Adsorption Isotherms Research Articles

Harnessing waste palm-based activated carbon/difluoromethane pair for sustainable low-emission cooling systems

An adsorption cooling system (ACS) offers distinct advantages over conventional systems, including improved energy efficiency, waste heat power, low-emission refrigerant employment, and simplified mechanical design. The performance of ACS is greatly affected by the selection of the adsorbent/refrigerant pair. In this study, we experimentally investigate the adsorption capacity of difluoromethane (CH2F2) onto several highly porous waste palm-based activated carbons (PACs). Elemental analysis, SEM, XRD, and FT-IR spectroscopy are performed on raw, carbonized, and activated samples to gain deeper insights into their surface morphology and functional groups. Difluoromethane adsorption isotherms of the PACs are obtained using a high-precision thermogravimetric analyzer at typical operating adsorption and desorption temperatures of ACS. One of the studied PAC/difluoromethane pairs achieves a benchmark uptake of 2.741 kg difluoromethane per kg adsorbent at 30°C and 1893 kPa equilibrium pressure. The experimental data are correlated with substantial accuracy using the Dubinin-Astakhov (D–A) and Tóth isotherm models to predict adsorption performance under experimentally unexamined operating conditions. Furthermore, for this PAC/difluoromethane pair, key performance indicators such as specific cooling effect (SCE), coefficient of performance (COP), Clapeyron cycle (P-T-W) diagram, and heat of adsorption (Qst) are evaluated. The results demonstrate that the PAC/difluoromethane pairs have excellent potential for the development of high-performance, low-emission ACS.

Adsorption of Orange G on Activated Porous Carbon Derived from Coal Tar Pitch: Experimental and DFT Study.

A coal tar pitch-based porous carbon adsorbent (CPA) was synthesized through a straightforward method involving the heating of a mixture of KOH and coal tar pitch (CTP). This CPA exhibited a high surface area of 1811.2 m2 g-1 and a large pore volume of 0.94 cm3 g-1 when prepared with a CTP to KOH mass ratio of 1:4 at 800 °C. Parameters such as the heating temperature and activator dose were optimized to enhance the adsorption efficiency. The prepared CPA was extensively characterized by SEM, XRD, FTIR, and BET measurements. Notably, CPA presented a distinct adsorption performance for Orange G (OG), achieving a maximum adsorption capability of 449.7 mg g-1. Kinetic studies indicated that the adsorption process followed the pseudo-second-order model, while the adsorption isotherm data demonstrated that both chemical and physical interactions favored OG adsorption. Thermodynamic analysis revealed that the adsorption of OG on CPA was spontaneous and exothermic and increased the entropy. Density functional theory (DFT) calculations provided insights into the adsorption mechanism, highlighting electrostatic interactions, hydrogen bonds, and π-π interactions as the dominant processes governing OG adsorption onto the adsorbent.

Eco-friendly impact of a novel green Melilotus officinalis extract as a sustainable inhibitor to reduce acid corrosion of copper.

In this study, we deployed green Melilotus officinalis extract (MOE) as a corrosion inhibitor for copper. The anticorrosion properties of MOE for Cu in 1 M HNO3 were investigated by various experimental and numerical techniques, including potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and a weight loss (WL) method at different temperatures. Additionally, scanning electron microscopy (SEM) coupled with energy-dispersive X-ray analysis (EDX) and atomic force microscopy (AFM) were utilized to examine the surface morphology of Cu with and without the extract. By contrasting the inhibition effectiveness with and without the extract, the inhibition efficiency (% IE) was observed. The WL method revealed that 300 ppm of the extract had an IE of 93.8% for Cu immersed in one molar HNO3 solution. The MOE was classified as a mixed type according to the PDP study since it delayed both cathodic and anodic processes, with a cathodic predominance. At 25-45 °C, MOE's free adsorption energies were 23.1-21.5 kJ mol-1, showing that mixed-type adsorption occurred on the Cu surface. Additionally, the Langmuir adsorption isotherm and the adsorption data from the WL tests of MOE showed a good match. The extract could adsorb spontaneously onto the metal surface, according to the thermodynamic conditions. Analysis of the corrosion product using different techniques revealed that a protective layer had formed on the metal's surface. Hence, MOE had a good corrosive inhibitive effect on Cu in HNO3 solution. It turned out that all the methods used gave consistent results.

Synthesis, characterization and adsorption of Pb(Ⅱ), Cd(Ⅱ) and Cu(Ⅱ) by red mud/polyacrylic acid/sodium carboxymethyl cellulose hydrogel

Heavy metal pollution in water and pollution hazards caused by red mud disposal are urgent environmental problems to be solved. Red mud waste can be utilized as resources by preparing hydrogels. By employing free radical polymerization, a red mud/polyacrylate/sodium carboxymethyl cellulose hydrogel (RMAAC) was synthesized using red mud (RM) as the main component, sodium carboxymethyl cellulose (SCMC) as the grafting substrate, N, N’-methylene bisacrylamide (MBA) as the crosslinking agent, and potassium persulfate (KPS) as the initiator. The proportions of MBA, KPS, and SCMC were optimized using the response surface method. The adsorption kinetics and isothermal adsorption model were applied to analyze the adsorption characteristics, while XRD, FTIR, SEM-EDS, and XPS characterization methods were employed to study the adsorption mechanism. The results demonstrated that the optimal proportions of MBA, KPS, and SCMC in RMAAC were determined to be 0.15 %, 0.2 %, and 1.5 %, respectively, and the addition of 0.5 % RM to enhance the adsorption performance of the hydrogel. The adsorption processes of Pb(II), Cd(II), and Cu(II) by RMAAC followed the pseudo-second-order kinetic model and the Langmuir model, suggesting chemisorption through a single molecular layer as the main adsorption mechanism. The maximum theoretical adsorption capacities of the three heavy metal ions at 25°C were determined to be 730.16, 292.71, and 215.37 mg/g, respectively. It was found that RMAAC exhibited a higher affinity toward Pb(II) compared to Cu(II) and Cd(II). Characterization analyses revealed that ion exchange and coordination chelation were the predominant mechanisms involved in the adsorption of Pb(II), Cd(II), and Cu(II) by RMAAC.

Study of the Adsorption of Eriochrome Black T on Charged Macrospheres Based on Polyglycidyl Methacrylate-Graft-Polyvinyl Chloride

The efficient removal of pollutants from aqueous systems remains a significant challenge in environmental science and engineering, particularly when dealing with hazardous dyes commonly found in industrial wastewater. Our research described in this paper investigated the adsorption of the dye, Eriochrome Black T (EBT), a synthetic azo dye widely used in various industries, onto charged macrospheres based on polyglycidyl methacrylate-graft-polyvinyl chloride (P1). The macrospheres were prepared using the synthesized graft copolymer P1 by the phase inversion method and functionalized by quaternary hydrazine to introduce charged groups on the surface of these macrospheres, enhancing their affinity for the anionic EBT dye. The effects of initial dye concentration, contact time and temperature on the adsorption process were evaluated. Furthermore, adsorption isotherms and kinetic models were applied to elucidate the mechanism of this adsorption process. The results demonstrated that the experimental data of the adsorption process was well-fitted by the Langmuir model isotherm and the charged macrospheres exhibited excellent adsorption capacity for EBT. In the thermodynamic study the adsorption process was found to be exothermic and spontaneous at room temperature. Besides, the kinetics study revealed that the adsorption process was better described by the pseudo-second-order model (R2= 0.992) than the pseudo-first-order model (R2= 0.963), suggesting that chemisorption was the adsorption process. The mechanism of this adsorption was mainly based on electrostatic interactions and hydrogen bonding between the adsorbent and the adsorbate.

Adsorption Properties of Fishbone and Fishbone-Derived Biochar for Cadmium in Aqueous Solution

Cadmium (Cd) contamination in aquatic ecosystems is a serious global environmental issue. Biochar derived from agricultural wastes has recently attracted remarkable attention as it is used as an absorbent in combating heavy metal contamination of water bodies. In the present study, the absorption efficacy of fish bone (FBM) and fishbone-derived biochar prepared at 200 °C, 400 °C, 600 °C, and 800 °C (referred to as B200, B400, B600, and B800, respectively) for the Cd ion (Cd2+) in aqueous solution was investigated. The results showed that high-temperature pyrolysis could optimize the pore structure and specific surface area of FBM, and Cd2+ successfully adsorbed onto FBM and fishbone-derived biochar. High-temperature pyrolysis significantly increased the FBM adsorption capacity for Cd2+ by 49.5–135.1%, with the optimal pyrolysis temperature being 600 °C. Furthermore, the kinetic data of FBM and fishbone-derived biochar for Cd2+ were in better alignment with the pseudo-second-order model, their adsorption isotherms were better in accordance with the Langmuir models, and the thermodynamic analysis showed that the adsorption process was monolayer and favorable adsorption. Moreover, the potential adsorption mechanisms of Cd2+ on FBM and fishbone-derived biochar might be related to pore filling, ion exchange, complexation with oxygen functional groups, and precipitation with the minerals on the biochar surface. Fishbone-derived biochar has significant potential for wastewater treatment and agricultural waste applications.

