DOWEX ion exchange resin

DOWEX ion exchange resin

Nantong Hairuo Chemical Co., Ltd

DOWEX fine-grained resin is produced through selective control of suspension polymerization technology for industrial resins with a production standard of 16-50 mesh. The obtained resin is composed of complete spherical beads, which have excellent kinetic and filling properties in chromatographic separation, and avoid the problems caused by grinding or crushing the resin.

Dow offers a wide range of fine-grained resins suitable for chromatographic separation in the fine chemical and pharmaceutical industries. We can provide anionic and cationic resins with particle sizes ranging from 50-100, 100-200, and 200-400 mesh. The crosslinking degree (calculated as a percentage of divinylbenzene content) includes 2%, 4%, and 8%. Such a wide range of product lines allows you to choose resins with good permeability, water holding capacity, and total capacity for specific applications.

Dow's extensive resin selection not only enhances your ability to optimize laboratory separation, but also simplifies the adjustments typically necessary during process scaling up. This helps ensure that your success in the laboratory can be translated into the success of pilot and large-scale production facilities.

DOWEX fine-grained resin is a durable, pH resistant, clean, and predictable separation medium that can maintain consistent and reliable performance in chromatographic separation in the fine chemical and pharmaceutical industries.

The sturdy and insoluble structure of DOWEX fine-grained resin is based on a microporous copolymer of styrene and divinylbenzene (DVB), which has strong antioxidant, reducing, mechanical wear and crushing abilities. In addition, this structure does not dissolve in common solvents.

DOWEX fine-grained resin is produced through direct synthesis manufacturing process. This ensures that the resin beads are intact and spherical, which is cleaner, more reliable, and more stable in performance compared to grinding resin. Grinding resin is composed of irregularly shaped particles and contains' fine powder 'or extremely fine particles. Fine powder is a common cause of processing difficulties: dust is generated when processing dry resin; When used as a chromatographic medium or filtering aid, it can clog the sintered plate or filter cartridge; In batch processing applications, the settling time will be prolonged; And it will exacerbate the loss of resin due to physical wear and tear.

Strict particle size and permeability control is achieved by controlling the suspension polymerization process, resulting in strict control of the particle size of DOWEX fine-grained resin. Meanwhile, the percentage of divinylbenzene (DVB) used in the process is also controlled to determine the crosslinking degree (or permeability) of the resin. These factors ensure that we have a range of products with specific and reliable performance characteristics to choose from.

Naming Rules for Dow Resin

Used to identify DOWEX ™ The naming convention for fine-grained resins aims to convey specific information about resin types and crosslinking degrees. There are three types of resins: strong acid cation exchange resin, code '50W'; type I strong base anion exchange resin, code '1'; Type II strong base anion exchange resin, code named '2'. According to Dow's naming convention, one of these three codes will be used in conjunction with an 'X' number describing the degree of crosslinking of the resin (the X number represents the percentage of divinylbenzene [DVB] in the resin copolymer). Therefore:

DOWEX 50WX8 is a strong acid cationic resin containing 8% DVB.

DOWEX 1X4 is a type I strong base anion resin containing 4% DVB.

How to evaluate and select DOWEX fine-grained resin

Table 1 contains basic information about the entire series of DOWEX fine-grained resins. Please use this form to select the most suitable resin candidate product for your application.

Table 1 DOWEX ™ Full range of fine-grained resin options ¹, ²

Resin modelMesh sizeIonic formWater holding capacity (%)Total exchange capacity (meq/mL)Bulk densityCapacity per barrel (lbs/5 ft ³)

Cationic resin

DOWEX 50WX250 - 100H⁺74 - 820.646230

DOWEX 50WX2100 - 200H⁺74 - 820.646230

DOWEX 50WX2200 - 400H⁺74 - 820.646230

DOWEX 50WX450 - 100H⁺64 - 721.148240

DOWEX 50WX4100 - 200H⁺64 - 721.148240

DOWEX 50WX4200 - 400H⁺64 - 721.148240

DOWEX 50WX850 - 100H⁺50 - 561.750250

DOWEX 50WX8100 - 200H⁺50 - 581.750250

DOWEX 50WX8200 - 400H⁺50 - 581.750250

Anionic resin

DOWEX 1X250 - 100Cl⁻65 - 750.744220

DOWEX 1X2100 - 200Cl⁻70 - 800.644220

DOWEX 1X2200 - 400Cl⁻70 - 800.644220

DOWEX 1X450 - 100Cl⁻50 min.1.044220

DOWEX 1X4100 - 200Cl⁻55 - 631.044220

DOWEX 1X4200 - 400Cl⁻55 - 631.044220

DOWEX 1X850 - 100Cl⁻43 - 481.244220

DOWEX 1X8100 - 200Cl⁻39 - 451.244220

DOWEX 1X8200 - 400Cl⁻39 - 451.244220

Although the chemical and physical properties of ion exchange resins are defined by specific measurement values, the actual performance of the resin also depends on the interrelationship between its characteristics and the application conditions under which it operates.

Here is a brief discussion of the three basic factors you may consider when selecting resin:

The influence of application conditions on resin working capacity

Resins with higher ion exchange capacity may not necessarily provide large working capacity in specific applications. In fact, for a specific solution, the crosslinking degree of the resin may play a more important role in determining solute absorption than ion exchange capacity.

The effective porosity of resin is affected by solvent conditions, including ionic strength, pH value, and organic modifiers. Providing a range of DOWEX resins with different degrees of crosslinking can help evaluate the molecular size in solution and determine good resins for specific applications.

