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Search Results (178)

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Keywords = Dubinin–Radushkevich

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22 pages, 5921 KiB  
Article
Adsorption Capacity, Reaction Kinetics and Thermodynamic Studies on Ni(II) Removal with GO@Fe3O4@Pluronic-F68 Nanocomposite
by Ali Çiçekçi, Fatih Sevim, Melike Sevim and Erbil Kavcı
Polymers 2025, 17(15), 2141; https://doi.org/10.3390/polym17152141 - 5 Aug 2025
Abstract
In recent years, industrial wastewater discharge containing heavy metals has increased significantly and has adversely affected both human health and the aquatic ecosystem. The increasing demand for metals in industry has prompted researchers to focus on developing effective and economical methods for removal [...] Read more.
In recent years, industrial wastewater discharge containing heavy metals has increased significantly and has adversely affected both human health and the aquatic ecosystem. The increasing demand for metals in industry has prompted researchers to focus on developing effective and economical methods for removal of these metals. In this study, the removal of Ni(II) from wastewater using the Graphene oxide@Fe3O4@Pluronic-F68 (GO@Fe3O4@Pluronic-F68) nano composite as an adsorbent was investigated. The nanocomposite was characterised using a series of analytical methods, including Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) analysis. The effects of contact time, pH, adsorbent amount, and temperature parameters on adsorption were investigated. Various adsorption isotherm models were applied to interpret the equilibrium data in aqueous solutions; the compatibility of the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models with experimental data was examined. For a kinetic model consistent with experimental data, pseudo-first-order, pseudo-second-order, Elovich, and intra-particle diffusion models were examined. The maximum adsorption capacity was calculated as 151.5 mg·g−1 in the Langmuir isotherm model. The most suitable isotherm and kinetic models were the Freundlich and pseudo-second-order kinetic models, respectively. These results demonstrate the potential of the GO@Fe3O4@Pluronic-F68 nanocomposite as an adsorbent offering a sustainable solution for Ni(II) removal. Full article
(This article belongs to the Section Polymer Composites and Nanocomposites)
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25 pages, 3387 KiB  
Article
Efficiency of Spirulina sp. in the Treatment of Model Wastewater Containing Ni(II) and Pb(II)
by Eleonora Sočo, Andżelika Domoń, Mostafa Azizi, Dariusz Pająk, Bogumił Cieniek, Magdalena M. Michel and Dorota Papciak
Materials 2025, 18(15), 3639; https://doi.org/10.3390/ma18153639 - 1 Aug 2025
Viewed by 290
Abstract
In this work, the biosorption potential of Spirulina sp. as an effective and eco-friendly biosorbent for the removal of Ni(II) and Pb(II) ions from aqueous solutions was investigated. Detailed characterization of the biosorbent was carried out, including surface morphology, chemical composition, particle size, [...] Read more.
In this work, the biosorption potential of Spirulina sp. as an effective and eco-friendly biosorbent for the removal of Ni(II) and Pb(II) ions from aqueous solutions was investigated. Detailed characterization of the biosorbent was carried out, including surface morphology, chemical composition, particle size, zeta potential, crystallinity, zero-point charge, and functional group analysis. Batch tests were performed to determine the kinetic constants and adsorption equilibrium of the studied ions. The adsorption behavior of Spirulina sp. was described using six adsorption isotherms. The best fit was obtained for the Redlich-Peterson and Langmuir isotherms, indicating that monolayer adsorption occurred. The maximum biosorption capacities for Ni(II) and Pb(II) were 20.8 mg·g−1 and 93.5 mg·g−1, respectively, using a biosorbent dose of 10 g·L−1, initial metal concentrations ranging from 50 to 5000 mg·L−1, at pH 6, 20 °C, and a contact time of 120 min. Low values of the mean free energy of adsorption (E) in the Dubinin–Radushkevich and Temkin model (0.3 and 0.1 kJ·mol−1 for Pb(II) and 0.35 and 0.23 kJ·mol−1 for Ni(II)) indicate the dominance of physical processes in the ion binding mechanism. The adsorption of Pb(II) ions was more effective than that of Ni(II) ions across the entire range of tested concentrations. At low initial concentrations, the removal of Pb(II) reached 94%, while for Ni(II) it was 80%. Full article
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23 pages, 1784 KiB  
Article
Study on the Adsorption Characteristics of Spirulina Dry Powder Biomass for Rare Earth Element Praseodymium(III): Adsorption Isotherms, Kinetics, and Thermodynamics Analysis
by Zhenxiang Hu, Caixia Zhang and Qing Shu
Separations 2025, 12(8), 195; https://doi.org/10.3390/separations12080195 - 25 Jul 2025
Viewed by 329
Abstract
Aimed at developing an economical and efficient biosorbent for the adsorption and separation of rare earth ions, this study employed Spirulina dry powder biomass as a biosorbent to investigate its removal performance for Pr3+ in aqueous solutions. Experimental results demonstrated that under [...] Read more.
