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Search Results (484)

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Keywords = recyclable adsorbent

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10 pages, 1591 KiB  
Communication
Adsorptive Separation of Chlorobenzene and Chlorocyclohexane by Nonporous Adaptive Crystals of Perethylated Pillar[6]arene
by Sha Wu, Yuyue Chi, Qian Dong and Jiong Zhou
Molecules 2025, 30(15), 3312; https://doi.org/10.3390/molecules30153312 - 7 Aug 2025
Viewed by 299
Abstract
The separation of chlorobenzene (CB) and chlorocyclohexane (CCH) using traditional industrial separation technologies (distillation, fractionation, and rectification) is a great challenge due to their close boiling points. Here, we report an innovative method for the separation of the mixture [...] Read more.
The separation of chlorobenzene (CB) and chlorocyclohexane (CCH) using traditional industrial separation technologies (distillation, fractionation, and rectification) is a great challenge due to their close boiling points. Here, we report an innovative method for the separation of the mixture of CB and CCH by nonporous adaptive crystals (NACs) of perethylated pillar[6]arene (EtP6). NACs of EtP6 (EtP6α) can selectively adsorb CCH vapor from the vapor mixture of CB and CCH (v:v = 1:1) with a purity of 99.5%. Furthermore, EtP6α can be recycled for five times without a significant loss of performance. Full article
(This article belongs to the Special Issue Recent Advances in Supramolecular Chemistry)
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16 pages, 1369 KiB  
Article
Recycling Waste Cottonseed Hulls to Biomaterials for Ammonia Adsorption
by Thomas Klasson, Bretlyn Pancio and Allen Torbert
Recycling 2025, 10(4), 158; https://doi.org/10.3390/recycling10040158 - 6 Aug 2025
Viewed by 345
Abstract
Ammonia emissions in poultry houses are common and pose health concerns for animals and workers. However, effective control of these emissions with sustainable products is lacking. Therefore, we investigated if an agricultural byproduct, cottonseed hulls, could be recycled through pyrolysis and used to [...] Read more.
Ammonia emissions in poultry houses are common and pose health concerns for animals and workers. However, effective control of these emissions with sustainable products is lacking. Therefore, we investigated if an agricultural byproduct, cottonseed hulls, could be recycled through pyrolysis and used to remove ammonia from air. In this study, the efficacy of ammonia removal was observed using cottonseed hull biomaterials pyrolyzed at seven different temperatures: 250, 300, 350, 400, 500, 600, and 700 °C. In this study, ammonia was passed through a column filled with pyrolyzed material, and ammonia in the filtered air was monitored. The results showed that materials pyrolyzed at intermediate temperatures of 350 and 400 °C were the most efficient at ammonia removal and were able to adsorb approximately 3.7 mg NH3/g of material. Despite extensive characterization, ammonia adsorption could not be linked to intrinsic material properties. Evaluation of the materials showed that the carbon in the pyrolyzed materials would be stable over time should the spent material be used as a soil amendment. 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 422
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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27 pages, 4623 KiB  
Article
Preparation and Application of Wetland-Plant-Derived Biochar for Tetracycline Antibiotic Adsorption in Water
by Qingyun Chen, Hao Tong, Xing Gao, Peng Li, Jiaqi Li, Haifeng Zhuang and Suqing Wu
Sustainability 2025, 17(14), 6625; https://doi.org/10.3390/su17146625 - 20 Jul 2025
Viewed by 416
Abstract
Every year, a large amount of antibiotics enter aquatic environments globally through discharging of pharmaceutical wastewater and domestic sewage, emissions from agriculture, and livestock, posing a severe threat to ecosystems and human health. Therefore, it is essential to develop efficient adsorption materials for [...] Read more.
