污水污泥水热炭活化过一硫酸盐对水热废水的降解特性和机理研究

Process Water Treatment by Sewage Sludge-Derived Hydrochar Activated Peroxymonosulfate: Degradation Performance and Mechanism

摘要: 水热炭化被认为是处理污水污泥的有效方法。然而，水热废水已成为制约该方法可持续发展的瓶颈。强氧化剂过一硫酸盐(PMS)很容易通过光、电、过渡金属和碳材料等方式被激活，产生SO₄∙⁻自由基，有效处理废水中有机污染物。因此，通过水热炭化的方式制备了污泥水热炭，探究了污泥水热炭激活PMS降解水热废水的可行性，考察了水热炭化温度、水热废水初始pH和降解时间对水热废水中可溶性化学需氧量(SCOD)降解效率的影响。结果表明，HC₂₀₀活化PMS降解PW₁₆₀效果最好。降解时间为15分钟时，最大SCOD降解效率达到了38.1%。但水热废水初始pH对SCOD降解影响不明显。HC₂₀₀可以在相对较宽的pH范围(3~9)内有效降解SCOD。水热炭脱灰实验结果表明，水热炭中铁元素会影响PMS激活。脱灰水热炭降解前后XPS分析表明，C = O官能团是活化PMS的主要官能团。因此，水热炭通过两个途径激活PMS：(1) HC₂₀₀含氧官能团(C = O)活化PMS；(2) HC₂₀₀中铁元素激活PMS，从而促进SCOD降解。

Abstract: Hydrothermal carbonization (HTC) is considered as an effective method for sewage sludge (SS) treatment. However, process water (PW) has become a bottleneck for the sustainable development of HTC. Peroxymonosulfate (PMS) was readily activated by light, electricity, transition metals, carbon nanotubes and so on, to produce SO₄∙⁻ free radicals for the effective degradation of organic pollutants in wastewater. Therefore, sewage sludge-derived hydro char was prepared in this study to activate PMS for the degradation of PW. Effects of HTC temperature, initial pH of PW and degradation time on the degradation efficiency of soluble chemical oxygen demand (SCOD) in PW were investigated. Results showed that HC₂₀₀ could activate PMS and had the best degradation effect on PW₁₆₀. The maximum degradation efficiency of 38.1% was achieved at 15th minute. The pH of initial PW has little effect on SCOD degradation, and HC₂₀₀ is suitable for SCOD degradation in a relatively wide pH range (3~9). Hydrochar deashing experiment showed that iron in hydrochar could activate PMS. XPS analysis of deashed hydrochar before and after degradation indicated that C = O functional group was the main functional group in activating PMS. Therefore, hydrochar activate PMS by two ways to promote the degradation of SCOD: (1) oxygen-containing functional group (C = O) in HC₂₀₀; (2) iron in HC₂₀₀.