Search Results (7,677)

Sample storage is a key factor in odour quantification. This study investigates the loss of odorous compounds in Nalophan™ sampling bags during storage, simulating real-world transport and storage conditions. The goal was to quantify compound leakage over time by varying operational parameters to identify the most significant losses. The tested compounds—sulphur, oxygenated, and hydrocarbon VOCs—were prepared in the laboratory at 10 ppm. Tests were conducted on 12 L Nalophan™ bags with sampling intervals of 0, 6, 30, 48, and 100 h, exceeding the EN 13725 guideline limits (30 h). To evaluate recovery, environmental and internal humidity and temperature were varied. Additionally, the adsorption surface was increased by inserting Nalophan™ flakes inside the bags. The results show that under ambient conditions, losses during 30 h are contained and are within the order of instrumental uncertainty for all the tested compounds. A higher ambient temperature and humidity did not significantly affect recovery. In contrast, internal humidity appeared to have a more noticeable effect, particularly affecting low molecular weight sulphur compounds and oxygenates. These findings suggest optimal storage strategies for olfactometric samples, highlighting that significant losses do not occur within the EN 13725:2022 storage time limits. Moreover, even exceeding these time limits, the observed losses remain limited to 100 h. Full article

Although the exponential increase in photovoltaic installations does contribute to mitigating climate change, it has posed the problem of photovoltaic (PV) residue. As PV panels contain strategic metals, their recovery has become a priority. This paper therefore employs a mesoporous carbon impregnated with P507 extractant as adsorbent to selectively recover gallium and indium from solutions simulating the leachate of end-of-life CIGS (Copper Indium Gallium Selenide) cells in a fixed-bed. The previous batch results obtained in our lab show that both metals can be selectively separated by simply adjusting the initial pH, with large adsorption capacities (44.97 mg/g for gallium and 34.24 mg/g for indium). The obtained breakthrough curves were fitted to the Thomas, Yan, Yoon, and HSDM (Homogeneous Surface Diffusion Model) models using a simulation program developed in Python 3.12 obtaining good results in all cases (R² > 0.9). The estimated parameters were used to predict the experimental breakthrough curve for a different experiment that had not been used for parameter estimation, being the best predictive results the obtained with the HSDM. This is logical, given that unlike the other three models, it is mechanistic. Full article

Microbially induced carbonate precipitation (MICP), as an eco-friendly biomineralization technology, has opened up an innovative path for the green and low-carbon development of the mining industry. Unlike conventional methods, its in situ solidification minimizes environmental disturbances and reduces carbon emissions during construction. This article reviews the research on MICP technology in various scenarios within the mining industry, summarizes the key factors influencing the application of MICP, and proposes a future research direction to fill the gap of the lack of systematic guidance for the application of MICP in this field. Specifically, it elaborates on the solidification mechanism of MICP and its current application in the solidification and storage of tailings, heavy metal immobilization, waste resource utilization, carbon sequestration, and field-scale deployment, establishing a technical foundation for broader implementation in the mining sector. Key influencing factors that affect the solidification effect of MICP are discussed, along with critical engineering challenges such as the attenuation of microbial activity and the low uniformity of calcium carbonate precipitation under extreme conditions. Proposed solutions include environmentally responsive self-healing technologies (the stimulus-responsive properties of the carriers extend the survival window of microorganisms), a one-phase low-pH injection method (when the pH = 5, the delay time for CaCO₃ to appear is 1.5 h), and the incorporation of auxiliary additives (the auxiliary additives provided more adsorption sites for microorganisms). Future research should focus on in situ real-time monitoring of systems integrated with deep learning, systematic mineralization evaluation standard system, and urea-free mineralization pathways under special conditions. Through interdisciplinary collaboration, MICP offers significant potential for integrated scientific and engineering solutions in mine waste solidification and sustainable resource utilization. Full article

