Journal of Environmental Chemical Engineering最新文献

Photocatalytic H₂O₂ production and cleavage of lignin C-C bonds is a typical strategy that follows sustainable development. Unfortunately, the photocatalytic efficiency of these two reactions still faces significant challenges. Herein, a carbon nitride photocatalyst (tri/hep-CN) with sulfur-chloride co-doped triazine and heptazine structures was synthesized. It was simultaneously used for photocatalytic H₂O₂ production and lignin C-C bond cleavage. In the air atmosphere, the yield of H₂O₂ reached 1171.9 μmol•g⁻¹•h⁻¹ after the addition of β-1 lignin model 1,2-diphenylethanol (Dpol) to the solvent. The yield of H₂O₂ increased by 20 times compared with no addition of Dpol. The lignin C-C bond in Dpol is also efficiently broken, producing benzaldehyde and benzyl alcohol. tri/hep-CN has excellent photogenerated carrier separation efficiency and positive valence potential, which improves the photocatalytic H₂O₂ production and lignin C-C bond cleavage performance. Notably, coupling photocatalytic H₂O₂ production with lignin C-C bond cleavage to fully use photogenerated electrons and holes is also very important to obtain outstanding photocatalytic performance. Mechanistic studies have shown that photocatalytic H₂O₂ production follows an indirect reaction mechanism. Meanwhile, the cleavage of lignin C-C bond follows the C_β radical mechanism and the single electron transfer mechanism. This work is very instructive for simultaneous photocatalytic H₂O₂ production and lignin C-C bond cleavage studies.

Exploring new system for chemical recycling of plastic is an effective way to convert plastic waste into energy. Herein, the use of supercritical CO₂ (ScCO₂) to promote the catalytic degradation of polystyrene (PS) with high yield of aromatic oils was proposed. ScCO₂ provided a homogeneous environment for the reaction, which not only facilitated the swelling of PS, but also inhibited the formation of coke, beneficial for the degradation of PS to aromatic oils. In addition, CO₂ as an oxidant reacted with PS or intermediates to generate new products. NiO@C catalyst prepared by doping carbon material in NiO had a simple preparation process, an abundance of porous structure and strong acidic sites, thus improving the catalytic activity. Under the co-action of ScCO₂ and NiO@C, the yield of aromatic oils produced from PS was up to 89.3 ± 0.6 wt% at 300 °C with a reaction time of 2 h and a catalyst loading amount of 10 wt%. Moreover, the NiO@C catalyst was used for three cycles without obvious change in the catalytic performance. The efficient catalytic degradation of PS to aromatic oils by ScCO₂ promoted NiO@C catalysis provides a potential route for simultaneously recycling plastic and sequestering carbon.

Persulfate advanced oxidation technology (PS-AOPs) is known as a novel wastewater treatment method. Considering the poor self-stability of Bi₂O₃/CuBi₂O₄, we synthesized Bi₂O₃/CuBi₂O₄/BiOBr ternary composite material and established the non-radical pathway-dominated peroxymonosulfate (PMS) activation system. The study indicated that BiOBr promoted electron migration on the material surface. Bi₂O₃/CuBi₂O₄/BiOBr/Vis/PMS system exhibited excellent catalytic performance (86.83 % within 100 min), significantly higher than Bi₂O₃/CuBi₂O₄ (63.19 %) and BiOBr (60.35 %). Furthermore, it has strong catalytic activity and adaptability to various environmental conditions. By quenching experiments and EPR analysis, ${\text{O}}_2^{-}\bullet$ and 1O₂ were the main active species. Finally, possible degradation pathways and intermediates were predicted through liquid mass spectrometer (LC-MS), and toxicity analysis was conducted on levofloxacin (Lev) and intermediates. The degradation mechanism may be attributed to the construction of double Z-scheme heterojunction, photogenerated electron transfer and ROS generation through the redox cycle of Cu²⁺/Cu⁺ and Bi⁵⁺/Bi³⁺.

The nanozyme, identified among the top ten emerging technologies in chemistry, has shown rapid development in nano-catalysis for tumour treatment, particularly through its Fenton-like reaction. Herein, a novel iron, nitrogen-doped carbon dots (Fe, N-CDs) with nanozyme catalytic properties was designed, which was then surface-modified onto resorcinol-formaldehyde (RF) resin. Subsequently, a heterogeneous photo-Fenton-like cascade system was constructed to produce and activate photo-generated hydrogen peroxide (H₂O₂) in situ. Within a broad pH range of 5–9, Fe, N-CDs/RF composites demonstrated superior photocatalytic activity compared to RF alone. Under visible light irradiation, degradation of chloroquine phosphate (CQ) was achieved with a degradation rate constant (k) 3.2 times higher than that observed for RF. Active species capture experiments revealed that hydroxyl radicals (•OH) and superoxide radicals (•O₂^-) are crucial in propelling the photocatalytic reaction. Furthermore, Density Functional Theory (DFT) calculations indicated that introduction of nanozymes enhances the transfer of electrons from RF surfaces to Fe, N-CDs, high adsorption ability of Fe, N-CDs towards H₂O₂ (E_ads=-5.45 eV) in the Fe, N-CDs/RF composites was exploited, thereby augmenting their photocatalytic activity. The possible degradation mechanism of CQ was proposed, and environmental toxicity of CQ degradation intermediates was assessed by seed experiments. This study extends the application scope of carbon dot nanozymes in self-sufficient photo-Fenton systems.

A large amount of bischofite is produced in the process of potassium extraction from salt lake, which seriously affects the ionic balance of brine system. In this study, a high-purity magnesia spinel refractory raw material with a spinel-wrapped periclase structure was directly prepared using bischofite by a precipitation-sintering approach. A coupling process of one-time crude magnesium chloride solution recrystallization and three-time precipitates washing was employed to remove crucial impurities (sodium, potassium, boron, etc.) and prepare the magnesium hydroxide precipitates with a high purity of 99.37 %. The lightly calcined magnesia gained from the high-purity magnesium hydroxide precipitates and white corundum were then employed for preparing the refractory raw materials. The effects of particle size and dosage of white corundum on the phase distribution, microstructure, and physical properties of the materials were thoroughly studied. The results illustrated that the prepared refractory raw materials were mainly composed of periclase and spinel phases, showing a distinct spinel-wrapped periclase structure that could enhance the physical properties. Therefore, the prepared refractory raw materials showed a high bulk density of 3.46 g·cm⁻³, a low apparent porosity of 2.46 %, and a linear shrinkage rate of 12.33 %, under the optimum conditions of white corundum particle size of 3.00 μm and alumina/magnesia mass ratio of 3:10.

The sustainable remediation of chromium (Cr) contaminated sites is of concern. Although electrokinetic remediation is a promising remediation technology, Cr(III) removal has been hindered by its low mobility. Conventional enhancement techniques are costly and environmentally risky. Therefore, this work attempts to establish a sustainable three-dimensional electrokinetic remediation (3D-EKR) system for the effective removal of Cr in a low-voltage electric field (0.2 V/cm). The Mn/NH₂-functionalized particle electrodes (Mn/NH₂-GAC) with the synergistic effects of adsorption and oxidation were prepared. Two groups of treatments were conducted, one using commercial activated carbon (3D-EKR) and the other using Mn/NH₂-GAC (Mn/NH₂-3D-EKR). The total Cr removal efficiency was up to 91.50 %, and the Cr(III) leaching toxicity decreased by 78.57 %. The Cr(III) removal of Mn/NH₂-3D-EKR was almost twofold that of 3D-EKR, while the cost and greenhouse gas emissions per unit mass of Cr(III) removal were only half of those of 3D-EKR. The environmental impacts were determined through a life cycle assessment (LCA), which revealed that the remediation process can be considered environmentally friendly. Batch experiments and characterization analyses reveal that the Cr removal was the result of a synergistic effect of electromigration, adsorption, and redox processes. The final in-situ removal of Cr was achieved by separating the Mn/NH₂-GAC from the soil. The synergistic remediation of Cr-contaminated sites by oxidation and adsorption provides a sustainable option for the reduction of Cr toxicity.

