Chromium (VI) and zinc (II) waste water co-treatment by forming layered double hydroxides: Mechanism discussion via two different processes and application in real plating water

► Chromium (VI) and zinc (II) plating water co-treatment by forming layered double hydroxides was investigated. ► Adsorption after synthesis (AAS) and adsorption during synthesis (ADS) were designed in order to get a reasonable and applicable method. ► ADS has a higher adsorption amount and faster adsorption speed than AAS. ► A raw material containing cement and Ca(OH)2 was feasible and effective in co-treating chromium (VI) and zinc (II) plating water via ADS.