Search Results (2,448)

This study aimed to explore innovative sorbent materials for the remediation of contaminated marine environments, with a focus on metal removal from seawater. Adsorption tests were carried out to evaluate the performance of single-cell proteins (SCPs), a protein-rich biomass derived from industrial by-products, in comparison with commercial activated carbon (AC). Given the increasing need for sustainable and effective approaches in sediment remediation and water treatment, identifying alternatives to conventional sorbents is of particular relevance. Results showed that SCPs exhibited higher affinity for Cr than for Zn, while multi-metal solutions improved adsorption, suggesting synergistic interactions possibly linked to surface charge effects and ternary complex formation. Importantly, SCPs demonstrated competitive and, in some cases, superior performance compared to AC, highlighting their potential as an innovative and sustainable material. Moreover, when the absorbent materials were combined, SCP and AC mixes outperformed both the individual adsorbents and the expected additive efficiencies, achieving significantly higher removal yields for both metals, particularly at low concentrations. Overall, these findings suggest that SCPs, alone or in combination with AC, represent a promising strategy for the removal of heavy metals from marine systems, offering new opportunities for the treatment of contaminated sediments and seawater. Full article

With the rapid increase in solid waste generated worldwide, sustainable approaches for the recovery of resources considering environmental protection are required. As one of the emerging strategies in recent years, biochar has shown great potential due to its high carbon stabilization, adjustable porosity and tunability. This review focuses on the critical assessment of the available technologies for biochar upgrading, with a specific objective of biochar physicochemical functionality improvement and critical materials recovery in line with circular economy targets. We systematically review physicochemical activation methodologies, functionalizations and leaching approaches, accounting for their effects on surface area, porosity and functional group chemistry. Particular attention is paid to the dual functionality of upgraded biochar (i) as a catalyst support for thermochemical processes and (ii) as a medium for the recycling of essential nutrients (e.g., phosphorus, potassium, magnesium, calcium). It is evidenced that customized activation can further improve its adsorption and catalytic efficiency as well as promote near-total nutrition extraction. This review positions advanced biochar as an enabling multipurpose technology across sustainable material production, nutrient cycling and waste valorization in the circular bioeconomy. Full article

As a cost-effective and environmentally benign photocatalyst, hydrothermal carbonation carbon (HTCC) has been extensively studied in the fields of resource utilization and environmental remediation. In this study, HTCC photocatalysts with efficient photocatalytic performances were prepared from straw using acid modification under hydrothermal conditions. The as-prepared HTCC photocatalysts were applied to the degradation of microcystin-LR and the reduction of aqueous Cr(VI). The critical role of acid modification in the photocatalytic performances of the HTCC photocatalysts was systematically investigated. The results demonstrated that acid-modified photocatalysts exhibited a significantly enhanced removal efficiency for Cr(VI) and microcystin-LR under visible light irradiation. A series of characterization techniques, including Raman spectroscopy and N₂ adsorption–desorption analysis, revealed that the superior photocatalytic activities of acid-modified HTCC could be attributed to its higher aromatization level, enhanced light-harvesting ability, and increased concentration of active sites compared with pristine HTCC. Furthermore, electron spin resonance (ESR) and trapping experiments indicated that hydrogen radicals (·H) served as the primary active species in the photocatalytic Cr(VI) reduction of straw-based HTCC. This work provides both practical and theoretical insights into the resource utilization of agricultural waste and the remediation of environmental pollution. Full article

The provision of potable water for armed forces at their operational sites necessitates a robust treatment chain to ensure the production of safe drinking water from potentially contaminated local water sources. Relying on single-use water bottles is not considered an eco-friendly option and on-site production may exhibit limited efficiency depending on the water contamination. This study therefore aimed to define a mobile processing chain that could efficiently produce drinking water on-site while offering a multi-barrier level of protection. To evaluate the system, contaminated water was prepared from different water sources and then spiked with various inorganic contaminants (metals, anions: Cl⁻, F⁻, I⁻, NO₂⁻, NO₃⁻, SO₄²⁻, CN⁻), organic contaminants (e.g., pesticides, petroleum hydrocarbons, polycyclic aromatic hydrocarbons, chlorinated solvents), and energetic compound (perchlorate) at levels ranging from 5 to 50 times the standard water quality criteria. A specific treatment process was defined optimized and evaluated at flow rates reaching 500 L/h. This treatment chain includes the following: a sediment filter, a greensand filter, a cation exchange resin, an anion exchange resin, an activated carbon adsorption filter, ultrafiltration, a UV lamp, and a reverse osmosis (RO) unit. This treatment system successfully met all water quality criteria, providing a reliable and effective alternative to an RO-only treatment regime. Full article