In this study, high-yield biopolymer/ceramic hollow fibers were fabricated via a facile, modified polyol process in a spinneret setup, enabling the controlled adsorption of Cu²⁺ ions. Post sintering transformed these into catalytic copper-decorated carbon/ceramic (alumina) composite hollow fibers, with alginate serving as both a metal ion binder and a copper nanoparticle stabilizer. The resulting hollow fibers featured porous walls with a high surface area and were densely decorated with copper nanoparticles. Their structural and morphological characteristics were analyzed, and their NO reduction performance was assessed in a continuous flow configuration, where the gas stream passed through both the shell and lumen sides of a fiber bundle in a tangential flow mode. This study also examined the stability, longevity and regeneration potential of the catalytic fibers, including the mechanisms of deactivation and reactivation. Carbon content was found to be decisive for catalytic performance. High-carbon fibers exhibited a light-off temperature of 250 °C, maintained about 90% N₂ selectivity and sustained a consistently high NO reduction efficiency for over 300 h, even without reducing gases like CO. In contrast, low-carbon fibers displayed a higher light-off temperature of 350 °C and a reduced catalytic efficiency. The results indicate that carbon enhances both activity and selectivity, counterbalancing deactivation effects. Owing to their scalability, durability and effectiveness, these catalytic fibers and their corresponding bundle-type reactor configuration represent a promising technology for advanced NO abatement. Full article

The efficient removal of elemental mercury (Hg⁰) from coal-fired flue gas is a critical challenge in environmental governance. This study proposes utilizing waste fluid catalytic cracking catalyst (WFCC) as the potential support for Hg⁰ catalytic oxidation. After activation (AFCC) via calcination decarbonization, a composite support (AFCC-PG) was fabricated using palygorskite (PG) as a binder. Subsequently, VO_x was loaded onto the support to form the VO_x/AFCC-PG catalyst for Hg⁰ removal. Experimental results demonstrate that the VO_x/AFCC-PG catalyst achieves >95% Hg⁰ removal efficiency under simulated flue gas conditions (150 °C, GHSV = 6000 h⁻¹) while maintaining excellent stability over 60 h. Furthermore, Hg-TPD and XPS analyses indicate that the synergistic lattice oxygen oxidation–adsorption established between VO_x and the AFCC-PG plays a key role in efficient Hg⁰ removal. This study proposes a cost-effective strategy for both the resource utilization of waste catalysts and the control of mercury pollution in coal-fired flue gas. Full article

The presence of galena, sphalerite (cleiophane), and Carbonaceous Material (CM) in sulphide ore complicates the application of a direct-differential flotation flowsheet due to increased mutual interactions between both marketable concentrates and final tailings. Flotation tests, measurements of electrokinetic (zeta) potential, adsorption of sulphydric collectors, and colorimetric indicators were employed to elucidate the cause-and-effect relationships underlying the reduction in contrast of the flotation properties of galena and cleiophane surfaces. It was established that galena and cleiophane exhibit comparable flotation responses when using diesel oil within a pH range of 6–8. While high galena recovery is anticipated, the similar recovery of cleiophane is attributed to the ZnS zeta potential approaching zero in this pH interval. Experimental results demonstrated a distinct difference in the flotation behavior of galena and cleiophane, both with natural surface oxidation and following the removal of sulphoxy films. The application of Carbonaceous Material depressants derived from wood processing by-products (lignin-sulphonates) resulted in a significant decrease in sphalerite recovery. Although the flotation rate constant for Carbonaceous Material in the presence of lignin-sulphonate-based depressants decreases, the overall recovery to concentrate increases over time. The implementation of a bulk-differential flowsheet, involving the preliminary removal of CM prior to the bulk Pb-Zn flotation of lead-zinc sulphide ore, has been demonstrated to be effective. Full article