Aimed at developing an economical and efficient biosorbent for the adsorption and separation of rare earth ions, this study employed Spirulina dry powder biomass as a biosorbent to investigate its removal performance for Pr3+ in aqueous solutions. Experimental results demonstrated that under optimized conditions (pH = 5, adsorbent dosage = 2.0 g/L, initial Pr3+ concentration = 100 mg/L, and adsorption time = 60 min), the removal efficiency of Pr3+ reached 79.0%. FT-IR and XPS characterization confirmed the participation of various functional groups on the Spirulina surface in the adsorption process. When 0.1 mol/L HNO3 was used as the desorption agent, the desorption rate of Pr3+ from Spirulina reached 91.7%, demonstrating excellent regeneration performance. At different temperatures (298–318 K), the adsorption data were fitted using Langmuir, Freundlich, Dubinin–Radushkevich, and Redlich–Peterson models. Among them, the Langmuir model (R2 ranged from 0.993 to 0.999) provided the best fit, and the adsorption capacity of Spirulina for Pr3+ was in the range of 51.10 to 55.31 mg/g. Kinetic studies revealed that the pseudo-second-order model (R2 = 0.999) best described the adsorption process, with a rate constant of 0.054 g/(mg·min) (R2 was 0.999) at an initial Pr3+ concentration of 300 mg/L, indicating chemisorption-controlled behavior. Thermodynamic parameter analysis showed that within the experimental temperature range, ΔG0 < 0 and ΔS0 > 0, confirming that the adsorption process was spontaneous and endothermic. This study provides a novel technical approach for the green recovery of rare earth elements and highlights the potential of Spirulina biomass in rare earth resource recycling. Full article
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20 pages, 5033 KiB  
Article
Plant-Based Biosorbents for Copper(II) Removal: A Comparative Study of Biomass and Essential Oil Residues
by Lidia Ivanova, Paunka Vassileva, Albena Detcheva, Violeta Koleva and Ivalina Avramova
Appl. Sci. 2025, 15(14), 7695; https://doi.org/10.3390/app15147695 - 9 Jul 2025
Viewed by 196
Abstract
The present study compared the adsorption properties of two plant materials and the waste products after their essential oil extraction for removing Cu(II) ions from contaminated water. Methods like SEM, XRD, nitrogen adsorption, DTA, TGA, FTIR, and XPS were used for characterization of [...] Read more.
The present study compared the adsorption properties of two plant materials and the waste products after their essential oil extraction for removing Cu(II) ions from contaminated water. Methods like SEM, XRD, nitrogen adsorption, DTA, TGA, FTIR, and XPS were used for characterization of the materials. All materials showed similar porosity and structure, favoring Cu(II) biosorption. The effects of contact time, pH, temperature, sample amount, and initial metal concentration on Cu(II) removal were examined. Optimal pH was 4, with equilibrium reached in less than 10 min. Temperature and sample amount do not significantly influence the biosorption. The experimental data were fitted to the Langmuir, Freundlich, and Dubinin–Radushkevich isotherm models, and maximum adsorption capacities were calculated. The four plant materials proved to be effective biosorbents for removing copper ions from contaminated water. Desorption experiments using 1 M HNO3 and 0.1 M EDTA showed 100% recovery. The reusability of the most effective biosorbent was confirmed through four adsorption/desorption cycles with EDTA. This material was also used to study the possibilities of purifying a real sample of contaminated water. Full article
(This article belongs to the Special Issue Advanced Adsorbents for Wastewater Treatment)
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21 pages, 5124 KiB  
Article
Full-Scale Pore Structure and Gas Adsorption Characteristics of the Medium-Rank Coals from Qinshui Basin, North China
by Yingchun Hu, Shan He, Feng Qiu, Yidong Cai, Haipeng Wei and Bin Li
Processes 2025, 13(6), 1862; https://doi.org/10.3390/pr13061862 - 12 Jun 2025
Viewed by 522
Abstract
To elucidate the gas adsorption characteristics of medium-rank coal, this study collected samples from fresh mining faces in the Qinshui Basin. A series of experiments were conducted, including low-temperature carbon dioxide adsorption, low-temperature liquid nitrogen adsorption, mercury intrusion, and methane isothermal adsorption experiments, [...] Read more.
