Optimal Working Conditions Research Articles

The properties of cement stabilized dredged sludge solidifying in seawater and its application in the protection of subsea pipelines

Hundreds of millions of tons of dredged sludge are generated by waterway dredging worldwide every year. Traditional disposal of dredged sludge, such as in-situ stockpiling and offshore dumping, cannot avoid the waste of land resource and the pollution to marine environment. Sludge stabilization/solidification treatment currently used can achieve the reuse of drudged sludge but requires large investment and time. Therefore, how to turn waste into treasure in an effective, environmentally friendly and cheap way is a notable problem. In this study, the variation of strength of solidified sludge cured in air with water-cement ratio, water content and curing time by unconfined compression test was investigated, and the inner mechanism of strength influenced by water-cement ratio and water content was revealed by XRD test, which offered an optimal working condition. Also, solidified sludge with the maximum strength in the optimal working condition was immersed into seawater at different times, which showed the 7d strength after mixing completion for 8 h immersed into seawater could reach 20.60 MPa (1.37 times of the strength in air), and the prediction formulas considering all the parameters mentioned above were established. At last, a field test of solidified dredged sludge for protection of submarine pipelines was carried out in Bohai Bay, China, which demonstrated the feasibility of mixing dredged sludge with cement on board and solidifying in seawater environment. Compared to the traditional subsea pipeline protection solutions, the cost of using solidified sludge to protect subsea pipelines is 25 % and 39 % less than the cost of using sandbags and concrete mats, respectively. This study provides a more economic and environmentally friendly idea for dredged sludge treatment and subsea pipeline protection than the conventional methods, which provides a new source of green ocean building materials, reduces the pollution of the marine environment by the discharge of dredged sludge, turns waste into treasure and has wide applications in ocean engineering.

Multiple-Yolk-Shell NiO Microspheres for Selective Detection of m-Xylene.

m-Xylene is a volatile organic compound that is extensively used in various industrial processes. It is toxic, posing significant risks to human health and the environment. Therefore, developing gas sensors with high sensitivity and selectivity for m-xylene detection is critical. In this work, we demonstrated the synthesis of NiO-yolk double-shell (NiO-YDS) and NiO-yolk triple-shell (NiO-YTS) derived from NiO/Ni-BTC and NiO/Ni-PTA composites, respectively, using the microwave-assisted solvothermal method from Ni-BTC-derived NiO spheres. The NiO/Ni-BTC composite has trimesic acid (H3BTC) as an organic linker, while NiO/Ni-PTA has p-terephthalic acid (PTA). We investigated the sensing properties of these materials for 2-butanone, 2-nonanone, 3-methyl-1-butanol, acetone, benzene, ethanol, methanol, and m-xylene. These composites exhibited excellent sensitivity and selectivity for detecting m-xylene under dry conditions. Specifically, the NiO-YTS sensor showed a sensitivity of 217.5% to m-xylene, while the NiO-YDS sensor demonstrated a sensitivity of 179.8% at 350 °C in dry air. We emphasize the NiO-YTS composite due to its superior sensitivity and selectivity in detecting m-xylene compared with the NiO-YDS composite. The NiO-YTS sensor exhibited stable and reproducible sensing performance for 100 ppm of m-xylene under optimum working conditions, with a theoretical detection limit of 5.43 ppb and relatively fast response time (89 s) and recovery time (191 s). This work describes an easy method for synthesizing NiO-YDS and NiO-YTS derived from NiO/Ni-BTC and NiO/Ni-PTA composites. It demonstrates that these composites represent a new class of materials that can potentially enhance the sensitivity and selectivity of m-xylene gas sensors.

Research on faradic capacitive deionization regeneration method for absorption air conditioning system

The development of renewable energy driven air conditioning system is of importance for curbing the CO2 emission. Absorption air conditioning systems could be a good choice but for its low regeneration efficiency. Capacitive deionization (CDI) regeneration method has been proposed to improve the efficiency of absorption system by eliminating the energy waste in the traditional thermal regeneration method. The core part of CDI is the electrode normally made from porous carbon materials, which often suffers from low charge storage capacity and co-ion repulsion. On the purpose of performance optimization, this paper proposes a hybrid deionization (HCDI) regeneration method by fabricating the electrode from Faraday materials. Experimental research has been made on the regeneration capacity of the prepared electrodes. Investigation has been conducted on the performance of the HCDI method based absorption system. The influence of different parameters has been revealed. Compared with the porous carbon electrode, the Faraday electrode has raised the charge efficiency by 20%, and raised both the regeneration capacity and overall performance by 40%. Under optimized working conditions, the COP of the HCDI based absorption system has reached 3.51 in the experiments, which shows great potential for future application.

