Extremely Fast and Efficient Removal of Congo Red Using Cationic-Incorporated Hydroxyapatite Nanoparticles (HAp: X (X = Fe, Ni, Zn, Co, and Ag))

Congo red (CR) is a stable anionic diazo dye that causes allergic reactions with carcinogenic properties. The rapid removal of CR using cation-incorporated nanohydroxyapatite (pristine HAp: X (X = Fe, Ni, Zn, Co, and Ag)) was investigated. pristine cation ion-doped HAp adsorbents were coprecipitated subjected to hydrothermal ultrasound treatments subsequent microwave drying. dopant ions significantly engineered the crystallite size, crystallinity, particle size (decreased 38–77%), shape (a rod sphere modification by incorporation Ag+, Ni2+, Co2+ ions), colloidal stability (CS) adsorbent. These modifications aided in (98%) within one minute, adsorption rate found be higher (93–99%) compared previously reported rates. Furthermore, kinetic, Langmuir, Freundlich, DKR isotherms thermodynamic results confirmed on due strong chemical process. order maximum capacity Fe-HAp > Ag-HAp Co-HAp Zn-HAp. Whereas regeneration efficiency (92%) (42%) Ni-HAp (30%), other exhibiting poor recycling (1–16%). reveal as potential adsorbent for removing without formation byproducts.