Xinlei Yu,Xun Tao,Yunfei Gao,Lu Ding,Yanqin Wang,Guangsuo Yu,Fuchen Wang
Compared to the Claus process, selective H2S catalytic oxidation to sulfur is a promising reaction, as it is not subject to thermodynamic limitations and could theoretically achieve ~100% H2S conversion to sulfur. In this study, we investigated the effects of Co and Fe co-doping in ABO3perovskite on H2S selective catalytic oxidation. A series of LaFexCo1−xO3(x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) perovskites were synthesized by the sol-gel method. Compared to LaFeO3and LaCoO3, co-doped LaFexCo1−xO3significantly improved the H2S conversion and sulfur selectivity at a lower reaction temperature. Nearly 100% sulfur yield was achieved on LaFe0.4Co0.6O3under 220 °C with exceptional catalyst stability (above 95% sulfur yield after 77 h). The catalysts were characterized by XRD, BET, FTIR, XPS, and H2-TPR. The characterization results showed that the structure of LaFexCo1−xO3changed from the rhombic phase of LaCoO3to the cubic phase of LaFeO3with Fe substitution. Doping with appropriate iron (x = 0.4) facilitates the reduction of Co ions in the catalyst, thereby promoting the H2S selective oxidation. This study demonstrates a promising approach for low-temperature H2S combustion with ~100% sulfur yield.Keywords:hydrogen sulfide;selective oxidation;perovskite oxides;oxygen vacancy
Li Guo,Siwei Chen,Yue Jiang,Qihan Ding,Yunfei Yang,Jiali Zhi,Youheng Jia,Xiaoli Li
N and S co-doped porous carbon was prepared by decorating the waste disposable medical masks (WDMM) with thioacetamide (TAA) as the N/S source and then carbonizing at high temperature, which was subsequently incorporated Co-doped LaFeO 3 to obtain NSC@LaFe x Co 1-x O 3 catalysts. The resulting catalysts were used to construct an advanced oxidation process (AOP) based on activation of peroxymonosulfate (PMS) to degrade tetracycline (TC) in water. The physicochemical properties of the as-obtained catalysts were characterized and environmental factors affecting the catalytic performances of NSC@LaFe x Co 1-x O 3 /PMS were systematically investigated. The results showed that N and S co-doped porous carbon derived from thioacetamide (TAA)-functionalized WDMM at high temperature could be used as good support for LaFe x Co 1-x O 3 . The synergistic effects between N/S co-doped carbon and polyvalent metals (Co 2+ /Co 3+ and Fe 3+ /Fe 2+ ) endowed NSC@LaFe x Co 1-x O 3 with enhanced catalytic performances, in which nearly 100% of TC could be removed by NSC@LaFe 0.95 Co 0.05 O 3 /PMS system within 10 min under the conditions of 0.2 g/L of catalyst dose, 2.5 mmol/L of PMS concentration and 10 mg/L of initial TC concentration. Furthermore, the constructed NSC@LaFe 0.95 Co 0.05 O 3 /PMS system exhibited a wider pH adaptability (3.0 ∼ 10.0), good salt resistance and reusability as well as high mineralization. The mechanisms and possible pathways of TC degradation by NSC@LaFe 0.95 Co 0.05 O 3 /PMS system were proposed and the ecotoxicity of TC and its intermediates was also evaluated. This study demonstrated the feasible transformation of waste masks into porous carbon with high added value for water pollution control and remediation, accomplishing the dual purposes of recycling and resource utilization of waste masks and protecting the environment.
To improve the cleaning efficiency of the membranes for wastewater, perovskite LaFe x Co 1-x O 3-λ deposited SiO 2 catalytic membrane (PCM) with functionality of peroxymonosulfate (PMS) induced catalytic oxidation and membrane separation was prepared by employing LaFe x Co 1-x O 3-λ deposited SiO 2 as the functional layer on diatomite support. The perovskite LaFe x Co 1-x O 3-λ deposited SiO 2 functional layer was modified by doping Fe, which contributed to the generation of oxygen vacancies, resulting in the massive generation of singlet oxygen and sulfate radicals during the pollutant degradation processes. Besides, the heterogeneous catalyst was effectively immobilized by PCM, and the mass transfer was enhanced owing to the adequate curved channels and eddy diffusion, performing a preferable catalytic oxidation efficiency and permeability. The water yield and degrading efficiency for tetracycline hydrochloride aqueous solution (20 mg/L) were 1064.5 L/m 2 h and 99%, respectively. Simulated wastewater containing organic pollutant and oil was treated by PCM, demonstrating an attractive separation and catalytic performance. Furthermore, cycling and regeneration test indicated that the PCM exhibited favorable stability and regeneration abilities after 10 consecutive cycles. Therefore, PCM with capacities of separation and catalytic oxidation performed potential application in complex wastewater treatment.
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