> Is Ion Exchange Resin the same as “Pine Resin”? What are its Main Properties?

Originally, resins are gel-like hydrocarbon secretions of many plants, particularly coniferous trees. Later, some substances similar in traits to resins were also referred to as “resins”, such as epoxy resins, phenolic resins, ion exchange resins, and the like.

Ion exchange resin is a synthetic high-molecular polymer compound. Its functional performance depends on the manufacturing process, raw material formulation, polymerization temperature, crosslinker, and functional groups.

1. Physical Properties

I. Physical Form

Resin is a transparent or translucent substance, but its color varies from a different variety. Generally, the more impurities or crosslinkers exist in its raw materials, the darker the color of the resin will be. During the application of the resin, its color also sometimes changes for various reasons. Additionally, the shape of the resin is spherical, and the ratio of the integrated bead after the grinding test is required to reach 90% or more.

II. Particle Size

The particle size of the resin will affect the ion exchange speed, pressure loss, backwashing effect, and the like. The particles of the ion exchange resin used for the water treatment are preferably 20-40 mesh. The particle sizes should not vary too far from one to another. The effective particle size and the uniformity coefficient can stand for particle size.

III. Density

Resin’s density is associated with the water treatment process as well as resin loading, usually classified as:

  1. Dry True Density(generally about 1.6 g/ cm³)
  2. Moisture True Density(generally between 1.04 and 1.30)
  3. Moisture Bulk Density(generally between 0. 60 and 0.80)

IV. Moisture Holding Capacity(%)

The greater the moisture holding capacity of the resin is, the larger the porosity of the resin is and the less the resin is crosslinked.

V. Swelling Ratio

Resins will swell when it is placed in water, which is related to the degree of resin’s crosslinking, the exchange capacity of its active functional group, the density of electrolytes in the water, the properties of the exchangeable ions, etc. Resin swells and contracts during the process of ion exchange and resin regeneration, in which resin is prone to crack when it happens at times.

VI. Abrasive Resistance

Resin’s abrasion performance reflects the mechanical intensity of the resin. The amount lost by mechanical wear per year should be ensured not to exceed 7%.

VII. Solubility

Resins will be dissolved during use and affect the water quality when it contains oligomers.

VIII. Heat Resistance

Generally, the temperature resistance of cation resin is up to 100° C. The strongly basic anion resin can endure as high as 60° C while the weak anion resin can withstand 80°C. Additionally, the resin will crack due to icing if the temperature is below 0° C.

IX. Electroconductivity  

Dry resin is not electrically conductive while wet resin is.

2. Chemical Properties

I. The exchange reaction of the ion exchange resin is reversible, so it can be exchanged and regenerated, hence reusable.

II. Resin can be acidic or alkaline. The properties of H+ type ion exchange resin and OH type ion exchange resin are the same as those of the electrolyte acid and alkali, which can ionize the H+ and the OHin water.

III. Resin can undergo neutralization reactions with acids or alkalis as well as hydrolysis reactions because of its electrolyte properties.

IV. Due to different adsorption capacity, ion exchange resin is selective to absorb various ions.

V. ‘Exchange Capacity’ indicates how many ions the resin is capable of exchanging, which is often used in engineering design and operation management during water treatment process. It can be expressed by ‘Full Exchange Capacity’, ‘Working Exchange Capacity’, ‘Balanced Exchange Capacity’, etc. And the unit hereof is millimoles/liter or millimoles/gram, etc.

> Adsorption Resin – Instructions for Use

1. How To Store Resin?

The adsorption resin is usually stored in a wet state, with the temperature ranging from 0°C to 40°C. When the storage temperature is lower than 0°C, a clear saturated saline solution should be added to the package to soak the resin. If exposed to air, the resin may be partially dry and dehydrated. Therefore, to get rehydrated, considering its hydrophobicity in most cases, partially dehydrated adsorption resin should be fully soaked in methanol or other water-soluble solvents (such as ethanol, acetone). After being fully soaked, resin should be flushed with water to displace methanol.

2. Pretreatment Of Resin

In the production process of adsorption resin, industrial-grade raw materials are generally used hence not have been further purified. Therefore, a small amount of monomer, porogen, and other organic impurities are often left inside the resin. So pre-treatment must be proceeded prior to use.

Specific pretreatment methods are as follows:

  • Soak the resin to be filled in an ion exchange column for 2hrs, with 2 times the resin volume of methanol or other water-soluble solvents (such as ethanol, acetone), and stir it at times to make the resin completely swell.
  • Fill the fully swelled adsorption resin into an ion exchange column at a flow rate of 3-4 times the bed volume per hour, and then pour 5-8 times resin volume of methanol or other water-soluble solvents (such as ethanol, acetone) through the resin layer till the effluent stays separated after being diluted with water
  • Pour deionized water through the resin layer at a flow rate of 6-8 bed volumes per hour to replace methanol before qualifying the resin for use.

>Application of Macroporous Resin Adsorption Technology in Extraction of Medicine

1. The Basic Theory of Macroporous Resin Adsorption Technology

The adsorption technology of macroporous resin was a new tech innovation developed in the 1970s. It is based on the purification and refining method by pouring traditional Chinese decoction medicine compound through ion exchange columns where macroporous resins are placed so that the active ingredients would be adsorbed by resins and then released back to columns to be recycled after the elution process. And all impurities would be effectively removed hereby.