Every year, a large amount of antibiotics enter aquatic environments globally through discharging of pharmaceutical wastewater and domestic sewage, emissions from agriculture, and livestock, posing a severe threat to ecosystems and human health. Therefore, it is essential to develop efficient adsorption materials for rapid removal of antibiotics in water. In this study, abundant and renewable wetland plants (lotus leaves, Arundo donax, and canna lilies) were utilized as raw materials to prepare biochar through slow pyrolysis combined with KOH chemical activation. The prepared biochar was employed to adsorb typical tetracycline (TC) antibiotics (TC-HCl, CTC-HCl, OTC-HCl) from water. The results showed that the optimum biochar (LBC-600 (1:3)) was prepared at a pyrolysis temperature of 600 °C with the mass ratio of KOH to lotus leaf of 1:3. The optimum pH for the adsorption of the three antibiotics were 5, 4, and 3, respectively. The highest adsorption rates reached 93.32%, 81.44%, and 83.76% for TC-HCl, CTC-HCl, and OTC-HCl with 0.6 g/L of biochar, respectively. At an initial antibiotic concentration of 80 mg·L−1, the maximum adsorption capacities achieved 40.17, 27.76, and 24.6 mg·g−1 for TC-HCl, CTC-HCl, and OTC-HCl, respectively. The adsorption process conformed to the pseudo-second-order kinetic and Langmuir isotherm models, indicating that it was a spontaneous endothermic process and primarily involved monolayer chemical adsorption. This study transformed wetland plant waste into adsorbent and applied it for antibiotic removal, providing a valuable resource utilization strategy and technical support for recycling wetland plant residues and antibiotic removal from water environments. Full article
(This article belongs to the Section Sustainable Water Management)
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22 pages, 8995 KiB  
Article
Evaluation of the Adsorption Capacity of the BiOX (X = Cl, I) and BiOX-GO Nanomaterials (NMs) for Water Treatment
by Jorge H. Martinez-Montelongo, Martha L. Jiménez-González, Abner González-Pérez, Monika Mortimer, F. J. Avelar-González, Jorge E. Macias-Díaz and Iliana E. Medina-Ramírez
Processes 2025, 13(7), 2179; https://doi.org/10.3390/pr13072179 - 8 Jul 2025
Viewed by 424
Abstract
Water pollution is a global problem that severely impacts human and environmental health, water recycling, and the economy. In Mexico, due to water scarcity, potable water contains significant amounts of heavy metals (i.e., arsenic (As)); thus, there is a need for efficient and [...] Read more.
Water pollution is a global problem that severely impacts human and environmental health, water recycling, and the economy. In Mexico, due to water scarcity, potable water contains significant amounts of heavy metals (i.e., arsenic (As)); thus, there is a need for efficient and sustainable water treatment strategies. Bismuth oxyhalides, BiOX (X = Cl, Br, I), exhibit three-dimensional (3D) porous structures suitable for efficient adsorption activity. In addition, bismuth is an abundant and biocompatible element appropriate for fabricating sustainable environmental remediation technologies, such as adsorptive BiOX nanomaterials (NMs). In this study, we examine the adsorption capacity of BiOX (X = Cl, I), BiOX-GO (GO: graphene oxide) and GO NMs to remove methylene blue (MB), methyl orange (MO) and arsenite (AsO33−) from aqueous solution. BiOCl-GO 10%, BiOI, BiOI-GO 1%, BiOI-GO 10% and GO have an enhanced adsorption capacity, removing MB (20 ppm) within one hour using a low dose of NMs (1 mg/mL). In addition, BiOX-GO NMs can be easily separated from the solution and regenerated upon visible light activation due to the photocatalytic activity of the materials. The efficiency of the NMs under study for MO removal decreases, with the GO material having the highest efficiency (96%), followed by BiOX-GO 10% (78%). BiOCl-GO 1% removes arsenic from aqueous solution at low doses and short treatment times; 5 mg As/g adsorbent takes five hours; however, at longer adsorption times (24 h), BiOI-GO 1% excels in its arsenic removal capacity. Perlite-supported BiOCl NMs exhibit a weak capacity for water treatment due to the poor mechanical strength of perlite and the amount of surface-exposed BiOCl material. For the photocatalytic removal of arsenic (oxidation–adsorption), BiOI-GO 1% excels in arsenic removal with efficiencies > 70%. Full article
(This article belongs to the Special Issue Sustainable Adsorbent Materials for Wastewater Treatment)
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29 pages, 2767 KiB  
Article
Closed-Loop Valorization of Annatto Seed Waste into Biochar: A Sustainable Platform for Phosphorus Adsorption and Safe Nutrient Recycling in Agro-Industries
by Diana Guaya, Camilo Piedra and Inmaculada Carmona
Molecules 2025, 30(13), 2842; https://doi.org/10.3390/molecules30132842 - 2 Jul 2025
Viewed by 547
Abstract
Valorizing agro-industrial waste into functional materials for environmental remediation and resource recovery is essential for advancing circular economy models. This study presents a novel closed-loop strategy to convert annatto (Bixa orellana) seed residues into biochar for phosphate recovery from aqueous solutions [...] Read more.
