Conversions of Cement bypass waste to Nano-hydroxyapatite exploited in water purification

Abstract

Abstract The goal of this study is to convert cement bypass dust into a usable product called hydroxyapatite. Four hydroxyapatites’ samples (Kiln-HA1- Kiln-HA4) were successfully prepared in nano-scale (14.8–25.7 nm). The specific surface areas of all of the samples examined were high: Kiln-HA3 (161.5 m2/g) > Kiln-HA1 (130.2 m2/g) > Kiln-HA2 (81.9 m2/g) > Kiln-HA4 (54.1 m2/g).Tested nano- hydroxyapatite successfully removed Fe3+ and Mn2+ as pollutants from water with efficiencies of up to 95% for both Fe and Mn ions. The maximum adsorption capacities (qmax) of nano hydroxyapatite varied from 147 to 175 mg.g− 1 for adsorbed Fe (III), while were wide ranged from 204 to 344 mg.g− 1 for adsorbed Mn (II).Hydroxyapatite-selectivity for removing Mn and Fe ions in mixed solutions was as follows: Fe3+> Cu2+>Mn2+. In multiple cycles, the investigated materials were able to remove Fe and Mn ions without regeneration. The overall cost of producing 100 grams of hydroxyapatite from cement bypass waste is less than other calcium source which was 184 EGP/100g (9.32 €/100g).