Porous Adsorbents Research Articles

Recent Progress on Porous Carbons for Carbon Capture.

High emission of carbon dioxide (CO2) has caused CO2 levels to reach more than 400 ppm in air and led to a serious climate problem. In addition, in confined spaces such as submarines and aircraft, the CO2 concentration increase in the air caused by human respiration also affects human health. In order to protect the environment and human health, the search for high-performance adsorbents for carbon capture from high and low concentration gas is particularly important. Porous carbon materials, possessing the advantages of low cost and renewability, have set off a boom in the research of porous adsorbents, which have the opportunity to be utilized on a large scale for industrial carbon capture in the future. In this review, we summarize the recent research progress of porous carbons for carbon capture from flue gas and directly from air in the last five years, including activated carbon (AC), heteroatom-modified porous carbon, carbon molecular sieves (CMS), and other porous carbon materials, with a focus on the effects of temperature, water content, and gas flow rate of industrial flue gas on the performance of porous carbon adsorbents. We summarize the preparation strategies of various porous carbons and seek environmental friendly porous carbon materials preparation strategies under the premise of improving the CO2 adsorption capacity and selectivity of porous carbon adsorbents. Based on the effects of real industrial flue gas on adsorbents, we provide new ideas and evaluation methods for the development and preparation of porous carbon materials.

Valorization of Crab Shells as Potential Sorbent Materials for CO2 Capture.

This study delves into the potential advantage of utilizing crab shells as sustainable solid adsorbents for CO2 capture, offering an environmentally friendly alternative to conventional porous adsorbents, such as zeolites, silicas, metal-organic frameworks (MOFs), and porous carbons. The investigation focuses on crab shell waste, which exhibits inherent natural porosity and N-bearing groups, making them promising candidates for CO2 physisorption and chemisorption applications. Selective deproteinization and demineralization treatments were used to enhance textural properties while preserving the natural porous structure of the crab shells. The impact of deproteinization and demineralization treatments on CO2 adsorption and speciation at the atomic scale, via solid-state NMR, and correlated findings with textural properties and biomass composition were investigated. The best-performing sample exhibits a surface area of 36 m2/g and a CO2 adsorption capacity of 0.31 mmol/g at 1 bar and 298 K, representing gains of ∼3.5 and 2, respectively, compared to the pristine crab shell. These results underline the potential of fishing industry wastes as a cost-effective, renewable, and eco-friendly source to produce functional porous adsorbents.

Density Analysis of Adsorption Phase in the Thermodynamic Study of Shale Gas Adsorption.

Understanding the adsorption mechanism and precisely predicting the thermodynamic adsorption properties of methane at high pressure are crucial while very challenging for shale gas development. In this study, we demonstrated that the Langmuir adsorption model combining with different empirical methods to determine the adsorption phase density makes the calculated isothermal adsorption heat violate Henry's law at low pressure. For instance, the isothermal adsorption heat calculated by the Langmuir-Freundlich model contradicts Henry's law when the absolute adsorption quantity is zero. Given the current challenge in accurately calculating the adsorption phase density, it is necessary to impose constraints on the parameters of the adsorption model by adhering to Henry's law to maintain thermodynamic consistency. We found that the adsorption phase volume of methane molecules lies between the micropore volume and the total pore volume when shale adsorption reaches saturation. The adsorption mechanism involves not only filling micropores but also monolayer adsorption in meso-macro pores. The high-energy adsorption sites for methane are primarily concentrated in organic matter, while within these methane adsorption areas in shale, the high-energy adsorption sites for water are mainly located in kaolinite within clay minerals. The zero-pressure heat of adsorption is a temperature-independent thermodynamic index, yet it is influenced by the water content. It can therefore be selected as a quantitative measure to evaluate the impact of methane adsorption on water.

