Adsorption Of Carbamazepine Research Articles

Carbamazepine adsorption with a series of organoclays: removal and toxicity analyses

Organoclays have been used as efficient adsorbents for pharmaceutical pollutants present in waters. Carbamazepine (CBZ) is one of the drugs most frequently found in water bodies. In this study, four organoclays were prepared by modifying bentonite with the cationic surfactants hexadecyltrimethylammonium bromide (HDTMA) and octadecyltrimethylammonium bromide. The synthesized materials were characterized by XRD, CHN, FTIR, TG, BET and SEM analyses, confirming organophilization. The surfactants were interspersed in different arrangements in the interlayer space. CBZ sorption was investigated through batch equilibrium experiments, under variation of the pH, contact time, dosage of adsorbent, and initial drug concentration. Changes in pH showed no adsorption influence. CBZ sorption by the organoclays followed a pseudo-second-order kinetics. The best sorption performance was obtained for the BCN1-HDTMA100 clay, with a capacity of 34.34 ± 1.41 mg g−1, about ten times greater than the unmodified bentonite under the same conditions. This may be attributed to the higher surfactant content. The adsorption isotherm at 25 ºC showed linear behavior. Toxicity tests of the organoclays and corresponding medium in presence of CBZ were carried out. This is a novelty report. Most of the organoclays had no toxicity against Artemia salina. The toxicity of the medium after adsorptive treatment was eliminated. Organoclay-CBZ hybrids were also characterized after adsorption. FTIR and TG analyzes confirmed the incorporation of the drug. Hydrophobic interaction was the dominant contribution evaluated to the adsorption of CBZ. The results demonstrated that organoclays can be a promising alternative adsorbent for the removal of pharmaceutical pollutants in water remediation.

Effect of zeolites on the reduction of the ecotoxicity of carbamazepine in the environment

In this study, the impact of calcination of zeolites on the ecotoxicity of carbamazepine solutions in two matrices, water and synthetic sewage, was assessed. Two types of zeolites were tested: natural zeolite, in the form of a zeolite rock consisting mainly of clinoptilolite, and a synthetic zeolite type 5 A. Additionally, zeolites were calcined at a temperature of 200 °C. The kinetics of carbamazepine adsorption in aqueous solutions and in synthetic sewage matrix was determined. Higher adsorption capacity was obtained for carbamazepine aqueous solutions as well as zeolites after the calcination process. Considering type of zeolite, the highest and fastest uptake of carbamazepine was observed for natural zeolite after calcination. In the case of ecotoxicity, carbamazepine solutions before adsorption was the most toxic towards Raphidocelis subcapitata, next Aliivibrio fischeri and Daphnia magna, regardless to the matrix type. The differentiation in toxicity regarding the type of matrix was observed, in the case of algae and bacteria, higher toxicity was demonstrated by carbamazepine solutions in the water matrix, while in the case of crustaceans—the sewage matrix. After the adsorption process, the toxicity of carbamazepine solutions on zeolites decreased by 34.5–60.9 % for R. subcapitata, 33–39 % for A. fischeri and 55–60 % for D. magna, thus confirming the effectiveness of the proposed method of carbamazepine immobilization.

Carbamazepine Adsorption onto Giant Macroporous Silica and Adaptive Neuro-Fuzzy Inference System Modeling

AbstractThere is an imperative need to eliminate pharmaceutical residues from aquatic environments due to their hazardous properties, including toxicity, mutagenicity, and carcinogenicity, particularly when present in water sources. Conventional water treatment methods have proven insufficient in addressing nano-pollutants such as pharmaceutical residues. Consequently, the ongoing quest for economically viable, sustainable, and environmentally friendly removal mechanisms persists. In this particular study, we employed Giant Macroporous Silica (GMS) derived from marine sponges as a promising biosorbent. GMS exhibits commendable characteristics, including a high specific surface area, swift mass transfer capabilities, and non-discriminatory adsorption qualities. The efficacy of GMS in adsorbing carbamazepine (CBZ), a common drug residue, was scrutinized under diverse experimental conditions, including a sorbate/sorbent ratio ranging from 0.005 to 1.500 weight ratio, contact times spanning from 0 to 240 min, and initial pH values ranging from 5 to 9. Remarkably, at a concentration of 1000 µg L−1, GMS demonstrated an attractive adsorption rate (98.88%) of carbamazepine at pH 7.07, within 90 min. To enhance our understanding, we developed an ANFIS model utilizing the experimental parameters as inputs. The developed model exhibited a high correlation coefficient of 0.9944% and a root mean square error (RMSE) of 1.6693, indicating its dependability in accurately predicting the adsorption of CBZ on GMS. The results of our study highlight the efficacy of GMS in adsorbing CBZ, suggesting its considerable potential for adsorbing other pharmaceutical residues and nano-pollutants. Furthermore, we propose the possibility of developing a solid-phase extraction cartridge from GMS.

Effects of root-derived organic acids on sorption of pharmaceutically active compounds in sandy topsoil

The presence and fate of pharmaceutically active compounds (PhACs) in agricultural fields are rarely investigated. The present study highlights that root-derived low-molecular-weight organic acids (LMWOAs) affect the mobility of PhACs in cultivated humic Arenosol. Sorption experiments are conducted using three PhACs characterised by different physicochemical properties: carbamazepine (CBZ), 17α-ethinylestradiol (EE2), and diclofenac-sodium (DFC). The results suggest that the adsorption of EE2 is more intense than the other two PhACs, whereas DFC and CBZ are primarily dominated by desorption. LMWOAs mainly provide additional low-energy adsorption sites for the PhACs, and slight pH changes do not significantly affect the sorption mechanism. During competitive adsorption, the high-energy sites of the adsorbents are initially occupied by EE2 owing to its high adsorption energy (∼15 kJ/mol). The new low-energy binding sites enhance the adsorption of DFC (from 8.5 % to 72.0 %) and CBZ (from 31.0 % to 70.0 %) during multicomponent adsorption. LMWOAs not only affect adsorption by modifying the pH but also provide additional binding sites that allow the PhACs to remain in the root environment for a longer period. As the concentration of LMWOAs temporarily changes, so does the availability of PhACs in the root zone. Environmental changes in the humic horizon enhance the mobility of the adsorbed PhACs, which renders them continuously available for uptake by plants, thus increasing the possibility of PhACs entering the human food chain.

The crucial role of different NaOH activation pathways on the algae-derived biochar toward carbamazepine adsorption

In this study, algae present in wastewater were utilized as precursors for synthesizing a range of biochar (BC) samples to serve as efficient adsorbents for the removal of carbamazepine (CBZ). The impact of modification on BC, activated through the NaOH impregnation method (IBC), and the NaOH dry mixing-pyrolysis (DBC) method, was systematically explored. It was observed that only the surface of IBC became rough due to NaOH impregnation activation, while the DBC structure exhibited additional fine pores within its interior. Furthermore, after NaOH activation, a significant number of oxygen-containing functional groups were introduced onto the surface of the prepared BC samples, with the proportion of O species differing between the two NaOH activation methods. Based on the results from adsorption experiments and kinetic model simulation, CBZ adsorption by BC samples followed a monolayer homogeneous adsorption reaction with excellent pH tolerance, where H-bond (CO⋯H–N) was identified as the primary driving force. From an adsorption thermodynamics perspective, it is hypothesized that the high proportion of CO causes the ΔG value to shift from positive to negative, indicating that CBZ adsorption by DBC is a spontaneous reaction. Under optimal conditions, the DBC samples demonstrated an exceptional adsorption capacity, reaching 118.4 mg/g, with the removal rate of CBZ exceeding 99 %. This study offers theoretical insights into the preparation, modification, and adsorption mechanisms of BC-based adsorbents.

Elementary Steps in Steady State Kinetic Model Approximation for the Homo-Heterogeneous Photocatalysis of Carbamazepine

Elucidating physicochemical processes in the degradation of pollutants may optimize their removal from water sources. Although the photodegradation of carbamazepine (CBZ) in Advanced Oxidation Processes (AOPs) has been widely studied, there is no detailed report on the elementary steps of the kinetics. This study proposes a set of elementary steps for the AOP of CBZ, combining short-wave ultraviolet radiation (UVC), a homogeneous reagent (H2O2), and a heterogeneous catalyst (TiO2), which includes the excitation of both reagents/catalysts by UVC photons, the adsorption of CBZ by the excited TiO2, or its oxidation by hydroxyl radicals. Assuming the steady-state approximation on the intermediate products (excited TiO2, CBZ-excited TiO2 complex, and hydroxyl radicals) leads to rate laws for the degradation of CBZ, in which UVC radiation, TiO2, and H2O2 are pseudo-first-order at all concentrations or intensities and have no direct influence on CBZ pseudo-order, whereas CBZ shifts from pseudo-first-order at low concentrations to pseudo-zero-order at high concentrations. Several experiments to test the mechanism were conducted by varying CBZ, H2O2, and TiO2 concentrations and UVC radiation intensities. The measured results indeed fit the suggested mechanism for the first three, but the irradiation intensity appears to shift the CBZ influence from pseudo-second- to pseudo-first-order with increased intensities. Part of the elementary steps were changed to fit the results.

Impregnation of Modified Magnetic Nanoparticles on Low-Cost Agro-Waste-Derived Biochar for Enhanced Removal of Pharmaceutically Active Compounds: Performance Evaluation and Optimization Using Response Surface Methodology

In the present study, a magnetic nanocomposite based on biochar (BC) derived from sugarcane bagasse, nanoscale zerovalent iron (nZVI), and chitosan (CS) was fabricated to investigate its efficacy for the removal of two widely used pharmaceutically active compounds (PhACs), namely aspirin (ASA) and carbamazepine (CBZ). The synthesized nanocomposite (BC-CS@nZVI) was characterized using XRD, FTIR, and FESEM-EDX. The Response Surface Methodology–Central Composite Design (RSM-CCD) model was used for the optimization of removal efficacies for both drugs using five variables, i.e., adsorbent dose (0.05–0.1 g), pH (2–10), drug concentration (20–40 ppm), time (40–80 min), and temperature (40–60 °C). Under optimized conditions of adsorbent dose: 0.075 g, pH: 2, drug concentration: 30 ppm, time: 60 min, and temperature: 50 °C, the maximum removal efficiency of ASA drug was observed to be 97.8%, while in the case of CBZ drug under similar conditions with pH 6, the maximum removal was found up to 89.32%. The isotherm models revealed that both ASA and CBZ adsorption data fit well with the Langmuir isotherm showing monolayer adsorption. The kinetics of adsorption was well explained by the pseudo-first- and pseudo-second-order models in the case of ASA and CBZ, respectively. Thermodynamic parameters confirmed the feasibility of the reaction and its spontaneous and exothermic nature. The reusability and efficiency in water samples of the Ha’il region were investigated to demonstrate its potential for practical application.

Hydrogen Peroxide/Phosphoric Acid Modification of Hydrochars for Sulfamethoxazole and Carbamazepine Adsorption: The Role of Oxygen-Containing Functional Groups.

Emerging pollutants, such as sulfonamide antibiotics and pharmaceuticals, have been widely detected in water and soils, posing serious environmental and human health concerns. Thus, it is urgent and necessary to develop a technology for removing them. In this work, a hydrothermal carbonization method was used to prepare the hydrochars (HCs) by pine sawdust with different temperatures. To improve the physicochemical properties of HCs, phosphoric acid (H3PO4) and hydrogen peroxide (H2O2) were used to modify these HCs, and they were referred to as PHCs and HHCs, respectively. The adsorption of sulfamethoxazole (SMX) and carbamazepine (CBZ) by pristine and modified HCs was investigated systematically. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results indicated that the H2O2/H3PO4 modification led to the formation of a disordered carbon structure and abundant pores. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy results suggested that carboxyl (-COOH) and hydroxyl (-OH) functional groups of HCs increased after modification, which is the main reason for the higher sorption of SMX and CBZ on H3PO4/H2O2-modified HCs when compared with pristine HCs. In addition, the positive correlation between -COOH/C=O and logKd of these two chemicals also suggested that oxygen-containing functional groups played a crucial role in the sorption of SMX and CBZ. The strong hydrophobic interaction and π-π interaction between CBZ and pristine/modified HCs resulted in its higher adsorption when compared with SMX. The results of this study provide a novel perspective on the investigation of adsorption mechanisms and environmental behaviors for organic contaminants by pristine and modified HCs.

Alkyl chain length of quaternized SBA-15 and solution conditions determine hydrophobic and electrostatic interactions for carbamazepine adsorption

Santa Barbara Amorphous-15 (SBA) is a stable and mesoporous silica material. Quaternized SBA-15 with alkyl chains (QSBA) exhibits electrostatic attraction for anionic molecules via the N+ moiety of the ammonium group, whereas its alkyl chain length determines its hydrophobic interactions. In this study, QSBA with different alkyl chain lengths were synthesized using the trimethyl, dimethyloctyl, and dimethyoctadecyl groups (C1QSBA, C8QSBA, and C18QSBA, respectively). Carbamazepine (CBZ) is a widely prescribed pharmaceutical compound, but is difficult to remove using conventional water treatments. The CBZ adsorption characteristics of QSBA were examined to determine its adsorption mechanism by changing the alkyl chain length and solution conditions (pH and ionic strength). A longer alkyl chain resulted in slower adsorption (up to 120 min), while the amount of CBZ adsorbed was higher for longer alkyl chains per unit mass of QSBA at equilibrium. The maximum adsorption capacities of C1QSBA, C8QSBA, and C18QSBA, were 3.14, 6.56, and 24.5 mg/g, respectively, as obtained using the Langmuir model. For the tested initial CBZ concentrations (2–100 mg/L), the adsorption capacity increased with increasing alkyl chain length. Because CBZ does not dissociate readily (pKa = 13.9), stable hydrophobic adsorption was observed despite the changes in pH (0.41–0.92, 1.70–2.24, and 7.56–9.10 mg/g for C1QSBA, C8QSBA, and C18QSBA, respectively); the exception was pH 2. Increasing the ionic strength from 0.1 to 100 mM enhanced the adsorption capacity of C18QSBA from 9.27 ± 0.42 to 14.94 ± 0.17 mg/g because the hydrophobic interactions were increased while the electrostatic attraction of the N+ was reduced. Thus, the ionic strength was a stronger control factor determining hydrophobic adsorption of CBZ than the solution pH. Based on the changes in hydrophobicity, which depends on the alkyl chain length, it was possible to enhance CBZ adsorption and investigate the adsorption mechanism in detail. Thus, this study aids the development of adsorbents suitable for pharmaceuticals with controlling molecular structure of QSBA and solution conditions.

Sol-Gel Synthesis of New TiO2 Ball/Activated Carbon Photocatalyst and Its Application for Degradation of Three Hormones: 17α-EthinylEstradiol, Estrone, and β-Estradiol.

Many approaches have been investigated to eliminate pharmaceuticals in wastewater treatment plants during the last decades. However, a lack of sustainable and efficient solutions exists for the removal of hormones by advanced oxidation processes. The aim of this study was to synthesize and test new photoactive bio composites for the elimination of these molecules in wastewater effluents. The new materials were obtained from the activated carbon (AC) of Arganian spinosa tree nutshells and titanium tetrachloride by the sol gel method. SEM analysis allowed one to confirm the formation of TiO2 particles homogeneously dispersed at the surface of AC with a controlled titanium dioxide mass ratio, a specific TiO2 anatase structure, and a highly specific surface area, evidenced by ATG, XRD, and BET analysis, respectively. The obtained composites were revealed to quantitatively absorb carbamazepine (CBZ), which is used as a referred pharmaceutical, and leading to its total elimination after 40 min under irradiation with the most effective material. TiO2 high content disfavors CBZ adsorption but improves its degradation. In the presence of the composite, three hormones (17α-ethinylestradiol, estrone, and β-estradiol) are partially adsorbed onto the composite and totally degraded after 60 min under UV light exposure. This study constitutes a promising solution for the efficient treatment of wastewater contaminated by hormones.

Removal of carbamazepine from water using mixed matrix membranes (MMMs) based on polyethersulfone and mesomaterials

The presence of recalcitrant compounds in aquatic systems, such as carbamazepine (CBZ), has intensified due to the wastewater discharge increase. This study aimed to evaluate the PES/mesoparticles-based MMM transport properties and their CBZ adsorption capacities in aqueous solutions with different physicochemical characteristics using a statistical design method. MMMs were synthesized via the phase inversion method using polyethersulfone as a polymeric matrix and mesoparticles as filler materials (MCM-41, NH2-MCM-41, or SH-MCM-41). The MMMs were characterized by ATR-FTIR, DSC, SEM-EDS, TGA, and XRD. CBZ quantification was performed by ultra-performance liquid chromatography. The preliminary adsorption study showed that PES/SH-MCM-41-based MMMs present the highest potential for CBZ adsorption. The multivariate design results indicate that three independent variables (contact time, initial CBZ concentration, and the amount of SH-MCM-41 incorporated in MMM) significantly influence the MMM adsorption capacity, while pH does not affect it. Water permeability tests in MMMs showed a correlation between the H2O permeability and the porosity of the synthesized membranes. PES/SH-MCM-41-based MMM showed high porosity and good ability to remove CBZ from water, regardless of the pH of the aqueous solutions.

Adsorption of Carbamazepine in All-Silica Zeolites Studied with Density Functional Theory Calculations.

The anticonvulsant drug carbamazepine (-) is an emerging contaminant of considerable concern due to its hazard potential and environmental persistence. Previous experimental studies proposed hydrophobic zeolites as promising adsorbents for the removal of carbamazepine from water, but only a few framework types were considered in those investigations. In the present work, electronic structure calculations based on dispersion-corrected density functional theory (DFT) were used to study the adsorption of CBZ in eleven all-silica zeolites having different pore sizes and connectivities of the pore system (AFI, ATS, BEA, CFI, DON, FAU, IFR, ISV, MOR, SFH, SSF framework types). It was found that some zeolites with one-dimensional channels formed by twelve-membered rings (IFR, AFI) exhibit the highest affinity towards CBZ. A "good fit" of CBZ into the zeolite pores that maximizes dispersion interactions was identified as the dominant factor determining the interaction strength. Further calculations addressed the role of temperature (for selected systems) and of guest-guest interactions between coadsorbed CBZ molecules. In addition to predicting zeolite frameworks of particular interest as materials for selective CBZ removal, the calculations presented here also contribute to the atomic-level understanding of the interaction of functional organic molecules with all-silica zeolites.

An investigation on adsorption of carbamazepine with adsorbents developed from flax shives: Kinetics, mechanisms, and desorption

In this work, adsorbents based on hydrochars and steam activated hydrochars developed from flax shives were used to adsorb carbamazepine (CBZ) from simulated contaminated water. The adsorption kinetics was investigated at various temperatures (293–313 K) and times (2–96 h). Four different kinetic models were used to analyze the experimental CBZ adsorption kinetic data. Among the tested various models, the pseudo-second-order kinetic model provided the best simulation to the kinetic data of both adsorbents with R2 of being 0.98 and above, and activation energy of 31.8 and 16.45 kJ/mol, respectively. The determined adsorption rate constant of the steam activated hydrochars ((5.88–9.09) × 10−5) was much higher than that of the hydrochars ((2.81–6.44) × 10−6). Further, X-ray photoelectron spectra and Near-Edge X-Ray Absorption Fine Structure (NEXAFS) Spectroscopy analysis were done before and after loading with CBZ. The results show π-π electron donor-acceptor interaction played an important role on the adsorption mechanism of CBZ on the above-mentioned adsorbents. Hydrophobic interaction also contributed while the roles of hydrogen bonding and electrostatic attraction between CBZ and adsorbents with opposite charges is insignificant. Pore filling may contribute. Desorption of CBZ from CBZ-loaded adsorbents was investigated with various organic solvents, and water at different pH (2, 6 and 10), among which ethanol was the most effective solvent to desorb CBZ. Overall, the results demonstrated that flax shives are promising feedstocks to be made into adsorbents for treatment of wastewater contaminated by antibiotics and additional pharmaceuticals.

Active Pharmaceutical Ingredients Sequestrated from Water Using Novel Mesoporous Activated Carbon Optimally Prepared from Cassava Peels

The increasing occurrence of active pharmaceutical ingredients (APIs) in water systems coupled with their recalcitrance to conventional water treatment methods calls for research into more eco-friendly and cost-effective curbing media. Mesoporous cassava peel activated carbon (CPAC) was prepared under conditions derived from optimizing the surface area and yield with the temperature and holding time as the model inputs using the response surface methodology. The sequestration potential and mechanisms of the resultant activated carbon (AC) for active pharmaceutical ingredients from wastewater were studied using batch experiments. The CPAC adsorption kinetics and isothermal mechanisms for the three pharmaceuticals (carbamazepine (CBZ), clarithromycin (CLN), and trimethoprim (TRM)) were studied in both wastewater and Milli-Q water. The API concentrations were measured using liquid chromatography coupled to a mass spectrometer (LC-MS) system. The maximum removal efficiencies were 86.00, 58.00, and 68.50% for CBZ, CLN, and TRM for wastewater, which were less than those from the Milli-Q water at 94.25, 73.50, and 84.5%, respectively. The sorption process for the CLN was better explained by the Freundlich model, whereas the CBZ and TRM adsorption processes could suitably be explained by both the Langmuir and Freundlich models. At an initial concentration of 20 mgL−1 for all APIs and a CPAC dosage of 2.0 gL−1, the maximum adsorption capacities were 25.907, 84.034, and 1.487 mgg−1 for CBZ, TRM, and CLN, respectively. These results demonstrated the potential of CPAC to remove APIs from water, with its sequestration potential being more exhibited after the removal of the organic matter owing to the lower competition for active sites by the APIs. Additionally, positive adsorbates were better removed than negatively charged adsorbates due to the dominance of anions in the cassava peel lattice.

Theoretical study of the interaction of fullerenes with the emerging contaminant carbamazepine for detection in aqueous environments

The global increase in drug consumption exposes the growing need to develop new systems for the detection, capture, and treatment of bioactive molecules. Carbamazepine is one instance of such contaminants at the top of the ranking commonly found in sewage treatment systems. This work, therefore, presents a theoretical study of fullerene C60 and its derivatives with substitutional doping with B, Al, Ga, Si, Ge, N and P, for the detection and capture of carbamazepine is aqueous medium. Solvation effects were included by means of the Polarizable Continuum Solvent method. The results indicate that doped fullerenes are sensitive for the detection of carbamazepine both in gaseous and aquatic environments. Investigation on the intermolecular interactions between the drug and the fullerene molecule were carried out, allowing the characterization of the interactions responsible for stabilizing the adsorption of carbamazepine to the fullerenes. The theoretical survey revealed that fullerenes doped with Al, Ga, Si and Ge chemically adsorb carbamazepine whereas for the case of fullerenes doped with other heteroatoms physisorption is responsible for the molecular recognition. Relying on DFT calculations, the fullerene derivatives C59Al, C59Si and C59Ga are the most suitable to act both as a sensor and to uptake carbamazepine in aquatic environments.

Adsorptive removal of carbamazepine and ibuprofen from aqueous solution using a defective Zr-based metal-organic framework

In order to protect human health, animals, and the environment, it is essential to eliminate pharmaceutical substances like carbamazepine (CBZ) and ibuprofen (IBU) from water. Herein, the adsorption of CBZ and IBU was investigated from water using a Zr-based metal-organic framework (MOF). UiO-67(Zr)s with a variety of defects, obtained by benzoic acid (BA) modulator, and commercial activated carbon were applied to the adsorptive removal of CBZ and IBU. One MOF, UiO-67(Zr)-BA(10), showed impressive maximum adsorption capacities for CBZ and IBU (294 and 213 mg/g, respectively). UiO-67(Zr)-BA(10) showed much higher adsorption of CBZ, compared with any MOF and MOF composites; the adsorption capacity of the MOF for CBZ is ∼4.5 times that of commercial activated carbon. The efficient CBZ adsorption over UiO-67(Zr)-BA(10), under a wide range of pH conditions, might be attributed to the synergistic effects between porosity and defect sites; and explained with π–π, H-bonding, and van der Waals interactions. Additionally, the durability of the adsorbent allowed for simple regeneration even after several cycles without any noticeable loss in adsorptive performance. This work might provide a valuable insight, like loading adequate defects and increased porosity, in developing efficient MOF-based adsorbents for purification of water contaminated with pharmaceuticals.

Synthesis of mesoporous akaganeite functionalized maize cob biochar for adsorptive abatement of carbamazepine: Kinetics, isotherms, and thermodynamics

In this work, akaganeite (β-FeO(OH)) impregnated maize cob biochar (Fe-MCB) was prepared by direct hydrolysis, and its adsorptive potential was tested against aqueous solutions of carbamazepine (CBZ), an emerging contaminant. The adsorbent was characterized by standard methods, namely XRD, SEM-EDX, FT-IR, BET surface area analysis, and VSM. Fe-MCB exhibited mesoporous textural structure with paramagnetic behavior at room temperature. The equilibrium data were modeled using the Langmuir, Freundlich, Fowler-Guggenheim and Sips isotherm models. The adsorption data were best described by Fowler-Guggenheim with an estimated maximum adsorption capacity of 81.80 mg g−1. The adsorption rate was described by the pseudo-first-order (PFO) model. The thermodynamic functions, namely enthalpy (ΔH = -6.88 kJ mol−1), negative Gibbs free energy (ΔG) values, entropy (ΔS = 26.33 J mol−1), indicated that the adsorption was exothermic, spontaneous, with the increased disorder at the solid-liquid interphase. The adsorption mechanism is thought to entail dispersive interactions. Modified maize cob biochar is a potentially techno-economic sorbent for CBZ adsorption.

Investigations of chemical sensing properties of Al24N24, B24N24, and B24P24 nanoclusters toward carbamazepine: A DFT study

By employing density functional theory (DFT) calculations, the adsorption properties of carbamazepine (CBZ) molecules on the Al24N24, B24N24, and B24P24 nanoclusters were investigated for its detection. All calculations were executed at the B3LYP level of theory and 6-311G (d, p) basis set employing an empirical dispersion term (B3LYP-D) to consider dispersion interactions. The CBZ molecules were adsorbed on the Al24N24, B24N24, and B24P24 nanoclusters with adsorption energies of −38.02, −16.96, and −16.00 kcal mol−1 in their most stable configuration, respectively. After the interaction of nanoclusters with CBZ, significant changes of −12.9%, –33.3%, and −7.7% in their electrical conductivity (σ) took place, respectively. These results indicate the higher sensitivity of the B24N24 nanocluster for its detection. Furthermore, the required time for CBZ desorption from B24N24 was about 0.03 s, demonstrating its short recovery time based on transition theory calculations. The possibility of CBZ detection in the liquid solution was investigated for the selected adsorption configurations. It was shown that they are stable in this phase, and the values of adsorption energies have not changed noteworthy. UV–vis spectroscopy results demonstrated that the B24N24 nanocluster's spectrum exhibits a more significant shift to the higher wavelength (lower energies) region. These results show that it is possible to utilize the B24N24 for the detection of CBZ.

Adsorption behavior of carbamazepine on Zn-MOFs derived nanoporous carbons: Defect enhancement, role of N doping and adsorption mechanism

Metal-organic frameworks (MOFs)-derived nanoporous carbons have attracted widespread concern as adsorbents to remove endocrine-disrupting chemicals (EDCs) in water. However, to explore MOFs-derived nanoporous carbons with high absorption performance is still one of the great challenges, and an in-depth analysis of the adsorption mechanism is insufficient. Herein, two nanoporous carbons were prepared through the pyrolysis of different Zn-MOFs, and their absorptivity was assessed using carbamazepine (CBZ) as the target pollutant. Owing to the higher specific area and the hierarchical pore structure, MOF-5-derived nanoporous carbon (MC) delivered a much higher adsorption capacity (663.7 mg/g) and faster uptake rate (634.5 mg/(g·min)) than ZIF-8-derived nanoporous carbon (ZC) and commercial powdered activated carbon (AC). Furthermore, the studies of the structure-absorptivity relationship revealed that the graphitic defect demonstrates an enhanced efficacy in the absorption performance of nanoporous carbons whereas the effect of the doped N is negligible. The hydrophobic interaction is the dominant contribution to the CBZ adsorption on MC rather than the π-π interaction, electrostatic attraction, and hydrogen bond. Profited from the unique adsorption mechanism, MC shows an excellent anti-interference capability and good reuse stability. This work provides new insight into the design of high-efficiency adsorbents derived from MOFs toward the removal of EDCs from water.

Ternary FeS/γ-Fe2O3@N/S-doped carbon nanohybrids dispersed in an ordered mesoporous silica for efficient peroxymonosulfate activation

Heterogeneous activation of peroxymonosulfate (PMS) has gained much attention for wastewater treatment. It is important to develop efficient catalysts and understand the reaction mechanism. In this work, a novel ordered mesoporous composite catalyst, in which an intimate ternary nanohybrid containing γ-Fe2O3, FeS and N/S-doped carbon (C-N-S) highly dispersed in the mesoporous silica (SBA-15), is presented. Using the facile solvent-free nanocasting method, the composite is synthesized by directly heating a solid mixture of methionine (Met), Fe(NO3)3·9H2O and SBA-15. Under optimal conditions, the melting infiltration and confined pyrolysis enable the formation of γ-Fe2O3 nanoparticles, FeS nanoclusters and C-N-S with intimate contacts but no severe embedment and no pore blockage. The optimized composite exhibits outstanding performance in PMS activation for degradation of carbamazepine (CBZ) with rapid and complete removal and high mineralization. The high performance relies on the cooperative roles of FeS with interfacial ≡Fe(II) sites for activation of PMS, C-N-S for adsorption of CBZ and facilitation of electron transfer to circulate ≡Fe(II)/Fe(III), SBA-15 for easy aqueous dispersion and mass transportation and γ-Fe2O3 for easy magnetic separation. The concentration evolutions of ≡Fe(II) sites and PMS over the reaction process are tracked and correlated with the catalyst structure and performance. The radical pathway dominates the degradation and the PMS activation mechanism is discussed. This work could provide a facile route for the synthesis of ordered mesoporous composites and improve the understanding of metal/carbon composites for PMS activation.