To elucidate the gas adsorption characteristics of medium-rank coal, this study collected samples from fresh mining faces in the Qinshui Basin. A series of experiments were conducted, including low-temperature carbon dioxide adsorption, low-temperature liquid nitrogen adsorption, mercury intrusion, and methane isothermal adsorption experiments, which clarify the pore structure characteristics of medium-rank coals, reveal the gas adsorption behavior in medium-rank coal, and identify the control mechanism. The results demonstrate that the modified Dubinin–Radushkevich (D-R) isothermal adsorption model accurately describes the gas adsorption in medium-rank coal, with fitting errors remaining below 1%. Comprehensive pore structure analysis reveals that the coal pore volume consists primarily of absorption pores (<2 nm), transitional pores (10–100 nm), and seepage pores (>100 nm), while the specific surface area is predominantly contributed by absorption pores (<2 nm). At low pressures, gas molecules form monolayer adsorption on absorption pore (<2 nm) and adsorption pore (2–10 nm) surfaces. With increasing pressure, multilayer adsorption dominates. As pore filling approaches the maximum capacity, the adsorption rate decreases progressively until reaching an equilibrium, at which point the adsorption capacity attains its saturation limit. The adsorption data of the gas in medium-rank coal can be explained by the improved D-R isothermal adsorption model. The priority of gas filling in pores is different, and the absorption pore is normally better than the adsorption pore. The results provide a new idea and understanding for the further study of the coalbed gas adsorption mechanism. Full article
(This article belongs to the Section Energy Systems)
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31 pages, 6141 KiB  
Article
Fe3O4/SiO2 Nanocomposite Derived from Coal Fly Ash and Acid Mine Drainage for the Adsorptive Removal of Diclofenac in Wastewater
by Dance Mabu, Ngwako Joseas Waleng, Tshimangadzo S. Munonde, Azile Nqombolo and Philiswa Nosizo Nomngongo
Recycling 2025, 10(3), 99; https://doi.org/10.3390/recycling10030099 - 16 May 2025
Viewed by 1455
Abstract
The ubiquity of diclofenac (DCF) in the environment has raised significant concerns. Diclofenac is a non-steroidal anti-inflammatory drug that has been found in various environmental matrices at minimum concentrations that are harmful to aquatic and terrestrial organisms. Traditional wastewater treatment plants (WWTPs) are [...] Read more.
