Journal of Environmental Chemical Engineering最新文献

In the current CO₂ curing process, pure CO₂ gas with a concentration exceeding 99 % is primarily used. However, flue gas, which typically contains 10–30 % CO₂, can also be utilized for carbonization. This study sought to explore the viability of employing flue gas for carbonation and assessed the impact of impurity gases such as SO₂. Two typical industrial solid wastes (fly ash and coal gangue) were used to substitute a portion of the cement to prepare light aggregates, which were carbonized under varying concentrations of CO₂ and SO₂. The porosity and water absorption of the samples decreased after carbonation. A higher degree of carbonation was observed at increasing CO₂ concentration. Aggregates carbonated with 15 % CO₂ improved the CO₂ absorption by 48 %. The actual CO₂ uptake reached up to 58.3 % of the theoretical value. The presence of SO₂ has been found to impact the uptake of CO₂. The CO₂ uptake initially declined and then increased as the SO₂ concentration increased. The existence of SO₂ led to varied increases in the leaching concentrations of the aggregates following the process of carbonation, and some even exceed standard limits. In the presence of both CO₂ and SO₂, SO₂ reacted with the aggregates, resulting in the creation of calcium sulfate. This reaction disrupted the structure of the aggregate, facilitating the diffusion of CO₂ into the samples.

The widespread use of antibiotics in the medical industry and in animal husbandry has led to significant environmental pollution. Effective purification of high concentrations of tetracycline (TC) in practical pharmaceutical wastewater remains a substantial challenge. The integration of advanced oxidation with membrane separation technology shows great application potential. In this study, a P and N co-doped balsa wood membrane (PNWM) were fabricated using heteroatomic doped biochar material, aiming to synergize filtration and catalytic oxidation. The catalytic activity of the PNWM/peroxymonosulfate (PMS) system was systematically evaluated. Targeting TC as the pollutant, the PNWM/PMS system achieved a degradation efficiency exceeding 97 % within 30 min and a total organic carbon (TOC) removal efficiency of 63.9 %, surpassing the performance of unmodified wood-based membrane. These excellent results were attributed to the doping of N and P atoms, which increased surface defects and specific area, thereby enhancing the adsorption and degradation of TC by PNWM. The graphite N facilitated electron transfer, while pyridine N served as active sites for PMS activation. Additionally, the low electronegativity of the P formed electronic regions of varying intensities on the PNWM surface, contributing to PMS activation. The membrane process also enhanced mass transfer during the degradation process. Both radical (·OH, SO₄·ˉ, O₂·ˉ) and non-radical (¹O₂, electron transfer) pathways cooperated in TC degradation in PNWM/PMS system. Consequently, heteroatom-doped biochar film materials prepared through simple methods provide a promising approach for the effective treatment of refractory organic pollutants in wastewater.

CaO-based sorbents show great promise as materials for CO₂ capture. In this paper, three novel preparation methods were proposed to prepare three sorbent pellets based on carbide slag, respectively. The CO₂ cyclic capture performance of the sorbent pellets was also investigated. These three novel preparations consist of different binders (agar, gelatine) and different hydrophobic materials (silicone oil, liquid paraffin and silicone mold), respectively. The capture performance of these three sorbent pellets was compared with that of sorbent pellet prepared by existing preparation methods, which used agar as a binder and silicone oil as a hydrophobic material. In addition, the effects of the contents of nano-Al₂O₃ supports on the sorbent pellets were explored. Among the four preparation methods, the sorbent pellets prepared with agar as binder and silicone mold as hydrophobic material showed exhibiting the highest total capture capacity of 7.70 gCO₂/g during 15 cyclic captures. The nano-Al₂O₃ was used as support to alleviate the sintering of the sorbent pellets prepared with agar as binder and silicone mold as hydrophobic material, preserving most of the CO₂ diffusion channels. Among the sorbent pellets with varying contents of nano-Al₂O₃ support, the pellets with a 10:100 molar ratio of nano-Al₂O₃ to CaO demonstrated excellent mechanical properties and the highest CO₂ cycle capture performance. These pellets exhibited a capture capacity of 0.626 gCO₂/g on the first cycle, maintaining a capacity of 0.503 gCO₂/g by the 15th cycle. This work introduced a novel method for preparing sorbent pellets of efficient and stable cyclic capture.

This study explores the effectiveness of silicon quantum dots (SiQDs)—specifically, amine-functionalized (NSiQDs) and amine-hydroxyl-functionalized (NOSiQDs)—in optimizing thin-film nanocomposite (TFN) membranes for pervaporation dehydration of various alcohols. The SiQDs were integrated into the membranes via an innovative interfacial polymerization technique, involving the dispersion of SiQDs in an aqueous amine solution followed by polymerization with trimesoyl chloride. This approach ensured uniform integration of SiQDs, significantly enhancing the nanostructure and surface characteristics of the membranes. Such modifications led to improved water transport capabilities, substantially boosting pervaporation efficiency. Exceptional performance was demonstrated by the TFN-NOSiQDs(400) membranes, which achieved a peak permeation flux of 4195.8 g·m⁻²·h⁻¹ and maintained over 99 wt% water concentration in the permeate when tested with a 70 wt% isopropanol/water solution at 25°C. Comprehensive long-term stability assessments confirmed the robustness and consistent functionality of the membranes, highlighting their suitability for industrial applications that demand reliable and efficient alcohol separation processes.

Graphitic carbon nitride (g-C₃N₄) is a metal-free semiconductor material with moderate band gap ranging between 2.4 and 2.8 eV. Due to its certain light absorption performance in the visible light range, g-C₃N₄ material has shown good application prospects in the field of visible light photocatalysis. However, g-C₃N₄ also has defects such as small specific surface area, poor conductivity, low utilization of visible light, and high recombination rate of surface photo-induced electron and hole pairs, resulting in unsatisfactory photocatalytic performance. Therefore, it is necessary to modify g-C₃N₄ to improve its photocatalytic degradation performance. Fenton reaction refers to the process of using Fe²⁺ to activate H₂O₂ to produce highly active •OH radicals, which are then used for efficient oxidation and decomposition of organic pollutants. Therefore, the Fenton effect can be introduced into the modification process of g-C₃N₄. By utilizing the synergistic effect of photocatalytic reaction and Fenton/Fenton-like effect, more active species can be generated simultaneously, thereby achieving the goal of co oxidation and degradation of pollutants. This article reviews the research progress in the use of Fenton/Fenton-like reaction synergistic photocatalysis in the degradation of organic dyes in g-C₃N₄ based composite photocatalysts in recent years. Furthermore, the problems and development prospects of g-C₃N₄ based photocatalysts in pollutant reduction through the use of cooperative effect between the Fenton/Fenton-like reaction and photocatalytic process are discussed.