EDTA itself is a weak acid and can slightly decrease the pH of water when added in small amounts. However, the pH change caused by EDTA is typically minimal and may not be significant in most practical applications. The pH sensitivity of EDTA depends on factors such as the concentration of EDTA, the initial pH of the water, and the presence of other substances in the water that can buffer pH changes. It's important to note that the primary function of EDTA in heavy metal removal is to form stable complexes with the metal ions, rather than to significantly alter the pH of the water.

Heavy metals in water with a low pH become more soluble and bioavailable. But not dangerous the first priority the removal of metal. After treatment to maintain the pH you can add sodium hydroxide. Ethylene diamine tetraacetic acid (EDTA) is an excellent chelating agent and weak acid.

Thank you so much my dear Professor.