Study of Variation in Physiochemical Properties of a Worm Gearbox Lubricant by Blending Castor Oil in the Base Lubricant

In both industrial & heavy-duty applications, oil analysis can be a very effective strategy for preventing gearbox failure, cutting downtime, and managing maintenance costs. In any application, gearboxes are essential to production, the unplanned downtime and the resulting productivity losses can prove to be extremely expensive. Used oil analysis is a preventative maintenance procedure that can point out and pinpoint mechanical breakdown inside the system before it gets serious or becomes too expensive to fix. A thorough oil examination can identify wear, corrosion, and other changes that could be harmful to the health and durability of the machinery. To reduce machine wear, prevent contamination, or optimize working conditions in challenging environments, lubricants are carefully formulated by mixing additives in the base oil. A lubricant with a high acid content can cause varnish and sludge to accumulate, which can clog oil filters and cause machine parts to corrode. When a lubricant degrades, acidic byproducts are produced because of the base stock and additives' process of decomposition in the presence of heat and air. To assess the presence of acidic constituents in the oil or its acid concentration, Total Acid Number (TAN) oil testing is employed. The present work studies the effects on Total Acid Number (TAN) and Total Base Number (TBN) properties of commercial lubricant (EP 90) when castor oil is mixed in percentage concentration in it. The findings of this research have unveiled that the acidic characteristics of the base lubricant (EP90 commercial gear oil) increases as the percentage of castor oil additive is increased in the base lubricant oil.

Novel hybrid treatment for canal water recycling by integrating coagulation, catalytic ozonation, and filtration for agricultural sustainability

This study employed a novel approach, utilizing recycled alumina flocs after coagulation/flocculation (C/F) as a catalyst in catalytic ozonation (CO), along with the auxiliary catalyst sodium zeolite (Na-Z), where alumina produces hydroxyl radicals, and zeolite enhances molecular ozone reactions. This synergistic strategy focuses on treating contaminated canal water, recognizing that the presence of various pollutants can reduce the efficacy of a singular catalyst type. In the current investigation, alum, Na-Z, and rice husk (RH) were applied as a coagulant, catalyst, and filter media in C/F, CO, and filtration processes respectively. Four treatment technologies (C/F, O3, O3/Na-Z, and RHF) were studied independently and in four different combinations (O3–C/F, C/F–O3, C/F–O3/Na-Z, and C/F–O3/Na-Z–RHF) for the first time and their efficacious performance was evaluated. It was revealed that the combination-IV (C/F–O3/Na-Z–RHF) was a more efficient and economical treatment than others. This novel integrated treatment C/F–O3/Na-Z–RHF has remarkable removal efficiency of 99 %, 99 %, 85 %, 93 %, 100 %, 89 %, and 93 % for TSS, turbidity, COD, BOD5, fecal coliforms, cadmium, and copper respectively, under optimized working conditions. Also, treated canal water complied with the studied irrigation water quality guidelines. Notably, this efficient treatment combination halved the treatment time compared to others, potentially reducing the electrical energy demand of 11.45 kWh.m−3 and the overall operational treatment cost of 1.62 USD.m−3. Hence, the application of this efficient hybrid treatment system contributed to recycling canal water for agricultural use, livestock, and pasture watering, playing a crucial role in mitigating the water crisis.

Heat Pump Performance Mapping for Energy Recovery from an Industrial Building

Industrial buildings have numerous kinds of energy-losing equipment, such as engines, ovens, boilers and heat exchangers. Energy losses are related to inefficient energy use and lousy work conditions for the people inside the buildings. This work is devoted to the recovery of lost energy from industrial buildings. Firstly, the residual energy of the building is extracted to be used to warm water. Consequently, the work conditions of the people inside industrial buildings can be improved by maintaining the adequate temperature. The recovery of the energy is performed by a multipurpose heat pump system (HP system). The working fluid used in the HP system is R134a, which is a traditional and cheap working fluid. The thermophysical properties of R134a are obtained through the PC-SAFT equation of state. This work presents a performance mapping based on the intercepted areas framework to evaluate which working conditions are the optimal operating variables. The latter depends on several key parameters, such as compressor work, heat delivery, heat absorbed and exergetic efficiency. The results show that the optimal work conditions are found at different condenser and evaporator temperatures, and these may be limited by what the designer considers a sound performance of the heat pump system.

Air supply subsystem efficiency optimization for fuel cell power system with layered control method

Efficient and stable operation is critical for the large-scale commercialization of the proton exchange membrane fuel cell power system. The effective control and optimization of the operating conditions, such as oxygen excess ratio and cathode pressure of the air supply system, is a solution to improve the overall system efficiency. This work proposes a novel layered control method to achieve rapid and stable control of the operating conditions. The control structure in this paper consists of the optimization and control layers. A two-dimensional objective optimization function for the optimization layer is established to characterize the system efficiency based on theoretical analysis and experimental testing on the fuel cell power generation process and air supply system power consumption pattern. Then, a modified salp swarm algorithm with adaptive inertia weight is proposed to quickly and accurately obtain the optimal operating conditions for the maximum efficiency under different load current densities. Meanwhile, the local optimal solutions are avoided by introducing mutation operations. For the control layer, a third-order state space equation is developed to accurately describe the operating characteristics of the air supply system according to its operating principles. A feedback linearization-based sliding mode controller is designed to achieve rapid and stable control of the optimal working conditions outputted from the optimization layer. Finally, the fuel cell system was tested in the lab and verified on the fuel cell city buses. The results show that the system's operating efficiency is improved by 0.6 %–2.6 % at different current densities, and the hydrogen consumption of all three city buses is reduced by more than 5 %. The optimization effect was enhanced significantly. Therefore, the layered control method is effective in solving the optimization and control problems of the fuel cell power system.

Performance analysis and multi-objective optimization of a novel solid oxide fuel cell-based poly-generation and condensation dehumidification system

The application of energy supply systems based on fuel cells contributes to meeting the requirement of sustainable development, and developing high-efficiency, low-pollution, and multifunction poly-generation systems coupled with fuel cells is increasingly attractive. This study proposes a novel combined cooling, heating, power poly-generation and dehumidification system including a solid oxide fuel cell, a gas turbine, a double effect absorption refrigerator, a condensation dehumidification unit, an organic Rankine cycle, and a heat exchanger. Thermodynamic, economic, and environmental analysis models of the entire system are developed to evaluate system comprehensive performance. The effects of system parameters such as the inlet temperature of fuel cell, steam to carbon ratio, air flow rate, and high temperature generator temperature on system performance are analyzed. The analysis findings reveal that the proposed system can provide power, cooling, and heating of 551.904 kW, 20.307 kW, and 193.009 kW, and the dehumidification capacity per unit is 14.516 g/kg when 1.238 kg/s of humid air is treated. The system exergy efficiency is found to be 70.534 %, and the system cost rate is 15.578 $/h with carbon dioxide emission being 0.301 kg/kWh at the design condition. Two groups of multi-objective optimizations of the whole system are further conducted to acquire the optimal system performance and working conditions. The optimization results demonstrate that the optimal exergy efficiency of 72.912 % appears at point C1 in the first group of optimization with the lowest carbon dioxide emission being 0.293 kg/kWh, and the optimal qualities of humid air are found to be 1.606 kg/s at C2 and D2 in the second group of optimization. After optimization, the system carbon dioxide emission is decreased by 0.008 kg/kWh, the exergy efficiency is increased by 2.378 %, and the quality of humid air in dehumidification process is developed by 0.368 kg/s. In summary, the proposed poly-generation and dehumidification system can meet multifunction energy demands and achieve good performance, and the research work could also provide theoretical basis for developing evaluation and optimization technologies of fuel cell-based poly-generation systems.

Temperature-based energy changes in gold nanowire sensors for flow rate detection and failure prediction

This study delves into the dynamic operational states of nanowire sensors within microfluidic channels for flow velocity detection, classifying these states into decline, steady, and failure states. It conducts a comparative analysis of the steady-state operational characteristics of nanowire sensors across various voltages and inlet flow rates, alongside examining the interplay between nanowire resistivity and temperature. This investigation identifies an optimal working condition for the sensor at a 1 V operating voltage and a nanowire dimension of 150 × 150 nm. Employing both theoretical and experimental approaches, the research elucidates the convective heat transfer mechanism that underpins the functionality of the nanowire sensor for flow rate detection. It unveils the pattern of nanowire temperature changes during inlet flow rate measurement within a range from 10 to 50 μL/min range and establishes standard values of temperature and calorimetric differences for various flow velocities. Furthermore, the study achieves the prediction of the time to reach the steady and failure states under given operational conditions for the nanowire-based sensor. This advancement will enhance the reading precision of the signal output from the nanowire sensor, mitigate the risk of sensor failure, and contribute to prolonging the operational lifespan of equipment.

