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Treatment of DEHP-rich PVC waste in subcritical urine wastewater: Efficient dechlorination, denitrification, plasticizer decomposition, and preparation of high-purity phthalic acid crystals
Journal of Hazardous Materials ( IF 12.2 ) Pub Date : 2022-08-24 , DOI: 10.1016/j.jhazmat.2022.129820
Fu-Rong Xiu 1 , Xiaochun Tan 1 , Yingying Qi 1 , Mengmeng Wang 2
Affiliation  

It is difficult to dispose diethylhexyl phthalate-rich polyvinyl chloride (DEHP-rich PVC) waste due to the high level of chlorine and plasticizer. On the other hand, the denitrification of urine wastewater with high nitrogen content also faces great challenges. In this study, a synergistic treatment strategy was developed for the DEHP-rich PVC waste and urine wastewater by a subcritical water process. Subcritical urine wastewater (SUW) was used as a reaction medium in the synergistic treatment. PVC dechlorination, DEHP decomposition, and denitrification of urine wastewater were synchronously achieved in the one pot SUW. Under the optimal conditions (300 °C, 15 min, 1:5 g/mL), the PVC dechlorination ratio, urine wastewater denitrification ratio and DEHP decomposition ratio could reach 98.4%, 64.9%, and 99.2%, respectively. The decomposition of DEHP mainly included hydrolysis, nucleophilic substitution, and acylation. DEHP could be converted into phthalic acid crystal at 220 °C with a yield of 66.25% due to the efficient hydrolysis action of SUW. All the removed Cl was transferred from PVC matrix to aqueous phase. Hydroxyl nucleophilic substitution is the principal dechlorination path of PVC. The reactions between N-containing species and DEHP in SUW resulted in the high-efficiency denitrification of urine wastewater, and the N element was fixed in solid residue or transferred to oil phase as amides compounds. It is believed that the proposed SUW process is a promising technology for the synergistic treatment of DEHP-rich PVC waste and urine wastewater.



中文翻译:

亚临界尿废水中富含DEHP的PVC废液处理:高效脱氯、脱硝、增塑剂分解、制备高纯度邻苯二甲酸晶体

由于氯和增塑剂含量高,富含邻苯二甲酸二乙基己酯的聚氯乙烯(富含 DEHP 的 PVC)废物很难处理。另一方面,高含氮尿废水的反硝化也面临着很大的挑战。在本研究中,采用亚临界水工艺对富含 DEHP 的 PVC 废物和尿液废水制定了协同处理策略。亚临界尿废水(SUW)用作协同处理中的反应介质。PVC脱氯、DEHP分解、尿废水脱硝在一锅SUW中同步实现。在最佳条件下(300 ℃、15 min、1:5 g/mL),PVC脱氯率、尿废水脱硝率和DEHP分解率分别可以达到98.4%、64.9%和99.2%。DEHP的分解主要包括水解、亲核取代和酰化。由于 SUW 的高效水解作用,DEHP 可在 220 ℃下转化为邻苯二甲酸晶体,产率为 66.25%。所有去除的 Cl 都从 PVC 基质转移到水相。羟基亲核取代是PVC的主要脱氯途径。SUW中含氮物质与DEHP的反应导致尿液废水的高效反硝化,N元素以酰胺化合物的形式固定在固体残渣中或转移到油相中。相信所提出的 SUW 工艺是协同处理富含 DEHP 的 PVC 废物和尿液废水的有前景的技术。由于 SUW 的高效水解作用,DEHP 可在 220 ℃下转化为邻苯二甲酸晶体,产率为 66.25%。所有去除的 Cl 都从 PVC 基质转移到水相。羟基亲核取代是PVC的主要脱氯途径。SUW中含氮物质与DEHP的反应导致尿液废水的高效反硝化,N元素以酰胺化合物的形式固定在固体残渣中或转移到油相中。相信所提出的 SUW 工艺是协同处理富含 DEHP 的 PVC 废物和尿液废水的有前景的技术。由于 SUW 的高效水解作用,DEHP 可在 220 ℃下转化为邻苯二甲酸晶体,产率为 66.25%。所有去除的 Cl 都从 PVC 基质转移到水相。羟基亲核取代是PVC的主要脱氯途径。SUW中含氮物质与DEHP的反应导致尿液废水的高效反硝化,N元素以酰胺化合物的形式固定在固体残渣中或转移到油相中。相信所提出的 SUW 工艺是协同处理富含 DEHP 的 PVC 废物和尿液废水的有前景的技术。羟基亲核取代是PVC的主要脱氯途径。SUW中含氮物质与DEHP的反应导致尿液废水的高效反硝化,N元素以酰胺化合物的形式固定在固体残渣中或转移到油相中。相信所提出的 SUW 工艺是协同处理富含 DEHP 的 PVC 废物和尿液废水的有前景的技术。羟基亲核取代是PVC的主要脱氯途径。SUW中含氮物质与DEHP的反应导致尿液废水的高效反硝化,N元素以酰胺化合物的形式固定在固体残渣中或转移到油相中。相信所提出的 SUW 工艺是协同处理富含 DEHP 的 PVC 废物和尿液废水的有前景的技术。

更新日期:2022-08-24
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