Effect of coal gasification coarse slag on soil water and nutrition at an arid opencast coal mine site in Northwest China

AbstractThough amendment using coal gasification coarse slag (CGCS) has garnered attention, the intrinsic mechanism of how CGCS, a glassy material, works to amend physicochemical properties in the soil is not yet clear. This study aimed to analyze the effects of different CGCS particle sizes on soil water infiltration and nutrient retention, and to identify the relationship between the physicochemical properties of the amended soil and the water nutrient amendment. The continuous infiltration pattern of soil water and plant growth after the amendment was measured using an indoor continuous dynamic soil column simulation experiment and a field pot experiment of CGCS with different particle sizes (0.25, 1, and 2 mm). The CGCS amendment loosened the soil, improved the pore channels, and amended the water infiltration. However, this process was negatively correlated with CGCS particle size. The Kostiakov performed better in simulating soil water infiltration of heterogeneous dump soil. The CGCS amendment had no heavy metal risk and promoted plant growth. Though amendment enhanced nutrients, in terms of soil organic matter (SOM), the presence of C must be verified by a long team of nutrient cycling if it can be transformed into accessible SOM. Therefore, CGCS amended water nutrition by amending the soil's physical structure. Soil pore adsorption improved water nutrient availability and had a positive effect on chemical properties, which promoted crop growth. The amendment effect was greatest at 0.25 mm particle size.

Biological metal–organic frameworks for natural gas purification and MTO product separation

The use of porous solid adsorbents is an effective and excellent approach for the separation and purification of methanol-to-olefins product and methane (CH4). In this particular study, a series of adenine (AD)-based biological metal–organic frameworks (Bio-MOFs) {Their general formula is Cu 2 (AD) 2 (X) 2 [X = formic acid, acetic acid (AA), and propionic acid]} were proposed, which exhibited remarkable efficiency in the purification of CH4 and the separation of C3H6 from methanol-to-olefins product, ultimately yielding purified C2H4. The experimental findings demonstrate that different terminal ligands induce alterations in the pore microenvironment, consequently leading to variations in adsorption capacities and stability. Specifically, Cu-AD-AA exhibits the highest adsorption capacity and selectivity among the three MOFs, as confirmed by static adsorption isotherm testing and theoretical evaluation using ideal adsorbed solution theory (IAST) simulation. At 298 K and 1 bar, Cu-AD-AA exhibits 786 and 10.9 selectivity for C3H8/CH4 and C3H6/C2H4, respectively, surpassing the majority of MOFs materials. Furthermore, breakthrough experiments conducted in ambient conditions reveal that Cu-AD-AA possesses commendable separation capabilities, enabling one-step purification of C2H4 at varying proportions (C2H4/C3H6 = 50:50, 50:20, and 90:10), along with satisfactory recycling performance. Importantly, the synthesis of Cu-AD-AA utilizes simple and easily obtainable raw materials, thereby offering advantages such as cost-effectiveness, low toxicity, and facile synthesis that enhance its potential for industrial applications.

Studies into confined methane adsorption in shale nanopores using a simplified local density model

The large number of nanopores in shale reservoirs provide an effective storage space for gases, which can assist in accurately characterizing the confined adsorption characteristics, including the adsorption amount of fluid in nanopores that is important for a detailed understanding of shale gas storage mechanisms and production prediction. Although the simplified local density (SLD) model has been widely used to describe the behavior of confined adsorption in slit-like pores, its application in relation to cylindrical pores has not been studied in detail. In this study, the importance of fluid–fluid interaction and fluid–solid interaction has been analyzed, with the expressions for the distribution of confined attractive parameter in cylindrical pores are derived by combining with the (3/8)σff assumption to establish a new SLD model. The reliability of the new model was verified by the publicly available experimental methane excess adsorption data for shale at different temperatures and the simulation results from the Grand Canonical Monte Carlo (GCMC). Moreover, by comparing with the SLD model with the slit pore structure, it was found that the adsorption isotherms and the confined fluid density distribution pattern characterized by the SLD model with the cylindrical pores were closer to the actual reservoir conditions of shale. In addition, the densities characterized by SLD models with a (3/8)σff assumption and with a (1/2)σff assumption at different Λb have been discussed and analyzed, and it is found that the selection of a suitable Λb would help to improve the accuracy of SLD model. The results might provide new theoretical insights into confined methane adsorption, with the new SLD model providing better engineering applications in shale gas development, gas storage, and pore structure characterization.