Green leaching and predictive model for copper recovery from waste smelting slag with choline chloride-based deep eutectic solvent

This research was performed to investigate the optimization of copper recovery from copper smelting slag (CSS) with a deep eutectic solvent as green reagent. The effect of important parameters on leaching efficiency of copper and zinc (as well as dissolution of iron), such as leaching time, leaching temperature, liquid/solid ratio, and particle size was studied. In order to model the copper recovery, an optimization method was used. According to the chemical analysis of CSS, the slag contains 0.9% copper, 3.3% zinc, and 36.7% iron. Also, it was found that the CSS is mainly composed of Fe2SiO4, Fe3O4, and SiO2. Copper-containing structures were determined as CuO and CuS. As a result of leaching experiments, 80% copper and 61% zinc recoveries were obtained at 48 h, 95 °C, 1/25 g·ml–1, and -33 μm. It is noted that the iron and silicon dissolution remained negligible under the selected conditions. According to the mathematical model, the highest copper leaching efficiency (up to 100%) could get under optimum working conditions as 48.5 °C leaching temperature, 40.1 hours leaching duration, and 62.3 ml·g–1 liquid/solid ratio. Also, the proposed model revealed that wide range of experimental levels can be used as leaching parameter to get desired metal leaching efficiency.

Utilizing WFSim to Investigate the Impact of Optimal Wind Farm Layout and Inter-Field Wake on Average Power

This paper presents a comprehensive study on optimizing wind farm efficiency by controlling wake effects using the WFSim dynamic simulation model. Focusing on five key factors—yaw wind turbine position, yaw angle, wind farm spacing, longitudinal wind turbine spacing, and yaw rate—we qualitatively analyze their individual and combined impact on the wind farm’s wake behavior and mechanical load. Through a quantitative approach using the orthogonal test method, we assess each factor’s influence on the farm’s overall power output. The findings prioritize the following factors in terms of their effect on power output: yaw wind turbine position, yaw angle, wind farm spacing, longitudinal spacing, and yaw rate. Most significantly, this study identifies optimal working conditions for maximizing the wind farm’s average power output. These conditions include a wind turbine longitudinal spacing of 7.0D, a wind farm spacing of 15.0D, a yaw angle of 30°, and a yaw rate of 0.0122 rad/s, with the first and second rows of turbines in a yaw state. Under these optimized conditions, the wind farm’s average power output is enhanced to 35.19 MW, marking an increase of 2.86 MW compared to the farm’s original configuration. Additionally, this paper offers an analysis of wake deflection under these optimal conditions, providing valuable insights for the design and management of more efficient wind farms.

Burnout among Polish paramedics: insights from the Oldenburg Burnout Inventory.

Emergency medical services rely heavily on paramedics who, as frontline responders, face unique stressors that can potentially lead to burnout. This pilot study utilizes the Oldenburg Burnout Inventory (OLBI) to assess burnout levels among Polish paramedics. The aim is to contribute to the understanding of burnout in this specific professional context and identify key factors influencing burnout dimensions. Future research will build on these preliminary findings. A cross-sectional study was conducted from March 01 to April 30, 2023, utilizing an online survey accessible to Polish paramedics. The OLBI, a validated tool, was employed to measure burnout, focusing on two dimensions: exhaustion and withdrawal of involvement. Among the 147 participating paramedics, the majority were male (65.99%). Paramedics exhibited burnout symptoms across both dimensions measured by The Oldenburg Burnout Inventory scale (OLBI), with an average level for lack of commitment recorded at 20.09, an average level for exhaustion at 20.60. The study revealed that 41.5% of paramedics experienced low burnout, 44.9% reported moderate burnout, and 13.6% faced high burnout risks. Analysis showed that women experienced significantly higher levels of exhaustion compared to men (p = 0.01). This pilot study provides valuable initial insights into burnout among Polish paramedics. The OLBI's two-factor structure, evaluating exhaustion and disengagement, proved reliable and valid in this context. The prevalence of burnout, with over 60% of paramedics experiencing moderate to high levels, highlights the urgency of addressing burnout in this profession. Future research will be essential to explore the underlying causes and develop targeted interventions. Understanding the factors contributing to burnout among paramedics is crucial for developing targeted interventions. Strategies should focus on stress management training, organizational support, and well-being initiatives. Addressing gender-specific differences in burnout experiences is essential for tailoring interventions effectively. Proactive psychological support mechanisms and optimized working conditions can enhance paramedics' overall well-being, ensuring their continued effectiveness in providing emergency medical services.

