Ping Ning

Recovering copper (Cu) from strongly acidic copper wastewater (SACW) is essential for resource sustainability and environmental preservation, but conventional technologies bear high economic costs and generate secondary pollution. Here, we demonstrate a biomass waste-mediated hydrothermal reduction process that simultaneously removes and recovers Cu as metallic Cu from SACW. The process operates under mild conditions (180 °C, 7 h) and achieves over 99% removal of Cu(II) across a wide concentration range, directly reducing Cu(II) to metallic Cu(0) without incorporation into hydrochar. Notably, the liquid products from biomass hydrothermal treatment, particularly 2-furoic acid, served as electron donors for Cu(II) reduction, with its C2/C3 atoms potentially providing electron transfer channels that drive the stepwise reduction of Cu(II) to Cu(0). In a 5 L pilot test with two types of industrial wastewater, the technology achieved >99% Cu(II) removal (residual <0.5 mg/L) and recovered metallic Cu with a purity of 99.9% after simple calcination. Life-cycle assessment and technoeconomic analysis highlight superior economic and environmental benefits when treating high-concentration copper-containing wastewater, establishing a sustainable, generalized hydrothermal reduction platform for efficient Cu recovery from industrial wastewaters. This work establishes a chemistry-driven paradigm for sustainable wastewater treatment, enabling efficient circular recovery of high-value resources from acidic metal-containing wastewaters.

Regulating the size of active centers in catalysts exerts a profound effect on their activity and selectivity. Here, we demonstrate a strategy for precise control over the size of Ag species on Al₂O₃, enabling the 2%Ag/Al₂O₃ catalyst to be tailored for various catalytic reactions. Building on the mechanism wherein hydroxyl groups serve as anchoring sites for Ag, we synthesized hydroxyl-rich Al₂O₃ supports and subsequently reduced the hydroxyl content through roasting. This approach allowed Ag species to exist on the Al₂O₃ surface as isolated atoms, clusters, or nanoparticles. As the Ag size increased from single atoms to clusters and nanoparticles, the catalyst's O₂ activation ability was progressively enhanced, leading to significant performance variations in the O₂-involved reactions. Notably, the synthesis of this hydroxyl-rich support is facile and reproducible. Our findings offer valuable insights into the rational design of supported Ag catalysts with controllable active center sizes for diverse catalytic applications.

A crown ether–ionic liquid functionalized ion-exchange membrane was developed for selective Li ⁺ /Mg ²⁺ separation in electrodialysis, achieving a Li ⁺ /Mg ²⁺ selectivity of 10.45 at pH 7.5 with enhanced permeability, pH responsiveness, and stability.

In pursuing sustainable environmental solutions, the concept of ‘waste to treasure’ has emerged as a promising approach. In this study, a new process is proposed to combine solid copper slag with hydrogen peroxide (H₂O₂) to remove nitrogen oxides (NOx) from acidic exhaust gases, thus effectively utilizing waste materials. Firstly, different smelting slags were screened to determine the catalytic potential of copper slag for hydrogen peroxide. Subsequently, the catalytic activity of the copper slags at various stages of the copper smelting process was thoroughly evaluated and optimized. In addition, a multifactorial evaluation of slow-cooled copper slag catalysts for removing NOx was carried out. Preliminary indications are that the iron phase in the copper slag is identified as the main source of catalytic activity sites. The results suggest that Fe²⁺/Fe³⁺ sites on the surface of the Fe phase in the slow-cooled copper slag may be crucial in improving the NOx removal efficiency. The main reactive oxygen species detected in the system were ·OH, ·O₂⁻, and ¹O₂. In addition, the transformation products, formation pathways, and reaction mechanisms of NO in the liquid phase were initially investigated and determined. This study provides a green and sustainable path for the utilization of solid waste and management of atmospheric fumes in the non-ferrous metal industry and offers new perspectives to address environmental challenges in industrial processes.

Herein, targeting arsenic-containing acidic wastewater generated from washing arsenic-containing flue gas with concentrated sulfuric acid, the arsenic removal efficiency using H₂S was investigated. The effects of H₂S concentration, the gas flow rate, H₂SO₄ concentration, temperature, and Cl⁻/F⁻ ions on arsenic removal were studied. Results indicate that H₂S concentration is the primary factor. Arsenic was precipitated as amorphous As₂S₃, reducing residual arsenic to 0.28 mg/L. Cl⁻ enhanced arsenic removal, yielding a residual concentration of 0.68 mg/L, while F⁻ exhibited a dual effect: the inhibition at low concentrations and promotion at high concentrations. At 100 g/L F⁻, the residual arsenic was 29.59 mg/L. These effects are attributed to Cl⁻/F⁻ altering the surface electrochemical properties of As₂S₃ particles. Additionally, both ions improved As₂S₃ hydrophobicity. This study provides insights for purifying arsenic-containing sulfuric acid.

The present paper proposes an advanced process to effectively recover and fully use iodine from steel dust-derived zinc suboxide, with considerations of effectiveness in the process and industrial viability. It includes, for example, alkali wash for the dissolution of iodine into an alkaline solution from steel dust and uses mechanical vapor recompression (MVR) to concentrate the dissolved iodine by preparing the solution for the air-blowing-out process. The hydrogen iodide is also oxidized under acidic conditions with the addition of hydrogen peroxide to form crude iodine, estimated at about 20 tons annually. As a matter of fact, using this process, up to 1.2 million tons of steel waste dust can be treated in a year, turning what was previously considered waste into something of value. The thermodynamic relationship between iodine recovery and pH value is further discussed in this study, pointing out that under alkaline conditions, iodine is predominantly in the form of iodide (I⁻) and iodate (IO₃⁻), while at less than pH 2.8, it is in its molecular form I₂. These insights would provide a theoretical backbone for maximum extraction efficiency, guiding process parameters toward optimum recovery and judicious use of the resource.