Valorizing agro-industrial waste into functional materials for environmental remediation and resource recovery is essential for advancing circular economy models. This study presents a novel closed-loop strategy to convert annatto (Bixa orellana) seed residues into biochar for phosphate recovery from aqueous solutions and real agro-industrial wastewater. A novel ternary modification with Fe, Zn, and Mn metals was applied to enhance the phosphate adsorption performance of the biochar. Materials were synthesized via pyrolysis at 600 °C and 700 °C, with ABC-M700 exhibiting the highest performance. Comprehensive characterization (FTIR, SEM–EDS, and XRF) confirmed the successful incorporation of metal (oxy)hydroxide functional groups, which facilitated phosphate binding. Adsorption studies revealed that ABC-M700 achieved a maximum phosphate removal capacity of 6.19 mg·g−1, representing a 955% increase compared to unmodified ABC-N700 (0.59 mg·g−1), and a 31% increase relative to ABC-M600 (4.73 mg·g−1). Physicochemical characterization indicated increased surface area, well-developed mesoporosity, and the formation of metal (oxy)hydroxide functionalities. ABC-M700 achieved a maximum adsorption capacity of 73.22 mg·g−1 and rapid kinetics, removing 95% of phosphate within 10 min and reaching equilibrium at 30 min. The material exhibited notable pH flexibility, with optimal performance in the range of pH 6–7. Performance evaluations using real wastewater from the same agro-industry confirmed its high selectivity, achieving 80% phosphate removal efficiency despite the presence of competing ions and organic matter. Phosphate fractionation revealed that 78% of adsorbed phosphate was retained in stable, metal-associated fractions. Although the material showed limited reusability, it holds potential for integration into nutrient recycling strategies as a slow-release fertilizer. These findings demonstrate a low-cost, waste-derived adsorbent with strong implications for circular economy applications and sustainable agro-industrial wastewater treatment. This study establishes a scalable model for agro-industries that not only reduces environmental impact but also addresses phosphorus scarcity and promotes resource-efficient waste management. Full article
(This article belongs to the Special Issue Porous Carbon Materials: Preparation and Application)
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12 pages, 1686 KiB  
Article
Research on the Chlorine Removal and Upgrading of Waste Plastic Pyrolysis Oil Using Iron-Based Adsorbents
by Hyo Sik Kim, Hyun-Ji Kim, Jihyeon Kim, Jin-Ho Kim, Tae-Jin Kang, Suk-Hwan Kang, Yeji Lee, Soo Chool Lee, Chi-Seong Chang and Jong Wook Bae
Energies 2025, 18(13), 3434; https://doi.org/10.3390/en18133434 - 30 Jun 2025
Viewed by 446
Abstract
The emergence of plastics as an essential item in modern society has led to the problem of accumulating plastic waste. Accordingly, research is being conducted around the world to reduce the production of new plastics and develop technologies to recycle waste plastics. Among [...] Read more.
The emergence of plastics as an essential item in modern society has led to the problem of accumulating plastic waste. Accordingly, research is being conducted around the world to reduce the production of new plastics and develop technologies to recycle waste plastics. Among the existing waste plastic recycling technologies, oil production is possible through pyrolysis, but the pyrolysis oil produced in this way has a wide carbon range (more than C5–C25), and a very high olefin content (the presence of aromatic compounds), and the resulting high calorific value of pyrolysis oil is limited in its application range. In the case of oil obtained by pyrolyzing waste plastic containing Cl, there is a concern about corrosion in the reactor. Accordingly, it is possible to diversify the range of use of pyrolysis oil produced by suppressing corrosion through Cl removal as well as oil upgrading through cracking. Therefore, this study used red mud mixed with a series of adsorbents for Cl removal and pyrolysis oil upgrade. The adsorbent was physically mixed with a binder (kaolin or methylcellulose) and activated carbon, and the results before and after the reaction were confirmed through basic characteristic analysis. Full article
(This article belongs to the Special Issue Pyrolysis and Gasification of Biomass and Waste, 3rd Edition)
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25 pages, 3589 KiB  
Article
Enhanced Copper Adsorption with Sustainable Biochar Derived from Kitchen Waste
by Ghenwa Kataya, May Issa, Zahraa El Charif, David Cornu, Batoul Taleb, Mikhael Bechelany and Akram Hijazi
Water 2025, 17(13), 1887; https://doi.org/10.3390/w17131887 - 25 Jun 2025
Viewed by 789
Abstract
The escalating threats of climate change, pollution, and a rapidly growing global population are putting immense pressure on water resources, highlighting the urgent need for innovative wastewater recycling solutions. This study explores the potential of biochar, derived from common kitchen waste as a [...] Read more.