The ubiquity of diclofenac (DCF) in the environment has raised significant concerns. Diclofenac is a non-steroidal anti-inflammatory drug that has been found in various environmental matrices at minimum concentrations that are harmful to aquatic and terrestrial organisms. Traditional wastewater treatment plants (WWTPs) are not fully equipped to remove a range of pharmaceuticals, and that explains the continued ubiquity of DCF in surface waters. In this study, an Fe3O4/SiO2 nanocomposite prepared from acid mine drainage and coal fly ash was applied for the removal of DCF from wastewater. Major functional groups (Si–O–Si and Fe–O) were discovered from FTIR. TEM revealed uniform SiO2 nanoparticle rod-like structures with embedded dark spherical nanoparticles. SEM-EDS analysis discovered a sponge-like structure fused with Fe3O4 nanoparticles that had significant Si, O, and Fe content. XRD demonstrated the crystalline nature of the nanocomposite. The surface properties of the nanocomposite were evaluated using BET and were 67.8 m2/g, 0.39 cm3/g, and 23.2 nm for surface area, pore volume, and pore size, respectively. Parameters that were suspected to be affecting the removal process were evaluated, including pH, nanocomposite dosage, and sample volume. The detection of DCF was conducted on high-performance liquid chromatography with diode-array detection (HPLC-DAD). Under optimum conditions, the adsorption process was monolayer, and physisorption was described using the Langmuir and Dubinin-Radushkevich (D-R) isotherm models. The kinetic data best fitted the pseudo-first order kinetic model, indicating a physisorption adsorption process. The thermodynamic experimental data confirmed that the adsorption process was spontaneous. The results obtained from real water samples showed 95.28% and 97.44% removal efficiencies from influent and effluent: 94.83% and 88.61% from raw sewage and final sewage, respectively. Overall, this work demonstrated that an Fe3O4/SiO2 nanocomposite could be successfully prepared from coal fly ash and acid mine drainage and could be used to remove DCF in wastewater. Full article
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19 pages, 3865 KiB  
Article
Magnetically Modified Bentonite for Optimized Erythromycin Removal via RSM and DFT Analysis
by Ying-Chieh Hung, Yu-Qi Wu, Ru-Hau Ye, Hsiu-Min Hung and Gui-Bing Hong
Molecules 2025, 30(8), 1792; https://doi.org/10.3390/molecules30081792 - 16 Apr 2025
Viewed by 466
Abstract
Erythromycin (ERY), an antibiotic widely used in human and veterinary medicine, persists in the environment due to its low degradability, accumulating in wastewater and soil. This study presents a novel adsorbent synthesized by magnetically modifying calcined natural bentonite with Fe3O4 [...] Read more.
Erythromycin (ERY), an antibiotic widely used in human and veterinary medicine, persists in the environment due to its low degradability, accumulating in wastewater and soil. This study presents a novel adsorbent synthesized by magnetically modifying calcined natural bentonite with Fe3O4 nanoparticles to enhance ERY removal. The modification increased the surface area, with the highest adsorption observed at pH 11. Adsorption studies revealed that the Dubinin–Radushkevich isotherm model and pseudo-first-order kinetic model best described the adsorption behavior. Response surface methodology (RSM) was employed to optimize key parameters, including adsorbent dosage, temperature, and contact time. The quadratic model indicated optimal conditions of 41.9 mg adsorbent, 29.1 °C, and 9.6 h of contact time, yielding a maximum ERY removal efficiency of 96.2%. Density functional theory (DFT) analysis provided a molecular-level understanding of the adsorption mechanism, identifying strong interactions between ERY, Fe3O4, and bentonite. The theoretical binding energy aligns with experimental results, confirming the role of magnetic modification in promoting ERY adsorption. This study demonstrates a promising approach for mitigating ERY contamination in aqueous environments. Full article
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21 pages, 13359 KiB  
Article
A Novel Zinc-Based MOF Featuring 2,4,6-Tris-(4-carboxyphenoxy)-1,3,5-triazine: Structure, Adsorption, and Photocatalytic Activity
by Magdalena Angelova, Hristina Lazarova, Vanya Kurteva, Rositsa Nikolova, Rusi Rusew and Boris Shivachev
Crystals 2025, 15(4), 348; https://doi.org/10.3390/cryst15040348 - 8 Apr 2025
Viewed by 701
Abstract
A metal–organic framework, MOF-S1, was synthesized via a solvothermal reaction between 2,4,6-tris-(4-carboxyphenoxy)-1,3,5-triazine (TCPT) and zinc nitrate hexahydrate. Single-crystal and powder X-ray diffraction analyses confirmed the formation of hexagonal rod-shaped crystals with a trigonal (P-31c) structure featuring a two-fold interpenetrated 3D framework. [...] Read more.
