Correlation among preparation methods/conditions, physicochemical properties, and catalytic performance of Rh/hydroxyapatite catalysts in N 2 O decomposition

Biochar addition under straw return reduces carbon dioxide and nitrous oxide emissions in acidic tea field soil

Straw return and biochar application are prevalent agricultural practices that bolster soil health, enhancing crop yields. However, their synergistic effects on carbon dioxide (CO2) and nitrous oxide (N2O) emissions in the acidic tea field soil at different age stages have not been fully elucidated. Herein, tea field soil with 5 and 15 years planting (5a and 15a, respectively) were individually incubated in five distinct indoor experiments: control, soil with urea (N), soil with urea and biochar (N + C), soil with urea and straw (N + S), and soil with urea, biochar, and straw (N + C + S). The results demonstrated that the pH values under 15a (4.1-5.6) were significantly lower than those under 5a (5.8-7.3), and both straw and biochar addition effectively improved soil acidification. Straw or biochar addition alone acted as carbon sources, leading to heightened N2O and CO2 emissions. N + S increased N2O emissions (3.17 and 5.85-fold) and CO2 cumulative emissions (6.43 and 2.33-fold) under 5a and 15a compared with the control. Relative to N treatment, biochar addition alone increased CO2 emission (1.22 and 1.35-fold) under 5a and 15a, and increased N2O emissions by 14.73% under 5a, decreased N2O emissions by 74.65% under 15a. However, the combined application of straw and biochar reduced N2O (49.4%,17.58%) and CO2 emissions (57.83% and 33.60%) due to stimulating biochar adsorption, respectively, compared with N + S treatment under 5a and 15a. Therefore, biochar and straw addition together can effectively increase soil fertilizer and inhibit greenhouse gas emissions, this study provides an insightful way and effective option for improving acid soil and protecting high soil health with a low greenhouse gas emission intensity.

Hydroxyapatite, a multifunctional material for air, water and soil pollution control: A review

Hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂), a calcium phosphate biomaterial, is a very promising candidate for the treatment of air, water and soil pollution. Indeed, hydroxyapatite (Hap) can be extremely useful in the field of environmental management, due in one part to its particular structure and attractive properties, such as its great adsorption capacities, its acid-base adjustability, its ion-exchange capability and its good thermal stability. Moreover, Hap is able to constitute a valuable resource recovery route. The first part of this review will be dedicated towards presenting Hap's structure and defining properties that result in its viability as an environmental remediation material. The second will focus on its use as adsorbent for wastewater and soil treatment, while indicating the mechanisms involved in this remediation process. Finally, the last part will impart all findings on Hap's applications in the field of catalysis, whether it be as catalyst, as photocatalyst, or as active phase support. Hence, all of the above will have served in showcasing the benefits gained by employing hydroxyapatite in air, water and soil clean-up.

Bimetallic Rh–Fe catalysts for N2O decomposition: effects of surface structures on catalytic activity

Well-homogenized RhFe alloy nanoparticles and core–shell structured Fe@Rh nanoparticles were highly dispersed on SBA-15 and then applied to N₂O catalytic conversion.

Catalytic decomposition of N2O over Rh/Zn–Al2O3 catalysts

Promoted oxygen adsorption–desorption properties of smaller Rh₂O₃ nanoparticles supported on Zn-modified γ-Al₂O₃ result in a superior activity for N₂O decomposition.