This study aims to present the preparation of date stone activated carbon (DSAC) through physical activation with carbon dioxide. The Brunauer–Emmett–Teller (BET) technique, Boehm titrations, elemental analysis, Raman and Fourier-transform infrared (FTIR) spectroscopy have been used to characterize the raw material (date stone), date stone activated carbon (DSAC) produced, Congo Red (CR) and to investigate the adsorption phenomena. The study of the DSAC porous material revealed the dominance of micropores with a specific surface area greater than 535.9 m² g⁻¹ and an approximate volume value equal to 0.208 cm³ g⁻¹. The Langmuir model predicted an adsorption capacity of approximately 27.77 mg g⁻¹, while a 90% removal efficiency for CR dye was achieved under neutral pH conditions. Thermodynamic analysis confirmed that the adsorption of CR on DSAC has a spontaneous (ΔG° < 0) and exothermic (ΔH° < 0) character. The adsorption mechanism of CR on DSAC was proposed and discussed, based on the determination of electrostatic interactions being identified as a critical factor that controls the adsorption phenomenon of CR on DSAC. A 2³ full factorial design was implemented to systematically investigate the effects of three critical parameters (temperature, adsorbent dosage, and pH) on the adsorption performance. Statistical analysis indicated that all three primary factors significantly influenced the results. The square correlation coefficient of the model (R²-sq of 97.26%) was in good agreement with the statistical model. The variable is considered statistically significant when the p-value is lower than 0.05. These findings, supported by experimental data, strongly indicate that DSAC possesses remarkable potential as a sustainable and effective bio-adsorbent for wastewater remediation applications capable of removing diverse contaminants with high efficiency. Full article

Capacitive de-ionization (CDI) holds great promise for water desalination, while the widely used activated carbon (AC) electrodes suffer from a low salt adsorption capacity (SAC) and poor long-term stability due to the co-ion effect and electrode oxidation. Inspired by membrane-based CDI, we deposited polyethyleneimine (PEI), an ion exchange polymer with positive charge and ion selectivity, onto an AC electrode to serve as an anode for addressing these issues. Firstly, compared to traditional AC and commercial AEM-AC, the PEI-doped AC (PDAC) anode delivered a superior SAC of 36.3 mg/g, as the positively charged PEI enhanced electrostatic attraction, suppressed the co-ion effect, and offered extra sites. However, it showed poor cycling stability with 77.1% retention, owing to mass loss and anode oxidation. We further developed an electrode coated with a PEI-based membrane (PMAC), which exhibited a balanced performance with a high SAC of 33.4 mg/g and significantly improved long-term retention of 97.5%. The hydrophilic PEI membrane, strongly adhered to the AC surface, shortened the ion diffusion resistance and effectively prolonged the electrode lifespan. A systematic comparison between AC, AEM-AC, PDAC, and PMAC revealed the mechanism for PMAC’s notable enhancement. These findings establish a framework for designing novel CDI electrodes and advancing sustainable water desalination. Full article

Leachate from the Magtaa Kheira landfill exhibits complex physicochemical characteristics that restrict the efficacy of single-treatment processes. This study assessed a sustainable two-stage treatment strategy combining coagulation–flocculation and adsorption. During the initial stage of the study, both aluminum sulfate (AS) and a bio-based coagulant derived from Moringa oleifera seeds (MOS) were evaluated for their effectiveness in the pretreatment of leachate. Box–Behnken Design combined with Response Surface Methodology was used to optimize the coagulation process using aluminum sulfate (AS). The highest removal efficiencies were 91% for turbidity and 85% for chemical oxygen demand (COD) removal, achieved at an AS concentration of 1.44 g·L⁻¹ and an initial pH of 8. In parallel, the performance of MOS extract was investigated as an eco-friendly alternative to AS. An FTIR analysis revealed the presence of protein-associated hydroxyl (3288 cm⁻¹) and carboxyl and amine groups (1647 cm⁻¹), which are integral to destabilization via hydrogen bonding, while SEM confirmed a surface morphology conducive to effective floc formation. MOS demonstrated comparable turbidity removal to AS, significantly reducing both sludge generation and chemical consumption. Following the coagulation stage, treated leachates were passed through a granular activated carbon (GAC) column, enhancing overall COD removal to over 94% to reach acceptable discharge and reuse levels. The coagulation–adsorption sequence, incorporating both chemical and bio-based coagulants, provides an efficient and sustainable approach for the treatment of complex leachate, addressing both performance and environmental considerations. Full article

The adsorptive removal of tetracycline (TC) in aqueous solution, a widely used antibiotic, was investigated using activated carbon derived from cotton textile waste. The valorization of textile waste provides a sustainable strategy that not only reduces the growing accumulation of discarded textiles but also supports a circular economy by transforming waste into efficient adsorbent materials for the removal pharmaceutical contaminants. This dual environmental and economic benefit underscores the novelty and significance of using cotton-based activated carbons in wastewater treatment. In this study, cotton textile waste was utilized as a raw material for the preparation of adsorbents via pyrolysis under nitrogen at 600 °C followed by chemical modification with H₂SO₄ solutions (1, 2, and 3 M). The sulfuric-acid modified-carbons (SMCs) were characterized by BET surface area analysis, FTIR spectroscopy and SEM imaging. Batch adsorption experiments were carried out to evaluate the effects of key operational parameters including contact time, initial TC concentration and solution pH. The results showed that the material treated with 2 M H₂SO₄ displayed the highest adsorption performance, with a specific surface area of 700 m²/g and a pore volume of 0.352 m³/g. The pH has a great influence on TC adsorption; the adsorbed amount increases with the initial TC concentration from 5 to 100 mg/L and the maximum adsorption capacity (74.02 mg/g) is obtained at pH = 3.8. The adsorption behavior was best described by Freundlich isotherm and pseudo-second-order kinetic models. This study demonstrates that low-cost and abundantly available material, such as cotton textile waste, can be effectively repurposed effective adsorbents for the removal of pharmaceutical pollutants from aqueous media. Full article

2-methylisoborneol (MIB, d = 0.6 nm) and dimethyl disulfide (DMDS, d = 0.7 nm) produced by algal metabolism are the main olfactory contaminants of drinking water. Activated carbon (AC) adsorption is an effective method to remove MIB/DMDS, yet critical gaps remain regarding the dominant factors and mechanisms governing their different adsorption performance. The microporous filling mechanism is the dominant mechanism for the adsorption of MIB and DMDS by AC. Surface functional groups play a supporting role in the adsorption process by modulating the hydrophilicity/hydrophobicity of the carbon surface. This study systematically evaluated the adsorption performance of three ACs—coconut shell-derived (CSC), coal-based (CAC), and Sargassum-derived (SAC)—for MIB and DMDS removal. Comparative analysis revealed the superior adsorption performance of CSC, achieving 87.41% removal of MIB and 71.2% removal of DMDS at 20 mg/L. Both MIB and DMDS adsorption adhere to the Langmuir isotherm, indicating monolayer coverage with uniform energy. Kinetic studies demonstrated that the PSO model fits the MIB adsorption process best, while the PFO model fits the DMDS adsorption process best. The FTIR confirmed physical adsorption, with no new chemical bonds formed. Furthermore, regenerated CSC retains significant adsorption capacities, achieving 85.89% and 68.49% of the original capacity for MIB and DMDS, respectively, after five regeneration cycles. This research provides fundamental insights into the mechanistic role of AC properties in odorant removal processes, supporting its sustainable application in water treatment. Full article

