Dear Alejandro Bartolomé Ortega,

Solubility of Brij 52 (POLYOXYETHYLENE 20 CETYL ETHER ) in water and ethanol:

Sigma tests this product for solubility in water. At 50 mg/mL a colorless solution that is clear to slightly hazy is obtained. Solutions at 1% and 2% in water have remained clear at 2-8°C overnight, but the addition of salts, even small amounts, may cause precipitation of the detergent from solution. It is reported soluble in alcohol, dispersible in cottonseed oil and insoluble in mineral oil or propylene glycol.

https://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma/Product_Information_Sheet/1/p5884pis.pdf

Hoping this will be helpful,

Rafik

Yes, Rafik is right...