenerated (or replaced), the cycle is repeated.
Vacuum suction filters are usually used at significant concentrations of the solid phase in the initial suspension. Druk filters are used to separate fine suspensions with low solids' concentration. To facilitate the unloading of the sediment, the bodies of the Druk filters are made detachable. If unloading is necessary, to release the quick-release connection of the body section, the lower section with a grate is lowered and rotated by about 180 degrees (to facilitate unloading). The advantages of suction filters are their simplicity and high-quality sediment washing. The main disadvantage of these filters is their low specific performance.
Vacuum suction filters are usually used at significant concentrations of the solid phase in the initial suspension. Druk filters are used to separate fine suspensions with low solids' concentration. To facilitate the unloading of the sediment, the bodies of the Druk filters are made detachable. If unloading is necessary, to release the quick-release connection of the body section, the lower section with a grate is lowered and rotated by about 180 degrees (to facilitate unloading). The advantages of suction filters are their simplicity and high-quality sediment washing. The main disadvantage of these filters is their low specific performance.
Application in drug manufacturing
In most methods for obtaining narcotic and potent substances, there is a filtration step, often vacuum filtration is necessary. The need to use different equipment depends on the scale of production. When synthesizing a few grams, it is sufficient to use a conventional coffee filter (filter paper), with regular production of hundreds and thousands grams batches, vacuum filtration is required to speed up the process. Vacuum filtration on a Büchner flask is limited by the volume of the Büchner flask, the size and capacity of the Büchner funnel, and the time it takes to empty the Büchner flask and unload the Büchner funnel. For a larger production of kilograms, tens of kilograms of substances, more efficient filtration is required. It is provided by Nutsche filters. Increased loading, increased filtration speed, as well as their advantages in ease of use and so on (see below Key advantages) make them an indispensable tool in a large-scale clandestine laboratory for the production of Amphetamine, Methamphetamine, MDMA, Mephedrone, a-PVP and so on.
Nutsche filter design
The walls of the filter are made of special glass (borosilicate), and the filter is made of various porous materials. It can be: fluoroplastic, glass, stainless steel, filter cloth. A standard Nutsche always consists of the following elements: a housing with a so-called false bottom, where a filter partition is fixed. Key elements are usually made corrosion resistant. The listed elements and the stirrer are quite easy to additionally cover with plastic, enamel. You can also use rubber. This is what distinguishes Nutsche from other types of filtering devices.
To use the Nutsche filter, you will need to create a suitable Vacuum. The Rotary-vane pump is suitable for this purpose, which will create the right pressure for fast filtration.
To use the Nutsche filter, you will need to create a suitable Vacuum. The Rotary-vane pump is suitable for this purpose, which will create the right pressure for fast filtration.
Filter partition and simplest Nutsche filter design
Key advantages
- There is no contact between substances, the human operator, therefore, sterile work, operations with dangerous, toxic substances are possible.
- Nutsche can be heated (prevents crystallization) or cooled (reduces the solubility of the precipitate).
- It is possible to work with substances that are sensitive to light by replacing the glass with a tinted one.
- Pretty efficient separation of matter into phases: solid, liquid.
- Simple design, no need for expensive equipment
- Quite long service life.
Work stages
- Filling the reservoir with the required suspension.
- Direct filtering.
- Adding rinse solution to the filter.
- Thorough washing of the precipitate and drying.
- Sediment collection, filter partition restoration.
Video manual
Nutsche filters selection
Choosing the right Nutsche filter for your needs starts with choosing a manufacturer, budget, and time to buy. Next, you should select the appropriate Nutsche filter size based on the amount of reaction mass per load that you will need to filter.
Suppliers
There are many companies, which produce and sell this laboratory equipment. Your choice depends on your budget. Here represented only Chinese suppliers and, hence, prices quite low. European and US manufacturers don't publicate equipment prices on their websites. However, their prices will be higher. Valid prices for 02.2022.
Zhongyi Kori(Zhengzhou)Equipment Co.,Ltd - https://www.korireactor.com
NANJING NINGKAI INSTRUMENT CO.,LTD - https://www.pharmasources.com
Shanghai Kesheng Instrument Co., Ltd. - https://shkesheng.en.alibaba.com
Last edited by a moderator: