Impact of Cadmium Contamination on Fertilizer Value and Associated Health Risks in Different Soil Types Following Anaerobic Digestate Application.

Cadmium (Cd) contamination in the soil potentially hampers microbial biomass and adversely affects their services such as decomposition and mineralization of organic matter. It can reduce nitrogen (N) metabolism and consequently affect plant growth and physiology. Further, Cd accumulation in plants can pose health risks through vegetable consumption. Here, we investigated consequences of Cd contamination on fertilizer value and associated health risks following the application of biogas residues (BGR) to various soil types. Our results indicate that the application of BGR to all soil types significantly increased dry matter (DM) yield and N uptake. However, the Cd contamination negatively affected DM yield and N recovery from BGR in a dose-dependent manner. Organic N mineralization from BGR also decreased in Cd-contaminated soils. The highest DM yield and N recovery were recorded in sandy soil, whereas the lowest values were observed in clay soil. Cadmium was accumulated in spinach, and health risk index (HRI) associated with its dietary intake revealed that consuming spinach grown in Cd-contaminated soil, with or without BGR, is unsafe. Among the soil types, values of daily intake of metals (DIM) and HRI were lowest in clay soil and highest in sandy soil. However, the application of BGR curtailed HRI across all soil types. Notably, the application of BGR alone resulted in HRI values < 1, which are under the safe limit. We conclude that soil contamination with Cd reduces fertilizer value and entails implications for human health. However, the application of BGR to the soil can decrease Cd effects.

Insight into UV-induced simultaneous photocatalytic degradation of Ti3C2Tx MXene and reduction of U(VI).

With the development of MXene as the efficient adsorbent for U(VI), the tendency of MXene coming into contact with U(VI) in wastewaters increases. Motivated by UV light irradiation applied in wastewater treatments, the UV light induced photochemical co-transformation of Ti3C2Tx MXene and U(VI) is studied. To clarify the role of U(VI) induced Ti3C2Tx aggregation in phototransformation of Ti3C2Tx, the aggregation kinetics of Ti3C2Tx in the presence of various valent radioactive ions are investigated, obtaining the critical coagulation concentrations (CCC) of Ti3C2Tx for Cs+, Sr2+, UO22+, Eu3+, and Th4+. Besides, the colloidal stability of UV-induced Ti3C2Tx as a function of standing time is discussed. The results show that the aggregation behavior of Ti3C2Tx induced by radioactive ions follows the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory and the Schulze-Hardy rule. The UV irradiation will change the physicochemical properties and colloidal stabilities of Ti3C2Tx. Furthermore, the degradation of Ti3C2Tx can be accelerated by UV irradiation and further promoted by the presence of U(VI). The removal of U(VI) is highest in the case of Ti3C2Tx combined with UV irradiation via adsorption and reduction. This study provides an example demonstrating that the simultaneous transformation of Ti3C2Tx (adsorbent) and U(VI) (adsorbate) to mild toxic components.

Impact of Bi Doping into Boron Nitride Nanosheets on Electronic and Optical Properties Using Theoretical Calculations and Experiments.

In the present work, boron nitride (BN) nanosheets were prepared through bulk BN liquid phase exfoliation while various wt. ratios (2.5, 5, 7.5 and 10) of bismuth (Bi) were incorporated as dopant using hydrothermal technique. Our findings exhibit that the optical investigation showed absorption spectra in near UV region. Density functional theory calculations indicate that Bi doping has led to various modifications in the electronic structures of BN nanosheet by inducing new localized gap states around the Fermi level. It was found that bandgap energy decrease with the increase of Bi dopant concentrations. Therefore, in analysis of the calculated absorption spectra, a redshift has been observed in the absorption edges, which is consistent with the experimental observation. Additionally, host and Bi-doped BN nanosheets were assessed for their catalytic and antibacterial potential. Catalytic activity of doped free and doped BN nanosheets was evaluated by assessing their performance in dye reduction/degradation process. Bactericidal activity of Bi-doped BN nanosheets resulted in enhanced efficiency measured at 0-33.8% and 43.4-60% against S. aureus and 0-38.8% and 50.5-85.8% against E. coli, respectively. Furthermore, In silico molecular docking predictions were in good agreement with in-vitro bactericidal activity. Bi-doped BN nanosheets showed good binding score against DHFR of E. coli (- 11.971 kcal/mol) and S. aureus (- 8.526 kcal/mol) while binding score for DNA gyrase from E. coli (- 6.782 kcal/mol) and S. aureus (- 7.819 kcal/mol) suggested these selected enzymes as possible target.

Unveiling land footprint of solar power: A pilot solar tower project in China.

Land occupation by solar power installations has become a rising concern that may cause adverse impacts on natural ecosystems and biodiversity. Existing studies mainly adopt a local perspective to view land use requirements of solar power and forget that the solar-based electricity system is subordinate to the macro economy and nourished by the material, machinery and service support by various economic sectors. To manifest a key aspect of the footprint of solar power on land resources, this study uncovered the extensive industrial land use initiated by the infrastructure of a representative pilot solar-based electricity plant using a systems perspective. The results in this study show that in magnitude, land footprint by the infrastructure of the pilot solar plant amounts to three times as much as the onsite land area. Also, the land footprint calculated is revealed as one order of magnitude larger than a previous finding that includes primary materials only, and four to seven times higher than the onsite land use by coal-based electricity plants. The outcome implies that existing environmental management policies need to be re-evaluated by putting enough emphasis on the land displacement by solar power systems along the production chain.

High Performance Tandem Solar Cells with Inorganic Perovskite and Organic Conjugated Molecules to Realize Complementary Absorption.