The excessive emission of cadmium (Cd²⁺) poses a serious threat to the aquatic environment due to its high toxicity and bioaccumulation potential. This study constructed three types of vertical-subsurface-flow constructed wetlands configured with iron–carbon–zeolite composite substrates, including an iron–carbon–zeolite constructed wetland (TF-CW), a zeolite–iron–carbon constructed wetland (FT-CW), and an iron–carbon–zeolite mixed constructed wetland (H-CW), to investigate the purification performance and mechanisms of constructed wetlands for cadmium-containing wastewater (0~6 mg/L). The results demonstrated that iron–carbon–zeolite composite substrates significantly enhanced Cd²⁺ removal efficiency (>99%) through synergistic redox-adsorption mechanisms, where the iron–carbon substrate layer dominated Fe-Cd co-precipitation, while the zeolite layer achieved short-term cadmium retention through ion-exchange adsorption. FT-CW exhibited superior NH₄⁺-N removal efficiency (77.66%~92.23%) compared with TF-CW (71.45%~88.05%), while iron–carbon micro-electrolysis effectively inhibited NO₃⁻-N accumulation (<0.1 mg/L). Under cadmium stress, Typha primarily accumulated cadmium through its root systems (>85%) and alleviated oxidative damage by dynamically regulating antioxidative enzyme activity, with the superoxide dismutase (SOD) peak occurring at 3 mg/L Cd²⁺ treatment. Microbial community analysis revealed that iron–carbon substrates promoted the relative abundance of Bacteroidota and Patescibacteria as well as the enrichment of Saccharimonadales, Thauera, and Rhodocyclaceae (genera), enhancing system stability. This study confirms that iron–carbon–zeolite CWs provide an efficient and sustainable technological pathway for heavy metal-contaminated water remediation through multidimensional mechanisms of “chemical immobilization–plant enrichment–microbial metabolism”. Full article

The pharmaceutical contamination of water, especially by widely used drugs, presents important environmental and health concerns due to the inefficiency of conventional treatment methods. The present study proposes a sustainable solution using biochar (Bch) obtained from tomato waste, functionalized with Fe₃O₄ and MnO₂ nanoparticles, for the removal of paracetamol from aqueous solutions. The composite materials were synthesized, characterized, and evaluated under varying conditions, including pH, temperature, contact time, initial drug concentration, and adsorbent dose. The materials exhibited porous structures with wide pore size distributions. Optimal removal efficiency was achieved for 30 mg L⁻¹ paracetamol concentration, pH 2, 25 °C, 0.3 g L⁻¹ adsorbent dose, and 20 min contact time. The Freundlich isotherm provided the best fit for the adsorption data. Kinetic studies revealed that the pseudo-second-order model best described the adsorption process. Thermodynamic parameters indicated that the process was spontaneous, feasible, and exothermic. Compared with similar materials derived from agricultural waste, the tomato waste-based composites demonstrated competitive adsorption capacities. These findings suggest that Bch-HCl/MnO₂ and Bch-HCl/Fe₃O₄/MnO₂ are promising, cost-effective adsorbents for mitigating pharmaceutical pollutants in wastewater. Full article

The energy requirements for conditioning spaces have been increasing primarily due to population growth and climate change. This paper shows a comparison between an adsorption (ADC) and absorption cooling (ABC) systems to keep a building below the 25 °C set-point in dynamic conditions, utilizing a latent heat storage tank with MgCl₂·6H₂O and erythritol, and employing evacuated tube and parabolic trough collectors. The storage tank geometry is a plate heat exchanger. An auxiliary system was incorporated to control the temperature range of the solar cooling systems. The results showed that the coefficient of performance was kept around 0.40–0.60 and 0.70 for adsorption and absorption cooling, respectively. The latent heat storage tank with erythritol captured more solar energy than MgCl₂·6H₂O. A maximum solar fraction of 0.96 was obtained with MgCl₂·6H₂O, a thickness of 0.15 m, 20 m² of parabolic trough collector area, and absorption cooling, while the energy supply was fully satisfied with a solar collector with erythritol, a thickness of 0.1 m, 13 m² of parabolic trough area, and absorption cooling. In general, erythritol obtained better results of solar collector fractions than MCHH; however, it has less thermal stability than MgCl₂·6H₂O, and the cost is higher. Full article

