Molecular distillation is a special liquid liquid separation technology, operating under extremely high vacuum.He is according to,the molecular motion of a different material has different mean free path of the physical characteristics and achieve the purpose of separation,and the liquid at a temperature below the boiling point will be the separation,and is especially suitable for the separation of high boiling point,heat sensitive and easily oxide system.Because of its boiling point distillation temperature is lower than the material,distillation pressure reduction,heating time is short, high characteristics and high degree of separation,which can greatly reduce the separation cost of high boiling point material,excellent protection of sensitive material quality.The molecular distillation technology is used for the purification of natural health care products and functional oils, etc. it can get rid of the shackles of chemical treatment,and it can keep the pure natural properties

Molecular Distillation process is characterised by short residence time at the operating temperature, high heat transfer coefficient, absence of hotspots, possibility of continuous operation, low working pressures of the order of 0.001 mbar. The feed material is fed to the wiped film molecular distillation plant, a unique roller-wiper system ‘wipes’ this liquid on the heated evaporator. The centrally located condenser condenses the vapour, to get the required fraction condensed. Material handled in the WFMD: Vitamin A, Vitamin E, Monoglycerides, insecticides, pharmaceuticals, Silicone oils, perfumery and flavours, essential oils , petrolium industry including waste lube oil re-refining.

According to the principle of thermodynamics shows that, under certain temperature and pressure of the molecular mean free path L=0.707K*T/(πd²P), in D for effective molecular diameter; P for molecular space in which the pressure; T for the molecular environment temperature; K is the Boltzmann constant (Fu and Chen, 1979).

By the molecular mean free path of the movement of the formula, we can see that different kinds of molecules, because of the difference of the effective diameter of the molecule, the mean free path is different, that is, different kinds of escaping from the molecular level not and other molecular collision of flight distance is not the same. Light molecular mean free path, small molecular mean free path, if in away from the liquid surface is smaller than the mean free path of molecular light rather than heavy molecular mean free path set a condensing surface, making molecular light falling on the condensing surface chant condensation, and heavy molecules reach the condensing surface and return to the original level, so as to realize the mixture separation.

The typical molecular distillation unit consists of two kinds of centrifugal and rotary film blowing, and the rotating film – type molecular distillation device includes a variable – layer jacket, a condenser and a rotating scraper system.When the material is distilled, the material enters the rotating distributor continuously, and the centrifugal force is swung onto the heating wall, and the film is evenly distributed on the inner wall and downwards flowing.. This unique structure has obvious advantages:

1.The relative volatility of the mixture was explained by the relative volatility of the mixture, and the relative volatility of molecular distillation wasαm=p₁/p₂(M₁/M₂)^0.5,And conventional distillation of volatile alpha =p₁/p₂,The p₁/p₂ is the ratio of the vapor pressure of light recombination in a certain circumstance, the molecular weight of M₁ for the light component, and the molecular weight of M₂ for the reorganization.

2.Low pressure distillation, condensation and evaporation was very close to the surface and materials by steam must not throttle to the condensing surface, operating pressure can reach 0.01 mbar.

3.Evaporating temperature is low, in the molecular distillation device, the separation of mixtures is due to the different kinds of escaping from the molecular level the mean free path of different nature to achieve, does not need to be boiling, so molecular distillation is operating at a very low boiling point temperature.

4.Heating time is short, the mixed liquid is like a thin film thickness (much less than 1 mm), almost equal to the evaporation surface and the heating surface area, makes the material along the heated surface leave and evaporate quickly, very short residence time, about tens of seconds.

5.Low energy consumption, blows the membrane design almost no products remain in the inner wall of the heating, can avoid the clogging phenomenon; fast steam condensed, compact structure, small vacuum pump can meet the requirements of vacuum, reduce energy consumption; rapid replacement of material, does not produce mixture; therefore, molecular distillation, especially for those with ordinary distillation product loss, poor quality material.

Molecular distillation can be widely applied to various aspects of the national economy,especially suitable for the separation of high boiling point,heat sensitive and easily oxidized materials,such as separation and purification of fatty acids; distillation separation of natural and synthetic paraffin products; separation purification Jiao Shawan cod liver oil (ene); production of high concentration of monoglyceride;monomer MDI,TDI and two yuan of fatty acid separation polyurethane material;extraction of natural products VE;free fatty acid separation of oil products in special silicone oil; purification; separation of a small amount of solvent in natural extracts;application in polymer manufacturing; alkylpolyglucosides carotene purification;solation and purification;separation of hydrocarbons in petrochemical industry, purification of organic intermediates,antioxidant, lecithin;plastics industry by purification of plasticizer;refined emulsifier in food industry and purification of functional oil refining industry of traditional Chinese medicine;pharmaceutical intermediates;natural essential oil in the perfume industry decolorization,deodorization,improve purity etc..The summer and the purpose of the summer to give some practical examples to illustrate.

Application of Molecular Distillation Technique in Food Products

Molecular distillation can be applied in different parts of the food production. That is particularly reasonable for separating heat-sensitive and useful oxidation materials by dividing and purifying unsaturated fats.

1. Carotene Extraction

Carotene is a type of nutrient used in food. Today more people use ordinary carotene instead of industrial carotene. The whole process of producing industrial carotene needs triple molecular distillation; carotene-containing products can reach 40%.

2. Fat Extraction

Monoglyceride is widely used in the food emulsion business. The forensic molecular distillation technique is a typical case of that much-announced process study. The entire investigation process, similarly, has a directly investigated molecular distillation process. The most widely recognized assembly methods are to consolidate the era of the first oil solution of presumably low content of monoglyceride-containing products by 40 percent, 7 percent glycerol, and 35 percent glycerides.

