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APT(S) 제조 시 전기투석법을 이용한 H<sub>2</sub>WO<sub>4</sub>(Aq)내의 Na 제거 방법에 관한 연구
강용호,현승균,Kang, Yong-Ho,Hyun, Soong-Keun 한국자원리싸이클링학회 2017 資源 리싸이클링 Vol.26 No.6
APT (Ammonium paratungstate)는 금속절단 공구, 드릴의 날, 광산공구, 군사무기 재료 등 산업 전반에 다양한 용도로 사용되며, 고순도의 APT(S)를 제조하기 위해서는 $Na_2WO_4$ 수용액으로부터 전환된 $H_2WO_4$ 내의 불순물 정제 공정이 필요하다. 이미 널리 알려진 기존의 습식방법인 $Na_2WO_4$ 수용액에 HCl(Aq)을 첨가하여 $H_2WO_4(S)$을 제조하는 경우에는 불순물인 Na를 200 ppm 이하로 제거하는데 어려움이 있다. 이러한 점을 개선하기 위하여 본 연구에서는 양이온 격막을 이용한 전기투석 공정을 통해 Na를 제거하는 보다 경제적이고 효율적인 방법을 연구하였다. 폐 텅스텐 초경드릴 및 스크랩을 용해하기 위해 첨가되었던 $Na_2CO_3(S)$로 인한 $H_2WO_4$ 수용액 내의 다량의 Na를 전기투석 공정을 통해 20 ppm 이내로 제거함으로써 전기투석법 이용 시 Na 제거 효과가 큼을 확인하였다. APT (Ammonium paratungstate) is widely used in various industries such as metal cutting tools, drill bits, mining tools, and military inorganic materials. In order to produce high purity APT(S), an impurity purification step in an aqueous $Na_2WO_4$ convert $H_2WO_4$ solution is required. It is difficult to remove impurity Na of 200 ppm or less when $H_2WO_4(S)$ is prepared by adding HCl(Aq) to an aqueous solution of $Na_2WO_4$, which is a well-known conventional wet method. However, in this study, a more economical and efficient method of removing Na through electrodialysis using a cationic membrane was studied. A large amount of Na in aqueous solution of $H_2WO_4$ due to $Na_2CO_3(S)$ which was added to dissolve waste tungsten carbide drill and scrap was removed to 20ppm or less through electrodialysis process, and it was confirmed that the effect of Na removal was great when using electrodialysis.
NO2 sensing properties of WO3-decorated In2O3 nanorods and In2O3-decorated WO3 nanorods
이중무,현승균,Tae-Kyoung Ko,Bumhee Nam 나노기술연구협의회 2019 Nano Convergence Vol.6 No.40
n2O3 nanoparticle (NP)-decorated WO3 nanorods (NRs) were prepared using sol–gel and hydrothermal methods. The In2O3 NRs and WO3 NPs were crystalline. WO3 NP-decorated In2O3 NRs were also prepared using thermal evaporation and hydrothermal methods. The NO2 sensing performance of the In2O3 NP-decorated WO3 NR sensor toward NO2 was compared to that of the WO3 NP-decorated In2O3 NR sensor. The former showed a high response to NO2 due to a significant reduction of the conduction channel width upon exposure to NO2. In contrast, the latter showed a far less pronounced response due to limited reduction of the conduction channel width upon exposure to NO2. When the sensors were exposed to a reducing gas instead of an oxidizing gas (NO2), the situation was reversed, i.e., the WO3 NP-decorated In2O3 NR exhibited a stronger response to the reducing gas than the In2O3 NP-decorated WO3 NR sensor. Thus, a semiconducting metal oxide (SMO) with a smaller work function must be used as the decorating material in decorated heterostructured SMO sensors for detection of oxidizing gases. The In2O3 NP-decorated WO3 NR sensor showed higher selectivity for NO2 compared to other gases, including reducing gases and other oxidizing gases, as well as showed high sensitivity to NO2.