The aluminum hydroxide precipitation process from sodium aluminate solution was studied by adding the new synthesized active seeds and industrial seed separately. The results show that the precipitation rate reached 47, 81, and 68% at 60 h by adding industrial seed, seed A, and seed B (active seeds), respectively. Specific surface area, composition, morphology, and particle size distribution of seeds/precipitated products from supersaturated sodium aluminate solutions were investigated by Brunauer, Emmett, and Teller (BET) analysis, X-ray crystallography (XRD) analysis, Scanning electron microscope (SEM) images, and Power-spectral-density (PSD) analysis. Also, to study and understand the functional groups on the surface of seed/precipitated products and precipitation mechanisms, Fourier-transform infrared spectroscopy (FTIR) analysis was recorded. The result showed that the precipitation rate of the active seeds is higher than that of the industrial seed owing to the higher surface area, more active sites, crystal defects, and finer particle size that cause rise to nucleation for gibbsite. Also, improved precipitation of aluminum hydroxide from sodium aluminate solution may be due to the predominant phase crystallized of bayerite in the composition of active seeds. The FTIR analysis shows that the decline of the precipitation process in the presence of industrial seed may be due to oxalate–Al bonds and the impurity of carbonate.

Graphical Abstract

中文翻译：

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新合成的活性种子和工业种子对铝酸钠溶液中氢氧化铝沉淀的影响

通过分别添加新合成的活性种子和工业种子，研究了铝酸钠溶液中氢氧化铝的沉淀过程。结果表明，通过添加工业种子，种子A和种子B（活性种子），在60 h时的降水率分别达到47％，81％和68％。通过Brunauer，Emmett和Teller（BET）分析，X射线晶体学（XRD）分析，扫描电子显微镜（SEM）研究了过饱和铝酸钠溶液中的种子/沉淀产物的比表面积，组成，形态和粒径分布）图像，以及功率谱密度（PSD）分析。另外，为了研究和理解种子/沉淀产物表面的官能团和沉淀机理，记录了傅里叶变换红外光谱（FTIR）分析。结果表明，由于较高的表面积，更多的活性位点，晶体缺陷和更细的粒度导致了菱镁矿的形核，活性种子的沉淀速率高于工业种子的沉淀速率。同样，氢氧化铝从铝酸钠溶液中沉淀的改善可能归因于活性晶种组合物中钠铝石的主要相结晶。FTIR分析表明，存在工业种子的情况下沉淀过程的下降可能是由于草酸盐-Al键和碳酸盐杂质引起的。氢氧化铝从铝酸钠溶液中沉淀的改善可能是由于活性晶种成分中钠铝石的主要相结晶。FTIR分析表明，存在工业种子的情况下沉淀过程的下降可能是由于草酸盐-Al键和碳酸盐杂质引起的。氢氧化铝从铝酸钠溶液中沉淀的改善可能是由于活性晶种成分中钠铝石的主要相结晶。FTIR分析表明，存在工业种子的情况下沉淀过程的下降可能是由于草酸盐-Al键和碳酸盐杂质引起的。

图形概要