- Chemical Engineering Department, Vaal University of Technology, Vanderbjilpark, 1911, South Africa.
- Chemical Engineering Department, Vaal University of Technology, Vanderbjilpark, 1911, South Africa; - Centre of Excellence in Carbon Based Fuels, School of Chemical and Minerals Engineering North-West University, Potchefstroom Campus, Private Bag X6001, Potchefstroom, 2520, South Africa.
J Environ Manage. 2021 Apr 15;284:112006. doi: 10.1016/j.jenvman.2021.112006. Epub 2021 Jan 31.
Pyrolysis has shown great potential for sewage sludge valorisation and management by producing value-added chemicals. Although the product process yields are extensively studied, a few studies exist without consensus on the kinetic properties of sewage sludge pyrolysis. As a result, a study to investigate the thermal decomposition characteristics of Gauteng sewage sludge (GSS) at various heating rates (10, 20, and 30 °C/min), its pyrolysis kinetic parameters, reaction mechanism and thermodynamic properties was meticulously conducted. The results show that sewage sludge decomposition occurs in three stages, whereby the main decomposition (active pyrolysis) takes place at 150-570 °C. Fourier transform infrared spectroscopy (FTIR) analysis results confirm progression of thermal decomposition of GSS and drive off volatile compounds and formation of aromatic structures during TGA studies of GSS. An increase in heating rate shifts the characteristic temperatures towards higher temperatures with the highest decomposition rate of 1.10%/min.mg at 30 °C/min. The activation energies of GSS pyrolysis were calculated using Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose and Starink methods and averaged as 225.92, 218.04 and 218.97 kJ/mol, respectively. GSS pyrolysis involves complex reaction chemistry with high reactivity whereby reactions that follow third order and three-dimensional diffusion-reaction mechanisms dominated the process. However, these mechanisms cannot be used explicitly to define the global pyrolysis kinetics due to the occurrence of multiple simultaneous reactions. The obtained thermodynamic and kinetic data will advance and amplify the design, simulation and optimisation of global energy pyrolysis units for production of value-added chemicals.
热解在通过生产增值化学品来实现污水污泥增值和管理方面显示出巨大的潜力。尽管产品工艺收率得到了广泛研究，但很少有研究对污水污泥热解的动力学特性达成共识。因此，进行了一项研究，以在不同加热速率（10、20 和 30°C/min）下研究豪登省污水污泥（GSS）的热分解特性、其热解动力学参数、反应机制和热力学性质。结果表明，污水污泥分解发生在三个阶段，其中主要分解（活性热解）发生在 150-570°C。傅里叶变换红外光谱（FTIR）分析结果证实了 GSS 的热分解进展，并在 GSS 的 TGA 研究中逐出挥发性化合物并形成芳构化结构。加热速率的增加会将特征温度推向更高的温度，在 30°C/min 时，最高分解速率为 1.10%/min.mg。使用 Flynn-Wall-Ozawa、Kissinger-Akahira-Sunose 和 Starink 方法计算了 GSS 热解的活化能，并平均为 225.92、218.04 和 218.97 kJ/mol。GSS 热解涉及复杂的反应化学，具有高反应性，其中遵循三级和三维扩散反应机制的反应主导了该过程。然而，由于同时发生多个反应，这些机制不能明确用于定义全局热解动力学。获得的热力学和动力学数据将推进和放大用于生产增值化学品的全球能源热解单元的设计、模拟和优化。