Highly efficient mesoporous aluminium-magnetite-alginate magnetic composite for defluoridation of water

One of the few elements that can have negative health impacts in both conditions, when consumed in excess or insufficiency is fluoride. In current study, aluminium magnetite alginate composite (AMA) was fabricated and applied using batch adsorption of fluoride as well as by using statistical modelling. Heterogeneous surface as revealed from scanning electron micrograph, thermal stability shown by thermal studies, high surface area of 29.77 m2 g−1, pore volume 0.1987 cm3 g−1 with mesoporous structure having average pore radius of 133 Å shown by BET analysis, fare degree of magnetization from VSM analysis were the important features of this material. Screening experiments and batch trials were carried out to obtain optimum working conditions. pH of 3.0, dosage of 50 mg, interaction period of 60 min and concentration of 50 mg L−1 depicted maximum defluoridation efficacy of about 94%. The adsorption capacity was found to be 60.08 mg g−1 in accordance with Langmuir adsorption isotherm, while pseudo second order kinetics was followed. Overall effects of various factors on sorption process were optimized using response surface methodology (RSM). Regeneration potential of AMA has been demonstrated for 10 adsorption-desorption cycles, showing more than 60% efficiency in tenth cycle. The AMA composite shows E-factor value 0.004 depicting it is sustainable in environment. In short, this novel composite showed excellent morphological, magnetic, functional properties that led to enhanced adsorption efficiency in short span of time that can be regenerated and reused in multiple cycles.

Establishment and preliminary application of neutralizing antibody detection method for human respiratory syncytial virus

Objective: To establish a Plaque-reduction Neutralization Test (PRNT) for the detection of neutralizing antibody titers of Human Respiratory Syncytial Virus (HRSV) and optimize the conditions for preliminary application. Methods: The CHO expression system was used to produce palivizumab monoclonal antibody (palivizumab) and the influencing factors such as cell type, cell culture duration, fixation and permeabilization protocols, and blocking agents. The reproducibility of the method was verified and its correlation was verified with conventional PRNT. Finally, the optimized PRNT assay was further used to determine neutralizing antibody titers against HRSV subtypes A and B in BALB/c mouse serum (immunized by intramuscular injection of HRSV fusion proteins). Results: Palivizumab was expressed at approximately 50 mg/L. The optimal working conditions for PRNT were as follows: culturing HEp-2 cells for 2 days, fixing with 4% (V/V) paraformaldehyde at room temperature for 15 min followed by 0.2% (V/V) Triton X-100 permeabilization for 15 minutes as the optimal fixation-permeabilization and removing the blocking step. The overall coefficient of variation (CV) for the reproducibility validation of this method was <15%, showing a good linear relationship with the conventional PRNT. The Spearman correlation coefficient rs was 0.983. This method was used to detect neutralizing antibody titers in mouse sera against HRSV subtype A strain long and subtype B strain 9320, and the fusion proteins combined with AlOH and CpG adjuvant induced the highest neutralizing antibody titers in mice. Conclusion: The HRSV neutralizing antibody assay established in this study is rapid, reproducible, high-throughput, and can be used to detect neutralizing antibodies to HRSV subtypes A and B.

Phosphorus recovery from ultrafiltered membrane wastewater by biochar adsorption columns: The effect of loading rates

The present study used bench scale columns filled with biochar for phosphorous (P) recovery from real ultrafiltered wastewater. No studies are available about the potentiality of biochar using ultrafiltered real wastewater. Therefore, this study aimed to assess phosphate (PO43−) recovery by biochar-packed columns employing real treated wastewater from an ultrafiltration process. Three flow rates were tested, specifically 0.7, 1.7 and 2.3 L h−1, to gain insights into the optimal working conditions. Results revealed that the maximum amount of PO43− recovery (namely, 3.43 mg g−1 biochar) can be achieved after 7 h by employing the highest tested flow rate. Furthermore, the phosphorus exchange capacity (PEC) was inversely correlated with the feeding flow rate (FFR), with PEC values equal to 35, 25 and 9 % for FFR of 0.67, 1.7 and 2.3 L h−1, respectively. The pseudo-first order model best approximated the adsorption kinetics, thus suggesting that the adsorption of phosphate by biochar depends on its concentrations (i.e. physiosorption mechanism).