High-Performance Porous Organic Polymers for Environmental Remediation of Toxic Gases.

Sulfur dioxide (SO2) is a harmful acidic gas generated from power plants and fossil fuel combustion and represents a significant health risk and threat to the environment. Benzimidazole-linked polymers (BILPs) have emerged as a promising class of porous solid adsorbents for toxic gases because of their chemical and thermal stability as well as the chemical nature of the imidazole moiety. The performance of BILPs in SO2 capture was examined by synergistic experimental and theoretical studies. BILPs exhibit a significantly high SO2 uptake of up to 8.5 mmol g-1 at 298 K and 1.0 bar. The density functional theory (DFT) calculations predict that this high SO2 uptake is due to the dipole-dipole interactions between SO2 and the functionalized polymer frames through O2S(δ+)···N(δ-)-imine and O═S═O(δ-)···H(δ+)-aryl and intermolecular attraction between SO2 molecules (O═S═O(δ-)···S(δ+)O2). Moderate isosteric heats of adsorption (Qst ≈ 38 kJ mol-1) obtained from experimental SO2 uptake studies are well supported by the DFT calculations (≈40 kJ mol-1), which suggests physisorption processes enabling rapid adsorbent regeneration for reuse. Repeated adsorption experiments with almost identical SO2 uptake confirm the easy regeneration and robustness of BILPs. Moreover, BILPs possess very high SO2 adsorption selectivity at low concentration over carbon dioxide (CO2), methane (CH4), and nitrogen (N2): SO2/CO2, 19-24; SO2/CH4, 118-113; SO2/N2, 600-674. This study highlights the potential of BILPs in the desulfurization of flue gas or other gas mixtures through capturing trace levels of SO2.

A fractal Langmuir adsorption equation on coal: Principle, methodology and implication

The conventional Langmuir equation based on the homogeneous surface assumption is failed to characterize the gas adsorption in coal due to the obvious heterogeneity of the coal pore structure. Therefore, a novel fractal Langmuir adsorption equation on coal is proposed based on the fractal characteristics of pore heterogeneity in this paper. The pore heterogeneity in coal displays obvious fractal characteristic, which can be characterized by the fractal dimension for the pore tortuosity (DT) and the fractal dimension for the pore size (Df). The principles and methodology of the proposed equation are deduced and summarized in detail. The results indicate that the proposed fractal Langmuir adsorption equation displays the higher accuracy than the conventional Langmuir equation. In addition, the proposed equation is the function of the fractal dimension for the pore tortuosity (DT), the fractal dimension for the pore size (Df), and the pore structural parameters (λmin, λmax, and L), which more comprehensively reflects the influence of pore structure on adsorption. Therefore, the proposed equation achieves a breakthrough in the calculation of the methane adsorption capacity in pores with different pore diameter ranges, which can more accurately reflect the methane adsorption in coal pores compared with the conventional Langmuir equation.

A new initiators-free technique for synthesizing stable amine-impregnated polymeric aerogel using electron beam radiation for CO2 capture

New research in reducing CO2 emissions is ongoing to mitigate global warming. New ways are continuously sought to efficiently capture flue gases emitted by industries, one of which is using porous adsorbents like aerogels. The use of chemical initiators is the traditional way of synthesizing aerogels for CO2 capture; however, it pollutes the environment to some extent. This study finds an initiator-free method of synthesizing the aerogel which is faster and more stable yet green. The method involves exposing oil-in-water emulsions containing monomer mixtures along with other chemicals to a radiation dose of 10–50 kGy range using an electron accelerator. The polymeric aerogel was formed within 5 min after exposure to optimum dosage, which was then characterized to evaluate the physio-chemical changes. The test revealed that the aerogel synthesized at 40 kGy EB radiation dose exhibits the maximum PEI loading capacity of 4.1 g/g of aerogel. Furthermore, the CO2 adsorption performance of an optimized amine-impregnated polymeric aerogel was 4.45 mmol/g at 30 °C. Interestingly, this aerogel was able to preserve the initial capacity without significant decrease even after five adsorption-desorption cycles. The proposed method is likely to be of great significance in the field of CO2 capture.