Biochar is increasingly recognized as a multifunctional soil amendment that improves soil fertility, nutrient cycling, and crop productivity. Studies across field, greenhouse, and incubation settings show that biochar enhances nutrient retention, reduces leaching, and regulates carbon, nitrogen, and phosphorus cycling. Its effects are shaped by intrinsic physicochemical properties and interactions with soil minerals, microbial communities, and enzymatic processes. Short-term benefits of biochar applications often include improved nutrient adsorption and water regulation, while long-term applications support stable soil organic matter formation, root development, and fertilizer use efficiency. Biochar also reshapes soil microbial diversity and activity. Beneficial bacterial groups such as Proteobacteria and Actinobacteria, along with fungi such as Mortierella, respond positively, enhancing nitrogen fixation, phosphorus solubilization, and organic matter decomposition. Meanwhile, biochar applications could suppress pathogens. Enzyme activities, including urease and phosphatase, are typically stimulated, driving nutrient mobilization. Yet outcomes remain context-dependent, with biochar feedstock, application rate, soil conditions, and crop type influencing results; excessive use may suppress enzymatic activity, reduce nutrient availability, or shift microbial communities unfavorably. Practically, biochar can improve fertilizer efficiency, restore degraded soils, and reduce greenhouse gas emissions, contributing to climate-smart agriculture. Future work should prioritize long-term, multi-site trials and advanced analytical tools to refine sustainable application strategies. Full article

The incorporation of Arthrospira platensis into dairy products offers health benefits but is limited by its undesirable aroma and flavor. This study evaluated three deodorization strategies—adsorption by activated carbon, extraction with ethanol, and fermentation with Saccharomyces cerevisiae—to improve the sensory profile of A. platensis and enhance its acceptability in yogurt. Deodorized powders were characterized for proximal and volatile composition and used to formulate yogurts at five concentrations (0.5–2.5% w/v). Texture, aroma volatile profile, and sensory attributes were assessed after yogurt production, while shelf-life quality attributes were monitored over 29 days of refrigerated storage. Yogurts containing fermented A. platensis showed higher sensory scores (>8.7/10), the greatest purchase intent (>71.4%), and improved texture, remaining acceptable at an addition level of 2.5%. In contrast, yogurts with untreated or carbon-activated treated A. platensis were only acceptable at low addition levels (≤0.5%) due to off-flavors and textural issues. Ethanol effectively reduced aldehydes and ketones (such as Safranal and β-Ionone), while fermentation eliminated pyrazines and generated desirable alcohols and acids (such as 1-Pentanol and Butanoic acid). These findings highlight fermentation as a promising strategy to deodorize A. platensis and improve its integration into dairy matrices, enabling the development of functional yogurts with enhanced sensory quality and nutritionally relevant microalgae content. Full article

The increasing atmospheric CO₂ concentration is one of the major environmental challenges, necessitating not only emission reduction but also effective carbon utilization. Non-thermal plasma-catalytic CO₂ conversion offers an efficient pathway under mild conditions by synergistically combining plasma activation with catalytic surface reactions. In this study, mesoporous ceria catalysts were synthesized by different methods and characterized using N₂ adsorption–desorption, SEM, XRD, XPS, CO₂-TPD, and XRF techniques. The materials exhibited distinct textural and electronic properties, including variations in surface area, pore structure, and basicity. Plasma-catalytic CO₂ dissociation experiments were conducted in a dielectric barrier discharge reactor at near-room temperature. Among the synthesized catalysts, Ce(mp)-4 demonstrated the highest CO₂ conversion of 32.3% at a 5 kV input voltage and superior energy efficiency, which can be attributed to its meso-macroporous structure that promotes microdischarge formation and enhances CO₂ adsorption–desorption dynamics. CO was the only product obtained, with near-100% selectivity. Catalyst stability testing showed no deactivation while spent catalyst characterization indicated carbon-containing species. The findings in this study highlight the critical role of tailored pore structure and basic-site distribution in optimizing plasma-catalytic CO₂ dissociation performance, offering a promising strategy for energy-efficient CO₂ utilization. Full article