All-inorganic halide perovskite solar cells (PerSCs) have achieved rapid development in recent years. However, limited by narrow absorption bands, the power conversion efficiency (PCE) of all-inorganic halide PerSCs lag behind the organic-inorganic hybrid ones. In this contribution, to expand their absorption spectra and enhance the PCE, tandem solar cells (TSCs) with inorganic perovskite and organic conjugated molecules are constructed, utilizing CsPbI2Br as an ultraviolet-visible light absorber and a PTB7-Th:IEICO-4F bulk-heterojunction (BHJ) active layer as a near-infrared light absorber. To physically and electronically connect the front and rear subcells, P3HT/MoO3/Ag/PFN-Br is introduced as an interconnecting junction. Finally, the TSCs exhibit a remarkably higher PCE of 17.24% compared to that of the single junction PerSCs (12.09%) and organic solar cells (OSCs) (10.89%). These results indicate that the combination of all-inorganic perovskite and a low bandgap organic active layer for TSCs is a feasible approach to realize broad spectra utilization and efficiency enhancement.

A simple method for preparing ultra-light graphene aerogel for rapid removal of U(VI) from aqueous solution.

In this study, graphene aerogel (GA) was successfully prepared through a simple hydrothermal method. The resulting GA exhibited a porous network structure with a large specific surface area (350.8 m2/g), ultra-light mass and easy separation from water. The pHIEP value of the GA was estimated to be 3.5. The adsorption process and the factors that affect adsorption capacity were studied. The adsorption could be conducted in a wide pH range from 2.0 to 7.0. The maximum adsorption capacity of GA towards U(VI) at pH 4.0 and T = 298 K was 238.67 mg/g calculated from the Langmuir model. The GA had greatly rapid adsorption property for the removal of U(VI) at pH 4.0. Kinetic data showed good correlation with pseudo-second-order equation. Fourier transform infrared spectroscopy and X-ray photoelectron spectrometry characterizations showed that GA adsorbed U(VI) through chemical interaction by oxygen-containing and nitrogen-containing groups functional groups. The results show that GA has excellent application potential as an adsorbent material for removing U(VI) from aqueous solution.

Gamma-ferric oxide nanoparticles decoration onto porous layered double oxide belts for efficient removal of uranyl.

Layered double oxides (LDO) and γ-Fe2O3 have been demonstrated to be promising adsorbents to remove radioactive elements from aqueous media. Herein, magnetic γ-Fe2O3 nanoparticles decoration onto porous layered double oxides belts (γ-Fe2O3/LDO) were fabricated by in situ solid-state thermolysis technique combined with Fe(III)-loaded layered double hydroxides as a precursor. The microstructure, chemical composition, and magnetic properties of γ-Fe2O3/LDO were characterized in detail. The as-obtained γ-Fe2O3/LDO was employed as an adsorbent for the elimination of U(VI) from water. The adsorption process followed the Langmuir model with the maximal adsorption capacity of U(VI) onto γ-Fe2O3/LDO being 526.32 mg·g-1 at 303 K and pH 5, which surpassed pristine LDO and many other materials. The Fourier transformed infrared spectra and the X-ray photoelectron spectra analysis suggested that the interaction mechanism was mainly controlled by the surface complexation and electrostatic interactions. All in all, the γ-Fe2O3/LDO with remarkable adsorption capacity, excellent regeneration, and easy magnetic separation opens a new expectation as a suitable material for the cleanup of U(VI) from contaminated water.

Layered Heterostructures of Ultrathin Polymeric Carbon Nitride and ZnIn2 S4 Nanosheets for Photocatalytic CO2 Reduction.

The rational construction of heterostructures by using layered semiconductors with two-dimensional (2D) nanosheet configurations is promising to improve the efficiency of CO2 photoreduction. Herein, the fabrication of layered heterojunction photocatalysts (PCN/ZnIn2 S4 ) by in situ growth of 2D ZnIn2 S4 nanosheets on the surfaces of ultrathin polymeric carbon nitride (PCN) layers is presented for greatly enhanced CO2 conversion with visible light. The solution-processed self-assembly strategy renders the building of uniform and intimate junctions between PCN layers and ZnIn2 S4 subunits, which remarkably accelerates the separation and transfer of photogenerated charge carriers. In addition, the layered composites can also promote CO2 adsorption and strengthen the visible-light absorption. Consequently, the optimized PCN/ZnIn2 S4 sheet-shaped composite shows reinforced photoactivity for deoxygenative CO2 conversion, affording a high CO-production rate of 44.6 µmol h-1 , which is 223 times higher than that of the pristine PCN nanosheets. Moreover, the heterojunction photocatalyst also exhibits high stability during repeated runs for five cycles.

Modulating Crystallinity of Graphitic Carbon Nitride for Photocatalytic Oxidation of Alcohols.

Exploiting efficient photocatalysts with strengthened structure for solar-driven alcohol oxidation is of great significance. The photocatalytic performance of graphitic carbon nitrides can be considerably promoted by modulating its crystallinity. Results confirmed that a high crystallinity accelerates the separation and transfer of photogenerated charge carriers, thus providing more free charges for photoredox reactions. More importantly, the high crystallinity facilitated the adsorption of benzyl alcohol and desorption of benzaldehyde and simultaneously lowered the energy barrier for O2 activation. As a result, the crystalline carbon nitride exhibited a roughly twelvefold promotion with respect to the normal carbon nitride. The remarkable enhancement of activity can be attributed to the synergistic effects of increased electron-hole separation and increased surface reaction kinetics. These findings will open up new opportunities to modulate the structure of polymers for a wide variety of organic reactions.