Large-scale preparation of N-doped microporous-dominated carbon-based adsorbents for efficient removal of Chromium(VI): The synergistic effect of different nitrogen configurations

Carbon-based adsorbents with abundant resources, environmental friendliness, and sufficient adsorption sites have broad application prospects for efficient removal of Chromium (Cr(VI)) in aquatic environment. Pursuing a heavy metal adsorption material and advancing it from the laboratory to the actual water environment are of great importance. Herein, we developed a general synthesis strategy for large-scale preparation of N-doped microporous-dominated carbon-based adsorbents (NC-s) via a direct pyrolysis process of ethylene diamine tetraacetic acid tetrasodium. The NC-s samples had abundant microporous, different nitrogen configurations and large specific surface area (503 m2 g−1). Due to these advantages, the NC sample prepared at 800 °C (NC-800) possessed high adsorption capacity toward Cr(VI) (167.3 mg g−1) toward Cr(VI), fast adsorption process (180 min), and good reusability. Through specific experiments and density functional theory (DFT) calculations, we proposed that the adsorption mechanism of NC-s samples was primarily determined by the ion exchange/electrostatic attraction-reduction-complexation synergy, and the mechanism included adsorption-reduction of Cr(VI) and immobilization of Cr(III). Graphitic-N and pyridinic-N adsorbed Cr(VI) in solution mainly by electrostatic attraction, while pyrrolic-N mainly reduced the toxicity primarily by reducing Cr(VI) to Cr(III). These insights prove that the nitrogen-doped porous carbon-based adsorbents prepared in this study can effectively reduce Cr(VI) pollution in water environment.

Hypercrosslinked polymers with hierarchical pores synthesized using biphenyl crosslinker for carbon dioxide capture

Microporous hypercrosslinked polymers have an upright capacity to develop into prime materials in energy and environmental applications in the near future. The chemical tunability, structural robustness and high surface area are some of the critical factors that lead to their application in the gas adsorption area. Three novel hypercrosslinked porous polymers viz. PABMC, PFBMC and PPzBMC were synthesized via the Friedel-Crafts alkylation process using 4,4′-bis(chloromethyl)biphenyl as the external cross-linker and anhydrous FeCl3 as the catalyst. The polymers obtained are found to be microporous with very high surface areas of 983 m2/g, 1002 m2/g, and 1265 m2/g, respectively, for PABMC, PFBMC and PPzBMC. The polymers PABMC, PFBMC and PPzBMC exhibited appreciable carbon dioxide uptake of 10.18 wt%, 12.02 wt% and 14.18 wt%, respectively, at 273 K. The results reveal a practical approach to synthesizing low-cost heteroatom-rich hypercrosslinked organic polymers with hierarchical pores for gas adsorption and storage applications.

Synthesis and absorption property of hybridized zinc silicate adsorbent based on natural Illite/Smectite clay

Hybridized zinc silicate adsorbent (Zn–Si/(I/S)) with excellent adsorption property was synthesized by hydrothermal-roasting process based on Illite/Smectite (I/S) clay. The morphological structures and elemental compositions of adsorbents were analyzed by various characterization techniques, and the Zn–Si/(I/S) adsorbent had a 2-D film-like structure. In addition, the average pore size was obviously increased. The Zn–Si/(I/S) adsorbent had a good adsorption performance for cationic dyes and antibiotics, and the adsorption process was influenced by the structure, pore size, type and surface groups of the pollutants. The results of adsorption isotherm, kinetic and thermodynamic model fitting showed that: i) the adsorption performance depended on the pore size and surface charge rather than the specific surface area, ii) the proposed second-order kinetic model and Freundlich isotherm model fitted the adsorption process of RhB better, iii) the thermodynamic analysis proved that the adsorption process proceeded spontaneously by heat absorption. In summary, the adsorption mechanism was controlled by electrostatic attraction, chemical conjugation, ion exchange, hydrogen bonding interactions and pore adsorption.

