共查询到20条相似文献,搜索用时 140 毫秒
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采用熔融结晶法对精馏塔处理过的硝基氯苯废料回收进行了研究。考察了指定进料组成下,降温速率、结晶终温、结晶时间等操作条件对对硝基氯苯(p-NCB)和间硝基氯苯(m-NCB)结晶过程的影响,以及对位结晶与间位结晶的差异。给出了2种典型进料组成的最优操作分离条件:进料质量分数w(p-NCB)=89.31%、w(m-NCB)=10.69%时,降温速率0.049 1℃/min、结晶时间480 min、结晶终温60℃;进料质量分数w(m-NCB)=76.03%、w(p-NCB)=23.97%时,降温速率0.015 8℃/min、结晶时间440 min、结晶终温27℃。实验表明,硝基氯苯间位结晶提纯比对位结晶提纯困难得多,采用实验中获得的最佳分离条件,w(p-NCB)≥90%的原料经单级结晶就可以得到纯度99%以上的产品,w(m-NCB)≥90%的原料通过二级结晶也可得到纯度99%以上的产品,而进料质量分数较低时经过多级结晶也能得到纯度99%以上的产品。 相似文献
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叙述了用重结晶法分离精制制取高纯度对二氯苯及邻二氯苯的工艺流程.用此法可高产率地得到纯度99.8%左右的对二氯苯,99.0%以上的邻二氯苯. 相似文献
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从辣椒素总碱(Capsaicinoids)中提取高纯度的辣椒索及二氢辣椒素单体,建立了分离工艺条件。以TLC实验筛选适当的洗脱流动相,低压硅胶柱层析分离纯化,产物用两相法重结晶,TLC及HPLC监测分离效果及产品纯度。结果表明优选的流动相为混合溶剂石油醚:丙酮=8:2(体积比),纯化分离得到辣椒素和二氢辣椒索,纯度分别从64%和29%提高到97%和96%。 相似文献
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This study aimed to obtain paeonol with high purity by using the combination of steam distillation and antisolvent recrystallization (ASR) and to reduce the energy consumption and CO2 emission in the preparation process. First, different experimental parameters were optimized by response surface methodology (RSM). Under the optimal conditions, the purity and yield of the as-obtained paeonol were about 98% and 56.97%, respectively. The physicochemical properties of purified paeonol were tested, showing consistency with those of standard paeonol. The energy consumption and CO2 emission of the preparation process of ASR and single-solvent recrystallization were also investigated. Results showed that the energy consumption and CO2 emission of ASR were about 4.41 J/mg and 0.006 kg/mg, respectively, which were 6.89 J/mg and 0.0095 kg/mg lower than those of ethanol recrystallization, respectively, and 50.22 J/mg and 0.0144 kg/mg lower than methanol those of recrystallization, respectively. The above results showed that ASR could obtain paeonol with high purity in a high-efficiency, low-energy, and environmentally protective manner. 相似文献
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研究了以菱锶矿为原料,通过煅烧、浸取、除杂、重结晶、碳化等步骤制取高纯碳酸锶的工艺。并对影响该工艺的主要因素进行了讨论。该工艺不使用盐酸等酸浸工序,具有产品纯度高、不含氯离子、工艺简单、原料利用率高、“三废”排放少等特点。 相似文献
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PP透明剂后处理的研究 总被引:1,自引:0,他引:1
本论文基于改善DBS类成核剂在加工中产生臭味及提高PP透明性的设想,采用国内DBS第二代成核剂(CHII),先后用丙酮、异丙醇(IPO)、乙醇、N,N-二甲基酰胺(DMF)和环醚类溶剂(SA)等对其进行了重结晶提纯;研究了提纯条件(不同溶剂、温度、溶剂用量)对CHII的重结晶收率、熔点、表观密度和热性能的影响,其中用溶剂SA效果最好;确定了以17/1为最佳溶剂/溶质重量比用量。经溶剂后处理的CHII比粗产品的纯度上有了很大的提高。CHII经纯化后。在1700.Ocm^-1处的C=O峰消失。 相似文献
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重结晶提纯碳酸二苯酯的溶剂选择 总被引:1,自引:0,他引:1
为了寻找重结晶法提纯碳酸二苯酯(DPC)的适宜溶剂,文章对DPC重结晶溶剂的选择及影响DPC纯度的因素进行了研究。结果表明:乙醇是重结晶纯化DPC的适宜溶剂,DPC在乙醇中溶解度在5—15℃的区间内变化缓慢,重结晶中止温度在15℃左右,DPC的收率高于89.0%。乙醇和DPC比率(质量比)采用8∶5为重结晶DPC时的适宜比率。通过对重结晶溶剂的进一步研究,发现采用水-乙醇的混合溶剂作为重结晶溶剂时,可以明显提高DPC的收率。水的质量分数在25.0%—35.0%范围内时,DPC的收率大于93.0%,纯度高于99.6%。其纯度符合合成聚碳酸酯的要求。 相似文献
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《国际聚合物材料杂志》2012,61(5):532-542
High purity in high yield L-lactide was prepared using a new purification method, and poly-L-lactide (PLLA) with ultra-high weight average molecular mass and narrow polydispersity index was synthesized by ring-opening polymerization. The effects of the purification method on the purity and yield of L-lactide were investigated, and the influences of initiator concentration, polymerization temperature and polymerization time on the weight average molecular mass of PLLA were also studied. A synthetic purification method involving a water bath and two times recrystallization could improve the purity of L-lactide to 100%. The yield of L-lactide reached 40.6% and increased 12.1% compared with the recrystallization method. Poly-L-lactide with a weight average molecular mass of about 102.4 × 104 and a polydispersity index of 1.16 was obtained when polymerization was conducted with molar ratio of monomer to initiator ([M]/[I]) of 12000 for 24 h at 140°C. 相似文献