The specific surface area of calcium hydroxide is of critical importance.
High-specific-surface-area calcium hydroxide is now internationally recognized as a high-quality dry desulfurization agent and a versatile, widely used product. With a specific surface area exceeding 40 m²·g⁻¹, it features a unique porous structure, exceptional reactivity, excellent dispersibility, and a high utilization rate.
Whether produced via dry or wet digestion processes, the preparation of high-specific-surface-area calcium hydroxide typically requires the introduction of auxiliary modifiers. These agents serve to lower the surface energy of the calcium hydroxide crystals, prevent agglomeration, and alter the crystal morphology and particle size—thereby increasing the specific surface area of the final product.
Currently, by incorporating crystal-habit modifiers or adjusting process parameters, it is possible to synthesize calcium hydroxide crystals with diverse morphologies—such as layered, plate-like, cubic, spherical, or dumbbell-shaped structures—thereby imparting a wide range of functional properties to the material.
In environmental remediation, calcium hydroxide serves as a pH adjuster to neutralize acidic wastewater (such as that from electroplating or textile dyeing and printing) and is used in flue-gas desulfurization (where it absorbs SO₂ to form calcium sulfite, CaSO₃). It also functions as a solidifying agent for heavy metals and a treatment agent for acidic gases, effectively removing pollutants and mitigating environmental risks.
In agriculture, calcium hydroxide is used to amend acidic soil (pH < 5.5), facilitating the release of essential nutrients like phosphorus and potassium. It also accelerates the decomposition of organic matter in compost and helps inactivate pathogens.
In industrial manufacturing, calcium hydroxide acts as a flux in glass production and an accelerator for rubber vulcanization. It is also a key raw material for producing bleaching powder, light calcium carbonate, and calcium phosphate.
Furthermore, due to its strong alkalinity, calcium hydroxide is used in dentistry as a root canal paste to eliminate bacteria within infected root canals. In the field of cultural heritage conservation, it reacts with CO₂ to form calcium carbonate, which enhances the consolidation and stability of historical artifacts.
In recent years, research on Ca(OH)₂ has focused on optimizing its properties and expanding its range of applications:
Through nanotechnology, Ca(OH)₂ can be synthesized as nanoparticles (with a particle size of <100 nm), significantly enhancing its performance in high-value-added sectors such as catalysis and the development of composite materials.
In environmental applications, it is utilized to neutralize acidic wastewater (e.g., from electroplating or textile dyeing and printing), precipitate heavy metal ions, and facilitate flue-gas desulfurization—absorbing SO₂ to produce calcium sulfite (CaSO₃) and thereby reducing air pollution.
In recent years, extensive research has been conducted on the controllable construction of the microstructure of Ca(OH)₂. Among these efforts, a strategy centered on the synergistic optimization of surfactant-mediated regulation and the CaO hydration (digestion) process has garnered significant attention.
Surfactants can effectively regulate grain size, morphology, and pore structure by modulating the interfacial tension of the reaction, as well as altering the nucleation and growth rates—along with the anisotropic growth behavior—of Ca(OH)₂ crystals.
Among the various regulating agents, polyol-type surfactants—characterized by a molecular structure rich in hydroxyl functional groups—can actively participate in the nucleation and crystal growth of Ca(OH)₂ through coordination with Ca²⁺ ions and the formation of hydrogen bonds. Given their excellent water solubility and chemical stability, they are considered promising candidates for the synthesis of Ca(OH)₂ with a high specific surface area.