The urgent need to address the climate crisis demands a swift transition from fossil fuels to renewable energy. Clean hydrogen, produced through ethanol steam reforming (ESR), offers a viable solution. Traditional ESR operates at atmospheric pressure, requiring costly separation and compression of hydrogen. High-pressure ESR, however, improves hydrogen purification, streamlines processes like pressure swing adsorption, and reduces operational costs while enhancing energy efficiency. High-pressure ESR also enables compact reactor designs, minimizing equipment size and land use by compressing reactants into smaller volumes. This study evaluates two nickel-based commercial catalysts, AR-401 and NGPR-2, under high-pressure ESR conditions. Key parameters, including reaction temperature, steam-to-ethanol ratio, and weight hourly space velocity, were optimized. At 30 bars, 700 °C, and a steam-to-ethanol ratio of 9, both catalysts demonstrated complete ethanol conversion, with hydrogen selectivity of 65–70% and yields of 4–4.5 moles of H₂ per mole of ethanol. Raising the temperature to 850 °C improved hydrogen selectivity to 74% and yielded 5.2 moles of H₂ per mole. High-pressure ESR using renewable ethanol provides a scalable, efficient pathway for hydrogen production, supporting sustainable energy solutions. Full article

Phosphates are key pollutants involved in the eutrophication of water bodies, creating the need for efficient and low-cost strategies for their removal in order to meet environmental quality standards. This study presents a comparative thermodynamic evaluation of phosphate ion adsorption from aqueous solutions using two sustainable and readily available materials: autoclaved aerated concrete (AAC) and pumice stone (PS). Batch experiments were conducted under acidic (pH 3) and alkaline (pH 9) conditions to determine equilibrium adsorption capacities, and kinetic experiments were carried out for the best-performing adsorbent. Adsorption data were fitted to the Langmuir and the Freundlich isotherm models, while kinetic data were evaluated using pseudo-first-order and pseudo-second-order models. The Freundlich model showed the best correlation (R² = 0.90 − 0.97), indicating the heterogeneous nature of the adsorbent surfaces, whereas the Langmuir parameters suggested monolayer adsorption, with maximum capacities of 1006.69 mg/kg for PS and 859.20 mg/kg for AAC at pH 3. Kinetic results confirmed a pseudo-second-order behavior, indicating chemisorption as the main mechanism and the rate-limiting step in the adsorption process. To the best of our knowledge, this is the first study to compare the thermodynamic performance of AAC and PS for phosphate removal under identical experimental conditions. The findings demonstrate the potential of both materials as efficient, low-cost, and thermodynamically favorable adsorbents. Furthermore, the use of AAC, an industrial by-product, and PS, a naturally abundant volcanic material, supports resource recovery and waste valorization, aligning with the principles of the circular economy and sustainable water management. Full article

Natural zeolites have gained attention as low-cost adsorbents for the removal of heavy metals (HMs) from wastewater. However, their performance can be compromised by the presence of competing cations such as ammonium (NH₄⁺). This study investigated the competitive adsorption and desorption dynamics of NH₄⁺ and six HMs (Cd, Cr, Cu, Ni, Pb, and Zn) on two natural zeolites. Batch and column experiments using synthetic wastewater were conducted to evaluate the effects of different NH₄⁺ concentrations, pH, and particle size on HM removal efficiency and desorption effects. Results showed that increasing NH₄⁺ concentrations significantly reduce HM adsorption, with total capacity decreasing by ~45% at 100 mg/L NH₄-N in kinetic tests. Adsorption isotherms of the HM mixture for both zeolite types followed a clear sigmoidal trend, which was captured well by the Hill model (R² = 0.99), with loading rates up to 56.14 mg/g. Pb consistently exhibited the highest affinity for zeolites, while Cd, Cr, Ni, and Zn were most affected by NH₄⁺ competition in the column tests. Desorption tests confirmed that NH₄⁺ rapidly re-mobilises adsorbed metals, in particular Cd, Cu, and Zn. Slightly acidic to neutral pH conditions were optimal for minimising HM remobilisation. These findings underscore the need to consider competitive interactions and operational conditions when applying natural zeolites for HM removal, especially in ammonium-rich environments such constructed wetlands, soil filters, or other decentralised applications. Full article