Balance solute absorption requirements and pressure drop

Solute absorption is influenced by particle size and usually increases as the particle size decreases. The absorption of L-tryptophan acid by DOWEX 1X4 resin with different particle sizes in batch adsorption tests. Standard 20-50 mesh resins exhibit slower absorption isotherms than finer particle size resins.

However, in some applications, selecting resin based solely on small particle size may lead to operational difficulties. Figure 3 shows that as the resin particle size inside the column decreases, the frictional loss (i.e. pressure drop) of the liquid flowing through the column increases. Although the use of smaller particle size resins can improve the kinetic characteristics of specific processes, the increase in pressure drop must be taken into account when selecting equipment, determining operating parameters, and evaluating the potential for scaling up production.

When evaluating the solute absorption capacity and pressure drop of resins in a specific system, certain experimental steps can be helpful. To measure solute absorption, batch experiments can be used: over time, measure the absorption of solutes in a known concentration solution by a specific volume of resin. This type of batch experiment is very useful for determining the influence of particle size and identifying the effects of various factors, including pH, temperature, ionic strength, and competitive solutes, which can affect the chemical interactions of active ion exchange sites, overall process kinetics, and the rate of ion exchange.

When comparing pressure drop, it is necessary to study the effluent with the same viscosity as the process fluid. Whenever possible, try to use actual process fluids for experiments to ensure that the pressure drop observed during the comparison process can reflect the situations that may be encountered in actual operations.

Factors affecting resin stability

The operational stability of ion exchange resin largely depends on the specific process. Therefore, conducting stability testing under actual process conditions is an important part of resin evaluation and selection process.

Ion exchange resins are resistant to a wide range of chemical conditions and can be washed across the entire pH range without any adverse effects. In addition, ion exchange resins are resistant to most inorganic and organic solutions, except for strong oxidants.

Avoid using nitric acid or chromic acid solutions, bleach or chlorine containing solutions, and peroxides. Exposure to strong oxidants such as nitric acid can cause rapid oxidation of the resin. Under specific conditions, this may trigger potential explosive reactions.

The slow degradation caused by oxygen may be influenced by catalysis. Therefore, in an oxidizing environment, the contact between resin and metal ions (including iron, manganese, and copper) should be minimized as much as possible.

The physical stability of resin is also affected by the product processing method. Thick resin beds, small diameter beds, high flow rates, and frequent pumping or stirring can all lead to resin breakage and loss.

By understanding the physical conditions imposed by the system and process, it is possible to minimize crushing losses caused by mechanical factors. For example, if the chemical environment is changed to adjust the solvent retention capacity, the resin may undergo rapid shrinkage expansion. If the resulting permeation impact weakens the chemical structure of the resin beads, it may lead to breakage and loss. In most cases, damage caused by shrinkage expansion is a combination of osmotic shock and mechanical effects on the chromatographic column, as described in the 'Laboratory Column Loading Tips' section on pages 7 and 8 of this briefing.

To evaluate the stability of resin in a specific process, create a system model using actual process samples. Subjecting the small columns of each candidate resin to multiple loading, recovery, and regeneration cycles using the actual product liquid and subsequent chemical conditions. Using microscopy to measure the stability performance of resin under simulated conditions.

Column installation prompt

Laboratory scale chromatography columns can be used to obtain valuable process development and resin feasibility information.

Although laboratory chromatography column experiments can provide valuable comparative data for resin selection and determination of process operating parameters, their results cannot be directly amplified without considering system design factors. In addition, laboratory column research should not replace the development and operation of pilot systems before amplification. The following are the basic guidelines for loading laboratory chromatography columns:

Fine grained resin can be used for ordinary glass columns, but it is better to use columns that can withstand pressures of about 3 kg/cm ² or higher.

Warning: Under certain conditions, the expansion of some resins may generate sufficient force to cause the glass column to break. It is recommended to use chromatography columns equipped with overload protection safety tubes or glass columns with plastic protective covers during laboratory evaluations. The inner diameter of the chromatography column should not be less than 1.5 centimeters. Smaller columns may generate wall effects, which can interfere with chromatographic separation and affect the penetration point of the resin.

Before installing the column, it is necessary to clean the resin with a flow that can cause significant swelling, in order to hydrate and activate the resin. Subsequently, use the slurry method to install the column, paying attention to eliminating bubbles. Do not let the pillar dry up. Settle the column bed through the mobile phase at a rate slightly higher than the normal operating flow rate (for example, if the operating flow rate is 2.0 mL/min, settle the column bed at a flow rate of 2.5 mL/min).

After filling the column, the system needs to be cycled between the elution phase and the regeneration phase to determine if significant shrinkage expansion phenomena occur. Before conducting actual sample evaluation, resin should be replenished or column bed volume adjusted at this time. A laboratory chromatography column equipped with an adjustable plunger can simplify this fine-tuning process.

To determine the optimal loading and elution rate, the first step is to load a sample of approximately 10% of the column volume (for concentrated samples), or a sample volume equivalent to approximately 75% of the theoretical exchangeable capacity of the dilute solution. The above sample flow rate of 0.5 times the bed volume per hour is more suitable as the starting point. The specific fine-tuning requirements will depend on the concentration of components in the feed, the required product purity, and the ease of separation.

Application:

Cation exchange separation of silver and other elements on Dowex 50w-X8 using mixed solvents

Adsorption of Strontium in Sulfuric Acid Solution by Dowex 50W-X Resin

Preliminary Study on Separation Conditions of Ytterbium Lutetium by Dowex 50W × 8 Cation Exchange Resin

DOWEX ion exchange resin