| 1. |
- Wang, Chaoqian, et al.
(författare)
-
A stepwise microwave synergistic pyrolysis approach to produce sludge-based biochars : Feasibility study simulated by laboratory experiments
- 2020
-
Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 272, s. 1-10
-
Tidskriftsartikel (refereegranskat)abstract
- A stepwise microwave synergistic pyrolysis (SMSP) approach is proposed as a new way to relieve disposal problems of the sewage sludge. Here the sludge is first pre-pyrolyzed by a conventional heating stage, and then rapidly pyrolyzed by a microwave-induced heating stage without any extra microwave absorbers or blending needed. Under simulated process pyrolysis conditions, the dried sludge, intermediate and final sludge-based biochar samples were prepared in the laboratory. Their chemical composition, microstructure and morphology, and leaching toxicity of heavy metals were carefully characterized and analyzed by various techniques such as proximate and ultimate analysis, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller (BET), and scanning electron microscope equipped with energy-dispersive x-ray spectroscopy (SEM-EDX). Results showed that the pre-pyrolytic biochar can be rapidly heated up to 1100 °C within 5 min under microwave irradiation. The pre-pyrolytic stage increased the carbonization and ash enrichment degree of the sludge which itself acted as a good microwave absorber while achieving a quick temperature rise under microwave irradiation. The ash remaining ratio and the specific surface area of the biochar derived from the SMSP approach (labelled as SBC2) are increased by 6.46% and 16.17% respectively, compared with the conventional biochar sample (SBC1). And SBC2 still had diverse surface functional groups kept after SMSP. The residual ratios of Ni, Cu, Zn, Pb, Cr and Cd in SBC2 was more noticeable than in SBC1 but the leaching ratios quite the contrary. Vitrification is also well proved by the increment of quartz peak detected by XRD tests, and the formation of melted glassy spheres with elemental composition of Si, Ca, Al observed by SEM-EDX. It can favorably increase solidification level and decrease leaching toxicity of heavy metals in the SBC2. The feasibility of this proposed SMSP concept has been positively supported by our experimental results. The properties of the sludge-based biochar produced from the SMSP approach also show great potential to be utilized as precursors to produce various adsorbents.
|
|
| 2. |
- Zhang, Xiaorong, et al.
(författare)
-
Review of chemical looping process for carbonaceous feedstock Conversion : Rational design of oxygen carriers
- 2022
-
Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 325
-
Forskningsöversikt (refereegranskat)abstract
- The chemical looping partial oxidation (CLPO) process as a technology of chemical looping process (CLP) is recognized as a potential strategy for the efficient and clean conversion of fuels into syngas/H2. Herein, in view of the importance of low-cost high-performance metal oxides as oxygen carriers (OCs) for this conversion, we systematically review the classification and CLPO applications of such OCs and discuss the improvement of OC reactivity and stability via the creation of metal–metal or metal–support synergism, the generation of oxygen vacancies, and the enhancement of deactivation resistance. Further, we present the results of theoretical and experimental characterizations probing ion diffusion and surface reactions to provide insights into the related reaction mechanisms and touch on the challenges and opportunities of developing metal oxides with excellent reactivity and long-term cycling stability in CLP. Thus, this review facilitates the design and performance regulation of OCs for future energy conversion systems.
|
|