A metal–organic framework, MOF-S1, was synthesized via a solvothermal reaction between 2,4,6-tris-(4-carboxyphenoxy)-1,3,5-triazine (TCPT) and zinc nitrate hexahydrate. Single-crystal and powder X-ray diffraction analyses confirmed the formation of hexagonal rod-shaped crystals with a trigonal (P-31c) structure featuring a two-fold interpenetrated 3D framework. A comprehensive characterization—including NMR spectroscopy, thermogravimetric analysis, and surface area measurements (using Langmuir, t-plot, Horváth–Kawazoe, and Dubinin–Radushkevich models)—revealed an ultramicroporous material with a Langmuir surface area of 711 m2/g and a median pore width of ~6.5 Å. Adsorption studies using Congo Red, Methylene Blue, Methyl Orange, and Rhodamine B demonstrated the rapid uptake and effective removal from aqueous solutions, with kinetic modeling indicating a dominant chemisorption mechanism. Photocatalytic tests under UV irradiation yielded degradation efficiencies of ~93% for Methyl Orange and ~74% for Rhodamine B. These findings suggest that MOF-S1 is a promising candidate for wastewater treatment applications and UV-related processes, offering a strong adsorption capacity and thermal stability. Full article
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20 pages, 11501 KiB  
Article
Selective Adsorption of Lead in Mixed Metals Wastewater System by Lignin-Carbon-Supported Titanate Nanoflower BC@TNS Adsorbent: Performance and Mechanism
by Jielan Feng, Lei Zhong, Zekun Yang, Chak-Yin Tang, Wing-Cheung Law, Ruchun Wu and Fengwei Xie
Coatings 2025, 15(3), 317; https://doi.org/10.3390/coatings15030317 - 9 Mar 2025
Cited by 1 | Viewed by 820
Abstract
This study introduced a novel type of biochar–titanate nanosheet (BC@TNS) composite for the selective adsorption of Pb(II) from wastewater containing various heavy metal ions. The biochar derived from lignin–carbon pyrolysis forms the scaffold, while titanate nanosheets coat it via an alkaline hydrothermal reaction. [...] Read more.
This study introduced a novel type of biochar–titanate nanosheet (BC@TNS) composite for the selective adsorption of Pb(II) from wastewater containing various heavy metal ions. The biochar derived from lignin–carbon pyrolysis forms the scaffold, while titanate nanosheets coat it via an alkaline hydrothermal reaction. The synthesis was confirmed through analytic characterizations, revealing a distinctive morphology of TNS nanoflowers consisting of numerous nanosheets incorporated into the BC support. BC@TNS achieved maximum adsorption capacities of 37.89 mg/g for Pb(II), 13.38 mg/g for Cd(II), and 8.47 mg/g for Zn(II), demonstrating its remarkable selectivity for Pb(II). Kinetic studies using Weber–Morris, PFO, and PSO models indicated that Pb(II) adsorption was primarily driven by chemisorption, whereas Cd(II) and Zn(II) adsorption were predominantly governed by physisorption. Isotherm analysis using Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin models revealed that Pb(II) adsorption involved both monolayer and multilayer processes, while Cd(II) and Zn(II) adsorption were primarily monolayer. Detailed insights from scanning electron microscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS) analyses further elucidated these mechanisms. The superior selectivity of BC@TNS for Pb(II) was further validated in multicomponent simulated HMs containing 10 co-existing metal ions, maintaining a high Pb(II) adsorption efficiency of 75.68%, highlighting its potential for selective Pb recovery. Moreover, the adsorbent demonstrated excellent regeneration capacity and recyclability. The BC@TNS adsorbent shows great potential for the selective and efficient removal of Pb(II) ions from wastewater, offering a sustainable solution for environmental protection. Full article
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27 pages, 5206 KiB  
Article
Enhanced Adsorption of Methylene Blue in Wastewater Using Natural Zeolite Impregnated with Graphene Oxide
by Gabriela Tubon-Usca, Cyntia Centeno, Shirley Pomasqui, Amerigo Beneduci and Fabian Arias Arias
Appl. Sci. 2025, 15(5), 2824; https://doi.org/10.3390/app15052824 - 5 Mar 2025
Cited by 2 | Viewed by 1709
Abstract
The use of graphene oxide (GO) in combination with mesoporous materials has gained interest in the development of adsorbents. In this study, GO was impregnated into zeolite at three concentrations (ZGO2.5, ZGO5, and ZGO10) through a simple thermal process to enhance the adsorption [...] Read more.
