C | Special Issue : Adsorption on Carbon-Based Materials

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8 pages, 1729 KiB

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H₂ Adsorption on Small Pd-Ni Clusters Deposited on N-Doped Graphene: A Theoretical Study

by Brenda García-Hilerio, Lidia Santiago-Silva, Adriana Vásquez-García, Alejandro Gomez-Sanchez, Víctor A. Franco-Luján and Heriberto Cruz-Martínez

C 2024, 10(3), 73; https://doi.org/10.3390/c10030073 - 13 Aug 2024

Viewed by 1107

Abstract

The study of novel materials for H₂ storage is essential to consolidate the hydrogen as a clean energy source. In this sense, the H₂ adsorption on Pd_4-nNi_n (n = 0–3) clusters embedded on pyridinic-type N-doped graphene (PNG) was [...] Read more.

The study of novel materials for H₂ storage is essential to consolidate the hydrogen as a clean energy source. In this sense, the H₂ adsorption on Pd_4-nNi_n (n = 0–3) clusters embedded on pyridinic-type N-doped graphene (PNG) was investigated using density functional theory calculations. First, the properties of Pd_4-nNi_n (n = 0–3) clusters embedded on PNG were analyzed in detail. Then, the H₂ adsorption on these composites was computed. The E_int between the Pd_4-nNi_n (n = 0–3) clusters and the PNG was greater than that computed in the literature for Pd-based systems embedded on pristine graphene. Consequently, it was deduced that PNG can more significantly stabilize the Pd_4-nNi_n (n = 0–3) clusters. The analyzed composites exhibited a HOMO–LUMO gap less than 1 eV, indicating good reactivity. Based on the E_ads of H₂ on Pd_4-nNi_n (n = 0–3) clusters embedded on PNG, it was observed that the analyzed systems meet the standards set by the DOE. Therefore, these composites can be viable alternatives for hydrogen storage. Full article

(This article belongs to the Special Issue Adsorption on Carbon-Based Materials)

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21 pages, 6472 KiB

Open AccessArticle

Two Birds with One Stone: High-Quality Utilization of COVID-19 Waste Masks into Bio-Oil, Pyrolytic Gas, and Eco-Friendly Biochar with Adsorption Applications

by Tongtong Wang, Di Zhang, Hui Shi, Sen Wang, Bo Wu, Junchao Jia, Zhizhen Feng, Wenjuan Zhao, Zhangyue Chang and Dalal Z. Husein

C 2024, 10(3), 70; https://doi.org/10.3390/c10030070 - 7 Aug 2024

Viewed by 1696

Abstract

As a common necessity, masks have been used a lot in recent years, and the comprehensive utilization of waste masks has become a research priority in the post-COVID-19 pandemic era. However, traditional disposal methods suffer from a range of problems, including poor utilization [...] Read more.

As a common necessity, masks have been used a lot in recent years, and the comprehensive utilization of waste masks has become a research priority in the post-COVID-19 pandemic era. However, traditional disposal methods suffer from a range of problems, including poor utilization and insecurity. To explore new solution ideas and efficiently utilize waste resources, waste masks and biomass wastes were used as raw materials to prepare mask-based biochar (WMB), bio-oil, and pyrolytic gas via oxygen-limited co-pyrolysis in this study. The obtained solid–liquid–gas product was systematically characterized to analyze the physicochemical properties, and the adsorption properties and mechanisms of WMB on the environmental endocrine bisphenol A (BPA) were investigated. The co-pyrolysis mechanisms were also studied in depth. Furthermore, the strengths and weaknesses of products prepared by co-pyrolysis and co-hydrothermal synthesis were discussed in comparison. The results indicated that the waste masks could shape the microsphere structure, leading to richer surface functional groups and stable mesoporous of WMB. Here, the risk of leaching of secondary pollutants was not detected. The theoretical maximum adsorption of BPA by WMB was 28.73 mg·g⁻¹. The Langmuir and Pseudo-second-order models optimally simulated the isothermal and kinetic adsorption processes, which are a composite of physicochemical adsorption. Simultaneous pyrolysis of mask polymers with biomass polymers produces bio-oil and pyrolytic gas, which is rich in high-quality aliphatic and aromatic compounds. This could have potential as an energy source or chemical feedstock. The co-pyrolysis mechanisms may involve the depolymerization of waste masks to produce hydrocarbons and H radicals, which in turn undergo multi-step cleavage and oligomerization reactions with biomass derivatives. It is recommended to use the co-pyrolysis method to dispose of waste masks, as the products obtained are significantly better than those obtained by the co-hydrothermal method. This work provides a new contribution to the resourcing of waste masks into high-quality products. Full article

(This article belongs to the Special Issue Adsorption on Carbon-Based Materials)

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19 pages, 4311 KiB

Open AccessArticle

Theoretical Studies on the Dynamical Behavior of Atom/Ion Migration on the Surface of Pristine and BN-Doped Graphene

by Tong-Kun Zhang, Li-Jun Zhou and Jian-Gang Guo

C 2024, 10(3), 59; https://doi.org/10.3390/c10030059 - 3 Jul 2024

Viewed by 905

Abstract

Using the potential function method, a theoretical model of the interaction was presented, and the interaction force between atoms/ions and (doped) graphene was obtained. Based on the interaction force, the dynamical control equation of atom/ion migration was derived. The dynamical behavior of atom/ion [...] Read more.

Using the potential function method, a theoretical model of the interaction was presented, and the interaction force between atoms/ions and (doped) graphene was obtained. Based on the interaction force, the dynamical control equation of atom/ion migration was derived. The dynamical behavior of atom/ion migrating on finite-size graphene surfaces along a specific direction and the regulation of boron nitride (BN) doping on the migration behavior were studied. The results show that the atoms/ions exhibit different migration mechanical behaviors due to different lateral forces inside and at the edges of the graphene surface. In addition, near the normal equilibrium height, atoms/ions are mainly affected by the lateral force, and their migration behavior is also influenced by the initial position, initial height, initial lateral velocity, etc. Furthermore, BN doping can affect the energy barrier of atom/ion migration on the graphene surface and effectively regulate the migration behavior of atoms/ions at the edge of the graphene surface. The research results can provide a theoretical reference for graphene surface localization modification and graphene-based atom/ion screening and detection. Full article

(This article belongs to the Special Issue Adsorption on Carbon-Based Materials)

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20 pages, 3924 KiB

Open AccessArticle

Nitrogen-Doped Carbon Cryogels as Adsorbents: Efficient Removal of Organophosphate Pesticides from Water and Assessment of Toxicity Reduction

by Tamara Lazarević-Pašti, Vladan Anićijević, Radovan Karkalić, Miloš Baljozović, Biljana Babić and Igor A. Pašti

C 2024, 10(2), 56; https://doi.org/10.3390/c10020056 - 20 Jun 2024

Cited by 1 | Viewed by 1123

Abstract

Pesticides pose a significant threat to nontargeted organisms, and their pervasive use makes avoidance challenging. We employed nitrogen-doped carbon cryogels for the removal of organophosphate pesticides. The materials were synthesized and characterized using SEM, Raman spectroscopy, XPS, and BET analysis. Results revealed mesoporous [...] Read more.

Pesticides pose a significant threat to nontargeted organisms, and their pervasive use makes avoidance challenging. We employed nitrogen-doped carbon cryogels for the removal of organophosphate pesticides. The materials were synthesized and characterized using SEM, Raman spectroscopy, XPS, and BET analysis. Results revealed mesoporous cryogels with pore diameters ranging from 3 to 13 nm. Interestingly, the specific surface area did not change systematically with increasing nitrogen content. All investigated materials have similar composition and structural disorder. Dimethoate, malathion, and chlorpyrifos removal was investigated under stationary and dynamic conditions. Stationary conditions demonstrated successful removal of aliphatic dimethoate and malathion by all investigated materials. Conversely, the materials with the lowest and highest nitrogen content proved ineffective with aromatic chlorpyrifos. Under dynamic conditions, all materials effectively removed malathion and chlorpyrifos while exhibiting suboptimal performance for dimethoate adsorption. Application of nitrogen-doped carbon cryogels to tap water spiked with pesticides yielded successful results under the same conditions. Toxicity testing of treated samples revealed a consistent decrease in toxicity, indicating that contact with cryogels reduces the initial solution’s toxicity. This result also confirms that material–pesticide interaction does not lead to the formation of more toxic byproducts. The demonstrated efficacy suggests the potential application of these materials in water treatment. Full article

(This article belongs to the Special Issue Adsorption on Carbon-Based Materials)

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22 pages, 4863 KiB

Open AccessArticle

Acetaminophen Adsorption on Carbon Materials from Citrus Waste

by Marwa Gatrouni, Nedra Asses, Jorge Bedia, Carolina Belver, Carmen B. Molina and Nadia Mzoughi

C 2024, 10(2), 53; https://doi.org/10.3390/c10020053 - 8 Jun 2024

Viewed by 1369

Abstract

Biochar and carbon adsorbents from citrus waste have been prepared by thermal and chemical treatments; they have been used in the aqueous phase adsorption of acetaminophen (ACE) as a model emerging pollutant. These materials were fully characterized by elemental analysis, X-ray fluorescence (TXRF), [...] Read more.

Biochar and carbon adsorbents from citrus waste have been prepared by thermal and chemical treatments; they have been used in the aqueous phase adsorption of acetaminophen (ACE) as a model emerging pollutant. These materials were fully characterized by elemental analysis, X-ray fluorescence (TXRF), adsorption/desorption of nitrogen, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), point of zero charge (pH_pzc), scanning electron microscopy (SEM), and thermogravimetric analyses (TGA/DTG/DTA). A magnetic carbon adsorbent was obtained by FeCl₃ activation under an inert atmosphere, giving rise to the best results in ACE adsorption. Adsorption equilibrium data were obtained at 298, 318, and 338 K and fitted to different models, corresponding to the best fitting to the Redlich–Peterson model. The maximum adsorption capacity at equilibrium resulted in 45 mg ACE·g⁻¹ carbon at 338 K. The free energy values were calculated, and values between −21.03 and −23.00 kJ·mol⁻¹ were obtained; the negative values confirmed the spontaneity of the process. The enthalpy and entropy of the adsorption process were obtained, giving rise to −6.4 kJ·mol⁻¹ and 49 J·mol⁻¹·K⁻¹, respectively, indicating a slightly exothermic process and an increase in the randomness at the solid–liquid interface upon adsorption, respectively. The adsorption kinetics were also studied, with the Elovich model being the one that gave rise to the best-fitting results. Full article

(This article belongs to the Special Issue Adsorption on Carbon-Based Materials)

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15 pages, 1901 KiB

Open AccessArticle

Enhancing Organic Contaminant Removal from Wool Scouring Wastewater Using Chemically Modified Biochars

by Simeng Li, Desarae Tasnady, Shannon Skelley, Blanca Calderon and Sherine Jiang

C 2024, 10(1), 6; https://doi.org/10.3390/c10010006 - 5 Jan 2024

Cited by 1 | Viewed by 2546

Abstract

In recent times, biochar has emerged as a promising and sustainable solution for COD reduction in wastewater treatment. This study explores the potential of chemically modified biochars as efficient adsorbents for the removal of organic contaminants, specifically oils, fats, and grease (OFG), from [...] Read more.

In recent times, biochar has emerged as a promising and sustainable solution for COD reduction in wastewater treatment. This study explores the potential of chemically modified biochars as efficient adsorbents for the removal of organic contaminants, specifically oils, fats, and grease (OFG), from wool scouring wastewater. Proximate analysis revealed distinct properties among the biochars, with KOH-treated biochar demonstrating the most promising characteristics, including lower volatile matter, higher fixed carbon content, and reduced ash content, indicating a stable and carbon-rich structure. A meticulous examination of the KOH-treated biochar’s surface characteristics revealed the presence of elevated carbon and nitrogen content, complemented by an expansive surface area measuring 724.4 m²/g. This surface area was at least twice as extensive as that observed in the other post-treated biochar samples. The kinetic adsorption of COD and soluble COD was well fitted by the pseudo-first-order model, with equilibrium achieved in approximately 200 min. The KOH-treated biochar exhibited the highest equilibrium adsorption capacities for both COD and soluble COD in both Dorset wool (Dorset) and Bluefaced Leicester (BFL) wastewater, highlighting its efficacy in OFG removal. Despite these promising results, further research is needed to explore biochar’s surface characteristics, pore structure, and performance under diverse conditions, as well as its integration with existing treatment processes and potential for regeneration and reuse. This study contributes to advancing sustainable wastewater treatment methods using chemically modified biochars. Full article

(This article belongs to the Special Issue Adsorption on Carbon-Based Materials)

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21 pages, 2817 KiB

Open AccessArticle

An Analysis of the Factors Influencing Cadmium Removal in Aquatic Environments by Chlorella vulgaris-Derived Solids

by Jafar Sufian, Mohammad Babaakbari Sari, Filippo Marchelli, Luca Fiori, Armen Avanes and Salahedin Moradi

C 2024, 10(1), 2; https://doi.org/10.3390/c10010002 - 25 Dec 2023

Viewed by 1821

Abstract

Chlorella vulgaris is an inexpensive microalga that could be employed for environmental remediation, but further investigations are needed to assess its suitability and optimal treatment methodology. With this aim in mind, this study focused on the raw biomass and the biochar and hydrochar [...] Read more.

Chlorella vulgaris is an inexpensive microalga that could be employed for environmental remediation, but further investigations are needed to assess its suitability and optimal treatment methodology. With this aim in mind, this study focused on the raw biomass and the biochar and hydrochar obtained from it, analyzing their physicochemical properties and testing them to capture cadmium from an aqueous environment. The adsorption/absorption tests assessed the effect of adsorbent dosage, pH, Cd concentration, and contact time, and the results were analyzed through a structural equation model. Biochar and hydrochar performed similarly and better than the raw biomass, with the highest Cd removal observed at an adsorbent dosage of 0.8 g L⁻¹, an initial concentration of Cd solution of 30 mg L⁻¹, a pH of 6, and a contact time of 30 min. The adsorption isotherm data for Cd could be well-described by the Langmuir and Temkin models. The results from the structural equation modeling revealed that the variables material type, dosage, and concentration all contributed to Cd removal in water, with time mediating these effects. Full article

(This article belongs to the Special Issue Adsorption on Carbon-Based Materials)

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13 pages, 2999 KiB

Open AccessArticle

Investigation of Adsorption Kinetics on the Surface of a Copper-Containing Silicon–Carbon Gas Sensor: Gas Identification

by Nina K. Plugotarenko, Sergey P. Novikov, Tatiana N. Myasoedova and Tatiana S. Mikhailova

C 2023, 9(4), 104; https://doi.org/10.3390/c9040104 - 3 Nov 2023

Viewed by 1628

Abstract

The low selectivity of materials to gases of a similar nature may limit their use as sensors. Knowledge of the adsorption kinetic characteristics of each gas on the surface of the material may enable the ability to identify them. In this work, copper-containing [...] Read more.

The low selectivity of materials to gases of a similar nature may limit their use as sensors. Knowledge of the adsorption kinetic characteristics of each gas on the surface of the material may enable the ability to identify them. In this work, copper-containing silicon–carbon films were formed using electrochemical deposition on the Al₂O₃ substrate with interdigitated Cr/Cu/Cr electrodes. These films showed good adsorption characteristics with several different gases. The adsorption kinetics of nitrogen dioxide, sulfur dioxide, and carbon monoxide on the film surface were investigated by the change in the resistivity of the material. Pseudo-first-order and pseudo-second-order kinetics, Elovich, Ritchie, and Webber intraparticle diffusion models were applied. It was found that the largest approximation factor and the lowest Root-Mean-Square Error and Mean Bias Error for all three gases were for the Elovich model. The advantages of silicon–carbon copper-containing films for gas sensor applications were shown. An algorithm for gas recognition was proposed based on the dependence of the change in the resistivity of the material under stepwise gas exposure. It was found that parameters such as the values of the extrema of the first and second derivatives of the R vs. t dependence during adsorption and the slope of R vs. t dependence in the Elovich coordinates are responsible for gas identification among several one-nature gases. Full article

(This article belongs to the Special Issue Adsorption on Carbon-Based Materials)

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15 pages, 2642 KiB

Open AccessArticle

Investigating the Adsorption Kinetics of Dimethoate, Malathion and Chlorpyrifos on Cellulose-Derived Activated Carbons: Understanding the Influence of Physicochemical Properties

by Tamara Lazarević-Pašti, Ana Jocić, Vedran Milanković, Tamara Tasić, Katarina Batalović, Stefan Breitenbach, Christoph Unterweger, Christian Fürst and Igor A. Pašti

C 2023, 9(4), 103; https://doi.org/10.3390/c9040103 - 3 Nov 2023

Cited by 4 | Viewed by 1967

Abstract

In light of the escalating environmental concerns regarding pesticide accumulation, it is imperative to devise efficient strategies for their removal. Among the various options, activated carbons have emerged as promising candidates for adsorptive pesticide removal due to their many advantages, such as large [...] Read more.

