钙硅摩尔比对硅钙石及磷结晶产品的影响

Effect of Ca/Si Molar Ratios on Structure of Calcium Silicate Hydrates Mineral and Product of Phosphorus Crystallization

以电石渣和白炭黑为原料合成硅钙石,并以硅钙石为晶种结晶,考察了不同钙硅摩尔比对硅钙石及磷结晶产品结构的影响;研究发现钙硅比的差异对硅钙石及磷结晶产品的影响较大,钙硅比为1.75∶1时合成羟基硅钙石与磷酸盐反应后的磷结晶产品主要为晶型异常的羟基磷灰石晶体,而其他几种钙硅比下的磷结晶产品主要为不同形式的磷酸钙,不同的钙硅比导致了硅钙石结晶程度的差异,影响了其反应活性,进而影响硅钙石释放Ca2+和OH-的能力,因此得到不同结构的磷酸钙及羟基磷灰石;钙硅比为1.75∶1的条件下合成的羟基硅钙石最有利于以结晶为羟基磷灰石的形式从废水中回收磷。

Calcium silicate hydrate mineral was synthesized by carbide slag and silica white and was crystallized by taking calcium silicate hydrate mineral as crystal, and the effect of different Ca/Si molar ratios on calcium silicate hydrate mineral and the structure of phosphorus crystallization product was examined. Research showed that the difference of Ca/Si molar ratios phosphorus crystallization products,that with Ca/Si had big influence on calcium silicate hydrate mineral and molar ratio of 1.75 ： 1, main phosphorus crystallization products were hydroxyapatite crystals with abnormal crystal form after synthesized hydroxyapatite reacted with phosphate, however,phosphorus crystallization products under other types of Ca/Si molar ratios were calcium phosphate with different forms, that different Ca/Si molar ratios led to the differences in crystallization level of calcium silicate hydrate mineral, whose reactive activity was affected and its Ca^2＋ and OH^- releasing capacity was further affected, as a result, calcium phosphate and hydroxyapatite with different structures were obtained. Under the condition of Ca/Si molar ratio of 1.75 ： 1, the synthesized hydroxy-calcium silicate hydrate mineral is mostly conducive to crystallization in the form of hydroxyapatite for phosphate recovery from wastewater