Insights into the Synergistic Effect and Inhibition Mechanism of Composite Conditioner on Sulfur-Containing Gases during Sewage Sludge Pyrolysis
Abstract
:1. Introduction
2. Results and Discussion
2.1. Sulfur Distribution in Products
2.1.1. Sulfur Balance
2.1.2. Release of Sulfur-Containing Gases
2.2. Effect of Conditioners on H2S Release
2.2.1. Effect of Single Conditioner
2.2.2. Synergistic Effect of Composite Conditioner
2.3. Effect of Conditioners on Sulfur Species in Char
2.3.1. Effect of Single Conditioner on Sulfur Species
2.3.2. Synergistic Effect of Composite Conditioners on Sulfur Species
2.3.3. Sulfur-Containing Mineral Components
3. Materials and Methods
3.1. Sample Preparation
3.2. Pyrolysis Experiment
3.3. Analytic Methods
3.4. Calculation Method
4. Conclusions
- (1)
- The release of H2S was suppressed by CaO, Fe2O3, and FeCl3 by 35.8%, 23.2%, and 9.1% at 650 °C, respectively. CaO mitigated gas-S release by promoting the transformation of organic sulfur into more stable oxidized forms, and by capturing gas-S. Fe2O3 demonstrated enhanced oxidizing capabilities, while FeCl3 inhibited the decomposition of organic sulfur and captured gas-S at high temperatures.
- (2)
- Utilizing a composite of CaO and FeCl3 within the temperature range from 350 to 450 °C, along with a composite of Fe2O3 and FeCl3 at 650 °C, can synergistically suppress the H2S release. Conversely, between 350 °C and 550 °C, the combination of Fe2O3 with FeCl3, and between approximately 550 and 650 °C, the composite of Ca-based and Fe-based conditioners, demonstrate a synergistic enhancement effect on the release of H2S.
- (3)
- In composite conditioning, the strong alkalinity of CaO neutralizes HCl, an acidic gas generated by the decomposition of FeCl3. This neutralization prevents HCl from interacting with inorganic or organic sulfides in the sludge, thus synergistically inhibiting H2S release. At 450 °C, this synergistic effect inhibits H2S release by 56.3%. Nonetheless, the formation of FeCa2O4 above 550 °C, reduces the sulfur-fixing capacity of the composite conditioners, and at 650 °C, it synergistically promotes the release of H2S by 26.3%.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
References
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Char-S (%) | Gas-S (%) | Tas-S (%) | |
---|---|---|---|
RS-700 | 79.1 | 15.1 | - |
RS-CaO | 90.6 | 7.0 | - |
RS-Fe2O3 | 89.8 | 6.9 | - |
RS-FeCl3 | 85.5 | 9.9 | - |
Samples | Proximate Analysis (wt.%) a | Ultimate Analysis (wt.%) a | ||||||
---|---|---|---|---|---|---|---|---|
Volatile Matter | Ash | Fixed Carbon | C | H | N | S | O b | |
RS | 31.2 | 64.7 | 4.1 | 15.88 | 2.64 | 2.52 | 1.11 | 13.15 |
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Cheng, S.; Chen, L.; Wang, S.; Yao, K.; Tian, H. Insights into the Synergistic Effect and Inhibition Mechanism of Composite Conditioner on Sulfur-Containing Gases during Sewage Sludge Pyrolysis. Molecules 2024, 29, 4110. https://doi.org/10.3390/molecules29174110
Cheng S, Chen L, Wang S, Yao K, Tian H. Insights into the Synergistic Effect and Inhibition Mechanism of Composite Conditioner on Sulfur-Containing Gases during Sewage Sludge Pyrolysis. Molecules. 2024; 29(17):4110. https://doi.org/10.3390/molecules29174110
Chicago/Turabian StyleCheng, Shan, Lianghui Chen, Shaoshuo Wang, Kehui Yao, and Hong Tian. 2024. "Insights into the Synergistic Effect and Inhibition Mechanism of Composite Conditioner on Sulfur-Containing Gases during Sewage Sludge Pyrolysis" Molecules 29, no. 17: 4110. https://doi.org/10.3390/molecules29174110