Search

VOCs can be used instead of ammonia as a reducing agent to remove NO, achieving the effect of removing VOCs and NO simultaneously. Due to the high energy consumption and low photocatalytic efficiency required for conventional thermocatalytic purification, photothermal coupled catalytic purification can integrate the advantages of photocatalysis and thermocatalysis in order to achieve the effect of pollutants being treated efficiently with a low energy consumption. In this study, samples loaded with Co and Mn catalysts were prepared using the hydrothermal method on Fe-MOF with various morphologies. The catalytic performance of each catalyst was analyzed by studying the effects of their physicochemical properties through various characterizations, including XRD, SEM, BET, XPS, H2-TPR, TEM and O2-TPD. The characterization results demonstrated that the specific surface area, pore volume, high valence Co and Mn atoms, surface adsorbed oxygen and the abundance of oxygen lattice defects in the catalysts were the most critical factors affecting the performance of the catalysts. Based on the results of the performance tests, the catalysts prepared with an octahedral-shaped Fe-MOF loaded with Co and Mn showed a better performance than those loaded with Co and Mn on a rod-shaped Fe-MOF. The conversions of acetone and NO reached 50% and 64%, respectively, at 240 °C. The results showed that the catalysts were capable of removing acetone and NO at the same time. Compared with the pure Fe-MOF without Co and Mn, the loaded catalysts showed a significantly higher ability to remove acetone and NO simultaneously under the combination of various factors. The key reaction steps for the catalytic conversion of acetone and NO on the catalyst surface were investigated according to the Mars–van Krevelen (MvK) mechanism, and a possible mechanism was proposed. This study presents a new idea for the simultaneous removal of acetone and NOx by photothermal coupling. [ABSTRACT FROM AUTHOR]

The substitution of ethyl acetate for ammonia in NH3-SCR provides a novel strategy for the simultaneous removal of VOCs and NO. In this study, three distinct types of biochar were fabricated through pyrolysis at 700 °C. MnOx and TiO2 were sequentially loaded onto these biochar substrates via a hydrothermal process, yielding a family of biochar-based catalysts with optimized dosages. Upon exposure to xenon lamp irradiation at 240 °C, the biochar catalyst designated as 700-12-3GN, derived from Ginkgo shells, demonstrated the highest catalytic activity when contrasted with its counterparts prepared from moso bamboo and loofah. The conversion efficiencies for NO and ethyl acetate (EA) peaked at 73.66% and 62.09%, respectively, at a catalyst loading of 300 mg. The characterization results indicate that the 700-12-3GN catalyst exhibits superior activity, which can be attributed to the higher concentration of Mn4+ and Ti4+ species, along with its superior redox properties and suitable elemental distribution. Notably, the 700-12-3GN catalyst has the smallest specific surface area but the largest pore volume and average BJH pore size, indicating that the specific surface area is not the predominant factor affecting catalyst performance. Instead, pore volume and average BJH pore diameter appear to be the more influential parameters. This research provides a reference and prospect for the resource utilization of biochar and the development of photothermal co-catalytic ethyl acetate and NO at low cost. [ABSTRACT FROM AUTHOR]

In this study, the degradation system of Shewanella oneidensis MR-1 and goethite was constructed with chlorpyrifos as the target contaminant. The effects of initial pH, contaminant concentration, and temperature on the removal rate of chlorpyrifos during the degradation process were investigated. The experimental conditions were optimized by response surface methodology with a Box–Behnken design (BBD). The results show that the removal rate of chlorpyrifos is 75.71% at pH = 6.86, an initial concentration of 19.18 mg·L−1, and a temperature of 30.71 °C. LC-MS/MS analyses showed that the degradation products were C4H11O3PS, C7H7Cl3NO4P, C9H11Cl2NO3PS, C7H7Cl3NO3PS, C9H11Cl3NO4P, C4H11O2PS, and C5H2Cl3NO. Presumably, the degradation pathways involved are: enzymatic degradation, hydrolysis, dealkylation, desulfur hydrolysis, and dechlorination. The findings of this study demonstrate the efficacy of the goethite/S. oneidensis MR-1 complex system in the removal of chlorpyrifos from water. Consequently, this research contributes to the establishment of a theoretical framework for the microbial remediation of organophosphorus pesticides in aqueous environments. [ABSTRACT FROM AUTHOR]