This study presents evaluation of biochar derived from silkworm cocoons for the adsorption of organic and inorganic contaminants from rainwater. The material was characterised using BET surface area analysis, scanning electron microscopy (SEM), and the point of zero charge (pH_PZC). The prepared biochar exhibited a well-developed surface area and demonstrated adsorption capacity toward both heavy metals and benzotriazole. The model rainwater was prepared by spiking real rainwater samples with Cu(II), Ni(II), Zn(II) ions, and benzotriazole (BT). Adsorption experiments were carried out under laboratory conditions to evaluate the effects of contact time, pH, and sorbent dosage. The experimental data were fitted to pseudo-first-order and pseudo-second-order kinetic models, as well as Langmuir/and Freundlich isotherms. The results showed that the adsorption of Cu(II) followed the Langmuir/Freundlich model, while the adsorption of Ni(II) benzotriazole was more consistent with the Freundlich model. Adsorption kinetics were best described by the pseudo-second-order model. The highest removal efficiencies were observed for Cu(II) (96%) and Ni(II) (88.8%), while Zn(II) removal was limited. Benzotriazole was also effectively adsorbed (97%), rapid adsorption occurred mainly within the first minute. Overall, the study highlights the selective adsorption behaviour of silkworm cocoon biochar and provides a comparative insight into the removal of organic and inorganic pollutants using a waste-derived adsorbent with surface properties comparable to those of activated carbon. Full article

Acetaminophen (APAP) is a widely used pharmaceutical increasingly detected as a contaminant in aquatic environments due to its persistent nature and incomplete removal by conventional wastewater treatment. This study investigates the adsorption performance and mechanisms of commercial activated carbon (M) and its hydrothermally modified form (MH) for APAP removal. Characterization via elemental analysis, X-ray photoelectron spectroscopy (XPS), and N₂ adsorption isotherms revealed that hydrothermal treatment reduced oxygen content and enhanced micro- and mesopore volumes, resulting in a more homogeneous and carbon-rich surface. Batch adsorption experiments conducted under varying pH (5–7) and temperature (30–40 °C) conditions showed that MH achieved up to 94.3% APAP removal, outperforming the untreated carbon by more than 15%. Kinetic modeling indicated that adsorption followed a pseudo-second-order mechanism (R² > 0.99), and isotherm data fitted best to the Langmuir model for MH and the Freundlich model for M, reflecting their differing surface properties. Adsorption was enhanced at lower pH and higher temperatures, consistent with an endothermic and pH-dependent mechanism. Complementary density functional theory (DFT) simulations confirmed that π–π stacking is the dominant interaction between APAP and the carbon surface. The most favorable configuration involved coplanar stacking with non-oxidized graphene (ΔG = −33 kJ/mol), while oxidized graphene models exhibited weaker interactions. Natural Bond Orbital (NBO) analysis further supported the prevalence of π–π interactions over dipole interactions. These findings suggest that surface deoxygenation and improved pore architecture achieved via hydrothermal treatment significantly enhance APAP adsorption, offering a scalable strategy for pharmaceutical pollutant removal in water treatment applications. Full article

This study presents a comparative analysis of two synthesis approaches for fabricating magnetic sorbents based on activated carbon (AC) incorporated with magnetite (Fe₃O₄) nanoparticles: hydrothermal synthesis and ultrasonic treatment. The results demonstrate that ultrasonic-assisted synthesis yields a magnetically responsive composite, us-AC/Fe₃O₄, exhibiting a Pb²⁺ removal efficiency of 92.84%, which is comparable to that of pristine activated carbon (99.0%). A key advantage of the synthesized composite lies in its facile recovery via magnetic separation following adsorption, rendering it a promising candidate for the remediation of heavy metal-contaminated water. Kinetic modeling suggests a dual adsorption mechanism: initial stages are governed by physisorption, while chemisorption dominates in the later phases. Adsorption isotherm modeling demonstrated that the Langmuir model provided the best description of Pb²⁺ adsorption on AC and us-AC/Fe₃O₄, with the highest sorption capacities observed for pristine activated carbon, followed by the ultrasonically modified composite, and comparatively lower values for the hydrothermally treated material. These findings underscore the potential of ultrasonic processing as an effective route for developing magnetically separable sorbents with high performance in aqueous heavy metal removal. Full article