Disclosing the intrinsic nature of efficient removal of antibiotics in N/S dual-doped porous carbon-based materials: The manipulation of internal electric field

N/S co-doping has emerged as a prevailing strategy for carbon-based adsorbents to facilitate the antibiotic removal efficiency. Nevertheless, the underlying interplay among N, S, and their adjacent vacancy defects remains overlooked. Herein, we present a novel in situ strategy for fabricating pyridinic-N dominated and S dual-doped porous carbon adsorbent with rich vacancy defects (VNSC). The experimental results revealed that N (acting as the electron donor) and S (acting as the electron acceptor) form an internal electric field (IEF), with a stronger IEF generated between pyridinic-N and S, while their adjacent vacancy defects activate carbon π electrons, thus enhancing the charge transfer of the IEF. Density functional theory (DFT) calculations further demonstrated that the rich charge transfer in the IEF facilitated the π-π electron donor-acceptor (EDA) interaction between VNSC and tetracycline (TC) as well as norfloxacin (NOR), and thus is the key to adsorption performance of VNSC. Consequently, VNSC exhibited high adsorption capacities toward TC (573.1 mg g−1) and NOR (517.0 mg g−1), and its potential for environmental applications was demonstrated by interference, environmentally relevant concentrations, fixed-bed column, and regeneration tests. This work discloses the natures of adsorption capacity for N/S dual-doped carbon-based materials for antibiotics.

Thermodynamic trends for evaluating hydrogen storage density and energy flow on Maxsorb-III, HKUST-1 and UiO-66 (Zr) MOFs

For CO2-free power generation in power plants or vehicles, hydrogen should be implemented as H2 possesses not only the highest energy density (120 MJ/kg) but also can be generated from the environment and reactions. However, H2 is difficult to store due to its low density at ambient conditions. To understand the efficacy of hydrogen interactions in porous materials including the randomness of hydrogen adsorption in terms of storage density, energy flow and dissipation, a thermodynamic study is required. This paper at first focuses on the study of H2 adsorption on various porous adsorbents such as activated carbons (AC types Maxsorb-III) and metal–organic frameworks (types UiO-66 (Zr) and HKUST-1 MOFs) and the results are presented in temperature-density co-ordinate system. Employing experimentally confirmed isotherms data of AC/MOFs + H2 systems, the density of H2 adsorbed phase, entropy flow and generation are evaluated. These results indicate the feasibility of hydrogen adsorption on functional adsorbents at various temperature and pressure. The simulation results show that the adsorbed phase densities of H2 on Maxsorb-III and HKUST-1 increase up to 18 kg/m3 and 20 kg/m3 at 5 bar and 77 K. The temperature-entropy diagram shows a close loop for the charging and discharging of hydrogen and ensures the storage of internal energy with less entropy dissipation under cryo-adsorption conditions.

Fabrication of Poly(Lactic Acid)@TiO2 Electrospun Membrane Decorated with Metal-Organic Frameworks for Efficient Air Filtration and Bacteriostasis.

