Search Results (5,936)

This review provides a critical and technically grounded assessment of continuous electrocoagulation processes (CEPs) for the treatment of industrial inorganic pollutants, emphasizing recent innovations, methodological developments, and practical outcomes. A comprehensive literature survey indicates that 53 studies published over the past 25 years have investigated CEPs for inorganic contaminant removal, with 36 focusing on standalone electrocoagulation systems and 17 exploring integrated CEPs approaches. Recent advancements in reactor design, such as enhanced internal mixing, optimized electrode geometry, and modular configurations, have significantly improved treatment efficiency, scalability, and operational stability. Evidence indicates that CEPs can achieve high removal efficiencies for a wide range of inorganic contaminants, including fluoride, arsenic, heavy metals (e.g., chromium, lead, nickel, iron), nitrates, and phosphates, particularly under optimized operating conditions. Compared to conventional treatment methods, CEPs offer several advantages, such as simplified operation, reduced chemical consumption, lower sludge generation, and compatibility with renewable energy sources and complementary processes like membrane filtration, flotation, and advanced oxidation. Despite these promising outcomes, industrial-scale implementation remains constrained by non-standardized reactor designs, variable operational parameters, electrode passivation, high energy requirements, and limited long-term field data. Furthermore, few studies have addressed the modeling and optimization of integrated CEPs systems, highlighting critical research gaps for process enhancement and reliable scale-up. In conclusion, CEPs emerge as a novel, adaptable, and potentially sustainable approach to industrial inorganic wastewater treatment. Its future deployment will rely on continued technological refinement, standardization, validation under real-world conditions, and alignment with regulatory and economic frameworks. Full article

Excessive phosphorus emissions are a significant driver of severe eutrophication in water bodies, and developing an efficient and cost-effective adsorbent for phosphorus removal is imperative. In this study, a Na-type zeolite was synthesized from coal gangue sourced from an open-pit mine in Xinjiang province, China. The synthesis process involved drying, crushing, alkali activation, aging, hydrothermal crystallization, and Na⁺ ion exchange. Orthogonal design identified the optimal synthesis parameters: an alkali-to-ash ratio of 1:1, aging at 20 °C for 12 h, and crystallization at 130 °C for 12 h. Aging time exerted the greatest influence on the phosphate removal efficiency. The optimized zeolite exhibited excellent phosphate adsorption performance, achieving a removal efficiency of up to 96% and a capacity of 16 mg/g. The adsorption kinetics followed both pseudo-first-order and pseudo-second-order models, indicating processes governed by combined physical and chemical mechanisms. Isotherm data fitting with Freundlich and Langmuir models suggested the presence of both homogeneous and heterogeneous active sites. Thermodynamic studies confirmed a spontaneous and endothermic process, increasingly favorable at higher temperatures. Characterizations via scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy confirmed the formation of Na-type zeolite and revealed structural and compositional changes following phosphate adsorption. Aluminum and calcium binding played key roles in the chemical adsorption mechanisms. This work not only offers a high-efficiency, low-cost solution for phosphorus removal from wastewater but also provides a sustainable pathway for the valorization of coal gangue in the Zhundong area of Xinjiang, China. Full article

This study investigates the feasibility of incorporating chemically recycled polyol (glycolysate), derived from semi-rigid polyurethane waste from the building industry, into rigid PUF formulations intended for thermal insulation applications. Glycolysis was performed using a diethylene glycol–glycerol mixture (4:1) at 185 °C in the presence of a dibutyltin dilaurate (DBTDL) catalyst. The resulting glycolysate was characterized by a hydroxyl number of 590 mg KOH/g. Foams containing 5–50% recycled polyol were prepared and described in terms of foaming kinetics, cellular structure, thermal conductivity, apparent density, mechanical performance, dimensional stability, flammability, and volatile organic compound (VOC) emissions. The incorporation of glycolysate accelerated the foaming process, with the gel time reduced from 44 s to 16 s in the sample containing 40% recycled polyol, enabling a reduction in catalyst content. The substitution of up to 40% virgin polyol with recycled polyol maintained a high closed-cell content (up to 87.7%), low thermal conductivity (λ₁₀ = 26.3 mW/(m·K)), and dimensional stability below 1%. Additionally, compressive strength improvements of up to 30% were observed compared to the reference foam (294 kPa versus 208 kPa for the reference sample). Flammability testing confirmed compliance with the B2 classification (DIN 4102), while preliminary qualitative VOC screening indicated no formation of additional harmful volatile compounds in glycolysate-containing samples compared to the reference. The results demonstrate that glycolysate can be effectively utilized in high-performance insulation materials, contributing to improved resource efficiency and a reduced carbon footprint. Full article