Which type of resins to be appropriately selected depends on what’s inside the medicine liquids and what to be extracted from them. Moreover, it is mainly the physical structures (eg. physical form, pore size, etc) of the adsorption resins, especially of the non-polar ones that take effect on adsorbing liquids’ ingredients.

The specific functionality varies from different resins. Such example as for the extraction of stevioside, AB-8 type is commonly used while the extraction of traditional Chinese medicine and purification of antibiotics are generally used in X-5 type. Furthermore, the basic procedures of its operation are mostly through: Traditional Chinese Herbal Extracting SolutionàPass Through Macroporous ResinsàResins Adsorb the Active IngredientsàElutionàEluentsàRecovered SolutionàMedicine LiquidsàDry OutàSemi-finished Products

This technology has been widely applied in the development of new Chinese herbal medicines and the production of Chinese patent medicines, primarily for the separation and purification process.

2. Advantages of Macroporous Resin Adsorption Technology in Herbal Extract Medicine Application

I. Reduce Dosis to Improve Intrinsic Quality and Preparation Level of Medication

The medicines refined by the macroporous resin adsorption technology function with highly dense efficacy composition and fewer impurities, and the extraction yield (of impurities) is only 2-5% of the original medicines while with the general boiling method, the extraction rate is about 20-30% and around 15% when ‘alcohol precipitation’ method is applied. As a result of this new adsorption technique, the reduced dosage and impurities greatly improved the performance of contemporary pharmaceuticals, particularly herbal medicines like TCM ones.  Compared to the bulky extract from traditional Chinese medicine decoction, the dosage is much smaller with highly active ingredients, selective-friendly for dosage form as well as production-effective.  

Both pharmacodynamics and clinical trials confirmed the improvement of the efficacy of the same medicine after adopting this adsorption process, in which impurity removal and maximization of extraction rate after purification are fulfilled thereof.

II. Reduce the Moisture Adsorption of Medicines

After treatment with macroporous resin adsorption technology, a large amount of strong moisture adsorption ingredients such as glucide, inorganic salt, mucus and the like from traditional pharmaceutical preparation technology can be effectively removed from decoction, which is beneficial to the production as well as the chemical stability of the polymorphism of drugs during storage phases.

III. Shorten the Production Cycle of Medicines

This adsorption tech can shorten the manufacturing lifecycle as the required equipment is simple and eliminate the needs for static precipitation, concentration and other time-consuming workflows. Besides, it saves the cost of packaging, which created good conditions for Chinese medicine to compete in the global market.

3. The Pharmaceutical Effects on the Medicine Efficacy by Applying Macroporous Resin Adsorption Technology and Precautions for Application

Through pharmacodynamic tests and clinical observations, a procedure functioning with a set of the mature process not only guarantees efficacy but also improves efficacy after purification and refining. Nevertheless, there are many technical issues in the application that must be noted: such as the selection of resin model. The specification and quality requirements of the resin itself play a decisive role in the purification effect and safety of the medicine extract.

Performances vary from different models. It is inappropriate to only use one type of resin to purify and refine the medicine compound as the composition of the extract is extremely complicated.

Moreover, during the process of purification and refining, it is necessary to select the pharmacodynamic experimental method associated with curative effects to track according to the needs of different treatments. Meanwhile, the effective chemical composition of the medications must be tracked to ensure the active ingredients are not lost during the processes, the efficacy is not reduced and the quality is stable enough.

The process conditions such as the usage of the resins, the maximum adsorption amount, the adsorption elution velocity, the height and diameter of resin columns, and the types and concentration of the elution solution must be optimized to be selected so that the quality and efficacy of medications will be ensured.

4. Issues & Concerns in the Application of Macroporous Resin Adsorption Technology

I.  Toxicity of the porogens and degradants
Due to macroporous resin’s network structure and its large pore feature, some organic solvents are required to be added during preparation. However, it is greatly concerned about the safety in use because most of these solvents are toxic liquids and stay inside the voids of the resin, commonly known as ‘porogens’. The likelihood of issues as for resin quality can be degraded in a long-term use or porogen is not completely removed is taking place.
However, after many experiments we have explored the treatment methods of porogens and degradants, and formed a complete set of testing measurements legitimized by the State Drug Administration, in order to establish quality control standards for benzene, methylbenzene, etc.

II. Secondary pollutions caused by the residue of medicine liquids

This concern rarely happens in large-scale manufacturers because within mass production, one type of resin is only designated for purifying and refining one type of medication. In other words, it is impossible to use one resin to adsorb active ingredients for making several drugs.  In most cases, the effective composition will be selectively retained corresponding to the required components of each drug.

III. Degraded adsorption capacity

This issue shall be easily solved as long as constantly detect on the component index of the medicine liquids before and after the macroporous adsorption resins are placed into exchange columns to verify if the adsorption amount is decreased, with a timely treatment or replacement of new resins.

5. The Application Prospect of Macroporous Resin Adsorption Technology

The extract obtained by macroporous resin’s adsorption and separation process results in smaller size and no moisture adsorption, and is easy to be made into various dosage forms with aesthetic configuration, especially suitable for granules, capsules and tablets, which upgraded the crude, large and dark preparations of traditional herbal medicines into modern forms.

As far as this macroporous resin technology itself is concerned, its process is quite simple and convenient. And the resin can be used repeatedly with a fair cost. With relatively simple equipment, this process can save a large amount of energy consumption, ingredients, packing materials, storage, transportation and other costs.

Today in global scope, macroporous resin adsorption technology has been widely applied in the production of western medicine, synthetic patent medicine, agentia, herbal extract, and other medicament associated.