Investigation of Release Kinetics of DOX from Polydopamine Nanocapsules Prepared by Hard Template Method

AbstractDevelopment of smart drug delivery systems (DDSs) for effective delivering drugs to targeted areas and achieving controlled drug release (CDR) is critical for cancer chemotherapy. The purpose of this study is synthesis of polydopamine (PDA) nanocapsules and analyze the adsorption and release properties of doxorubicin (DOX). PDA nanocapsules are manufactured using hard template approach. The influence of various parameters such as pH, adsorption time, and initial DOX content on the adsorption and release process is investigated. The resulting adsorption isotherm is consistent with the Langmuir isotherm, indicating that DOX adsorption on PDA nanocapsules is homogenous, uniform, and monolayer. PDA nanocapsules have an adsorption capacity of 689.6 mg g−1 under alkaline conditions, which is attributed to phenol group deprotonation mechanism and electrostatic repulsion. The adsorption kinetics are more consistent with the pseudo‐second‐order model. Furthermore, raising initial concentration of DOX results in a greatly increased adsorption capacity due to a larger driving force. Among the several parameters that can influence the pace and degree of DOX loading and release, local pH is regarded as a significant environmental component in the processes. Thus, pH‐responsive PDA nanocapsules have a significant potential for usage in locations with aberrant pH level, such as cancer tissue.

Investigating adsorption properties of CO2 and CH4 in subbituminous coals from Mamu and Nsukka formations: a molecular simulation approach

The study aimed to investigate the adsorption properties of methane (CH4) and carbon dioxide (CO2) in subbituminous coals from the Mamu and Nsukka formations, focusing on the CO2-Enhanced Coalbed Methane (ECBM) method. Proximate, ultimate, and FT-IR analyses determined the quality, age, and functional categories of these coals, confirming their subbituminous nature. Using molecular dynamics (MD) simulations, a unique amorphous subbituminous coal model was developed to study adsorption phenomena. Isosteric heat and adsorption isotherms for pure CO2 and CH4 were analyzed, alongside Grand Canonical Monte Carlo (GCMC) simulations to assess CO2 adsorption selectivity in a binary CO2 and CH4 mixture. Results showed that CO2 required more isosteric heat than CH4 in single-component scenarios and demonstrated stronger electrostatic interactions with heteroatom groups in the coal model, explaining its higher adsorption preference. In binary adsorption experiments, CO2 exhibited a higher affinity under specific conditions, particularly influenced by pressure variations. At lower pressures, CO2 selectivity decreased rapidly with increasing temperature, while at higher pressures, the influence of temperature diminished. These findings have established a theoretical and practical basis for optimizing CO2-ECBM extraction in Nigeria, highlighting the preferential adsorption of CO2 over CH4 in subbituminous coals from the Mamu and Nsukka formations under varying pressure and temperature conditions. Implementing CO2-ECBM extraction and storage in Nigeria could boost economic viability and help achieve net-zero goals, using insights from this study to guide policy development.Graphical

Efficient Removal of Antibiotics From Water via a Novel Magnetic Hypercrosslinked Polymer

ABSTRACTThe removal of antibiotic residues from environmental media is a significant challenge in the field of chemistry. In this work, we presented a simple and efficient method for eliminating tetracycline hydrochloride (TC) and chloramphenicol (CAP) from water. Initially, 1,4‐dichlorobenzene and ferrocene were employed as starting materials for the synthesis of hypercrosslinked polymers (HFDs) via Friedel–Crafts alkylation facilitated by a cross‐linking agent. Subsequent to this, an efficient magnetic adsorbent material (MHFD) was developed by the in situ oxidation of the iron source incorporated within the polymer matrix of HFDs. The resulting MHFDs demonstrated an impressive maximum Brunauer–Emmett–Teller (BET)–specific surface area of 1190 m2/g and exhibited a peak saturation magnetization of 11.8 emu/g. This work investigated the effects of four factors on the adsorption performance of MHFD‐10, including contact time, solution pH, dosage of MHFD‐10, and initial antibiotic concentration. The results revealed a remarkable conformity of the adsorption kinetics with the pseudo‐second‐order model and the adsorption isotherms with the Langmuir model. Thermodynamic analysis revealed that the adsorption process is spontaneous and exothermic. Specifically, at a temperature of 20°C, MHFD‐10 achieved maximum adsorption capacities of 193.95 mg/g for CAP and 268.60 mg/g for TC. Furthermore, these materials exhibited exceptional reusability, maintaining high adsorption capacities even after undergoing five consecutive reuse cycles.