The development of high-performance filtration materials is essential for the effective removal of airborne particles, and metal-organic frameworks (MOFs) anchored to organic polymer matrices are considered to be one of the most promising porous adsorbents for air pollutants. Nowadays, most air filters are generally based on synthetic fiber polymers derived from petroleum residues and have limited functionality, so the use of MOFs in combination with nanofiber air filters has received a lot of attention. Here, a conjugated electrostatic spinning method is demonstrated for the one-step preparation of poly(lactic acid) (PLA) nanofibrous membranes with a bimodal diameter distribution and the anchoring of Zeolitic Imidazolate Framework-8 (ZIF-8) by the introduction of TiO2 and in situ generation to construct favorable multiscale fibers and rough structures. The prepared PLA/TZ maintained a good PM2.5 capture efficiency of 99.97%, a filtration efficiency of 96.43% for PM0.3, and a pressure drop of 96.0 Pa, with the highest quality factor being 0.08449 Pa-1. Additionally, ZIF-8 was uniformly generated on the surface of PLA and TiO2 nanofibers, obtaining a roughened structure and a larger specific surface area. An enhanced filtration retention effect and electrostatic interactions, as well as active free radicals, can be generated for the deep inactivation of bacteria. Compared with the unmodified membrane, PLA/TZ prepared antibacterial characteristics induced by photocatalysis and Zn2+ release, with excellent bactericidal effects against S. aureus and E. coli. Overall, this work may provide a promising approach for the development of efficient biomass-based filtration materials with antimicrobial properties.

Waste treats waste: Facile fabrication of porous adsorbents from recycled PET and sodium alginate for efficient dye removal

Dye-contaminated water and waste plastic both pose enormous threats to human health and the ecological environment, and simultaneously solving these two issues in a sustainable and resource-saving way is highly important. In this work, a sodium alginate-polyethylene terephthalate-sodium alginate (SA@PET) composite adsorbent for efficient dye removal is fabricated using wasted PET bottle and marine plant-based SA via simple and energy-efficient nonsolvent-induced phase separation (NIPS) method. Benefiting from its porous structure and the abundant binding sites, SA@PET shows an excellent methylene blue (MB) adsorption capacity of 1081 mg g−1. The Redlich–Peterson model more accurately describes the adsorption behavior, suggesting multiple adsorption mechanisms. In addition to the electrostatic attractions of SA to MB, polar interactions between the PET matrix and MB are also identified as adsorption mechanisms. It is worth mentioning that SA@PET could be recycled 7 times without a serious decrease in performance, and the trifluoroacetic acid-dichloromethane solvent involved in the NIPS process has the possibility of reuse and stepwise recovery. Finally, the discarded adsorbent could be completely degraded under mild conditions. This work provides not only a composite adsorbent with excellent cationic dye removal performance for wastewater treatment, but also an upcycling strategy for waste PET.

Development of effective porous geopolymer adsorbent with high strength for copper(II) ion removal

Due to the serious consequences of the accumulation of heavy metals in organisms throughout the aqueous phase, the treatment of heavy metal pollution has received extensive attention. Porous geopolymer adsorbent (PGA) has been proposed as a promising remover of heavy metal ions due to its production convenience, low cost, and large surface area. However, it is easy to be broken under water impact. Besides, compared to some other adsorbents, the heavy metal ions capacity of PGA needs to be enhanced. In this paper, PGA with 1000 kg/m3 density was directly prepared based on solid waste including fly ash and slag at room temperature. Nano-silica (NS) was added to improve material strength. The compressive strength of PGA with 2 % NS addition increases up to 63.5 % compared with the material without NS addition, and the removal rate of Cu2+ goes to 78.4 % under this condition. Although the filling effect caused by NS addition is not beneficial for the adsorption ability improvement, the molecular dynamics simulation results confirm that the physical adsorption ability upward is mainly caused by the more Natrium-Aluminate-Silicate-Hydrate formation due to the decreasing Ca/Si ratio. Compared with Calcium-Aluminate-Silicate-Hydrate, Natrium-Aluminate-Silicate-Hydrate has a higher physical adsorption ability due to the evenly distributed electropositive region known from the density functional theory analysis, which contributes to PGA adsorption capacity from the outside environment.

