Search Results (210)

Although oily sludge is an industrial waste and difficult to separate, its calorific value can still reach 6000 cal/g, thus possessing significant recycling value. This study compares various types of non-thermal plasma for refining oily sludge. The pre-treatment technology utilized filtration combined with solvent extraction to extract the oil portion from the oily sludge. Subsequently, two types of non-thermal plasma, DC streamer discharge and dielectric plasma discharge, were used to crack and activate the oily sludge under different operating conditions. The fuel compositions and properties of the refined fuel treated by two types of non-thermal plasma were compared. The elemental carbon and oxygen of the oily sludge after treatment in a direct DBD plasma reactor for 8 min were 1.96 wt.% less and 1.38 wt.% higher than those of commercial diesel. The research results indicate that the pre-treatment process can effectively improve the refined fuel properties. After pre-treatment, the calorific value of the primary product from the oily sludge can reach 10,598 cal/g. However, the carbon residue of the oily sludge after pre-treatment remained as high as 5.58 wt.%, which implied that further refining processes are required. The streamer discharge plasma reactor used a tungsten needle tip as a high-voltage electrode, leading to a rather small treated range. Corona discharge and arc formation are prone to being produced during the plasma action. Moreover, the addition of quartz glass beads can form a protruding area on the surface of the oily sludge, generating an increase in the reacting surface of the oily sludge, and hence an enhancement of treatment efficiency, in turn. The direct treatment of DBD plasma can thus have a wider and more uniform operating range of plasma generation and a superior efficiency of plasma reaction. Therefore, a direct DBD type of non-thermal equilibrium plasma reactor is preferable to treat oily sludge among those three types of plasma reactor designs. Additionally, when the plasma voltage is increased, it effectively enhances fuel properties. Full article

A novel cost-effective, rapid, and eco-friendly method was described for the removal of carbon dioxide (CO₂) from the gaseous emissions of gasoline engines. This involved the use of a sandwich filter (~10 cm diameter) made of a nonwoven poly (m-phenylene isophthalamide) (Nomex) fabric loaded with a thin layer of activated carbon. The optimized filter, with an activated carbon mass of 2.89 mg/cm², a thickness of 4.8 mm, and an air permeability of 0.5 cm³/cm²/s, was tested. A simple homemade sampling device equipped with solid-state electrochemical sensors to monitor the concentration levels of CO₂ before and after filtration of the emissions was utilized. The data were transmitted via a General Packet Radio Service (GPRS) link to an Internet of Things (IoT)-based gas monitoring system for remote management, and real-time data visualization. The proposed device achieved a 70 ± 3.4% CO₂-removal efficiency within 7 min of operation. Characterization of the filter was conducted using a high-resolution scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and Brunauer–Emmett–Teller (BET) analysis. The effects of loaded activated carbon mass, fabric type, filter porosity, gaseous removal time, and adsorption kinetics were also examined. The proposed filter displayed several advantages, including simplicity, compactness, dry design, ease of regeneration, scalability, durability, low cost, and good efficiency. Heat resistance, fire retardancy, mechanical stability, and the ability to remove other gasoline combustion products such as CO, SO_x, NO_x, VOCs, and particulates were also offered. The filtration system enabled both in situ and on-line CO₂ real-time continuous emission monitoring. Full article

The intrinsic trade-off among sensitivity, response speed, and measurement range continues to hinder the wider adoption of flexible pressure sensors in areas such as medical diagnostics and gesture recognition. In this work, we propose a grid-structured polycaprolactone/thermoplastic-polyurethane nanofiber pressure sensor decorated with multi-walled carbon nanotubes (PCL/TPU@MWCNTs). By introducing a gradient grid membrane, the strain distribution and reconstruction of the conductive network can be modulated, thereby alleviating the conflict between sensitivity, response speed, and operating range. First, static mechanical simulations were performed to compare the mechanical responses of planar and grid membranes, confirming that the grid architecture offers superior sensitivity. Next, PCL/TPU@MWCNT nanofiber membranes were fabricated via coaxial electrospinning followed by vacuum-filtration and assembled into three-layer planar and grid piezoresistive pressure sensors. Their sensing characteristics were evaluated by simple index-finger motions and slide the mouse wheel identified. Within 0–34 kPa, the sensitivities of the planar and grid sensors reached 1.80 kPa⁻¹ and 2.24 kPa⁻¹, respectively; in the 35–75 kPa range, they were 1.03 kPa⁻¹ and 1.27 kPa⁻¹. The rise/decay times of the output signals were 10.53 ms/11.20 ms for the planar sensor and 9.17 ms/9.65 ms for the grid sensor. Both sensors successfully distinguished active index-finger bending at 0–0.5 Hz. The dynamic range of the grid sensor during the extension motion of the index finger is 105 dB and, during the scrolling mouse motion, is 55 dB, affording higher measurement stability and a broader operating window, fully meeting the requirements for high-precision hand-motion recognition. Full article

An integrated hybrid system was developed, incorporating sedimentation, anaerobic digestion, biological filtration, and a two-stage hybrid subsurface flow constructed wetland, horizontal subsurface flow constructed wetland (HSSFCW) and vertical subsurface flow constructed wetland (VSSFCW), to treat rural sewage in southern Jiangsu. To optimize nitrogen and phosphorus removal, the potential of six readily accessible industrial and agricultural waste byproducts—including plastic fiber (PF), hollow brick crumbs (BC), blast furnace steel slag (BFS), a zeolite–blast furnace steel slag composite (ZBFS), zeolite (Zeo), and soil—was systematically evaluated individually as substrates in vertical subsurface flow constructed wetlands (VSSFCWs) under varying hydraulic retention times (HRTs, 0–120 h). The synergy among substrates, plants, and microbes, coupled with the effects of hydraulic retention time (HRT) on pollutant degradation performance, was clarified. Results showed BFS achieved optimal comprehensive pollutant removal efficiencies (97.1% NH₄⁺-N, 76.6% TN, 89.7% TP, 71.0% COD) at HRT = 12 h, while zeolite excelled in NH₄⁺-N/TP removal (99.5%/94.5%) and zeolite–BFS specializing in COD reduction (80.6%). System-wide microbial analysis revealed organic load (sludges from the sedimentation tank [ST] and anaerobic tanks [ATs]), substrate type, and rhizosphere effects critically shaped community structure, driving specialized pathways like sulfur autotrophic denitrification (Nitrospira) and iron-mediated phosphorus removal. Annual engineering validation demonstrated that the optimized strategy of “pretreatment unit for phosphorus control—vertical wetland for enhanced nitrogen removal” achieved stable effluent quality compliance with Grade 1-A standard for rural domestic sewage discharge after treatment facilities, without the addition of external carbon sources or exogenous microbial inoculants. This low-carbon operation and long-term stability position it as an alternative to energy-intensive activated sludge or membrane-based systems in resource-limited settings. Full article

Extensive antibiotic use in swine production contaminates manure and wastewater with antibiotics. Discharging this waste into the environment, even after treatment, potentially fuels the spread of antibiotic resistance. This study investigated a full-scale swine wastewater treatment plant that combines coagulation–sedimentation, sand filtration, ozonation, activated carbon filtration, and a deaeration process. At each stage of this process, samples were collected and analyzed to determine their water quality parameters, antibiotic concentrations, and antibiotic resistance genes (ARGs). The experimental results showed coagulation–sedimentation effectively removed suspended solids (92.2%) and total phosphorus (96.9%). Ozonation significantly reduced antibiotic levels, including sulfamethazine by over 99.9%, although ARGs such as tetM, sul1, and sul2 were only removed at levels up to 95.9%. Interestingly, partial rebounds of sulfamethazine (438.9 μg/L) and marbofloxacin (0.40 μg/L) appeared in the final effluent, suggesting that desorption or operational factors (e.g., hydraulic fluctuation, filter media saturation, and pH) may affect the treatment process. In addition, strong correlations emerged between the levels of suspended solids and those of certain antibiotics (lincomycin, tiamulin), indicating particle-mediated sorption as a key mechanism. Even though ozonation and coagulation–sedimentation were found to contribute to the substantial removal of pollutants, the observed rebounds and residual ARGs highlight the need for optimized operational strategies and multi-barrier approaches to fully mitigate antibiotic contamination and inhibit the proliferation of resistant bacteria in swine wastewater. Full article

In this paper, the modification of natural clinoptilolite and mordenite zeolites from Almaty using acid treatment is addressed for the purposes of improving adsorption performance and for drinking water purification. Structural chemical transformation was characterized by the use of X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and Scanning electron microscope (SEM) techniques. Acid treatment led to a partial dealumination that was responsible for an increase in the number of surface defects and micropores, improvement in ion exchange capacity, and selectivity toward heavy metals. Additionally, modifications greatly enhance the uptake capacities of Pb²⁺, Cd²⁺, and As³⁺. The clinoptilolite post-modification removal efficiencies reached 94%, 86%, and 84%, respectively, while mordenite zeolites achieved 95%, 90%, and 87% removal efficiencies, respectively. The enhancement of performance was related to the increase in surface area and active sites for ion exchange, verified from analysis of the Brunauer-Emmett-Teller (BET) surface area. The use of different Bhatt and Kothari methods has revealed that adsorption processes followed Langmuir isotherm models for Pb²⁺ and Cd²⁺, whereas As³⁺ adsorption was better described by the Freundlich isotherm model. However, second-order kinetics indicate that chemisorption was the dominant mechanism. Such evidence indicates spontaneity and an endothermic process, as shown from thermodynamic studies. Results showed that modified zeolites indeed had a high degree of reusability, with over 80% of the adsorption capacity retained even after five cycles. Acid-modified zeolites can provide cheaper, greener methods of purification, generating only negligible secondary waste when compared to conventional methods of water purification, for example, activated carbon and membrane filtration. Results from this study proved that modified clinoptilolite and mordenite zeolites have the potential for sustainable heavy metal treatment in drinking water purification systems. Full article

Loofah is deemed a promising candidate for the purification of oily fumes. Our research utilized H₃PO₄ for initial activation of loofah (TCS), producing loofahderived carbon (TGSC-0). Subsequently, Fenton’s reagent was utilized for further modification to yield loofah-derived carbon (TGSC-1). TGSC-1 was used in the form of an adsorption column to simultaneously treat multiple pollutants from oily fumes, with surface Fe³⁺, Fe²⁺, and H₂O₂ catalyzing ·OH and ·OOH generation to enhance adsorption of the oils and non-methane hydrocarbon (NMHC). Characterization showed that the specific surface area of TGSC-1 was 427.97 m²/g and pore sizes ranged from 0.50 to 3.50 nm. The rich mesoporous and macroporous structures of TGSC-1 enhanced the capability of carbon layer adsorption. Langmuir adsorption kinetics suggested that adsorption proceeded via monolayer adsorption pathways, while L-τ lines revealed shorter protective effect times for adsorbing PM₁₀ and PM_2.5 than for oils and NMHC. The results indicated that TGSC-1 exhibited maximum saturated adsorption capacities of 25.79, 13.02, 9.82, and 15.99 mg/g for oils, NMHC, PM_2.5, and PM₁₀, respectively. Increasing resistance of the adsorption column exhibited a notable synergistic effect of filtration and adsorption in treating oily fumes. It combines renewable materials with low-energy processing, delivering eco-economic benefits for sustainable development and application. Full article

Acid mine drainage (AMD) is one of the main environmental problems in mining operations. The objective of this study was to assess AMD obtained from a copper mine via toxicity identification evaluation (TIE) using Daphnia magna and Chlorella vulgaris as indicator organisms. AMD was fractionated via filtration and aeration at pH 3 and 11, activated carbon, cation resin, anion resin, and ethylenediaminetetraacetic acid (EDTA). The results showed that unfractionated AMD has a low organic matter content (total chemical organic demand, COD_T-183.05 mg/L), low pH (3.9), and high sulfates concentrations (2900 mg/L) and metal ions in solution (0.2–418.9 mg/L), producing high toxicity to Daphnia magna (0.00016% v/v) and no observable acute toxicity to Chlorella vulgaris (72 h-RFU 64.9%). For Daphnia magna, TIE fractionations with the greatest reduction in acute toxicity (LC₅₀) were filtration/pH11 (non-toxic) and anion resin (LC₅₀ = 0.43% v/v), with toxicity reduction percentages of 100% and 99%, respectively. Because of this, Cu was determined to be the main cause of acute toxicity to Daphnia magna. For Chlorella vulgaris, the activated carbon fraction stands out, increasing the % relative fluorescence units by 4% from 48 h to 72 h, demonstrating tolerance to AMD. The TIE technique is presented as an effective strategy to identify toxic compounds in complex samples and evaluate their effect on environmentally relevant organisms. Therefore, this study allows the analysis of the ecological risk in aquatic environments affected by mining activities, which supports environmental decision-making and the design of efficient treatment strategies. Full article

Two-dimensional (2D) hexagonal boron carbon nitride (h-B_xC_yN_z) has garnered a lot of interest in the last two decades because of its remarkable physical and chemical characteristics. Because of the carbon atoms, it has a smaller gap than its cousin, boron nitride, and is hence more appropriate for a wider range of applications. In the frame of density functional theory, we discuss the structural, electronic, and magnetic properties of mono Ti-doped and Co-doped BC₆N (Ti/Co-BC₆N) at different sites of substitutional doping (Ti/Co) in the BC₆N monolayer. The mono substitutional doping at the B (Ti_B/Co_B), N (Ti_N/Co_N), and two different C (C1 (Ti_C1/Co_C1), C2 (Ti_C2/Co_C2)) sites, are investigated. The position of the Ti/Co dopant is an important parameter that changes the electronic state, magnetic moment, and adsorption activity of the pristine BC₆N nanosheet. We find that the adsorption of the gases NO, NO₂, CO₂, NH₃, N₂, and O₂ is significantly improved on the doped sheet at all doped positions compared to the adsorption on the pristine structure. The Ti/Co-BC₆N can adsorb NO and NO₂ better than CO₂ and NH₃. Ti_C1-BC₆N and Ti_B-BC₆N are the best doped sheets for adsorbing NO and NO₂, respectively. The CO₂ and the N₂ molecules are moderately adsorbed at all doped positions as compared to the other adsorbed molecules. Ti-doped sheets can adsorb the CO₂, NH₃, and O₂ better than the corresponding Co-doped sheets. We also study the adsorption of molecular hydrogen on our single-atom Ti/Co-doped systems, as well as on 4-atom Ti and Co clusters embedded in the BC₆N sheets. We show that the cluster-embedded sheets can adsorb up to four H₂ molecules. These novel findings are important for many applications of BC₆N, including spintronics, gas filtration, molecular sensing, and hydrogen storage. Full article

Flexible pressure sensors face the dual challenges of weak signal extraction and environmental noise suppression in wearable electronics and human-machine interfaces. This research proposes an intelligent pressure sensor utilizing chitosan/carbon nanotube/melamine sponge (CS/CNT/MS) composites, achieving high-performance sensing through a dual-stage noise reduction architecture that combines mechanical pre-filtration and electrical synergistic regulation. An innovative compressed-stitching encapsulation technique creates pressure sensors with equivalent mechanical low-pass filtering characteristics, actively eliminating interference signals below 3 kPa while maintaining linear response within the 3–20 kPa effective loading range (sensitivity: 0.053 kPa⁻¹). The synergistic effects of CS molecular cross-linking and CNTs’ three-dimensional conductive network endow the device with a 72 ms response time, 24 ms recovery speed, and over 3500-cycle compression stability. Successful applications in smart sport monitoring and tactile interactive interfaces demonstrate a material-structure-circuit co-design paradigm for mechanical perception in complex environments. Full article

Extracting aluminum from FA is an effective way to improve its utilization rate. Since aluminum oxide is found in high polymerization degree, inert substances such as mullite and sodium aluminosilicate make the reaction process difficult because of their stable chemical properties; within these highly polymerized matrices, the chemical stability of alumina typically persists across a broad temperature range from 1000 °C to over 1600 °C. To address the issue of stable mullite structure that hinders aluminum extraction, a combined acid-base method using sodium carbonate as an activating agent and hydrochloric acid at a temperature of 100 °C as a leaching agent is employed. XRD and SEM were used to analyze the phase characterization and microstructure of fly ash before and after activation and acid leaching, examining the effects of activation parameters and acid leaching parameters on the activation of FA and the aluminum extraction rate. The research results indicate that after calcination activation, mullite is transformed into zeolite, which is easily soluble in acid, and the aluminum within the activated molten material is transferred to the filtrate through acid leaching, achieving the goal of extracting aluminum. Under the activating conditions with sodium carbonate flux, the Al-O bonds in mullite are broken, the crystal structure is transformed, and the aluminum compounds obtained from hydrochloric acid leaching have a stable form of existence, which has a low impact on the error of the experimental results. When the material ratio of fly ash to sodium carbonate is 1:0.7, after reacting at a calcination temperature of 880 °C for 1.5 h, and leaching in 6 mol/L hydrochloric acid at 100 °C with a solid-liquid ratio of 1:6 for 2 h, the extraction rate of aluminum in fly ash is the highest, reaching 97%. Full article