In light of the escalating environmental concerns regarding pesticide accumulation, it is imperative to devise efficient strategies for their removal. Among the various options, activated carbons have emerged as promising candidates for adsorptive pesticide removal due to their many advantages, such as large surface area, well-developed porosity, and cost-effectiveness. However, the intricate relationship between the properties of these materials and their performance in pesticide adsorption remains largely unexplored. This study primarily focuses on examining the adsorption kinetics of three organophosphate pesticides: dimethoate, malathion (aliphatic), and chlorpyrifos (aromatic), using a range of cellulose-based activated carbon fibers with diverse specific surface areas, pore size distributions, and elemental compositions. By employing sophisticated data analysis tools, principal component analysis, and semi-empirical quantum chemical calculations, this study uncovers the importance of these distinct properties in efficiently removing structurally diverse pesticides. The results of the adsorption experiments suggested that these processes can be described using a pseudo-second-order kinetic model, which is confirmed via multiple linear regression. The obtained data suggest that the most effective carbon material for pesticide removal should have a pore diameter of approximately 4 nm, low oxygen content, a unimodal pore size distribution, and a high presence of sp² domains. The insights from this research have the potential to guide the development of improved adsorbents and facilitate the rational selection of adsorbents tailored to specific pollutants based on their physicochemical properties and the pollutants’ chemical structure. By shedding light on the vital connection between adsorbent properties and performance, our findings significantly advance sustainable and effective pesticide removal, thereby fostering a cleaner and healthier environment. Full article

(This article belongs to the Special Issue Adsorption on Carbon-Based Materials)

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20 pages, 8699 KiB

Open AccessArticle

The Adsorption of 2,4-Dichlorobenzoic Acid on Carbon Nanofibers Produced by Catalytic Pyrolysis of Trichloroethylene and Acetonitrile

by Anna M. Ozerova, Elena S. Tayban, Inna L. Lipatnikova, Arina R. Potylitsyna, Yury I. Bauman, Igor P. Prosvirin, Yury V. Shubin, Aleksey A. Vedyagin, Ilya V. Mishakov and Olga V. Netskina

C 2023, 9(4), 98; https://doi.org/10.3390/c9040098 - 11 Oct 2023

Cited by 1 | Viewed by 1672

Abstract

In this study, carbon nanofibers were synthesized by the catalytic pyrolysis of trichloroethylene (CNF-Cl) and its mixture with acetonitrile (CNF-Cl-N). The addition of acetonitrile resulted in the incorporation of nitrogen in the CNF (0.33 at%), the removal of chlorine, an increase in oxygen-containing [...] Read more.

In this study, carbon nanofibers were synthesized by the catalytic pyrolysis of trichloroethylene (CNF-Cl) and its mixture with acetonitrile (CNF-Cl-N). The addition of acetonitrile resulted in the incorporation of nitrogen in the CNF (0.33 at%), the removal of chlorine, an increase in oxygen-containing functional groups on the surface (from 1.6 to 3.6 at%), and an increase in the volume of mesopores (from 0.35 to 0.41 cm³·g⁻¹) and macropores (from 0.115 to 0.393 cm³·g⁻¹). The study of 2,4-DCBA adsorption on both CNFs revealed that the adsorption capacity showed dependence with a maximum on the 2,4-DCBA concentration in the solution, which was attributed to the electrostatic interactions of adsorbate with adsorbent at various pHs. The adsorption forces were effective over distances greater than the size of the 2,4-DCBA molecule, indicating volume pore filling. The maximum adsorption capacity occurred at 0.7–1.2 mM and a pH of 3.4 ± 0.1. CNF-Cl-N exhibited lower 2,4-DCBA adsorption than CNF-Cl-N due to its lower specific surface area, lower micropore volume, and higher concentration of oxygen-containing groups on the surface. However, these differences were not significant, suggesting that CNFs produced from both chlorine-containing wastes and their mixtures with nitrogen-containing compounds can be effectively used for water treatment to remove 2,4-DCBA. Full article

(This article belongs to the Special Issue Adsorption on Carbon-Based Materials)

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19 pages, 2523 KiB

Open AccessArticle

Investigating the Potential of Greener-Porous Graphene for the Treatment of Organic Pollutants in Wastewater

by Bhavya Joshi, Ahmed M. E. Khalil, Shaowei Zhang and Fayyaz A. Memon

C 2023, 9(4), 97; https://doi.org/10.3390/c9040097 - 7 Oct 2023

Cited by 1 | Viewed by 2243

Abstract

Pharmaceuticals have emerged as a new class of ecological pollutants and have majorly contributed to harmful effects on the environment and human health. The presence of these pharmaceuticals in wastewater treatment plants, ground, and seawater has been reported widely. Organic dyes and other [...] Read more.