Design and Optimization of a Silicon-Based Electrokinetic Microchip for Sensitive Detection of Small Extracellular Vesicles.

Detection of analytes using streaming current has previously been explored using both experimental approaches and theoretical analyses of such data. However, further developments are needed for establishing a viable microchip that can be exploited to deliver a sensitive, robust, and scalable biosensor device. In this study, we demonstrated the fabrication of such a device on silicon wafer using a scalable silicon microfabrication technology followed by characterization and optimization of this sensor for detection of small extracellular vesicles (sEVs) with sizes in the range of 30 to 200 nm, as determined by nanoparticle tracking analyses. We showed that the sensitivity of the devices, assessed by a common protein-ligand pair and sEVs, significantly outperforms previous approaches using the same principle. Two versions of the microchips, denoted as enclosed and removable-top microchips, were developed and compared, aiming to discern the importance of high-pressure measurement versus easier and better surface preparation capacity. A custom-built chip manifold allowing easy interfacing with standard microfluidic connections was also constructed. By investigating different electrical, fluidic, morphological, and fluorescence measurements, we show that while the enclosed microchip with its robust glass-silicon bonding can withstand higher pressure and thus generate higher streaming current, the removable-top configuration offers several practical benefits, including easy surface preparation, uniform probe conjugation, and improvement in the limit of detection (LoD). We further compared two common surface functionalization strategies and showed that the developed microchip can achieve both high sensitivity for membrane protein profiling and low LoD for detection of sEV detection. At the optimum working condition, we demonstrated that the microchip could detect sEVs reaching an LoD of 104 sEVs/mL (when captured by membrane-sensing peptide (MSP) probes), which is among the lowest in the so far reported microchip-based methods.

Mineralization of clofibric acid by persulfate-promoted catalytic subcritical water oxidation process using CoFe2O4@SiO2 catalyst

The design and use of innovative treatment processes are very important in preventing the possible toxic effects of organic pollutants in aquatic environments. One of these methods is the subcritical water oxidation method, which has been used recently. In the current study, the mineralization of clofibric acid (CFA) was carried out under more effective and mild conditions using persulfate (PS) as an oxidant and CoFe2O4@SiO2 catalyst by the subcritical water oxidation (sub-CWO) process. Characterization of the synthesized catalyst was performed through XRD, FTIR, TEM and SEM–EDS analyses. In the CFA oxidation with persulfate-promoted catalytic Sub-CWO process, optimum working conditions was determined as 15 mM PS, 40 min, 383 K, and 0.3 g L−1 catalyst dosage using the response surface method and Box–Behnken design. The catalyst's efficiency remained relatively stable after three cycles under optimal conditions, resulting in a 97% total organic carbon (TOC) removal. Decomposition products were determined and a degradation mechanism was proposed.

Assessment of navigators’ ergonomic awareness and working conditions on navigation bridges

Background: Merchant ships, despite huge technological progress, are still operated by qualified navigators. According to ergonomics principles, human is a part of the whole system and is affected by the surrounding environment. Objective: The purpose of the paper was to assess the ergonomic awareness of professional navigators, to understand their expectations towards navigation bridges and to check if they obtain enough support from their workplace. Methods: A special questionnaire was developed and 200 responses were obtained from seafarers with license of Officer Of the Watch or higher. Statistical analysis were carried out to find out relationships and differences between answers and groups of respondents. Results: Improper ergonomics and less than optimal working conditions were not isolated incidents and occurred to be rather common problem of the industry. The results suggest that ergonomic awareness is at relatively high level, however this knowledge is frequently not used in practice. Conclusions: Poor design and lack of proper ergonomics training might contribute to commonly experienced signs of fatigue, pain episodes and therefore reduced performance of seafarers. Navigators find ergonomics important, however navigation bridges often do not meet ergonomics and comfort standards, therefore there is still a room for improvement in this area.

