This study investigated the behavior and environmental impact of expanded polystyrene (EPS) in a simulated marine environment, focusing on the effects of UV exposure. Through a series of controlled experiments, it was found that UV-induced weathering increased the formation of smaller EPS degradation products, leading to higher concentrations of dissolved organic carbon (DOC) in the seawater. Additionally, it was suggested that the assembly behavior of dissolved organic matter (DOM) contributed to the reduction of DOC levels over time. The EPS layer exhibited slightly higher DOC concentrations compared to the seawater, likely due to hydrophobic interactions that retained degradation products near the EPS. Analysis of the soil layer revealed that EPS particles and degradation products settled or adsorbed more extensively under UV conditions, indicating a greater risk of sediment contamination. Soil layer elution experiments further confirmed that EPS particles and their degradation products could migrate through soil pores, posing a potential contamination risk to other environments. UV exposure resulted in a twentyfold increase in DOC release from EPS compared to dark conditions. These findings highlight the persistent pollution potential of EPS in marine environments, especially under UV exposure, and emphasize the need for effective EPS waste management and further research into its environmental impacts.

해양경찰청 경비함정의 선박용 디젤기관은 MTU와 Pielstick사의 고출력 엔진으로 윤활유의 성능이 매우 중요하다. 경비함정 엔 진의 부하변동이 많고 운행시간 등이 증가되면서 열에 의한 산화 및 연료유, 수분 등 혼입으로 동점도 등 윤활유 성질이 변할 수 있다. 본 연구에서는 윤활유의 열화요인 및 영향을 파악하기 위해 경비함정 윤활유를 사용 시간별(100, 200, 300, 400 hr)로 채취하였다. 채취된 윤활유로 열화요인 분석 위해 연료 혼입량 등을 측정하였다. 또한 열화 영향 분석을 위해 동점도 등을 측정하였다. 특히 윤활유의 산화 여부를 분석하기 위해 산화 안정도 등을 확인하였다. 열화의 외부요인인 연료 혼입량의 경우 사용 시간이 늘어나면서 5.1%에서 14.0%로 증가하였으며, 이에 따라 동점도는 낮아지는 결과를 보였다. 윤활유의 사용 시간이 늘어나면서 열 및 수분 혼입에 의한 산화는 확인할 수 없었다.

Hot section components of gas turbines are exposed to a high operating temperature environment. To protect these components, thermal barrier coatings (TBC) are applied to their surfaces. Yttria-stabilized zirconia (YSZ), which is widely used as a TBC material, faces limitations at temperatures above 1200 °C. To mitigate these issues, research has focused on adding lanthanide rare earth oxides and tetravalent oxides to prevent the phase-transformation of the monoclinic phase in zirconia. This study investigated the effects of varying TiO2 content in Nd2O3 and Yb2O3 co-doped YSZ composites. Increasing TiO2 content effectively suppressed formation of the monoclinic phase and increased the thermal degradation resistance compared to YSZ in environments over 1200 °C. These findings will aid in developing more thermally stable and efficient TBC materials for application in high-temperature environments.

본 연구는 대기 중 장기간 노출로 인해 열화된 Ni-rich NCM811(LiNi₀.₈Co₀.₁Mn₀.₁O₂) 양극 소재의 계면 저항 증가 및 전기화학적 성능 저하 문제를 해결하기 위해, 물리적 열처리 방법을 제안하였다. NCM811 양극 소재는 대기 중 수분 및 이산화탄소와의 반응에 의해 표면에 불순물이 형성되기 쉬우며, 이는 고체전해질과의 계면 저항을 증가시켜 전고 체전지 시스템에서의 성능 저하를 초래한다. 이러한 문제를 해결하기 위해, 열화된 NCM811 양극 소재를 O₂ 분위기 에서 열처리하여 표면의 불순물을 효과적으로 제거하고 양극 표면의 전도성을 향상시킴으로써, 양극-고체전해질 간의 계면 저항을 현저히 감소시키는 결과를 얻었다. SEM, XRD, ICP 분석을 통해 열화된 NCM811 양극 소재의 표면 특성 변화를 분석하였으며, 열처리 후 NCM811 소재의 계면 특성이 개선됨에 따라 전기화학적 성능 또한 상용 NCM811 소재와 유사한 수준으로 회복되는 것을 확인하였다. 특히, O₂ 분위기의 물리적 열처리 방법은 Ni-rich NCM811 양극 소재의 열화를 효과적으로 억제하고 고체전해질과의 계면 접촉을 개선하여, 황화물계 전고체전지의 전기화학적 성능 을 획기적으로 향상시킬 수 있는 유망한 기술임을 입증하였다. 이러한 결과는 전고체전지 상용화를 위한 핵심 전략으 로 적용될 수 있을 것으로 기대된다.

Activated carbon has broad application prospects for treating pollutants due to its easy availability, low cost and good adsorption. In our work, nano-activated carbons (NAC) with abundant functional groups are obtained by the oxidation modification of HNO3, ( NH4)2S2O8, and KMnO4, which are used to construct the particle electrodes to degrade NDEA in a continuous flow electrochemical reactor, and the influence of relevant factors on the performance of NDEA removal is discussed. The experimental data show that the optimal degradation efficiency is 42.55% at the conditions of 3 mL/min influent water flow, 0.21 M electrolyte concentration, 10 mA/cm2 current density, and 10 μg/mL initial NDEA concentration. The degradation of NDEA conforms to a quasi second order kinetic equation. The electrocatalytic mechanism of NAC electrodes for removing NDEA is firstly discussed. The effects of different free radicals on the degradation of NDEA are also demonstrated through free radical quenching experiments, indicating that the degradation of NDEA is dominated by ⋅OH. The degradation pathway of NDEA and final products are obtained using GC–MS. NAC particle electrodes as the cheap and efficient electrocatalyst in continuous flow electrochemical reactor system provide a greener solution for the removal of disinfection by-products from drinking water.

Hydrothermal and ultrasonic processes were used in this study to synthesize a single-atom Cu anchored on t-BaTiO3. The resulting material effectively employs vibration energy for the piezoelectric (PE) catalytic degradation of pollutants. The phase and microstructure of the sample were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM), and it was found that the sample had a tetragonal perovskite structure with uniform grain size. The nanomaterial achieved a considerable increase in tetracycline degradation rate (approximately 95 % within 7 h) when subjected to mechanical vibration. In contrast, pure BaTiO3 demonstrated a degradation rate of 56.7 %. A significant number of piezoinduced negative charge carriers, electrons, can leak out to the Cu-doped BaTiO3 interface due to Cu’s exceptional conductivity. As a result, a single-atom Cu catalyst can facilitate the separation of these electrons, resulting in synergistic catalysis. By demonstrating a viable approach for improving ultrasonic and PE materials this research highlights the benefits of combining ultrasonic technology and the PE effect.

In this work, we investigated the photo-degradation performance of MnO2-SiC fiber-TiO2 (MnO2-SiC-TiO2) ternary nanocomposite according to visible light excitation utilizing methylene blue (MB) and methyl orange (MO) as standard dyes. The photocatalytic physicochemical characteristics of this ternary nanocomposite were described by X-ray diffraction (XRD), scanning electron microscopy (SEM), tunneling electron microscopy (TEM), ultraviolet-visible (UV-vis), diffuse reflectance spectroscopy (DRS), electrochemical impedance spectroscopy (EIS), photocurrent and cyclic voltammogram (CV) test. Photolysis studies of the synthesized MnO2-SiC-TiO2 composite were conducted using standard dyes of MB and MO under UV light irradiation. The experiments revealed that the MnO2-SiC-TiO2 exhibits the greatest photocatalytic dye degradation performance of around 20 % with MB, and of around 10 % with MO, respectively, within 120 min. Furthermore, MnO2-SiC-TiO2 showed good stability against photocatalytic degradation. The photocatalytic efficiency of the nanocomposite was indicated by the adequate photocatalytic reaction process. These research results show the practical application potential of SiC fibers and the performance of a photocatalyst composite that combines these fibers with metal oxides.