The electrochemical degradation of Amoxicillin (AMOX), Ciprofloxacin (CIP), and Streptomycin (STR) utilizing Boron-Doped Diamond Electrodes (BDD) was explored under varying levels of applied electrical current density and initial buffer acidity. These pharmaceuticals were carefully selected to showcase the efficiency of electrochemical oxidation across different major chemical structure antibiotic families. The results demonstrated a positive correlation between higher applied current density and the elimination of antibiotics, as well as enhanced chemical oxygen demand (COD) removal rate. However, a negative impact was observed on the specific energy consumption (SEC). Notably, the highest antibiotics and COD removal efficiencies, along with the lowest SEC, were achieved at an applied current density of 45 mA/cm². Furthermore, the investigation highlighted the significant influence of the chemical structure of the selected antibiotics on their degradation process. At a current density of 15 mA/cm² and after 24 minutes of treatment, the degradation order was found to be AMOX > CIP > STR, with respective antibiotic removal efficiencies of 98.5 %, 87.8 %, and 81.1 %. Similarly, after 90 minutes of treatment, the COD degradation efficiency followed the order AMOX (50.4 %) > CIP (47.3 %) > STR (44.6 %), accompanied by decreasing levels of specific energy consumption, measuring 59, 61, and 67 kWh/kg COD, respectively, with an average current efficiency of 23–26 %. The pH had a significant effect on the streptomycin degradation rate, while it had a negligible impact on the degradation rate of ciprofloxacin. These findings shed light on the critical role of the pharmaceuticals' chemical structures and environmental conditions in governing the efficiency of their electrochemical degradation.

Hydrogen peroxide (H₂O₂) is vital in versatile applications and has attracted significant attention. Carbon-based semiconductors are recognized as promising candidates for photocatalytic (PC) H₂O₂ synthesis. This review provides a comprehensive overview of the latest advancements in PC H₂O₂ production, focusing on systems such as metal-organic frameworks (MOFs), graphite carbon nitride (CN), and covalent organic frameworks (COFs). It delves into the fundamental mechanisms of PC H₂O₂ generation, mainly through oxygen reduction and water oxidation reactions. It discusses various modification approaches to enhance the separation and transportation of photoinduced charge carriers in these materials. Additionally, the review explores the challenges and future opportunities within this field. In light of the growing interest in environmentally friendly and cost-effective methods of H₂O₂ production, this review emphasizes the necessity of a detailed examination of carbon-based photocatalysts capable of meeting these demands. By consolidating current research, identifying gaps, and highlighting the importance of further innovation, this review aims to advance the development of economically viable carbon-based photocatalysts. The insights are expected to guide future research and development efforts, ultimately contributing to the advancement of sustainable H₂O₂ production technologies.

Pollution of water with antibiotics is a very serious global issue. So, simple, fast, and ecofriendly detection of such pollutants in aqueous environments has aroused great attention. Several intriguing properties such as narrow emission band, large stokes shift, long luminesce decay time and resistance to photobleaching distinguishes europium-based materials from commonly used fluorophores in biology as a superior optical smart material for applications in diverse fields. Herein, strongly luminescent Eu³⁺-induced polyelectrolyte nanoaggregates (EINAP) were synthesized and successfully characterized. The biocompatible polysaccharides hyaluronic acid and chitosan are used to disperse organic europium complexes resulting in formation of hybrid nanoaggregates. As synthesized EINAP demonstrated excellent quantum yield (89.29 %) and luminescence lifetime (656 µs). The EINAP also have high sensitivity and low limit of detection with good analytical precision for nitrofuran antibiotics in aqueous environments. The luminescent nano sensor developed in this work could be a novel tool for assessment of antibiotic pollution in the environment. The overall sensing mechanisms for detection of nitrofurans in aqueous environments were found to be the combination of inner filter effect and photoinduced electron transfer respectively.