The escalating threats of climate change, pollution, and a rapidly growing global population are putting immense pressure on water resources, highlighting the urgent need for innovative wastewater recycling solutions. This study explores the potential of biochar, derived from common kitchen waste as a sustainable and efficient adsorbent for copper removal from contaminated water. Seven factors were studied for their influence on the adsorption process, including heavy metal concentration (50–250 ppm), biochar dosage (0.5–2.5 g), contact time (30 min to 29 h), temperature (20–80 °C), pH (2.67–8.07), and the efficacy of activated versus non-activated biochar, with activation carried out using phosphoric acid, silver nitrate, and sulfuric acid. Biochar characterization using Raman spectroscopy, specific surface area by Brunauer–Emmett–Teller analysis (BET), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Scanning Electron Microscopy—Energy Dispersive X-ray Spectroscopy (SEM-EDX), and zeta potential analysis revealed its robust adsorption capacity. Notably, silver nitrate-loaded biochar exhibited the highest adsorption capacity (24.44 mg/g) at 250 ppm of copper and the highest removal rate at about 99.3%, whereas phosphoric acid activation reduced this capacity to 5 mg/g due to structural damage. Importantly, biochar’s adsorption capacity was found to be pH-independent, simplifying operational requirements for treatment systems. Optimal conditions for maximum copper removal were determined to be 100 ppm of copper, a temperature of 60 °C, and a contact time of 30 min. The Langmuir isotherm model best described the adsorption process, indicating a monolayer adsorption with a maximum capacity of 23.25 mg/g. This comprehensive analysis underscores biochar’s potential as a cost-effective, efficient, and environmentally friendly solution for copper removal from wastewater. Full article
(This article belongs to the Section Wastewater Treatment and Reuse)
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17 pages, 4465 KiB  
Article
Sustainable Use of Expired Metoprolol as Corrosion Inhibitor for Carbon Steel in Saline Solution
by Mircea Laurențiu Dan, Nataliia Rudenko, Cristian George Vaszilcsin and George-Daniel Dima
Coatings 2025, 15(7), 742; https://doi.org/10.3390/coatings15070742 - 22 Jun 2025
Viewed by 529
Abstract
The current paper examines the sustainable possibility for recycling unused or expired Metoprolol (MET), a benzodiazepine derivative, as an effective corrosion inhibitor for carbon steel in saline solutions. Repurposing expired medicinal drugs aligns with green chemistry concepts and supports circular economy initiatives by [...] Read more.