The use of graphene oxide (GO) in combination with mesoporous materials has gained interest in the development of adsorbents. In this study, GO was impregnated into zeolite at three concentrations (ZGO2.5, ZGO5, and ZGO10) through a simple thermal process to enhance the adsorption of methylene blue (MB). Characterization of the resulting materials was performed using spectroscopic techniques such as UV-Vis and FT-IR spectroscopy, SEM, and EDS, confirming the presence of GO on zeolite. Batch experiments were conducted to evaluate their performance, analyzing contact time, pH effect, and adsorption kinetics. Pseudo-first-order, pseudo-second-order, and Elovich kinetic models were applied, and the adsorption mechanism was studied using Langmuir, Freundlich, Temkin II, and Dubinin–Radushkevich (D-R) isotherms at different temperatures. Optimal adsorption was achieved at 273 K, 100 mg L−1 of MB, adsorbent mass of 100 mg, 250 rpm, and pH 5–9, with 90% removal efficiency after 70 min. The pseudo-second-order, Freundlich, and D-R models best described the process (R2 > 0.98), suggesting a mixed physisorption–chemisorption mechanism. The maximum adsorption capacity from the D-R isotherm reached 119 mg g−1 at 333 K. Thermodynamic studies showed that adsorption was a spontaneous and endothermic process. These findings highlight the potential of GO-impregnated zeolite as an effective adsorbent for MB. Full article
(This article belongs to the Section Materials Science and Engineering)
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20 pages, 5316 KiB  
Article
Experimental Design of Polymer Synthesis for the Removal of 2,4-Dichlorophenoxyacetic Acid and Glyphosate from Water by Adsorption
by Tiago Teixeira Alves, Grasiele Soares Cavallini and Nelson Luis Gonçalves Dias Souza
Waste 2025, 3(1), 7; https://doi.org/10.3390/waste3010007 - 22 Feb 2025
Viewed by 1702
Abstract
Water pollution from herbicide contamination poses a significant environmental challenge, necessitating effective regenerative materials for their removal. 2,4-dichlorophenoxyacetic acid and glyphosate are among the most widely used herbicides for weed control. This study aimed to synthesize polymeric materials for the removal of these [...] Read more.
Water pollution from herbicide contamination poses a significant environmental challenge, necessitating effective regenerative materials for their removal. 2,4-dichlorophenoxyacetic acid and glyphosate are among the most widely used herbicides for weed control. This study aimed to synthesize polymeric materials for the removal of these compounds from aqueous media. The study evaluated adsorption capacity, isotherms, kinetics, regeneration capacity, and the influence of pH on adsorption, alongside disinfection tests. Biodegradable polymers including chitosan, sodium alginate, and guar gum were cross-linked and characterized using infrared and Raman spectroscopy. Two samples (experiment C and M) exhibited adsorption capacities of 49.75 ± 1.474 mg g−1 and 26.53 ± 1.326 mg g−1 for glyphosate and 2,4-dichlorophenoxyacetic acid, respectively. Optimal adsorption was observed at pH 3.00 and 6.00 for glyphosate and 3.00 for 2,4-dichlorophenoxyacetic acid. The Langmuir and Dubinin–Radushkevich isotherms best described the adsorption behavior of glyphosate and 2,4-dichlorophenoxyacetic acid, respectively. Kinetic studies indicated that the adsorption process followed a pseudo-second-order model. Infrared and Raman absorption spectra confirmed cross-linking in the polymer samples. Regeneration tests showed that 2,4-dichlorophenoxyacetic acid adsorption remained consistent over three reuse cycles, while glyphosate adsorption increased. Disinfection tests using Escherichia coli and total coliforms demonstrated a significant reduction in colony-forming units, supporting the suitability of the material for this application. Full article
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15 pages, 2361 KiB  
Article
From Waste to Value: Banana-Peel-Derived Adsorbents for Efficient Removal of Polar Compounds from Used Palm Oil
by Duangdao Channei, Panatda Jannoey, Punyanuch Thammaacheep, Wilawan Khanitchaidecha and Auppatham Nakaruk
Appl. Sci. 2025, 15(4), 2205; https://doi.org/10.3390/app15042205 - 19 Feb 2025
Viewed by 2163
Abstract
The banana chip industry generates significant quantities of waste, including banana peels and used palm oil, which present both environmental and economic challenges. This study explored converting banana peel waste into porous adsorbents via chemical and thermal activation using sulfuric acid (S-BP) and [...] Read more.
