摘要
为了研究七钼酸铵结晶过程的工艺条件和热力学参数,以四钼酸铵为实验原料,采用氨溶冷却结晶的方法生产七钼酸铵,通过响应面分析法优化了各单因素条件对七钼酸铵结晶收率的影响规律,最后求取了结晶过程的热力学参数。结果表明:结晶的最佳工艺条件为料液比为0.25g/m L,搅拌速度158.33r/min,冷却终温7.90℃,考虑实际情况微调此条件进行了3组重复性验证实验,得到七钼酸铵结晶收率为77%左右,质量均达到化学纯,满足国标要求,颗粒大小基本均匀。此外,热力学参数ΔH,ΔG,ΔS三者均小于零,表明七钼酸铵冷却结晶是非自发溶液混乱度减小的放热过程。
The technological conditions and thermodynamic parameters of crystallization process of ammonium heptamolybdate were studied. A method of ammonia-dissolving and cooling crystallization was used for producing ammonium heptamolybdate with ammoinum tetramolybdate as experimental material. Response Surface Methodology was used to optimize the effect of single factor on the crystallization yield of ammonium heptamolybdate. Finally,the thermodynamic parameters were obtained. The results showed that the optimum conditions: feed liquid ratio of 0. 25 g/m L,stirring speed of 158. 33 r/min,cooling temperature of 7. 90℃. Considering the actual situation,three groups of repeated verification experiments were carried out under the trimming optimum conditions and the ammonium heptamolybdate yield was about 77%. The qualities belong to chemical purity and meet the requirements of national standards and the products had uniform sizes. In addition,the thermodynamic parameters of ΔH,ΔG and ΔS were less than zero,it showed that the process of ammonium heptamolybdate cooling crystallization was non spontaneous,confusion decreasing and exothermic process.
出处
《西北大学学报（自然科学版）》
CAS
CSCD
北大核心
2017年第6期852-858,共7页
Journal of Northwest University（Natural Science Edition）
基金
陕西省青年科技新星基金资助项目(2016KJXX-32)
关键词
七钼酸铵
四钼酸铵
冷却结晶
响应面分析法
热力学
ammonium heptamolybdate
ammoinum tetramolybdate
cooling crystallization
response surface methodology
thermodynamics
作者简介
张旭,男,陕西三原人,从事化工结晶工艺研究.;通讯作者：李冬,男,陕西西安人,西北大学副教授,从事化学工艺研究.