The current paper examines the sustainable possibility for recycling unused or expired Metoprolol (MET), a benzodiazepine derivative, as an effective corrosion inhibitor for carbon steel in saline solutions. Repurposing expired medicinal drugs aligns with green chemistry concepts and supports circular economy initiatives by reducing pharmaceutical waste and averting the production of new synthetic inhibitors. The technical benefit of recycling expired MET drugs pertains to the elimination of costs associated with organic inhibitor manufacturing and the decrease in disposal expenses for the expired medication. A combination of electrochemical techniques (potentiodynamic polarization and electrochemical impedance spectroscopy) and quantum chemical calculations was employed to evaluate the inhibitory mechanism and efficacy of MET. At a concentration of 10−3 M, MET reduced the corrosion current density from 19.38 to 5.97 μA cm−2, achieving a maximum IE of 69.1%. Adsorption Gibbs free energy, determined using different adsorption isotherms, revealed that interactions between metal atoms and MET adsorbed molecules have a chemical character with a ∆Goads value of −50.7 kJ·mol−1. Furthermore, quantum chemistry calculations indicate that the investigated drug, owing to its molecular structure (EHOMO = −9.12 eV, ELUMO = 0.21 eV, µ = 3.95 D), possesses the capacity to establish an adsorption layer on the metal surface, thereby impeding the diffusion of molecules and ions involved in the overall corrosion process. The results obtained using the different techniques were in good agreement and highlighted the effectiveness of MET in the corrosion inhibition of carbon steel. Full article
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15 pages, 3262 KiB  
Article
Preparation and Application of Cellulose-Based Materials with Selective Adsorption of Dyes
by Linlin Bai, Yuxing Chen, Huiting Ma and Xu Meng
Polymers 2025, 17(12), 1653; https://doi.org/10.3390/polym17121653 - 14 Jun 2025
Viewed by 410
Abstract
A cellulose-based material with high adsorption capacity and surface area was developed by selecting appropriate copolymer monomers for structural design. This material was used for selective dye adsorption in wastewater treatment. The copolymer was characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), [...] Read more.
A cellulose-based material with high adsorption capacity and surface area was developed by selecting appropriate copolymer monomers for structural design. This material was used for selective dye adsorption in wastewater treatment. The copolymer was characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier-transform infrared spectroscopy (FTIR) to investigate its microstructure, structure, thermal stability, and thermal decomposition. We explored the factors affecting dye adsorption, including dye type, adsorption reaction time, initial dye concentration, copolymer dosage, temperature, and the acidity or alkalinity of the reaction environment. The results showed that as the adsorption reaction time increased, the amount of adsorbed Rhodamine B dye gradually increased, and the initial stage (0–20 min) increased rapidly. When the initial dye concentration was 15 mg/L, the adsorption capacity (qe) was at its maximum (3.67 mg/g). In addition, when the amount of copolymer used was 5 mg/10 mL, the adsorption capacity (qe) was the highest (12.37 mg/g). High-temperature conditions were favorable for adsorption, with the maximum adsorption capacity (qe) at 35 °C (13.48 mg/g). The prepared copolymer exhibited significant adsorption performance in acidic environments (pH = 3). The polymer adsorbed with dye was degraded by UV irradiation, avoiding secondary pollution caused by recycling. Full article
(This article belongs to the Section Biobased and Biodegradable Polymers)
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16 pages, 4129 KiB  
Article
Quaternary Amine-Functionalized Reed Straw Bioadsorbent: Synergistic Phosphate Recovery and Sustainable Nutrient Recycling in Circular Economy Systems
by Zhan Yang, Qi Zhang, Changyi Liu, Haodong Zhang and Zhe Qin
Sustainability 2025, 17(12), 5301; https://doi.org/10.3390/su17125301 - 8 Jun 2025
Viewed by 548
Abstract
The scarcity of phosphorus resources and the excessive accumulation of phosphates in aquatic environments pose significant threats to ecological systems and human health, while traditional treatment methods often fail to achieve effective resource recovery and reuse. This study aims to develop an efficient [...] Read more.
The scarcity of phosphorus resources and the excessive accumulation of phosphates in aquatic environments pose significant threats to ecological systems and human health, while traditional treatment methods often fail to achieve effective resource recovery and reuse. This study aims to develop an efficient method for phosphate removal and resource recycling through the modification of reed straw (MRS) by introducing amine groups. Key operational parameters such as packed bed height, flow velocity, and initial solute concentration were systematically investigated to optimize MRS’s adsorption efficiency. Experimental results demonstrated that under optimized conditions, MRS achieved a maximum phosphate adsorption capacity of 8.337 mg/g and maintained over 80% efficiency after nine adsorption–desorption cycles. Utilizing the desorbed solution as a nutrient solution significantly enhanced maize seedling growth, increasing stem height by 23.8%, fresh weight by 51.3%, and phosphorus content by 80.7%. These findings highlight MRS’s potential, not only as an effective phosphate adsorbent, but also as a means of successful phosphorus resource recovery and recycling, indicating promising applications in environmental remediation and resource management. Full article
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17 pages, 4589 KiB  
Article
Prepared of Titanate as Pb (II) Adsorbent from SCR Waste Catalyst by Sub-Molten Salt Method: A Sustainable Strategy for Hazardous Waste Recycling and Heavy Metal Remediation
by Ling Zeng, Weiquan Yuan, Mingming Yu, Heyue Niu, Yusupujiang Mubula, Kun Xu and Zhehan Zhu
Sustainability 2025, 17(11), 4823; https://doi.org/10.3390/su17114823 - 23 May 2025
Viewed by 497
Abstract
To address the disposal challenges of waste SCR catalysts and the urgent need for sustainable solutions in heavy metal pollution control, this study proposes a green resource utilization strategy based on the sub-molten salt method to convert waste SCR catalysts into highly efficient [...] Read more.