We have intended and preparation of hierarchically absorbent materials were covered with a NiMn2O4 and acts as a catalyst for azo dye degradation. The polyaromatic-based (PA) absorbent compounds were initially constructed by bromomethylated aromatic hydrocarbons which undergo self-polymerization in presence of ZnBr as a reagent and cross linker is bromomethyl methyl ether. The absorbent black materials with a 3D network were prepared by direct carbonization and activation of the as-prepared PA. The hydrothermal method was adapted for the preparation of carbon hybrid material C@NiMn2O4 powder's catalytic activity is effective in reducing p-nitrophenol to p-aminophenol and decolorizing carbon-based dyes like methyl orange (MO), methyl yellow (MY), and Congo red (CR) in aqueous media at 25 °C when NaBH4 is added. UV–visible spectroscopy was used to analyze the dyes' breakdown at regular interval.

The presence of tetracycline (TC) has been detected in the human living environment, and its complex structure makes it difficult to degrade. The green and efficient utilization of electroactivated persulfate advanced oxidation technology for the degradation of tetracycline remains a challenge. In this study, N-doped reduced graphene oxide (N-rGO) was prepared using a hydrothermal treatment method with urea as the nitrogen source. Four different mass ratios of graphene oxide (GO) to urea were synthesized, and the optimal mass ratio was determined through degradation experiments of tetracycline. The N-rGO/EC/PMS three-dimensional electrocatalytic system was constructed, and the influence of the experimental data on TC degradation, such as initial pH, PMS dosage and voltage, was determined. Characterization analysis using scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and other methods was conducted. The efficient catalytic ability of N-rGO was demonstrated through the generation of hydrogen peroxide ( H2O2) and consumption of peroxymonosulfate (PMS). The superiority of the three-dimensional (3D) electrochemical advanced oxidation process was proposed by combining different systems. Furthermore, the presence of hydroxyl radicals (.OH), persulfate radicals ( SO4 ·−), and singlet oxygen (1O2) was identified using electron spin resonance (ESR) technology. The utilization of N-rGO as a three-dimensional electrode, coupled with the advantages of PMS activation and electrochemical oxidation processes, is a promising method for treating organic pollutants in wastewater.

The untreated effluent dropping into the environment from various textile industries is a major issue. To solve this problem, development of an efficient catalyst for the degradation of macro dye molecules has attracted extensive attention. This work is mainly focused on the synthesis of nickel–manganese sulfide decorated with rGO nanocomposite (Ni–Mn-S/rGO) as an effective visible photocatalyst for degradation of textile toxic macro molecule dye. A simple hydrothermal method was used to synthesize Ni–Mn-S wrapped with rGO. The prepared composites were characterized using various techniques such as X-ray diffraction (XRD), high-resolution scanning electron microscopy (HR-SEM), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infra-red spectrometer (FTIR), and ultra violet–visible (UV–Vis) spectroscopy. The photocatalytic performance of nickel sulfide (NiS), manganese sulfide (MnS), nickel–manganese sulfide (Ni–Mn-S), and Ni–Mn-S/rGO nanocomposite was assessed by analyzing the removal of acid yellow (AY) and rose bengal (RB) dyes under natural sun light. Among these, the Ni–Mn-S/rGO nanocomposite showed the high photocatalytic degradation efficiency of AY and RB dyes (20 ppm concentration) with efficiency at 96.1 and 93.2%, respectively, within 150-min natural sunlight irradiation. The stability of photocatalyst was confirmed by cycle test; it showed stable degradation efficiency even after five cycles. This work confirms that it is an efficient approach for the dye degradation of textile dyes using sulfide-based Ni–Mn-S/rGO nanocomposite.

