Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D5042-90 – Standard Test Method Technical Guide
📋 Scope and Terminology
ASTM D5042‑90 (Reapproved 2009) provides a standard method for estimating organic fouling on particulate anion exchange resins using total organic carbon (TOC) measurements. Organic fouling is defined as “the buildup of organic material in or on anion exchange resins by sorption during the service cycle and incomplete removal during regeneration.” All values in the standard are stated in SI units.
⚙️ Test Procedure and Key Parameters
A sample of the resin is contacted with a sodium chloride/sodium hydroxide solution at an elevated temperature. After a specified contact time, the aqueous phase is analyzed for TOC to determine the concentration of organic material released. The high NaCl concentration of the test solution may interfere with the response of the TOC analyzer; calibration with standards prepared in the same matrix is required.
| 🟦 Parameter | 📏 Specification | 🎯 Notes |
|---|---|---|
| Solution Composition | Sodium chloride/sodium hydroxide | High ionic strength matrix |
| Temperature | Elevated temperature | As detailed in the standard |
| Contact Time | Specified duration | Per the test method |
| Measurement | Total Organic Carbon (TOC) | Refer to D2579 or D4839 |
| Unit System | SI units | Standard for all values |
📊 Significance and Interferences
Organic fouling is a major factor in the unsatisfactory performance of anion exchange resins. This test provides a general estimate of fouling and can indicate the need for influent pretreatment, remedial cleaning, or resin replacement. Because the chemical structures of fouling organics are generally unknown and are expressed only as carbon content, interpretation of results for predictions of performance or cleaning effectiveness requires caution. The method may not remove or detect cation sloughage products or declumping agents.
⚠️ High sodium chloride concentration in the test solution may interfere with TOC analyzer response. Always calibrate with standards prepared in the NaCl/NaOH matrix.
💡 Samples may be taken before or after plant regeneration, or both, depending on the type of information desired. This decision is left to the user’s judgment.
❓ Frequently Asked Questions
🔍 What is the principle behind D5042‑90? The test extracts organic foulants from the resin using a hot NaCl/NaOH solution and measures the released organic carbon as TOC to estimate fouling.
💡 How should sampling be performed? Follow Practices D2687 for sampling particulate ion‑exchange materials. Sampling timing (pre‑ or post‑regeneration) depends on the information needed.
⚡ What are the main interferences? The high salt content can affect TOC analyzers, and some organic compounds (e.g., cation sloughage products) may not be detected by this method.
📌 Why is this test method important? It helps assess the degree of organic fouling, guiding decisions on resin maintenance, cleaning, or replacement to restore performance.