To address the disposal challenges of waste SCR catalysts and the urgent need for sustainable solutions in heavy metal pollution control, this study proposes a green resource utilization strategy based on the sub-molten salt method to convert waste SCR catalysts into highly efficient lead ion adsorbents. Titanate-based adsorbent materials with a loose porous structure were successfully prepared by optimizing the process parameters (reaction temperature of 160 °C, NaOH concentration of 70%, and reaction time of 2 h). The experiments showed that the adsorption efficiency was as high as 99.65% and the maximum adsorption capacity was 76.08 mg/g under ambient conditions (adsorbent dosage of 1.2 g/L, initial Pb(II) concentration of 100 mg/L, contact time of 60 min, and pH = 4). Kinetic analysis showed that the quasi-second-order kinetic model (R2 = 0.9985) could better describe the adsorption process, indicating chemisorption as the dominant mechanism. Characterization analysis confirmed that subsequent to the adsorption process, Pb3(CO3)2(OH)2 formed on the surface of the adsorbent material is the adsorption product of Pb(II) and C-O through ion exchange and surface complexation. This study transforms waste SCR catalysts into sustainable titanate adsorbents through a low-energy green process, providing an eco-efficient solution for heavy metal wastewater treatment while aligning with circular economy principles and sustainable industrial practices. Full article
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18 pages, 2153 KiB  
Article
Catalytic Biorefining of Cigarette Butts Recycling Waste
by Eric Borges Ribeiro, Maria Betânia d’Heni Teixeira, Thérèse Hofmann Gatti, Romulo Davi Albuquerque Andrade and Paulo Anselmo Ziani Suarez
Chemistry 2025, 7(3), 86; https://doi.org/10.3390/chemistry7030086 - 23 May 2025
Viewed by 713
Abstract
Urban solid waste (USW) is a promising alternative source of valuable chemical compounds. It is considered an adsorbent material due to its chemical structure, porosity and electronic charge available to form chemical bonds and can be recovered or transformed for use in bioprocesses [...] Read more.
Urban solid waste (USW) is a promising alternative source of valuable chemical compounds. It is considered an adsorbent material due to its chemical structure, porosity and electronic charge available to form chemical bonds and can be recovered or transformed for use in bioprocesses and industrial applications. This is the case with cigarette butts (CBs), which consist of thousands of substances that can be chemically converted for various purposes. This work showed high efficiency in the production of cellulose mass from the recycling of CBs, a patented technology in operation at the company Poiato Recicla—SP. The lignin-like solid (LLS)—a material obtained from the recycling of cigarette butts (CBs) by catalytic transfer hydrogenation (CTH), under non-rigorous conditions—showed high efficiency in its conversion into molecules of great interest. In the bio-oil obtained, characterized by analyses such as GCMS and RMN 2D HSQC, a mixture of predominantly hydrocarbons (many of them with cyclic and/or branched chains) was identified in almost all the experiments. This method demonstrates the potential of the TCH process for SSLs and completes the recycling chain designed for CBs, promoting their complete conversion into chemical compounds of greater interest. Full article
(This article belongs to the Topic Green and Sustainable Chemical Processes)
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13 pages, 477 KiB  
Article
Decoloration of Waste Cooking Oil by Maghnia Algerian Clays via Ion Exchange and Surface Adsorption
by Abdelhak Serouri, Zoubida Taleb, Alberto Mannu, Chahineze Nawel Kedir, Cherifa Hakima Memou, Sebastiano Garroni, Andrea Mele, Oussama Zinai and Safia Taleb
ChemEngineering 2025, 9(3), 50; https://doi.org/10.3390/chemengineering9030050 - 16 May 2025
Viewed by 891
Abstract
The purification of waste cooking oils (WCOs) through clay-based adsorption is an established recycling method, yet the relationship between clay composition and adsorption efficiency remains an area of active research. The aim of the present research work was to assess the performance of [...] Read more.