Pharmaceuticals have emerged as a new class of ecological pollutants and have majorly contributed to harmful effects on the environment and human health. The presence of these pharmaceuticals in wastewater treatment plants, ground, and seawater has been reported widely. Organic dyes and other organic contaminants which are being considered as emerging contaminants are now in the race among the top organic pollutants that need effective treatment. Removal of these contaminants via green adsorbents has become an essential requirement towards a green and cleaner environment. Herein, we report the efficacy of the novel greener porous graphene obtained via the near-green synthesis method as an adsorbent material for treating seven organic pollutants: Methyl orange, Methyl red, Rhodamine-B, Ciprofloxacin, Atenolol, Ibuprofen, and Carbamazepine. Batch tests were conducted to investigate the effect of adsorption time and varying adsorbent dosages. The obtained greener porous graphene showed fast kinetics, which was determined to be guided by pseudo second-order kinetics and the maximum pollutant removal efficiency (>80%) was seen at a high adsorbent dosage (2 mL injected from a 5 g/L solution). Furthermore, the nonlinear adsorption modeling confirmed that the greener porous graphene followed the Langmuir model for the dye rhodamine-B sorption and the Freundlich model for all the other six contaminants. This greener porous graphene can be considered an effective adsorbent for the removal of organic pollutants in wastewater. Full article

(This article belongs to the Special Issue Adsorption on Carbon-Based Materials)

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17 pages, 4953 KiB

Open AccessArticle

A Grand Canonical Monte Carlo Simulation for the Evaluation of Pore Size Distribution of Nuclear-Grade Graphite from Kr Adsorption Isotherms

by Giuliano M. Laudone and Katie L. Jones

C 2023, 9(3), 86; https://doi.org/10.3390/c9030086 - 4 Sep 2023

Cited by 1 | Viewed by 2515

Abstract

Characterizing materials with low surface areas or with very small sample sizes requires innovative approaches beyond traditional N

_{2}

and Ar adsorption measurements. The measurement of Kr adsorption isotherms is often employed to serve this purpose, yet its potential remains limited by the [...] Read more.

Characterizing materials with low surface areas or with very small sample sizes requires innovative approaches beyond traditional N

_{2}

and Ar adsorption measurements. The measurement of Kr adsorption isotherms is often employed to serve this purpose, yet its potential remains limited by the lack of models for the interpretation of the experimental results in terms of pore size distribution. In this work, simulated adsorption isotherms of Kr onto graphite in slit-shaped pores are generated with a Grand Canonical Monte Carlo method. The pore size distributions of nuclear-grade graphite samples and activated carbon are modelled by fitting simulated isotherms to the experimental data. The resulting distributions are favourably compared with those generated by commercially available modelling packages, based on the use of N₂ adsorption isotherms using GCMC and BJH methods. The new GCMC-Kr kernel developed in this study offers an alternative method for the evaluation of the distribution of pore sizes in nuclear graphite and other low surface area materials, which can be employed when N₂ and Ar adsorption measurements cannot be carried out. Full article

(This article belongs to the Special Issue Adsorption on Carbon-Based Materials)

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23 pages, 3344 KiB

Open AccessArticle

Evaluation and Optimization of Tour Method for Synthesis of Graphite Oxide with High Specific Surface Area

by Hanna Bukovska, Fernando García-Perez, Natalia Brea Núñez, Laura J. Bonales, Andrés Velasco, M. Ángeles Clavero, Javier Martínez, Alberto J. Quejido, Isabel Rucandio and M. Belén Gómez-Mancebo

C 2023, 9(3), 65; https://doi.org/10.3390/c9030065 - 5 Jul 2023

Cited by 3 | Viewed by 3178

Abstract

Many of the graphene-based structures exhibit an adsorption capacity due to their high specific surface area (SSA) and micropore volume. This capacity makes them competent materials for applications in energy and environmental sectors where efficiency is highly dependent on these properties for applications, [...] Read more.