Noble metal materials have been identified as high efficiency catalysts for electrocatalytic reduction of nitrate, and the synthesis and manufacture of high catalytic activity and environmentally friendly catalysts of activating hydrogen for water purification applications is extremely attractive. In this work, the Pd–Cu single-atom catalysts (Pd–Cu-N-BC) were first prepared by direct growth of Pd–Cu single-atom on bamboo biochar by regulating the concentration of precursors and doping method, and then enhanced electrocatalytic reduction nitrate performance and N2 generation. The results showed that Pd–Cu-N-BC displayed excellent catalytic activity and reusability in electrocatalytic reduction nitrate with a low potential of 0.47 V vs. RHE (@10 mA cm−2). The maximum nitrate removal efficiency and N2 generation could reach about 100% and 72.32% within 180 min, respectively. The density functional theory (DFT) calculations confirmed that Cu atoms could catalyze the electrochemical reduction of nitrate to nitrite, and Pd atoms anchored in the nitrogen-doped biochar (N-BC) lattice could catalyze electrochemical reduction of nitrite to N2 involving the formation of hydrogen radical (H*). The characterization results of XANES showed that electronic synergistic effect between Pd and Cu single atoms significantly promotes the N2 production through hydrogenation while inhibiting the generation of byproducts, leading to significantly enhanced electrocatalytic reduction of nitrate to N2. Finally, Pd–Cu-N-BC was designed as a 3D particle electrode for enhanced electrocatalytic reduction of nitrate, exhibiting excellent stability and reusability, which could be considered as a suitable candidate for applications in the remediation of nitrate contamination. Highlights: Excellent-active and N2 selective Pd–Cu-BC SACs were prepared through bamboo biochar; A typical three-dimensional electrocatalytic NO3-Nreduction system was proposed; N doping could reasonably modulate the electronic structure of Pd and Cu sites; Free radical (H*) played an important role in the nitrate electro-chemical reduction; Synergy between Pd and Cu in SACs could enhance NO3-N removal and N2 generation. [ABSTRACT FROM AUTHOR]

To clarify the buffering process and karst carbon sink effect of the karst soil with acid rain, experiments on the leaching of sulfuric acid rain were conducted at pH 3.5, 4.5, and 6.5 with different karst soil thicknesses. The buffering process of karst soil on acid rain occurred in the topsoil. During strong acid precipitation, the soil-exchangeable calcium and magnesium were predominantly exchanged with H+ in acid rain, while during weak acid precipitation, the amount of calcium and magnesium exchanged with H+ in acid rain was lower than the H+ generated via dissociation of soil CO2 dissolved in the precipitation. At pH 3.5, 4.5, and 6.5 precipitations, the δ13CDIC value in the leached liquid ranges from − 18.9 to − 14.2‰, − 19.0 to − 13.2‰, and − 12.0 to − 7.1‰, respectively, and with increasing precipitation intensity, the δ13CDIC value was increased, relatively stable, and decreased, respectively. A total of 74% of dissolved inorganic carbon (DIC) in the leached liquid was from soil CO2. In the karst soil area (soil thickness ≥ 10 cm), soil-exchangeable calcium and magnesium can buffer 33,303–336,987 mm in pH 3.5 precipitation and 145,701–371,550 mm in pH 4.5 precipitation, while the soil buffer in pH 3.5 precipitation can generate 0.22–1.04 mol m−2 carbon sink per year, and 0.39–0.64 mol m−2 carbon sink per year in pH 4.5 precipitation. [ABSTRACT FROM AUTHOR]