电催化臭氧氧化降解Cr(III)络合物与Cr同步回收特性与机理

Trivalent chromium (Cr(III)) usually forms highly stable complexes with organic ligands such as amino carboxylic and carboxylic compounds in tannery and electroplating effluents. Advanced oxidation processes such as ozonation, have been used for removal of such Cr(III)-organic complexes, but their promotion are still challenged by the formation of highly toxic hexavalent chromium (Cr(VI)) and production of abundant chromium sludge. Thus, new strategies are highly desired for highly efficient and environmentally friendly removal of Cr(III)-complexes from industrial effluents, i.e. efficient decomplexation, inhibition of Cr(VI) accumulation, and simultaneous recovery of Cr metal. In this project, we proposed a so-called Electro-peroxone process, integrating ozonation and in situ electrically generated H2O2, to realize dual functions of enhancement on decomplexation of Cr(III)-complexes via ·OH production from O3 decomposition and reduction of Cr(VI) formation by in situ electro-generated H2O2, and achieve metal recovery by electro-sorption/deposition. The effects of solution chemistry and operation parameters (e.g., pH, ozone dosage and current density) on the efficiency of the process will be studied, and the contribution of H2O2 to the synergetic decomplexation of Cr(III)-complexes and behavior of Cr(VI) reduction formed in situ will be elucidated. Furthermore, the behavior of Cr recovery on cathode by electro-sorption/deposition and the regeneration of the cathode will be examined. Finally, the applicability of the process in treatment of realistic effluent will be evaluated. This study will provide an alternative technique for efficient removal of toxic Cr(III)-complexes from wastewater.

制革、电镀等工业废水中三价铬常与氨羧/羟羧等配体形成稳定络合物而难于去除。臭氧氧化等高级氧化工艺降解该类络合物时易积累高毒性六价铬，且后续处理产生大量铬泥危废。因此，亟待解决在高效氧化破络的同时抑制六价铬积累这一难题，并实现铬的回收资源化。本项目提出了电化学原位产H2O2协同臭氧（电催化臭氧）氧化降解三价铬络合物及同步回收铬的方法，利用原位生成H2O2起到协同臭氧产·OH强化破络与原位削减六价铬的双重效果，同时通过电吸附/沉积实现铬的回收。通过研究pH、臭氧投量、电流密度等因素对破络效果、铬形态变化与回收的影响规律，探明电生H2O2双重作用机制，阐明该方法对氨羧/羟羧-三价铬络合物降解与铬形态调控的特性与机理。此外，探究阴极表面铬的电化学行为，揭示该过程同步回收铬的机理，发展阴极循环利用与再生方法。在此基础上探讨该工艺处理实际废水的性能，为三价铬络合废水的高效绿色处理提供技术参考。

制革、电镀等工业废水中Cr(III)常与氨羧/羟羧等配体形成稳定络合物而难于去除。臭氧氧化等氧化工艺降解该类络合物时易积累高毒性Cr(VI)，且后续处理产生大量铬泥危废。在高效氧化破络的同时抑制Cr(VI)积累，并实现Cr的回收资源化，是实现Cr(III)络合物高效绿色处理的关键。研究提出电化学原位产H2O2协同臭氧（电催化臭氧）氧化降解Cr(III)络合物及同步回收Cr的方法，解析pH、臭氧投量、电流密度等因素对破络效果、Cr形态变化与回收的影响规律，探明电生H2O2、电还原、电吸附对强化破络与中间Cr(VI)削减的作用机制，揭示阴极表面Cr的电化学行为，阐明电催化臭氧对Cr(III)络合物降解与Cr形态调控的效能与机理。在此基础上进一步研究该方法处理Cu(II)络合物并同步回收Cu的效果与机理，并验证该工艺处理实际络合重金属废水的性能。此外，基于研究发现的破络过程中金属形态转变促进破络作用，深入揭示光氧化过程中Cu、Cr价态转化强化破络行为与机理。.电催化臭氧能够高效降解Cr(III)络合物与同步回收Cr，Cr回收率达~90%，其中78.3%以无定型Cr(OH)3沉积于阴极，且Cr(VI)累积低于0.2 mg/L。该方法也能实现对Cu(II)络合物高效降解与Cu同步回收，Cu以零价Cu形式沉积于阴极，回收率高于90%。而且，该过程对实际络合重金属废水也取得满意的处理效果，Cr、Cu的回收率均高于80%。因此，电催化臭氧是一种高效去除毒性重金属络合物并同步回收重金属新技术，实现了重金属的资源化，减少了危废污泥产生，为络合重金属废水的高效、安全深度处理技术创新提供了理论依据与方法支持。