Study on the Corrosion Inhibition Performance of EDTMPS: Chelating Capacity and Application in Pulp Bleaching

 EDTMPS (sodium ethylenediaminetetra(methylenephosphonic acid)) is a highly effective organic phosphonic acid salt with strong chelating and dispersing properties. It is widely used in water treatment, textiles, papermaking, and other industries, demonstrating exceptional performance in preventing metal corrosion and removing heavy metal ions. The following section examines EDTMPS's chelating capacity toward various metal ions and its efficacy as a chelating agent in pulp bleaching processes. 1. Overview of EDTMPS

Chemical Name: Sodium Ethylenediaminetetra(methylenephosphonic) Acid

Molecular Formula: C₆H₁₂N₂O₁₂P₄Na₈

Molecular Weight: Approximately 735.99

Structural Formula: Contains multiple phosphonic acid groups capable of forming stable complexes with various metal ions.

Properties:

Highly soluble in water; insoluble in most organic solvents.

Stable across a wide pH range.

Excellent thermal stability and resistance to chlorine oxidation.

2. Chelating Capacity of EDTMPS for Different Metal Ions

EDTMPS forms stable complexes with various metal ions, including calcium, magnesium, iron, copper, and zinc. Its chelating capacity primarily depends on the following factors:

pH: EDTMPS exhibits strong chelating ability under neutral and alkaline conditions.

Temperature: Within a certain temperature range, EDTMPS's chelating capacity increases with rising temperature.

Concentration: Increasing EDTMPS concentration enhances its chelation efficiency.

Metal Ion Type: The stability of complexes formed between different metal ions and EDTMPS varies. For example, EDTMPS exhibits strong chelating ability toward calcium and magnesium ions, while also demonstrating excellent chelation effects on transition metal ions such as iron and copper.

3. Application of EDTMPS in Pulp Bleaching

In pulp bleaching, EDTMPS primarily functions as a chelating agent to remove or control metal ions in pulp, particularly transition metals like iron and manganese. These ions catalyze the decomposition of bleaching agents (e.g., hydrogen peroxide), reducing bleaching efficiency and potentially causing paper yellowing.

Application Effects

Enhanced Bleaching Efficiency: EDTMPS improves bleaching efficiency by chelating metal ions, thereby reducing bleaching agent decomposition.

Improved Paper Quality: Removing metal ions reduces paper yellowing, enhancing whiteness and brightness.

Extended Equipment Lifespan: EDTMPS also prevents metal ion corrosion of equipment, prolonging its service life.

Environmental Performance: EDTMPS exhibits good biodegradability and is environmentally friendly.

Usage Method

Addition Timing: Typically add EDTMPS during the early bleaching stage to fully chelate metal ions in the pulp.

Dosage: Determine EDTMPS dosage based on metal ion content in the pulp and desired chelation effect. The generally recommended dosage is 0.1%–1.0% (based on dry pulp weight).

pH Adjustment: Maintaining an appropriate pH level facilitates optimal chelation performance of EDTMPS. A pH range of 7.0–9.0 is generally recommended.

4. Experimental Studies

To further validate EDTMPS's performance in pulp bleaching, the following experimental studies can be conducted:

Chelation Capacity Testing: Evaluate EDTMPS's chelation ability by measuring its chelation rate for metal ions under different conditions.

Bleaching Efficiency Testing: Assess EDTMPS's impact on bleaching efficiency by comparing pulp brightness, whiteness, and bleaching agent consumption before and after EDTMPS addition.

Metal Ion Residue Testing: Determine residual metal ions in bleached pulp using ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometer) or other analytical methods to evaluate EDTMPS's removal efficacy.

5. Conclusion

As a highly efficient organic phosphonate chelating agent, EDTMPS demonstrates outstanding chelating capacity and application performance in pulp bleaching processes. It effectively removes metal ions from pulp, enhances bleaching efficiency, improves paper quality, and extends equipment lifespan. By strategically selecting the addition timing and dosage, the advantages of EDTMPS can be fully leveraged in actual production. We hope the above information proves helpful! For more detailed technical support or specific experimental data, we recommend contacting professional chemical suppliers or relevant research institutions.