Degradation of Anthraquinone dye wastewater by sodium percarbonate with CoO heterogeneous activation

AbstractBACKGROUNDAnthraquinone dyes have an anthraquinone structure as their nucleus, with one or more substituents forming different organic dyes. Anthraquinone dyes have a complex structure that allows them to exist stably in water environment, but also makes them more toxic than azo dyes. This results in varying degrees of harm to both humans and the environment as a result of residual dyes in the water or on the material’ surface. Sodium percarbonate (SPC) is a highly promising oxidant due to its green end product. Therefore, in this study, the catalytic performance and kinetic study of cobalt oxide (CoO) on SPC under different conditions were systematically investigated using RB19 as the target pollutant. The Box–Behnken Design (BBD) model was used to model the degradation of RB19 by CoO/SPC system, which gives the basis for practical application. The types of reactive oxygen species that effectively degrade RB19 and the potential degradation mechanism of the CoO/SPC system were revealed. At the same time, the CoO/SPC system was evaluated in terms of its practicality.RESULTSIn this work, the activation of SPC using CoO towards reactive blue 19 (RB19) degradation was explored. Experimental results showed that nearly 93.8% of RB19 could be removed within 30 min using 1 mmol L−1 SPC and 30 mg L−1 CoO. The three‐factor interaction effects of SPC concentration, CoO dosage and initial pH were investigated. The BBD model was set up to obtain the optimum working conditions of 1.039 mmol L−1 SPC, 33.35 mg L−1 CoO and the initial pH of 7.82, which gave a degradation rate of 95.372%. Additionally, it was confirmed that the solubility of Co2+ is consistently &lt;150 μg L−1, meeting the emission standard (1 ppm). The presence of Cl−, NO3–, and HA had a similar profile, with a slight promoting effect in small amounts and an inhibitory effect when introduced in excess. The introduction of SO42– had a negligible effect on RB19 degradation, whereas the presence of HCO3− produced a slight inhibitory effect. Furthermore, the presence of PO43– showed a strong inhibitory effect. The CoO/SPC system is suitable for other organic dyes (32.7%–100%) and antibiotics (97.1–100%). Electron paramagnetic resonance (EPR) analysis and quenching experiments confirmed the presence and relative contribution of free radicals in the CoO/SPC system as CO3•‐ (88.12%) &gt;O2•‐ (51.11%) &gt;1O2 (37.21%) &gt;•OH (5.27%) &gt; SPC (3.33%) &gt;CoO (0.09%). It has been confirmed that CoO activates SPC through electron transfer.CONCLUSIONThe present study describes a less time‐consuming, and more efficient method of treating anthraquinone dye wastewater that requires less oxidizer and catalyst, making it more economical. This proposes a straightforward, cost‐effective and efficient technique using SPC triggered by transition metal oxides. © 2024 Society of Chemical Industry (SCI).

Catalytic ozonation of reverse osmosis membrane concentrates by catalytic ozonation: Properties and mechanisms.

Ni-Mn@KL ozone catalyst was prepared for the efficient treatment of reverse osmosis membrane concentrates. The working conditions and reaction mechanism of the ozone-catalyzed oxidation by Ni-Mn@KL were systematically studied. Then, a comprehensive CRITIC weighting-coupling coordination evaluation model was established. Ni-Mn@KL was characterized by scanning electron microscopy, BET, X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive spectrometry, and X-ray fluorescence spectrometry and found to have large specific surface area and homogeneous surface dispersion of striped particles. Under the optimum working conditions with an initial pH of 7.9 (raw water), a reaction height-to-diameter ratio of 10:1, an ozone-aeration intensity of 0.3L/min, and a catalyst filling rate of 10%, the maximum COD removal rate was 60.5%. Free-radical quenching experiments showed that OH oxidation played a dominant role in the Ni-Mn@KL-catalyzed ozone-oxidation system, and the reaction system conformed to the second-order reaction kinetics law. Ni-Mn@KL catalysts were further confirmed to have good catalytic performance and mechanical performance after repeated utilization. PRACTITIONER POINTS: Ni-Mn@KL catalyst can achieve effective treatment of RO film concentrated liquid. High COD removal rate of RO membrane concentrated liquid was obtained at low cost. Ni-Mn@KL catalyst promotes ozone decomposition to produce ·OH and O2 -· oxidized organic matter. The Ni-Mn@KL catalyst can maintain good stability after repeated use. A CRITIC weight-coupling coordination model was established to evaluate the catalytic ozonation.