Application of sectionalized single-step reaction approach (SSRA) and distributed activation energy model (DAEM) on the pyrolysis kinetics model of upstream oily sludge: Construction procedure and data reproducibility comparison

Comprehensive kinetic modeling and product distribution for pyrolysis of pulp and paper mill sludge

Pyrolysis holds immense potential for clean treatment of pulp and paper mill sludge (PPMS), enabling efficient energy and chemical recovery. However, current understanding of PPMS pyrolysis kinetics and product characteristics remains incomplete. This study conducted detailed modeling of pyrolysis kinetics for two typical PPMSs from a wastepaper pulp and paper mill, namely, deinking sludge (PPMS-DS) and sewage sludge (PPMS-SS), and analyzed comprehensively pyrolysis products. The results show that apparent activation energy of PPMS-DS (169.25-226.82 kJ/mol) and PPMS-SS (189.29-411.21 kJ/mol) pyrolysis undergoes significant change, with numerous parallel reactions present. A distributed activation energy model with dual logistic distributions proves to be suitable for modeling thermal decomposition kinetics of both PPMS-DS and PPMS-SS, with coefficient of determination >0.999 and relative root mean square error <1.99 %. High temperature promotes decomposition of solid organic materials in PPMS, and maximum tar yield for both PPMS-DS (53.90 wt%, daf) and PPMS-SS (56.48 wt%, daf) is achieved at around 500 °C. Higher levels of styrene (24.45 % for PPMS-DS and 14.71 % for PPMS-SS) and ethylbenzene (8.61 % for PPMS-DS and 8.33 % for PPMS-SS) are detected in tar and could be used as chemicals. This work shows great potential to propel development of PPMS pyrolysis technology, enabling green and sustainable production in pulp and paper industry.

Investigation of the evolved pyrolytic products and energy potential of Bagasse: experimental, kinetic, thermodynamic and boosted regression trees analysis

This study explored bagasse's energy potential grown using treated industrial wastewater through various analyses, experimental, kinetic, thermodynamic, and machine learning boosted regression tree methods. Thermogravimetry was employed to determine thermal degradation characteristics, varying the heating rate from 10 to 30 °C/min. The primary pyrolysis products from bagasse are H2, CH4, H2O, CO2, and hydrocarbons. Kinetic parameters were estimated using three model-free methods, yielding activation energies of approximately 245.98 kJ mol-1, 247.58 kJ mol-1, and 244.69 kJ mol-1. Thermodynamic parameters demonstrated the feasibility and reactivity of pyrolysis with ΔH ≈ 240.72 kJ mol-1, ΔG ≈ 162.87 kJ mol-1, and ΔS ≈ 165.35 J mol-1 K-1. The distribution of activation energy was analyzed using the multiple distributed activation energy model. Lastly, boosted regression trees predicted thermal degradation successfully, with an R2 of 0.9943. Therefore, bagasse's potential as an eco-friendly alternative to fossil fuels promotes waste utilization and carbon footprint reduction.

Exploring multistep bischofite waste pyrolysis: insights from advanced kinetic analysis and thermogravimetric techniques

Pyrolysis technology is crucial for realizing waste bischofite resource utilization. However, previous studies overlooked the complexity of multistep pyrolysis, resulting in a lack of thorough knowledge of the pyrolysis behavior and kinetics. The pyrolysis products were characterized using XRD and FTIR to indicate the bischofite pyrolysis behavior. Additionally, the multistep kinetics was studied using the segmented single-step reaction (SSSR) and Fraser-Suzuki combined kinetic (FSCK) methods. The results show that the bischofite pyrolysis is divided into dehydration and hydrolysis. The former refers to removing crystalline water from MgCl2·nH2O (n = 4,6). At the same time, the latter is related to the removal of HCl, characterized by the strengthening of the Mg-O bond in the FTIR analysis and the emergence of MgOHCl·1.5H2O in the XRD examination. The two main stages are divided into three dehydration reactions (D-1, D-2, D-3) and three hydrolysis reactions (H-1, H-2, H-3) by DTG-DDTG or Fraser-Suzuki deconvolution. Compared with the SSSR method, the FSCK method has improved model repeatability for multistep kinetic parameters. Following Fraser-Suzuki deconvolution, the FSCK method creates almost the same activation energy results when using the Friedman (FR), Kissinger-Akahira-Sunose (KAS), and Vyazovkin (VZK). This work provides fundamental data to promote the maximizing waste bischofite resource utilization.