본 논문은 회분식 반응기에서 습식 산화법으로 합성한 칼륨 페레이트(VI)에 의한 난분해성 아조 염료Reactive Black 5의 분해 과정을 연구하는 것을 목적으로 한다. 수용액에서 RB5의 분해는 pH, Ferrate (VI) 투입량, 초기 농도, 수용액 온도 등 다양한 변수의 조건에서 연구되었다. RB5 경우에는 최대 분해 효율은 pH 7.0에서 63.2%가 달성되었으며, 이 실험 조건에서 얻은 kapp 값은 190.49 M-1s-1 으로 나타났다. 온도 또한 가장 중요한 매개 변수 중 하나로 연구되었으며, 그 결과로부터 온도(45°C까지)를 증가시키면 페레이트(VI)에 의한 아조 화합물 염료의 분해 효율이 증가하고, 온도가 45°C를 초과하면 분해 효율이 저하되는 것으로 나타났다.

Fe3O4/g-C3N4/TiO2 catalyst has been fabricated using a simple ultrasonic method with high photocatalytic activity. The morphology, structure and optical properties of Fe3O4/ g-C3N4/TiO2 were systematically investigated by a variety of characterization techniques. The optimum degradation conditions were investigated by degrading tetracycline (TC) under visible light irradiation. The results showed that the degradation efficiency was the highest when the initial TC concentration was 5.0 mg/L, the pH value was 11 and the catalyst dosage was 1.0 g/L. After 100 min of visible light irradiation, the degradation efficiency of TC achieved at 73.61%, which was 1.64 and 1.19 times that of g-C3N4 and Fe3O4/ g-C3N4, respectively. Moreover, Fe3O4/ g-C3N4/TiO2 had good stability and recyclability. The results of capture experiments showed that ‧O2 − and ‧OH were the main active species during the photocatalytic process, and a possible photocatalytic reaction mechanism of Fe3O4/ g-C3N4/TiO2 catalyst was proposed. This study provides a new way to improve the photocatalytic performance of g-C3N4, which has great potential in degrading pollutants such as antibiotics in wastewater.

Pharmaceutical products occurring in freshwater bodies create numerous problems for the water bodies owing to their bio-toxic nature. In order to remove such pharmaceutical pollutants, a novel Er-doped Bi4O5Br2/ g-C3N5 nanocomposite was prepared by one-pot synthesis and applied for the photocatalytic removal process. The Er ions doped on the surface of Bi4O5Br2/ g-C3N5 nanocomposite exhibited 97% degradation of tetracycline in 60 min under visible light irradiation, which is higher than pure g-C3N5 and Bi4O5Br2 photocatalysts. The improved photocatalytic properties are attributed to the outstanding visible light harvesting capacity and quick charge carrier separation efficiency which greatly reduced the recombination rate in the heterojunctions. Based on radical trapping experiments, the •O2 −, h+ and •OH radicals played a prominent role in the photodegradation reactions under visible light. Finally, the ternary Er-doped Bi4O5Br2/ g-C3N5 nanocomposite is effectively recyclable with quite a stable photocatalytic removal rate. This work enables a new perspective on the rational design of rare-earth-based nanocomposites for various pharmaceutical pollutants treatment processes.

Single-atom Pd clusters anchored on t-BaTiO3 material was synthesized using hydrothermal and ultrasonic methods for the effective piezoelectric catalytic degradation of pollutants using vibration energy. XRD patterns of BaTiO3 loaded with monoatomic Pd were obtained before and after calcining, and showed typical cubic-phase BTO. TEM and HAADF-STEM images indicated single-atom Pd clusters were successfully introduced into the BaTiO3. The piezoelectric current density of the prepared Pd-BaTiO3 binary composite was significantly higher than that of the pristine BaTiO3. Under mechanical vibration, the nanomaterial exhibited a tetracycline decomposition rate of ~95 % within 7 h, which is much higher than the degradation rate of 56.7 % observed with pure BaTiO3. Many of the piezo-induced electrons escaped to the Pd-doped BaTiO3 interface because of Pd’s excellent conductivity. Single-atom Pd clusters help promote the separation of the piezo-induced electrons, thereby achieving synergistic catalysis. This work demonstrates the feasibility of combining ultrasonic technology with the piezoelectric effect and provides a promising strategy for the development of ultrasonic and piezoelectric materials.