Detection Method of Polyaluminum Chloride Content

As an important coagulant in the field of Water Treatment, the detection of polyaluminum chloride (PAC) quality should be carried out around the core indicators, including alumina content, salinity, pH value and water insoluble content, etc. The following are the specific testing methods and procedures:

1. Detection of alumina content

Aluminum oxide content is the key index to measure the active component of PAC. The detection method is mainly by the complexation titration method. The specific steps are as follows:

Reagent preparation: ethylenediaminetetraacetate disodium (EDTA), zinc chloride standard solution, potassium fluoride solution, cresol orange indicator, etc.

Sample processing: weigh appropriate PAC samples, dissolve in water, and add excess EDTA solution complexed aluminum ions.

Titration analysis: The remaining EDTA was titrated with a standard solution of zinc chloride, then potassium fluoride was added to resolve the complex aluminum ions and titrated again to the end point.

Calculation: alumina content is calculated according to the volume of zinc chloride, sample mass and formula.

Note: Control reaction pH (sodium acetate buffer to 3.0~3.5) and synchronize blank test to eliminate error.

2. Salt inity detection

Salt inity reflects the degree of hydroxylation in PAC molecules and directly affects their flocculation performance. acid-base titration or potential titration is commonly used.

acid-base titration:

The PAC sample was reacted with hydrochloric acid to release the hydrogen ions in the hydroxyl group.

The sodium hydroxide standard solution was titrated to neutral, and the salinity base was calculated based on the volume consumed.

potentiometric titration:

Changes in pH were monitored using an automated potentiometric titrator and endpoints were determined using a titration curve.

Note: The purity and reaction temperature of the reagent should be strictly controlled to avoid interference factors affecting the results.

3. PH value detection

The pH value affects the stability and coagulation efficiency of the PAC solution. The detection methods include:

PH Method: immerse the electrode into PAC solution and record the results after value stabilization (the accuracy shall be calibrated to ± 0.01).

PH Test paper method: suitable for rapid detection, but the accuracy is low (suitable for preliminary judgment).

4. Other test items

Water-insoluble material content:

After dissolving the PAC samples, filter it, dry the filter residue and weigh it to calculate the proportion of insoluble material.

Detection of heavy metals and impurities:

Heavy metals such as arsenic and lead were determined by atomic absorption spectroscopy (AAS) or atomic fluorescence spectroscopy (AFS).

5. Testing instrument and quality control

Core instruments:

Titters (acid / base): for precise control of titration volume.

Analytical balance (precision 0.0001g): Ensure weighing accuracy.

Oven: for drying filter slag or samples.

quality control:

All tests shall follow the standard operating procedures and calibrate the instrument regularly.

Duplicate tests were averaged to ensure data reliability.

sum up

The detection of polyaluminum chloride requires comprehensive chemical analysis (such as titration method) and instrument analysis (such as spectroscopy method), and selects the adaptation method for different indexes. During the detection process, the experimental conditions should be strictly controlled to ensure the accuracy and reproducibility of the results.