The banana chip industry generates significant quantities of waste, including banana peels and used palm oil, which present both environmental and economic challenges. This study explored converting banana peel waste into porous adsorbents via chemical and thermal activation using sulfuric acid (S-BP) and 5% w/v acetic acid (A-BP) as activating agents. Characterization using field emission scanning electron microscopy (FESEM) and Brunauer–Emmett–Teller (BET) analysis revealed notable morphological distinctions and enhanced porosity. The BET surface areas of S-BP and A-BP were 338.959 m2/g and 201.722 m2/g, respectively, significantly higher than that of calcined banana peel (C-BP) at 3.202 m2/g. Despite the higher surface area of S-BP, A-BP, prepared under milder acetic acid conditions, was further investigated for adsorption studies. A-BP effectively reduced the free fatty acids (FFAs) in used palm oil from 3.108% to 1.69% within 30 min. Adsorption isotherms favored the Freundlich model (R2 = 0.9115), indicating multilayer adsorption behavior. The adsorption energy derived from the Dubinin–Radushkevich (D–R) model was determined to be 2.61 J/mol, indicating that the adsorption process primarily occurs through physisorption. This study highlights a sustainable approach to waste management and resource recovery, promoting circular economy principles in the banana chip industry. Full article
(This article belongs to the Special Issue New Approaches to Water Treatment: Challenges and Trends)
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18 pages, 3812 KiB  
Article
Dual-Activated Tamarix Gallica-Derived Carbons for Enhanced Glyphosate Adsorption: A Comparative Study of Phosphoric and Sulfuric Acid Activation
by Saliha Benaoune, Abdelkarim Merzougui, Rania Remmani, Narimene Bouzidi, Antonio Ruiz-Canales, Imane Akacha and Amir Djellouli
Materials 2025, 18(3), 511; https://doi.org/10.3390/ma18030511 - 23 Jan 2025
Cited by 3 | Viewed by 893
Abstract
This study investigates the efficacy of activated carbons (ACs) derived from Tamarix gallica (TG) leaves for glyphosate removal from aqueous solutions. Two chemical activation methods, using phosphoric acid (H3PO4) and sulfuric acid (H2SO4), were compared [...] Read more.
This study investigates the efficacy of activated carbons (ACs) derived from Tamarix gallica (TG) leaves for glyphosate removal from aqueous solutions. Two chemical activation methods, using phosphoric acid (H3PO4) and sulfuric acid (H2SO4), were compared to optimize adsorbent performance. The resulting materials, labeled AC-H3PO4 and AC-H2SO4, were comprehensively characterized using XRD, FTIR, SEM-EDS, BET analysis, and pHpzc determination, revealing distinct physicochemical properties. AC-H3PO4 exhibited a larger surface area (580.37 m2/g) and more developed pore structure compared to AC-H2SO4 (241.58 m2/g). Adsorption kinetics were best described by the pseudo-first-order model for both adsorbents. Isothermal studies demonstrated that AC-H3PO4 followed a pore-filling mechanism best described by the Dubinin–Radushkevich model, while AC-H2SO4 showed multilayer adsorption fitting the Freundlich model. Both adsorbents exhibited high glyphosate removal capacities, with maximum Langmuir adsorption capacities of 247.58 mg/g and 235.13 mg/g for AC-H3PO4 and AC-H2SO4, respectively. The mean free energy of adsorption (E) values confirmed physisorption as the dominant mechanism. This research highlights the potential of TG-derived activated carbons as sustainable and effective adsorbents for glyphosate remediation in water treatment applications, demonstrating the impact of activation methods on adsorption performance. Full article
(This article belongs to the Section Carbon Materials)
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18 pages, 9211 KiB  
Article
Cu0-Functionalized, ZIF-8-Derived, Nitrogen-Doped Carbon Composites for Efficient Iodine Elimination in Solution
by Jiuyu Chen, Chensheng Gao, Jingwen Chen, Fei Liu and Zhiwen Liu
Nanomaterials 2025, 15(2), 105; https://doi.org/10.3390/nano15020105 - 12 Jan 2025
Viewed by 1060
Abstract
The development of copper-based materials with a high efficiency and low cost is desirable for use in iodine (I2) remediation. Herein, Cu0-nanoparticles-functionalized, ZIF-8 (Zeolite Imidazole Framework-8)-derived, nitrogen-doped carbon composites (Cu@Zn-NC) were synthesized by ball milling and pyrolysis processes. The [...] Read more.