Many of the graphene-based structures exhibit an adsorption capacity due to their high specific surface area (SSA) and micropore volume. This capacity makes them competent materials for applications in energy and environmental sectors where efficiency is highly dependent on these properties for applications, such as water decontamination, solar cells or energy storage. The aim of this work is to study graphene-related materials (GRM) for applications where a high SSA is a requirement, considering the ideal SSA of graphene ≅ 2600 m²g⁻¹. For the synthesis of most of the GRMs, some oxidation method such as the Tour method is used to oxidize graphite to graphite oxide (GrO) as an initial step. Our work studies the optimization of this initial step to evaluate the best conditions to obtain GrO with the maximum possible SSA. The different parameters influencing the process have been evaluated and optimized by applying an experimental design (ED). The resulting materials have been characterized by Brunauer–Emmett–Teller (BET), elemental analysis (EA), X-ray diffraction (XRD) and Raman and scanning electron microscopy (SEM). The evaluation of the results shows a maximum SSA of GrO of 67.04 m²g⁻¹ for a temperature of 60 °C, a time of 12 h, a H₂O₂ volume of 50 mL and 4 g of KMnO₄. Full article

(This article belongs to the Special Issue Adsorption on Carbon-Based Materials)

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14 pages, 2657 KiB

Open AccessArticle

Efficient Heating of Activated Carbon in Microwave Field

by Ce Shi, Hongqing Shi, Hui Li, Hui Liu, Ehab Mostafa, Wenke Zhao and Yaning Zhang

C 2023, 9(2), 48; https://doi.org/10.3390/c9020048 - 8 May 2023

Cited by 5 | Viewed by 3224

Abstract

Activated carbon (AC) is widely utilized in water treatment, gas adsorption, and purification as well as the protection of environment due to the characteristics of prominent catalytic and adsorbent effect. The heating performances are therefore of significant importance for the further applications. The [...] Read more.

Activated carbon (AC) is widely utilized in water treatment, gas adsorption, and purification as well as the protection of environment due to the characteristics of prominent catalytic and adsorbent effect. The heating performances are therefore of significant importance for the further applications. The main objective of this study was therefore to detail the heating performance of activated carbon in microwave field, and the factors affecting the heating performance were also explored. In this study, the heating performance of AC as affected by microwave power (400, 450, 500, 550, and 600 W), feeding load (5, 10, 15, 20, and 25 g), and reactor volume (50, 100, 150, 200, and 250 mL) were detailed and reported. The results showed that when the microwave powers were 400, 450, 500, 550, and 600 W, the temperatures of AC increased to the desired value (about 200 °C) within 90, 85, 70, 60, and 35 s with average heating rates of 2.0, 2.2, 2.8, 3.0, and 5.9 °C/s, respectively. When the feeding loads were 5, 10, 15, 20, and 25 g, the temperatures of AC increased to desired temperature within 40, 70, 60, 50, and 50 s with average heating rates of 4.2, 2.8, 3.1, 3.50, and 3.55 °C/s, respectively. When the reactor volumes were 50, 100, 150, 200, and 250 mL, the temperatures of AC increased to the desired temperature within 25, 60, 70, 70, and 160 s with average heating rates of 7.6, 3.3, 2.8, 2.6, and 1.2 °C/s, respectively. In general, the faster heating rate of activated carbon was achieved at higher microwave power, more feeding load, and smaller reactor volume. Fitting formulae were given to predict the transient temperatures of AC in the microwave field, and the relative errors were in the ranges of −15.4~12.4%, −15.4~13.5% and −18.7~12.4% at different microwave powers, feeding loads, and reactor volumes, respectively. Full article

(This article belongs to the Special Issue Adsorption on Carbon-Based Materials)

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18 pages, 7665 KiB

Open AccessArticle

Recovery of Pd(II) Ions from Aqueous Solutions Using Activated Carbon Obtained in a Single-Stage Synthesis from Cherry Seeds

by Tomasz Michałek, Konrad Wojtaszek, Stanisław Małecki, Kamil Kornaus, Szymon Wandor, Julia Druciarek, Krzysztof Fitzner and Marek Wojnicki

C 2023, 9(2), 46; https://doi.org/10.3390/c9020046 - 28 Apr 2023

Cited by 5 | Viewed by 2364

Abstract

This paper describes a single-stage synthesis process for activated carbon using cherry seeds. The influences of the carbonization temperature and the time were investigated. Using the BET method, the surface area of the obtained activated carbons was determined, as well as the pore [...] Read more.