Molecular distillation can be used to produce synthetic nutrients like vitamin E. Another advanced use in the synthesis of nutrients E is the derivation of acetic acid. The process contains 10% of the refractive point results and about 2% of the resin.

3. Amide Obtainment

Unsaturated fatty amide is used as an emulsifier in physical work. It has anticorrosive reactions and amines that are obtained from the response. Even though the registration requirements for high product quality, but low performance, for example, 98.5% quality, the frequency of not more than 88%, the use of molecular distillation rate up to 94%, It can reduce half of the waste.

4. Purification of Natural Essential Oils

Solid spices such as unpredictable substances, high heat sensitivity, and regular recovery and purification processes, generally three-way molecular distillation, first-class oxidation, second-level odor or purification, bleaching, or third stage are used. For example, rose oil after molecular distillation can settle in the smell is not pleasant, deep shading and wax content of the top, so that the added value improved significantly.

5. Capsaicin Purification

The red pepper dye-containing 1% to 2% soluble, after two-stage molecular distillation processing, the products broke the remaining quantity that meets the quality requirements. Also, similarly, you can achieve the successful division of capsaicin and pigment, which contains 10% capsule. From the general supercritical pepper by molecular distillation processing, the allicin content can be increased to 25% or more.

The use of molecular distillation can improve product quality, system reliability, short maintenance time, and low biological consumption, and can be used in the usual process of technology improvement and new advances in the process. Even though molecular distillation equipment is more expensive than standard distillation equipment, current vacuum technology to balance the system is high performance. The high efficiency and decrease of workers can reduce distillation costs, and the degree of decrease is undoubtedly more than the price of the machine.

Application of Molecular Distillation Technique in Fine Chemicals

There are several applications of molecular distillation techniques in fine chemicals. The process is developed to allow separation of compounds which can be denatured at high temperatures. Lowering of pressure creates a partial vacuum where the boiling points of substances are reduced drastically. The method has been helpful in the separation of the following compounds:

1. Extracting Tocopherols from Soya Sludge

Tocopherols have low boiling points. They can be denatured when the temperature goes too high. The application of molecular distillation has proved to be highly effective in the extraction of the compounds. It preserves the chemical composition of the tocopherols in the extraction process.

2. Production of Lactic Acid

Too high temperatures can lead to denaturing of lactic acid. In the production of lactic acid, molecular distillation is applied to extract lactic acid from raw materials. It is used due to its ability to preserve the quality of lactic acid in the extraction process.

3. Paraffin Wax Extraction

The application of molecular distillation is used to extract paraffin wax. Temperatures can be lowered after lowering the pressure to achieve the desired temperature for the removal of the paraffin wax.

4. Monoglycerides Extraction

In the process of monoglycerides extraction, molecular distillation is applied. It is among the few processes you can use to get the monoglycerides from their raw materials. The method of molecular distillation aims at lowering the temperatures, which leads to the successful extraction of the monoglycerides.

5. Omega‐3 Fatty Acids

The extraction of omega -3 fatty acids from fish fats involves the application of molecular distillation. The fatty acids are sensitive to high temperatures. As a way of preventing their damage, the experts include the use of molecular distillation. It is a process that consists of the use of the latest equipment, which subjects the fatty acids to the most appropriate temperatures as a way of extracting the oils.

The Application of Molecular Distillation Technique in the Pharmaceutical Industry

The application of molecular distillation techniques in the pharmaceutical industry (also known as ‘short path’ distillation) is observed when two heat intolerant compounds need to be safely separated. Most organic and silicon compounds, for instance, cannot be exposed to temperatures greater than 250ºC without risk of serious degradation.

Instead of relying on traditional equipment like low pressure-packed or atmospheric distilling towers, molecular distillation uses high vacuum stills to convert heat from condensation processes into a viable catalyst for radiant heat release to the surface layer on the evaporator.

The distance between the condenser and evaporator must be kept short and clear of impediments. It is this close proximity and the application of much cooler distilling temperatures, which keeps organic compounds from disintegrating when heated.

Thus, within the pharmaceutical world, molecular distillation is most commonly used for the purposes of solvent swapping, separating chemical compounds, crystallization, purification from volatile impurities, and dry from water.

Solvent swapping, for example, plays a vital part in the creation of many different medicines. Often, multiple solvents are needed to create a particular medicinal substance, but they may be needed at different times and varying stages. Solvent swapping, via molecular distillation, is a way to add and extract compounds to active pharmaceutical ingredients without negatively affecting their temperature and solubility limits. The ‘swap’ happens when an active solvent is carefully extracted using distillation techniques and replaced with a new solvent.

Solvents are essential to the formulation of medicines such as penicillin, aspirin, topical ointments, and cough syrups and tinctures.

Some other applications are as follows:

• Adding compounds/solvents to active ingredients to create concentrated pharmaceutical solutions
• Upgrading of pharmaceutical substances for artificial feeding
• Incorporating blending ingredients to creams, ointments, and lotions to achieve a smooth consistency
• Dissolving pharmaceutical substances in active solutions to create topical pet products

Equipment Checklist for Pharmaceutical Distillation

Molecular distillation equipment of this type comes in a variety of sizes. Within the fine chemicals industry, units are typically sized anywhere from pilot size to one or two stages for feed rates of 5-450 l/h. Each has an independent vacuum group, chilling group, hot oil heating system, and control cabinet.