The development of copper-based materials with a high efficiency and low cost is desirable for use in iodine (I2) remediation. Herein, Cu0-nanoparticles-functionalized, ZIF-8 (Zeolite Imidazole Framework-8)-derived, nitrogen-doped carbon composites (Cu@Zn-NC) were synthesized by ball milling and pyrolysis processes. The as-prepared composites were characterized using SEM, BET, XRD, XPS, and FT-IR analyses. The results showed that the morphology of ZIF-8 changed from a leaf-like structure into an irregular structure after the introduction of a copper salt and carbonization. The copper in the pyrolysis samples was mainly in the form of Cu0 particles. The presence of an appropriate amount of Cu0 particles could increase the specific surface area of Cu@Zn-NC. The subsequent batch adsorption results demonstrated that the as-fabricated composites showed high I2 adsorption amounts (1204.9 mg/g) and relatively fast dynamics in an iodine–cyclohexane solution when the Cu content was 30% and the pyrolysis temperature was 600 °C, outperforming the other Cu-based materials. The isothermal adsorption followed both Langmuir and Dubinin–Radushkevich isotherm models, while the kinetics of I2 adsorption followed a pseudo-second-order kinetic model. The activation energy (Eα) of the adsorbent was determined to be 47.2 kJ/mol, according to the Arrhenius equation. According to the experimental and DFT analyses, I2-Zn interactions and I2-Cu0 chemisorption jointly promoted the elimination of iodine. In general, this study provided an operative adsorbent for the highly effective capture of iodine in solution, which might be worth applying on a large scale. Full article
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13 pages, 2250 KiB  
Article
Fluoride Adsorption from Water Using Activated Carbon Modified with Nitric Acid and Hydrogen Peroxide
by Maja Ergović Ravančić and Mirna Habuda-Stanić
Water 2024, 16(23), 3439; https://doi.org/10.3390/w16233439 - 29 Nov 2024
Cited by 1 | Viewed by 1563
Abstract
Adsorption on activated carbon is one of the most commonly used methods for removing excess amounts of fluoride from water. This research has tested the parameters of fluoride adsorption on four commercial activated carbons modified with nitric acid and hydrogen peroxide. The adsorption [...] Read more.
Adsorption on activated carbon is one of the most commonly used methods for removing excess amounts of fluoride from water. This research has tested the parameters of fluoride adsorption on four commercial activated carbons modified with nitric acid and hydrogen peroxide. The adsorption properties included the initial fluoride concentrations (2–40 mg/L), pH (4–9), dosage of activated carbon (2–20 g/L), contact time (15–360 min) and temperature (25–45 °C). The research results showed a decrease in the proportion of adsorbed fluoride by increasing its initial concentration, while an increase in temperature had a positive effect on the proportion of removed fluoride. The highest fluoride adsorption capacity of 1 mg/g belonged to HN-H2O2 active carbon at a temperature of 45 °C. The maximum adsorption capacities were recorded at pH 4 for all adsorbents oxidized with H2O2 (0.041–0.168 mg/g) and at pH 6 for all adsorbents oxidized with HNO3 (0.065–0.134 mg/g). An increase in the temperature to 45 °C resulted in the maximum increase in the adsorption capacity for all adsorbents, and the adsorbent HN-HNO3 (0.158 mg/g) had the highest adsorption capacity. Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherms were used to determine the adsorption mechanism. The experimental data showed the best match with the Freundlich model at all temperatures, while the pseudo-second-order kinetic model described the adsorption rate the best. Full article
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