The rising demand for platinum-group metals, driven by their essential applications in catalysis, energy storage, and chemical conversion, underscores the need to identify new sources for their recovery. Waste solutions originating from industrial processes offer a promising alternative source of noble metals. However, due to their typically low concentrations, effective recovery requires a highly targeted approach. In this study, we present a synthetic waste solution containing trace amount of Rh(III) ions as both a medium for metal ion recovery and a direct precursor for catalyst synthesis. Using a bimodal water–ethanol solvent system, ultra-small rhodium nanoparticles were synthesized and subsequently immobilized onto activated carbon fibers (ACFs) within a microreactor system. The resulting Rh@ACF catalyst demonstrated high efficiency in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP), serving as a model catalytic reaction. The Rh@ACF catalyst, containing 4.24 µg Rh per milligram of sample, exhibited notable catalytic activity, achieving 75% conversion of 4-NP to 4-AP within 1 h. Full conversion to 4-AP was also reached within 5 min, but requires extra NaBH₄ addition to the catalytic mixture. Full article

The chlorinated polyvinyl chloride (CPVC)/acrylonitrile–butadiene–styrene (ABS) composite represents an important class of engineering thermoplastics, offering a strong balance of flame retardancy, chemical resistance, mechanical properties, processability, and cost efficiency. Despite its widespread application, the flame-retardant mechanism in the CPVC/ABS system remains poorly understood. This work systematically investigated the non-monotonic flame-retardant behavior of CPVC/ABS composites through comprehensive characterization. The combustion performance, as determined by limiting oxygen index (LOI), UL-94 vertical burning tests, and cone calorimeter tests (CCTs), showed an unexpected pattern of flame retardancy initially improving then decreasing with reduced ABS content, which contradicted conventional expectations. The optimal composition at a CPVC/ABS ratio of 2:3 demonstrated good performance, achieving a UL-94 5VA rating and 47.3% reduction in total heat release (THR) relative to CPVC. A more stable and compact structure was observed from the morphology analysis of the residual char, and the thermogravimetric analysis further revealed a synergistic effect in carbonization behavior. The above flame-retardant mechanism could be interpreted by the combined effects of accelerated char formation during the early decomposition stage and significantly enhanced char crosslinking degree. These findings provided fundamental insights for designing high-performance flame-retardant polymer composites and facilitating their industrial implementation. Full article

Considering the high stability of water-in-oil (W/O) emulsions, contamination from emulsified pollutants poses a long-term risk to the environment. In this study, hybrid membranes composed of wheat gluten amyloid fibrils (WGAFs) and zein nanoparticles (ZNPs) were prepared and used as a separator to remove emulsified W/O droplets from the oily phase. ZNPs and WGAFs were synthesized through antisolvent method and fibrillation process. Next, a ZNP-functionalized wheat gluten AF/methyl cellulose (ZNP-WGAF/MC) hybrid membrane was fabricated, and its properties were investigated via various analytical techniques. Lastly, the separation efficiency of the ZNP-WGAF/MC hybrid membrane for various W/O emulsions was assessed using microscopy and light scattering. The formation of ZNPs or WGAFs was first verified via spectroscopic and microscopic methods. Our results indicated that the ZNP-WGAF/MC hybrid membranes were synthesized via chemical crosslinking coupled with the casting method. Furthermore, the incorporation of either WGAFs or ZNPs was found to improve the thermal stability and surface hydrophobicity of membranes. Finally, the separation efficiency of the ZNP-WGAF/MC hybrid membranes for various W/O emulsions was determined to be ~87–99%. This research demonstrates the potential of harnessing three-dimensional membranes composed of plant protein-based fibrils and nanoparticles to separate emulsified W/O mixtures. Full article

Chemical Mechanical Polishing (CMP) is a critical process in many industries where achieving superior surface quality through controlled material removal rates by using nano-abrasives is essential. This review examines key parameters of abrasives at the nanoscale, such as size, shape, aspect ratio, hardness, and surface modifications, through inorganic doping or organic molecule grafting and their influence on CMP performance. By analyzing recent studies, we explore how these parameters affect the tribological and chemical interactions during CMP and link these effects to the fundamental polishing mechanisms. Highlighting emerging trends, this work offers a roadmap for designing next-generation nano-abrasives that boost removal efficiency, enhance surface finish, and ensure process stability. Ultimately, controlling abrasive properties at the nanoscale is vital for advancing CMP technology toward more efficient, consistent, and high-quality results. Full article

Water contamination by emerging pollutants poses a significant environmental challenge, demanding innovative treatment technologies beyond conventional methods. Advanced oxidation processes (AOPs) utilizing niobium-based catalysts, particularly niobium oxide (Nb₂O₅) and its modified forms, are prominent due to their high chemical stability, effective reactive oxygen species (ROS) generation, and versatility. This review systematically examines recent advancements in Nb₂O₅-based catalysts across various AOPs, including heterogeneous photocatalysis, electrocatalysis, and Fenton-like reactions, highlighting their mechanisms, material modifications, and performance. Following PRISMA and InOrdinatio guidelines, 381 papers were selected for this synthesis. The main findings indicate that niobium incorporation enhances pollutant degradation by extending light absorption, reducing electron–hole recombination, and increasing ROS generation. Structural modifications such as crystalline phase tuning, defect engineering, and the formation of heterostructures further amplify catalytic efficiency and stability. These catalysts demonstrate considerable potential for water treatment, effectively degrading a broad range of persistent contaminants such as dyes, pharmaceuticals, pesticides, and personal care products. This review underscores the environmental benefits and practical relevance of Nb₂O₅-based systems, identifying critical areas for future research to advance sustainable water remediation technologies. Full article

High-silica–alumina coal gangue is rich in kaolinite, quartz, and other mineral components. The potential for resource utilization is huge, but the silica–aluminate structure is highly stable, and it is difficult to achieve efficient dissociation and elemental enrichment using traditional extraction processes. This study selects typical high-silica–alumina coal gangue as the research object and systematically studies the rules of the physical phase transformation mechanism and ion migration behavior in the activation process of the sodium-based additives stage. In addition, a graded leaching and separation processing route is established, realizing the effective separation and extraction of silica–alumina. The key parameters were optimized using response surface methodology (RSM), obtaining the optimal activation conditions of 800 °C, 30 min, and an additives ratio of 0.8. Under these conditions, the highest dissolution rates of silica and alumina are 82.1% and 92.36%, respectively. Characterization techniques such as XRD, FTIR, and SEM reveal that the activation mechanism of coal gangue involves the decomposition of the aluminosilicate framework and the erosion of sodium ions. At the same time, the chemical bonding reorganization contributes to forming water-soluble sodium silicate (Na₂SiO₃) and insoluble nepheline (NaAlSiO₄), which significantly promotes the release of Si and Al. When the activation temperature is too high, the nepheline phase is transformed into amorphous glassy sodium aluminate and precipitated on the surface, which gradually encapsulates the sodium silicate. This encapsulation restricts dissolution pathways, thereby leading to system densification. Moreover, enhanced resistance to acid attack leads to a decrease in the dissolution rates of Si and Al. This study elucidates the mineral phase reconstruction and element migration mechanisms involved in sodium-based activation and presents a viable approach for the high-value utilization of coal gangue. Full article

Recent concerns regarding artificial intelligent (AI) technologies have spurred studies into improving wastewater treatment efficiency and identifying low-carbon processes. Treating one cubic meter of wastewater necessarily consumes a certain amount of chemicals and energy. Approximately 20% of the total chemical consumption is attributed to phosphorus and nitrogen removal, with the exact proportion varying based on treatment quality and facility size. To promote sustainability in wastewater treatment plants (WWTPs), there has been a shift from traditional control systems to AI-based strategies. Research in this area has demonstrated notable improvements in wastewater treatment efficiency. This review provides an extensive overview of the literature published over the past decades, aiming to advance the ongoing discourse on enhancing both the efficiency and sustainability of chemical dosing systems in WWTPs. It focuses on AI-based approaches utilizing algorithms such as neural networks and fuzzy logic. The review encompasses AI-based wastewater treatment processes: parameter analysis/forecasting, model development, and process optimization. Moreover, it summarizes six promising areas of AI-based chemical dosing, including acid–base regents, coagulants/flocculants, disinfectants/disinfection by-products (DBPs) management, external carbon sources, phosphorus removal regents, and adsorbents. Finally, the study concludes that significant challenges remain in deploying AI models beyond simulated environments to real-world applications. Full article

The global problem of environmental pollution by textile particles from various sources has led to the need to research preventive methods to reduce the occurrence of particles in environmental systems. In this research, plasma and ozone pretreatment are used as environmentally friendly technologies to achieve specific surface modifications of polyester fabrics and create a stable polyester/chitosan structure that reduces the release of fibre particles during the washing process and does not affect mechanical and functional properties. The effects of advanced treatments of the surface of polyester fabrics were realised with argon (Ar) and oxygen (O₂) plasma and ozone (O₃) after subsequent modification with a chitosan agent. The efficiency of such pretreatments of the fabric surface as well as the stability of the polyester/chitosan structure was analysed on the basis of the changes in the physical-mechanical and chemical properties of the treated polyester standard fabric. Despite the changes in the mechanical properties of the pretreated materials, the favourable protective effect of chitosan in the resulting polyester/chitosan structures after advanced pretreatments was confirmed in all washing cycles, especially in the first cycles, which are considered crucial for significant particle release. Full article

