The modified ZnGa 2 O 4 microspheres were prepared by the conventional hydrothermal method and used to catalyze methane combustion reaction. Because Co 2+ and Zn 2+ have similar ion radii, so it seems that the Zn 2+ at the tetrahedral (T d ) position of ZnGa 2 O 4 was partially replaced by Co 2+ to adjust the oxygen distribution, and finally the Zn 1-x Co x Ga 2 O 4 (x = 0.1, 0.3) microspheres catalysts was obtained. X-ray photoelectron spectroscopy (XPS) analysis exhibited that Co 3+ were present in the Zn 1-x Co x Ga 2 O 4 (0.1, 0.3) samples, and interstitial oxygen were formed to maintain electrical neutrality. Oxygen temperature programmed desorption (O 2 -TPD) profiles showed that there was only one oxygen species desorption from ZnGa 2 O 4 sample, while the Zn 1-x Co x Ga 2 O 4 (0.1, 0.3) samples had two oxygen desorption peaks, that is the first one is surface adsorbed oxygen, the second is lattice oxygen. The catalytic methane combustion performance of the samples indicated that the partial substitution of Co 2+ for Zn 2+ in ZnGa 2 O 4 can effectively improve its activity.
Bing Ma,Yulong Li,Kui Wang,Xiaoran Dong,Jianzhong Yang,Lie Yang
Biomass, a traditional fuel derived from agricultural sources, offers renewable advantages over fossil fuels and remains widely used for heating, electricity generation, and cogeneration. Lightweight mesoporous particulate matter (LMP) is a by-product generated during the biomass combustion and incineration process. It was found that both metals and environmentally persistent free radicals (EPFRs) in LMP can lead to potential negative health effects. To identify the critical risk sources, in vitro physiological assays were conducted using simulated lung and gastrointestinal fluids to assess the bioaccessibility, distribution of reactive oxygen species (ROS), and oxidative potential of metals bound to LMP. The findings revealed that the bioaccessibility of LMP-bound metals varied depending on the target organ system. Furthermore, LMP-bound metals, rather than EPFRs or ROS inherently produced by LMP, were the primary contributors to the generation of free radicals, particularly superoxide anions. LMP-bound arsenic accounted for the highest health risks, contributing 95.76 % of the total non-carcinogenic risk (0.266) and 99.54 % of the total carcinogenic risk (4.100 × 10⁻⁵). However, at current exposure levels, LMP-bound metals as a whole did not pose significant non-carcinogenic or carcinogenic risks, nor did they induce severe oxidative stress. Our study further clarifies the mechanism of toxicity of pollutants to human health and provides a reliable basis for future protection and regulation.
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