Comparative study on the hydration behavior of calcium oxide derived from eggshell waste: Influence of procedure and hydration agent

In this study, calcium oxide was synthesized from waste eggshells and subsequently converted to calcium hydroxide via two distinct methods: hydrothermal (H) and bubble (B) techniques. The influence of synthesis parameters including hydration method, type of hydration agent (pure water or ethanol‐water mixture), temperature range (150 °C‐230 °C), and solid‐to‐liquid ratio on the physicochemical properties of the resulting calcium hydroxide was systematically investigated. Comprehensive characterization was conducted to evaluate structural, morphological, and surface characteristics. The bubble method yielded smaller crystallites, while lower hydrothermal temperatures were found to favor porosity and enhanced surface area. According to X‐ray Diffraction patterns, the sample labeled 230H04 (10 mL) exhibited the largest crystallite size (59.50 nm), whereas 230B31 demonstrated the highest surface area (31.14 m ² /g) and 150H31 the greatest pore volume (0.19 cm ³ /g). These findings highlight the critical role of synthesis route selection in tailoring the physicochemical properties of calcium hydroxide to meet specific application requirements.