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<p>This study focuses on the environmental applications of turning cement waste into nano-hydroxyapatite. Four interesting nano-hydroxyapatite (HAP1–HAP4) specimens were extensively characterized and designed. The surface texture analysis of all samples demonstrated high specific surface areas ranging from 161.5 to 54.1&#xa0;m<sup>2</sup>/g. Cement waste manufactured synthetic HAP with yields of up to 80%. The produced compounds were then tested for their ability to extract Fe(III) and Mn(II) ions from water. A remarkable 95% clearance efficiency has been achieved with a 0.3&#xa0;g/L dose of HAP, resulting in rapid clearance in 15&#xa0;min. Iron and manganese cations may readily replace the Ca<sup>2+</sup> sites in the hydroxyapatite structure, which has been demonstrated to act as a source of adsorption centers. Maximum adsorption capacities (q<sub>max</sub>) for Fe (III) vary from 147 to 175&#xa0;mg&#xa0;g<sup>−1</sup> for HAP1–HAP4, whereas those for Mn (II) ranged from 204 to 344&#xa0;mg&#xa0;g<sup>−1</sup>. The pseudo-second-order model better fits the absorption patterns of Mn(II) and Fe(III) than the pseudo-first-order model. Hydroxyapatite samples showed positive ∆S° values and negative ∆G° values at all working temperatures, indicating that the adsorption process is viable and spontaneous. Additionally, when ∆H° is positive, the purification process is endothermic and involves complex interactions between the adsorbent and adsorbate (e.g., adsorption &amp; ion exchange). The outcomes show that hydroxyapatite materials can extract Fe and Mn ions from real groundwater wells. HAP samples cost about 14.32 SAR/100&#xa0;g (185&#xa0;EGP/100&#xa0;g or 3.27&#xa0;€/100&#xa0;g).</p>

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Economic and viable utilization of cement waste dust for water remediation

  • 期刊论文

  • 发表日期：

    2026年2月17日

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  • S. El-Nahas,
  • M. M. Abou-Krisha,
  • R. R. Ahmed,
  • A. E. Mohamed,
  • M. S. A. El-sadek,
  • E. A. Abdelrahman,
  • H. M. Alsoghier

摘要

This study focuses on the environmental applications of turning cement waste into nano-hydroxyapatite. Four interesting nano-hydroxyapatite (HAP1–HAP4) specimens were extensively characterized and designed. The surface texture analysis of all samples demonstrated high specific surface areas ranging from 161.5 to 54.1 m2/g. Cement waste manufactured synthetic HAP with yields of up to 80%. The produced compounds were then tested for their ability to extract Fe(III) and Mn(II) ions from water. A remarkable 95% clearance efficiency has been achieved with a 0.3 g/L dose of HAP, resulting in rapid clearance in 15 min. Iron and manganese cations may readily replace the Ca2+ sites in the hydroxyapatite structure, which has been demonstrated to act as a source of adsorption centers. Maximum adsorption capacities (qmax) for Fe (III) vary from 147 to 175 mg g−1 for HAP1–HAP4, whereas those for Mn (II) ranged from 204 to 344 mg g−1. The pseudo-second-order model better fits the absorption patterns of Mn(II) and Fe(III) than the pseudo-first-order model. Hydroxyapatite samples showed positive ∆S° values and negative ∆G° values at all working temperatures, indicating that the adsorption process is viable and spontaneous. Additionally, when ∆H° is positive, the purification process is endothermic and involves complex interactions between the adsorbent and adsorbate (e.g., adsorption & ion exchange). The outcomes show that hydroxyapatite materials can extract Fe and Mn ions from real groundwater wells. HAP samples cost about 14.32 SAR/100 g (185 EGP/100 g or 3.27 €/100 g).