To meet the massive increase in energy demand, extensive research has been conducted over the past few decades on developing clean and sustainable energy storage methods. Hydrogen is considered as one of the most promising future energy carriers due to its high energy density and renewability, but it requires storage. Storing hydrogen using metal hydride offers several advantages, including stability, safety compactness and reversibility of the hydrogen absorption/desorption process. Thermal management during hydrogen storage using metal hydride is critically important since the reaction between the metal and hydrogen is highly exothermic. We are aiming to develop thermal storage systems based on composite phase change materials (CPCMs) that absorb the heat generated during hydrogen absorption and release it during desorption, in an effort to improve energy storage efficiency. Lightweight, shape-stable CPCMs are prepared by loading the selected organic phase change materials into expanded graphite and hydrophobic monolithic silica aerogel. The chemical structure, microstructure, thermal properties and leakage of CPCMs are investigated. These samples were subjected to variable power electrical heating to simulate the heat generated during hydrogen reaction, forming lanthanum hydride, according to its published reaction kinetics. Full article

Coal gangue, a primary solid waste by-product of coal mining and processing, constitutes approximately 10–15% of total coal output. Its accumulation poses substantial environmental challenges, including land occupation, spontaneous combustion, acid mine drainage, and heavy metal leaching. Despite its high silica and alumina content (typically exceeding 70% combined), the highly stable and crystalline structure of raw coal gangue limits its pozzolanic activity and adsorption efficiency. To address this limitation, this review emphasizes recent advances in activation strategies such as thermal (500–900 °C), mechanical (dry/wet grinding to less than 200 µm), chemical (acid/alkali treatments), microwave, and hybrid methods. The activated coal gangue resulted in an enhanced surface area (up to 55 m²/g), amorphization of kaolinite to metakaolinite, and the generation of mesoporosity under optimal conditions. This review critically examined the geotechnical applications, such as soil stabilization and mine backfill, highlighting the replacement of 50–75% of cementitious binder in backfilling and meeting the subgrade/base material strength criteria (UCS > 2 MPa). In geoenvironmental applications (adsorption of phosphate, dyes, heavy metals, and CO₂ mineralization), more than 90% of pollutant removal is attained. In construction applications, supplementary cementitious materials and sintered bricks are examined. Several critical knowledge gaps, including limited understanding of long-term durability, inconsistent activation optimization across different coal gangue sources, and insufficient assessment of environmental impacts during large-scale implementation, are clearly addressed. This review provides a roadmap for advancing sustainable coal gangue utilization and highlights emerging opportunities for cost-effective applications in the mining and construction sectors. Full article

Recent progress in microfluidic technologies has led to the development of compact and highly efficient electrochemical platforms, including lab-on-a-chip (LoC) systems, that integrate multiple testing functions into a single, portable device. Combined with smartphone-based electrochemical devices, these systems enable rapid and accurate on-site detection of food contaminants, including pesticides, heavy metals, pathogens, and chemical additives at farms, markets, and processing facilities, significantly reducing the need for traditional laboratories. Smartphones improve the performance of these platforms by providing computational power, wireless connectivity, and high-resolution imaging, making them ideal for in-field food safety testing with minimal sample and reagent requirements. At the core of these systems are electrochemical biosensors, which convert specific biochemical reactions into electrical signals, ensuring highly sensitive and selective detection. Advanced nanomaterials and integration with Internet of Things (IoT) technologies have further improved performance, delivering cost-effective, user-friendly food monitoring solutions that meet regulatory safety and quality standards. Analytical techniques such as voltammetry, amperometry, and impedance spectroscopy increase accuracy even in complex food samples. Moreover, low-cost engineering, artificial intelligence (AI), and nanotechnology enhance the sensitivity, affordability, and data analysis capabilities of smartphone-integrated electrochemical devices, facilitating their deployment for on-site monitoring of food and agricultural contaminants. This review explains how these technologies address global food safety challenges through rapid, reliable, and portable detection, supporting food quality, sustainability, and public health. Full article

With an aging population, the number of joint replacement surgeries is on the rise. One of the most common implant materials is cobalt–chromium–molybdenum (CoCrMo) alloy. Hence, the surface properties of this alloy have attracted increasing attention. In this study, nanosecond and femtosecond laser processing, followed by annealing, was employed to modify the CoCrMo surface. The effects of the treatment conditions on the surface morphology, structure, composition, hardness, roughness, contact angle, wear properties, and corrosion current were studied. Femtosecond laser processing with an energy density of 1273 mJ/cm², followed by heat treatment at 160 °C for 2 h, produced laser-induced periodic surface structures (LIPSS) without altering the chemical composition of the alloy and rendered the surface superhydrophobic. In contrast, nanosecond laser treatment at higher laser energy densities promoted the formation of an oxide layer, which improved the hardness and corrosion resistance of the substrate. Overall, the CoCrMo samples processed using the femtosecond laser system exhibited superior corrosion and wear resistance, with a protection efficiency of approximately 92%. Full article