This paper describes a single-stage synthesis process for activated carbon using cherry seeds. The influences of the carbonization temperature and the time were investigated. Using the BET method, the surface area of the obtained activated carbons was determined, as well as the pore distribution, while SEM images provided further insight into the structure of the surface. Next, the adsorption isotherm was derived. For the test, Pd(II) chloride complex ions were used. It was found that the obtained activated carbon were suitable for palladium(II) recovery from diluted aqueous solutions. Out of the tested parameters of carbon synthesis, the most optimal one was found to be 500 °C for 3 h. Additionally, it was confirmed that the increase in the adsorption temperature affects the increase in palladium load from 1.6 mg/g at 20 °C to 15.6 mg/g at 50 °C (for the best-performing sample). This fact may suggest that the process of adsorption is associated with chemical reactions. Full article

(This article belongs to the Special Issue Adsorption on Carbon-Based Materials)

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11 pages, 2485 KiB

Open AccessArticle

Removal of Arsenic(III) from Water with a Combination of Graphene Oxide (GO) and Granular Ferric Hydroxide (GFH) at the Optimum Molecular Ratio

by Athanasia K. Tolkou, Elena Cristina Rada, Vincenzo Torretta, Maria Xanthopoulou, George Z. Kyzas and Ioannis A. Katsoyiannis

C 2023, 9(1), 10; https://doi.org/10.3390/c9010010 - 15 Jan 2023

Cited by 4 | Viewed by 2602

Abstract

The occurrence of arsenic in water is a global problem for public health. Several removal technologies have been developed for arsenic removal from water, and adsorption onto iron oxy-hydroxides is the most widely used technique. Granular ferric hydroxide (GFH) has been used mainly [...] Read more.

The occurrence of arsenic in water is a global problem for public health. Several removal technologies have been developed for arsenic removal from water, and adsorption onto iron oxy-hydroxides is the most widely used technique. Granular ferric hydroxide (GFH) has been used mainly for As(V) removal, but it has the disadvantage that it can create a problem with the residual concentration of iron in the water. Moreover, graphene oxide (GO), which contains a large amount of reactive oxygen, exhibits high adsorbing capacity. In this study, the combined use of GO and GFH as adsorbent materials in different molar ratios was investigated in order to achieve the maximum As(III) removal from aqueous solutions. The effect of the adsorbent’s dosage, pH value, contact time, initial As(III), and different molar ratios of GO/GFH was examined. As depicted, the presence of GFH enhances the use of GO. In particular, the molar ratio of GO/GFH 2:1 (i.e., 0.2 g/L GO and 0.1 g/L GFH) is chosen as optimal at pH value 7.0 ± 0.1, while the removal percentage increased from 10 % (absence of GFH) to 90% with the simultaneous addition of GFH. Freundlich isotherm and pseudo-second-order kinetic models described the experimental data adequately and the highest adsorption capacity that was achieved was 22.62 μg/g. Full article

(This article belongs to the Special Issue Adsorption on Carbon-Based Materials)

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Open AccessReview

Comparison of Modified Peels: Natural Peels or Peels-Based Activated Carbons for the Removal of Several Pollutants Found in Wastewaters

by Athanasia K. Tolkou, Konstantinos N. Maroulas, Dimitrios Theologis, Ioannis A. Katsoyiannis and George Z. Kyzas

C 2024, 10(1), 22; https://doi.org/10.3390/c10010022 - 3 Mar 2024

Cited by 6 | Viewed by 3253

Abstract

Wastewater treatment has attracted much attention in recent years as a potential source of water, and there are some concerns about its safety for human use. Eco-friendly and cost-effective adsorbent materials were successfully synthesized from several peels, such as orange, banana, pomegranate, avocado, [...] Read more.

Wastewater treatment has attracted much attention in recent years as a potential source of water, and there are some concerns about its safety for human use. Eco-friendly and cost-effective adsorbent materials were successfully synthesized from several peels, such as orange, banana, pomegranate, avocado, kiwi, etc., and were used as natural adsorbents or as activated carbons derived from these peels for water and wastewater treatment. In this review, the latest research focusing on the effective modification of these peels for the removal of several pollutants found in wastewaters are summarized and compared, such as pharmaceuticals, dyes, heavy metals, and anions that are released in waste and have a negative impact on human and animal health. In this review, focus is given to activated carbon produced from fruit peels. Moreover, fruit peels as adsorbent materials, without previously being converted to activated carbon, are of limited use in the recent literature. Full article

(This article belongs to the Special Issue Adsorption on Carbon-Based Materials)

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