Pyrolysis and combustion characteristics of typical waste thermal insulation materials

Thermal insulation materials are important for building energy conservation, but their wastes have increased sharply. Furthermore, pyrolysis and combustion are increasingly utilized to dispose of solid wastes and convert them into value-added fuels. To better understand the pyrolysis and combustion characteristics of these materials, typical thermal insulation materials (expanded polystyrene (EPS) and extruded polystyrene (XPS)) were investigated by employing thermogravimetry and differential scanning calorimetry as well as cone calorimetry experiments. Pyrolysis behavior, kinetic parameters, pyrolysis index, thermodynamic parameters, endothermic properties and combustion parameters were estimated comprehensively. The results showed that EPS had better pyrolysis properties, while XPS had better combustion characteristics. Activation energies of EPS and XPS were 158.82 kJ/mol and 200.70 kJ/mol, respectively. Additionally, EPS had a higher pyrolysis stability index and comprehensive pyrolysis index, meaning a more intense reaction. Moreover, thermodynamic parameters indicated that the devolatilization products could be obtained easily from the two materials, and EPS and XPS could be converted into fuels. For the combustion, XPS had a smaller fire performance index and a larger fire growth index. These results can guide the reactor design and optimization for better converting polymer wastes into fuels and managing wastes.

Bio-Fenton-Assisted Biological Process for Efficient Mineralization of Polycyclic Aromatic Hydrocarbons from the Environment

The intensive production of fossil fuels has led to serious polycyclic aromatic hydrocarbon (PAH) contamination in water and soil environments (as PAHs are typical types of emerging contaminants). Bio-Fenton, an alternative to Fenton oxidation, which generates hydrogen peroxide at a nearly neutral pH condition, could ideally work as a pretreatment to recalcitrant organics, which could be combined with the subsequent biological treatment without any need for pH adjustment. The present study investigated the performance of a Bio-Fenton-assisted biological process for mineralization of three typical types of PAHs. The hydrogen peroxide production, PAH removal, overall organic mineralization, and microbial community structure were comprehensively studied. The results showed that the combined process could achieve efficient chemical oxygen demand (COD) removal (88.1%) of mixed PAHs as compared to activated sludge (33.1%), where individual PAH removal efficiencies of 99.6%, 83.8%, and 91.3% were observed for naphthalene (NAP), anthracene (ANT), and pyrene (PYR), respectively, with the combined process.

Mechanism of Magnetic Nanoparticle Enhanced Microwave Pyrolysis for Oily Sludge

In view of the high dielectric constant of magnetic nanoparticles, this paper intends to use it as a new type of microwave absorbing medium to accelerate the microwave pyrolysis process of oily sludge. Microwave thermogravimetric reaction and pyrolysis product staged collection devices were established, respectively. The main stage of pyrolysis process of oily sludge was divided based on the thermogravimetric experiments. Mechanism was studied through the characteristics of pyrolysis products and reaction kinetics simulation. Experimental results showed that the addition of magnetic ZnFe2O4 particle did not change the microwave pyrolysis process of oily sludge and the pyrolysis efficiency could be improved. Pyrolysis process was divided into three stages, rapid heating and water evaporation stage (20~150 °C), light component evaporation stage (150~240 °C) and heavy component cracking stage (240~300 °C). Due to the addition of magnetic ZnFe2O4 particles, the content of C4~C12 increased by 3.5%, and the content of C18+ decreased by 4.1%, indicating that more recombinant components participated in the reaction pyrolysis to form light gas components. The kinetic analysis showed that the activation energy of oily sludge decreased by 36.49% and the pre-exponential factor decreased by 91.39% in stage III, indicating that magnetic nanoparticles had good catalytic activity.