碱辅助四氧化三锰降解磷酸三丁酯及磷元素回收研究

Study on alkali-assisted degradation of tributyl phosphate by manganesetetroxide and phosphorus recovery

磷酸三丁酯(TBP)有机危废的无机化和资源化处置技术是一项重要的环保需求。基于化学链燃烧(CLC)的原理和TBP碱水解的机理构建碱辅助Mn_(3)O_(4)热氧化降解TBP的反应体系,开发TBP无机化同步磷元素资源化的新工艺。在TBP、NaOH、Mn_(3)O_(4)为1 ml:6g:13 g的较优比例下,220℃反应;3h后,磷元素从TBP向无机相转移的转化率可达到77.47%,同时TBP降解后气相产物中非甲烷总烃(NMHC)浓度仅为27.28 mg/m^(3),低于相关环境标准限值。采用乙醇沉淀法分离回收无机磷产物,通过X射线衍射(XRD)分析得知,含磷产物的主要成分为Na_(3)PO_(4)、NaPO_(3)、Na_(2)HPO_(4)和Na_(3)PO_(4)·8H_(2)O。根据TBP降解中间产物的质谱分析结果提出了TBP降解和磷元素迁移的可能路径。电子顺磁共振(EPR)分析证实羟基自由基(·OH)和超氧自由基(·O_(2)^(-))对TBP的降解过程具有重要的促进作用。

The inorganic and resource disposal technology of tributyl phosphate(TBP)organic hazardous waste is an important environmental protection demand.Based on the principle of chemical looping combustion(CLC)and the mechanism of alkaline hydrolysis of TBP,a reaction system of alkali-assisted thermal oxidation TBP by Mn_(3)O_(4) was constructed.A process of TBP degradation with simultaneous phosphorus recovery was developed.Under an optimal feed ratio of TBP,NaOH and Mn_(3)O_(4)(1 ml∶6 g∶13 g),the conversion rate of P from TBP to inorganic phase could reach 77.47%,and the non-methane hydrocarbon(NMHC)concentration of gas products was only 27.28 mg/m^(3),which was lower than the relevant environmental standard limit.Inorganic phosphorus products were separated and recovered by ethanol precipitation.X-Ray diffraction(XRD)analysis showed that the main components of phosphorus-containing products included Na_(3)PO_(4),NaPO_(3),Na_(2)HPO_(4) and Na_(3)PO_(4)·8H_(2)O.According to mass spectrometry analysis of TBP degradation intermediates,the possible pathways of TBP degradation and phosphorus migration were proposed.Electron paramagnetic resonance(EPR)analysis revealed that hydroxyl radical(·OH)and superoxide radical(·O_(2)^(-))played important roles in promoting the degradation of TBP.