Mai Ouyang,Kehui Hu,Qianwen Jiang,Qingda Yao,Hualong Zhou,Yupei Deng,Yiyue Shen,Fahui Li,Linghua Zhuang,Guowei Wang
Chrome tanning agent is the most widely used tanning agent with the best performances of finished leather , but the traditional chrome tanning process poses severe challenges because of the serious chromium pollution, thus the upgrading of cleaner chrome tanning process is imminent. In order to reduce the residual chromium in wastewater and increase the utilization rate of chrome tanning agent, 4-acetyl-heptanediate (AHA), a high exhaustion chrome auxiliary , was developed and applied in chrome retanning process. The results showed that AHA chrome retanning processes (AHA-6 and AHA-4) significantly reduced the chromium content in wastewater by 48.14% and 47.57%, and increased the chromium content in leather by 102.14% and 82.43%. COD and TDS values decreased by 43.82% and 31.46% with AHA-4 method. The addition of AHA obviously reduced the chromium concentration of wastewater, improved the chromium absorption rate, and promoted the cleaner chrome retanning process, which satisfied with the overall requirements of modern sustainable leather industry. The formation of AHA and chromium (III) was discussed using Gaussian 16 program to explain the high exhaustion chrome tanning agent mechanism. The work will guide on design and preparation of new high exhaustion chromium tanning agents for clean leather production.
Vanadium oxide s, such as V 2 O 5 and V 2 O 3 , are important metallurgy products and mainly used to prepare V-based alloys for steelmaking. At present, vanadium oxide s are mainly produced by complex sodium salt roasting process. Serious environmental pollution, such as emission of ammonia nitrogen wastewater and NH 3 , are restrictive problems. Here, a clean and sustainable method for V 2 O 3 preparation is proposed by one-step molten salt electrochemical reduction of soluble NaVO 3 , i.e. an indispensable intermediate in traditional V metallurgy. The pollution issues are well solved. The theoretical decomposition voltages of different vanadate to various low-valence vanadium oxides were calculated. NaVO 3 with a solubility of 14.7 wt% is the most suitable vanadate for the direct preparation of V 2 O 3 by molten salt electrolysis. The effects of cathode structure, NaVO 3 content, electrolysis temperature and voltage on current efficiency and electricity consumption were systematically studied. High-purity V 2 O 3 with uniform particle distribution is obtained and the lowest electricity consumption is only 2.86 kWhkg −1 . V 2 O 3 is mainly produced by one-step electrochemical reduction of soluble NaVO 3 through two-electron transfer process. The economic evaluation for ferrovanadium production is preliminarily carried out. Compared with the traditional process, the cost for ferrovanadium production is lower by the aluminothermic reduction of V 2 O 3 which is prepared by clean one-step electrolysis of soluble NaVO 3 .
危险品化学品经营许可证（带存储）