The purification of waste cooking oils (WCOs) through clay-based adsorption is an established recycling method, yet the relationship between clay composition and adsorption efficiency remains an area of active research. The aim of the present research work was to assess the performance of Maghnia bentonite in WCO decoloration and to gain information about the specific refining process. Thus, natural bentonite from the Maghnia region (Algeria) was investigated as an adsorbent for WCO refining for biolubricant production. The adsorption efficiency was evaluated under different conditions, achieving up to 70% decolorization at 10 wt% clay after 4 h of treatment. Structural characterization of the bentonite before and after adsorption was conducted using FT-IR spectroscopy, powder X-ray diffraction (XRD), and X-ray fluorescence (XRF) to assess compositional and morphological changes. FT-IR analysis confirmed the adsorption of organic compounds, XRD indicated minor alterations in interlayer spacing, and XRF revealed ion exchange mechanisms, including a reduction in sodium and magnesium and an increase in calcium and potassium. Adsorption kinetics followed a pseudo-second-order model, with desorption effects observed at prolonged contact times. The pHPZC of 8.3 suggested that bentonite adsorption efficiency is enhanced under acidic conditions. The high decoloration capacity of Maghnia bentonite, combined with the availability and the low cost of the material, suggests a possible industrial application of this material for WCO refinement, especially in lubricant production. Full article
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21 pages, 8384 KiB  
Article
Enhanced Fluoride Removal Performance from Water by Calcined-State Mayenite (Ca12Al14O33): Adsorption Characteristics and Mechanism
by Wenyun Zhu, Zhonglin Li, Yonghang Tan, Guixiang He, Xuexian Jiang, Yibing Li, Weiguang Zhang and Xiaolan Chen
Materials 2025, 18(10), 2189; https://doi.org/10.3390/ma18102189 - 9 May 2025
Viewed by 452
Abstract
This study achieved the preparation of budget-friendly stratified Ca-Al adsorbents using a simplified precipitation synthesis route with subsequent pyroprocessing, showing superior defluoridation capabilities in aqueous environments. The structural properties and defluoridation performance of the adsorbents were systematically investigated by optimizing critical synthesis parameters, [...] Read more.
This study achieved the preparation of budget-friendly stratified Ca-Al adsorbents using a simplified precipitation synthesis route with subsequent pyroprocessing, showing superior defluoridation capabilities in aqueous environments. The structural properties and defluoridation performance of the adsorbents were systematically investigated by optimizing critical synthesis parameters, including calcium-to-aluminum molar ratios, the solution pH during co-precipitation, and calcination temperature. Characterization results revealed that the optimal sample (prepared at a Ca/Al ratio of 2:3, initial pH of 10, and calcination temperature of 600 °C) exhibited a high specific surface area, ordered mesoporous structure, and abundant surface hydroxyl groups, facilitating efficient fluoride adsorption. Batch adsorption experiments demonstrated significant effects of adsorbent mass, solution pH, and initial fluoride concentration on removal efficiency. The isothermal adsorption characteristics conformed to the Langmuir model, complemented by pseudo-second-order kinetic compliance, which jointly confirmed chemisorption-dominated monolayer coverage. Notably, the maximum adsorption capacity reached 263.33 mg g−1, surpassing most comparable adsorbents reported in the literature. The material maintained a superior fluoride removal performance across a wide pH range (4~12) and exhibited superior recyclability. Rapid adsorption kinetics were observed, with equilibrium achieved within 60 min. The material showed a good removal effect in actual fluoride-containing smelting wastewater, which further proved its application potential. In addition, the analysis of the adsorption mechanism showed that the removal of fluoride was mainly achieved through the coordination between fluoride and metal ions and the ion-exchange reaction with surface hydroxyl groups. These findings suggest that the adsorbent has significant prospects for practical water quality fluoride removal applications. Full article
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