The recovery and control of volatile organic compounds (VOCs) have gained significant attention. Supported sulfonic acid materials show potential in converting aromatic VOCs into non-volatile sulfonic acid derivatives. However, their effectiveness is closely tied to the anchoring state of the sulfonic acid groups. In this study, two supported sulfonic acids, SSA@CdO and SSA@CaO, were synthesized via the respective reactions of CdO and CaO with chlorosulfonic acid to investigate how the properties of the supports influence sulfonic acid anchoring and reactivity toward o-xylene. Comprehensive characterization and performance tests revealed that sulfonic acid groups on CdO were covalently bonded, forming positively charged sites ([O_0.5Cd–O]^ɗ−–SO₃H^ɗ+) with high loading (9.7 mmol/g), enabling excellent o-xylene removal (≥95.6%) and adsorption capacity (51.67–91.59 mg/g) at 130–150 °C. In contrast, ion-paired bonding on CaO formed negatively charged sites ([O_0.5Ca]⁺:OSO₃H⁻), which were inactive in electrophilic sulfonation. This work provides new insights for enhancing supported sulfonic acid materials in VOC treatment. Full article

Atmospheric water harvesting, as an emerging water collection technology, is expected to mitigate water resource crises. Adsorption-based atmospheric water harvesting technology offers distinct advantages, including geographical independence and reduced reliance on ambient humidity levels. Herein, a thermoresponsive gel (PNIPAM/TO-CNF) integrated with lithium chloride was constructed to achieve accelerated moisture sorption and rapid desorption capabilities. In the designated PNIPAM/TO-CNF/LiCl gel, PNIPAM provided a temperature-responsive hydrophilic–hydrophobic transition network; the hydrophilicity and structural strength were enhanced by TO-CNF, the moisture absorption capacity was dramatically elevated by hygroscopic salt LiCl, and pore-forming agent polyethylene glycol created a favorable porous structure. This synergistic design endows the gel with an optimized hydrophilic network, temperature-responsive behavior, and a porous architecture conducive to water vapor transportation, thereby achieving rapid moisture absorption and desorption. Under 60% relative humidity, the gel exhibited a water vapor adsorption capacity of 144% within 1 h, reaching its maximum absorption capacity of 178% after 140 min. The gel exhibited an even more superior desorption performance: when heated to 70 °C, its moisture content rapidly decreased to 16% of its initial weight within 1 h, corresponding to the desorption of 91% of the total absorbed water. A simplified pore-forming methodology that enables the integration of temperature-responsive properties with efficient moisture transfer channels was reported in this paper, providing a viable design pathway for achieving accelerated adsorption–desorption cycles in atmospheric water harvesting. Full article

This study reports the separation of methyl ethyl ketone (MEK), a relevant compound in the biorefinery context, from aqueous solutions using activated carbons derived from avocado seed biomass. Two synthesis routes were explored via chemical and thermal activation with H₂SO₄ and KOH. A Taguchi experimental design was applied to tailor synthesis conditions, with MEK adsorption capacity as the target property. Adsorption kinetics and isotherms were evaluated to determine the thermodynamic behavior of MEK separation using the best-performing activated carbons. The carbon activated with H₂SO₄ achieved the highest adsorption capacity (142 mg g⁻¹) at 20 °C and pH 4, surpassing KOH-based materials. This enhanced performance correlated to increased surface area and acidic oxygenated functionalities. However, higher pH and temperature reduced the adsorption efficiency for all adsorbents. Comprehensive characterization was performed using XRD, XRF, FTIR, SEM, N₂ adsorption–desorption isotherms, pH at point of zero charge, and surface acidity/basicity analysis via Boehm titration. Thermodynamic data and surface characterization indicated that MEK adsorption occurs via a double-layer mechanism dominated by electrostatic interactions and hydrogen bonding. The findings highlight an optimized approach for tailoring avocado-based activated carbons to efficiently recover MEK from aqueous media, supporting its potential application in downstream purification of fermentation broths for biofuel production and energy transition processes. Full article