Hydrogel-based wastewater treatment technologies show certain outstanding features, which include exceptional efficiency, sustainability, reusability, and the precise targeting of specific contaminants. Moreover, it becomes possible to minimize the environmental impact when using these materials. Their flexibility, low energy consumption, and adaptability to meet specific requirements for different purposes offer significant advantages over traditional methods like activated carbon filtration, membrane filtration, and chemical treatments. Recent advancements in hydrogel technology, including new production methods and hybrid materials, enhance their ability to efficiently adsorb contaminants without altering their biocompatibility and biodegradability. Therefore, innovative materials that are ideal for sustainable water purification were developed. However, these materials also suffer from several limitations, mostly regarding the scalability, long-term stability in real-world systems, and the need for precise functionalization. Therefore, overcoming these issues remains a challenge. Additionally, improving the efficiency and cost-effectiveness of regeneration methods is essential for their practical use. Finally, assessing the environmental impact of hydrogel production, use, and disposal is crucial to ensure these technologies are beneficial in the long run. This review summarizes recent advancements in developing polymer-based hydrogels for wastewater treatment by adsorption processes to help us understand the progress made during recent years. In particular, the studies presented within this work are compared from the point of view of the synthesis method, raw materials used such as synthetic/natural or hybrid networks, and the targeted class of pollutants—dyes or heavy metal ions. In several sections of this paper, discussions regarding the most important properties of the newly emerged adsorbents, e.g., kinetics, the adsorption capacity, and reusability, are also discussed. Full article

The emphasis on physical activity and health monitoring has increased the demand for developing multifunctional, flexible sensors through straightforward methods. A hydrophobic, breathable, and flexible strain sensor was prepared using a filtration method, employing thermoplastic polyurethane (TPU) as a substrate, carbon nanocoils (CNCs) as conductive fillers, and polydimethylsiloxane (PDMS) as a binder. The sensing layer, prepared using the unique three-dimensional helical structure of carbon nanocoils, achieved a hydrophobic angle of 143° and rapidly changed the color of the pH test paper in 5 s. The sensor had a strain range of 40% and a gauge factor of 34, and achieved a linear fit of R² = 0.98 in the 5–35% strain range. The CNCs/TPU sensor exhibits high reliability and stability after 1000 tensile cycle tests. These favorable features ensure that the sensors are comfortable to wear and respond quickly and accurately to movements in all body parts, meeting the need for human motion detection. Full article

The large-scale use of air-conditioning equipment, while providing a comfortable living environment, has also brought about a series of problems. This study focuses on the growth and reproduction of Staphylococcus aureus on the surface of activated carbon in air-conditioning filtration systems. Experimental data were obtained under temperature conditions of 20 °C and 30 °C and relative humidity conditions of 10%, 50%, and 75% RH. Based on the experimental data, a mathematical model was established to predict the growth and reproduction of Staphylococcus aureus. The Logistic and Gompertz equations were used to fit the growth and reproduction curves under different temperature and humidity conditions, and the two models, commonly used for simulating microbial growth curves, were compared. The model with the best fit was selected to predict the amount of Staphylococcus aureus, providing some guidance for the actual lifespan of the adsorbent in filters. Full article

Air filters are crucial components of building ventilation systems. Compared to conventional air filter media like glass fibers and melt-blown fibers, electrospinning membranes are more efficient for capturing various pollutants due to the smaller pores present on the structure. In this paper, activated carbon filters were prepared with eco-friendly polylactic acid (PLA) and microcrystalline cellulose (MCC) using electrospinning to obtain a high-quality factor (QF) fibrous mat for aerosol particle matter (PM) filtration and volatile organic compounds (VOCs) adsorption. Several configurations of the final membranes were investigated and tested for fiber morphology and air filtration performance. Filtering efficiency and adsorption properties were evaluated in a real-scale room by measuring the particle penetration of the newly synthesized and commercial filters against neutralized aerosol particles (3% NaCl aqueous solution) and VOCs (methyl ethyl ketone). The calculated depolluting efficiencies were up to 98% in terms of PM and 55% for VOCs abatement, respectively. Our results indicate that the proposed hybrid membranes represent promising materials for highly efficient and sustainable air filters for home application systems. Full article