Customized anion-exchange covalent organic frameworks for efficient extraction of natural products

Extracting highly value-added products from natural systems with low concentrations and complex constituents is of great significance but remains a massive challenge. Herein, a series of dual-functional covalent organic frameworks with both anion exchange and pore adsorption abilities are designed and fabricated using the quaternary amine monomer doping strategy. Attributed to abundant ion exchange sites and selective pore adsorption, the COFs demonstrate high selectivity and loading capacity and fast adsorption for natural products (glycyrrhetinic acid, a high-value natural product), surpassing commercially available materials. Additionally, high-purity (>99%) glycyrrhetinic acid with a >90% extraction efficiency from natural fermentation systems is successfully achieved using a solid-phase extraction column with COFs as the separation medium. The separation column demonstrates outstanding reusability and reproducibility, providing great potential for COFs to serve as robust separation mediums for challenging natural product purification.

Synthesis of N/P/S Co-doped porous carbons by carbonizing polyphosphazene microspheres for highly selective adsorption of Pb (II)

Heteroatom-doping has emerged as a promising approach for enhancing the properties of carbon materials, particularly in the treatment of heavy-metal wastewater. However, the simultaneous synthesis of multi-heteroatom co-doped carbon materials poses significant complexity and challenges. Consequently, there is an increasing demand for the development of non-toxic and straightforward methods to prepare such materials. In this study, we present a novel approach for the synthesis of N/P/S co-doped porous carbonaceous adsorbents using polyphosphazene as precursors. Our focus is specifically on their effectiveness in adsorbing Pb (II). The results reveal that the synthesized adsorbents, denoted as carbonized polyphosphazene or CZ-600 exhibited a high carbon content co-doped with N, P and S atoms, as well as an abundance of oxygen-containing functional groups and a porous structure. These characteristics collectively contribute to the exceptional adsorption capacity of CZ-600 for Pb (II), with a maximum adsorption capacity of 121.7 mg/g and an equilibrium time as short as 20 min. Further investigations of the adsorption process involve fitting adsorption isotherm, kinetic, and thermodynamic models, revealing chemical adsorption as the predominant mechanism, supported by contributions from micropore adsorption and electrostatic interactions. This work proposes a sustainable and efficient solution for the treatment heavy-metal wastewater, which not only advances the understanding of heteroatom-doped carbon materials but also provides valuable insights into their practical applications in environmental remediation.

Enhancing brilliant green dye removal via bio composite chitosan and food-grade algae capsulated ruthenium metal-organic framework: Optimization of adsorption parameters by box-behnken design

A natural material made of chitosan (CS) and algae (food-grade algae, FGA) was cross-linked and loaded onto a ruthenium metal organic framework to create a bio-adsorbent (Ru-MOF@CS/FGA composite sponge) with the aim of adsorbing and eliminating Brilliant green (BG) from aqueous solutions. A range of methods were employed to analyze the Ru-MOF@CS/FGA composite sponge, such as X-ray photoelectron spectroscopy (XPS) for elemental analysis, Fourier transform infrared spectroscopy (FTIR) to ascertain the function groups, and scanning electron microscopy (SEM) to establish the surface morphology, and powder X-ray diffraction (PXRD) to study of single and multi-phase polycrystalline materials. Brunauer-Emmett-Teller surface area (BET) confirmed the adsorbent's high surface area and pore volume (826.85 m2/g and 1.28 cm3/g, respectively) and decreased to 475.62 m2/g and 0.74 cm3/g after adsorption. Determine the several factors that affect the adsorption process, such as pH, the adsorbent's dose, the initial BG concentration, and the effect of salinity. The adsorption process was fitted to pseudo-second-order kinetics and Langmuir isotherms. Dubinin-Radushkevich analysis revealed that the adsorption energy was 23.8 kJ/mol, indicating chemisorption as the mode of adsorption. It was discovered through examining the impact of temperature and computing positive-charged enthalpy and entropy that the adsorption process was endothermic, meaning that it increased in response to temperature. It is possible to reuse the Ru-MOF@CS/FGA composite sponge six times with acceptable efficiency, no change in its chemical composition, and comparable FT-IR, XPS, and XRD data before and after each reuse. Examine the mechanisms of adsorbent-adsorbate interaction, which may involve H-bonding, n-π stacking, electrostatic forces, and pore filling. The adsorption results were optimized with the Box Behnken-design (BBD).