Effect of reaction solvent on hydroxyapatite synthesis in sol-gel process

Synthesis of hydroxyapatite (HA) through sol–gel process in different solvent systems is reported. Calcium nitrate tetrahydrate (CNTH) and diammonium hydrogen phosphate (DAHP) were used as calcium and phosphorus precursors, respectively. Three different synthesis reactions were carried out by changing the solvent media, while keeping all other process parameters constant. A measure of 0.5 M aqueous DAHP solution was used in all reactions while CNTH was dissolved in distilled water, tetrahydrofuran (THF) and N,N-dimethylformamide (DMF) at a concentration of 0.5 M. Ammonia solution (28–30%) was used to maintain the pH of the reaction mixtures in the 10–12 range. All reactions were carried out at 40 ± 2°C for 4 h. Upon completion of the reactions, products were filtered, washed and calcined at 500°C for 2 h. It was clearly demonstrated through various techniques that the dielectric constant and polarity of the solvent mixture strongly influence the chemical structure and morphological prop...

本文报道了在不同溶剂体系中通过溶胶-凝胶法合成羟基磷灰石（hydroxyapatite, HA）的过程。分别以四水硝酸钙（calcium nitrate tetrahydrate, CNTH）和磷酸氢二铵（diammonium hydrogen phosphate, DAHP）作为钙源和磷源前驱体。在保持所有其他工艺参数不变的情况下，通过改变溶剂介质进行了三组不同的合成反应。所有反应均使用0.5 M DAHP水溶液，而CNTH则分别以0.5 M的浓度溶解于蒸馏水、四氢呋喃（tetrahydrofuran, THF）和N,N-二甲基甲酰胺（N,N-dimethylformamide, DMF）中。使用浓度为28–30%的氨水溶液将反应混合物的pH值维持在10–12范围内。所有反应均在40±2°C下进行4小时。反应完成后，产物经过滤、洗涤，并在500°C下煅烧2小时。通过多种技术手段明确证实，溶剂混合物的介电常数和极性对产物的化学结构及形貌特性具有显著影响……