Seed responses to change in ambient humidity and the consequences for storability

The study of seed moisture sorption isotherms helps us to understand the response of seeds to changes in moisture in their environment and how this might impact their longevity. A seed moisture isotherm shows the relationship between moisture content (MC) and water activity (aw) at a constant temperature. Seed MC is higher when it dries from a hydrated state (desorption) than when it rehydrates from a very dry state (adsorption) to the same RH, an effect known as hysteresis. Seeds on the desorption isotherm will age faster than seeds on the adsorption isotherm at the same RH due to higher MC, resulting in a more rapid decline in seed viability and vigour. In this study, moisture isotherms of seeds from diverse species were determined and modeled using the Guggenheim-Anderson-de Boer (GAB) model; the hysteresis effect was then quantified. The maximum hysteresis magnitude varied between 0.3 and 2.7% MC (occurring between 49 and 57% RH) when seeds were dried over silica gel (below 11% RH) and rehydrated. Cycling seeds between 30 and 50%, 20 and 50%, and 15 and 50% RH, it was found that seeds of barley, lupin, buckwheat, wheat and pea switch to the adsorption isotherm upon rehydration after drying at intermediate moisture levels. Thus, adsorbing seeds of these species have greater longevity than desorbing seeds at the same RH. In contrast, seeds of oilseed rape and yellow mustard do not show a hysteresis effect unless they are dried to very low MC (over silica gel), so the adsorbing seed longevity remains the same as desorbing seeds at a constant RH. It is important to consider the moisture history of seeds depending on species for better seed storage management.

Experimental and computational investigations on the synergistic inhibition mechanism of biphenyl quinoline quaternary ammonium and hexamethylenetetramine on the corrosion of J55 steel in 20 wt% HCl solution

The present study involves the synthesis of a novel biphenyl quinoline quaternary ammonium salt (BDQ) and its application in combination with hexamethylenetetramine (HMT) as a compounded corrosion inhibitor for acid stimulation, aiming to effectively prevent the corrosion of J55 steel in a 20 wt% HCl solution at 60 °C. The optimized BDQ/HMT mixture (with a mass ratio of 1:3) at 0.4 wt% produced a significant decrease in the corrosion rate of J55 steel to 3.7637 g/(m2·h), much lower than the requirement of 5.0 g/(m2·h) stipulated by the standard SY/T 5404–2019. The electrochemical analysis demonstrated that the BDQ/HMT mixture exhibited a mixed-type corrosion inhibitor with predominantly anodic characteristics, retarding both the anodic oxidation and cathodic reduction reactions of J55 steel in the HCl solution. The adsorption studies revealed that BDQ conformed to a Langmuir-type adsorption isotherm on J55 surfaces, driven by a combination of physisorption and chemical interactions, with chemical interactions playing a dominant role. Additionally, quantum chemical calculations and molecular dynamics simulation were also performed to elucidate the observed synergistic effect of BDQ and HMT.

Fabrication of magnetic Cu2O nanocomposites for enhanced iodide removal: Adsorption properties, mechanism and application

The presence of iodine in water poses significant health risks to humans and aquatic ecosystems, necessitating the development of efficient and sustainable remediation strategies. Here, we present Fe3O4/Ti3C2Tx/Cu2O-Cu nanocomposites as high-performance adsorbents for iodide removal. A multistep process was utilized in the fabrication of the nanocomposite, which involved the modification of Fe3O4 nanoparticles with polydopamine (PDA) and the assembly of Ti3C2Tx nanosheets, followed by the growth of Cu2O/Cu nanoparticles. The nanocomposites showed a maximum iodide adsorption capacity of 41.34 mg/g at 25 °C, following quasi second-order adsorption kinetics and the Langmuir adsorption isotherm. A thermodynamic study revealed that the adsorption process was exothermic and spontaneous. Additionally, the nanocomposite displayed excellent selectivity for iodide despite competing anions and retained over 50 % of its adsorption capacity after two washing cycles. A mechanistic investigation indicated that the removal of iodide was primarily due to the formation of insoluble CuI under acidic conditions and surface complexation between Cu2O and iodide under neutral conditions. Owing to its high adsorption capacity, good selectivity, magnetic separability, and reusability, the Fe3O4/Ti3C2Tx/Cu2O-Cu nanocomposite offers great promise for the effective remediation of iodide-contaminated water. This study provides valuable insights into the development and application of advanced functional materials for addressing the critical issue of water pollution due to iodine.

Adsorptive processes applied to the defluorination of groundwater for human consumption

Contamination of groundwater by fluoride ions can occur through both natural and anthropogenic activities, such as the discharge of industrial waste containing this compound. Thus, effective fluoride removal from groundwater is essential to ensure safe drinking water. This study evaluated the performance of adsorption techniques for defluoridating groundwater in Rio Grande do Sul, Brazil. Preliminary tests were conducted using synthetic solutions with a fluoride concentration of 5 mg.L−1, applying several adsorbents. Additionally, an ultrasonic process was used to synthesize an adsorbent from activated alumina pre-treated with carbon (AACP) and modified with ZnCl₂ (AA-ZnCl₂). The AACP and AA-ZnCl2 were characterized through BET, EDS, scanning electron microscopy, X-ray diffraction (XRD), and FT-IR analysis. A Central Composite Design and response surface methodology were applied to optimize adsorption efficiency, focusing these factors: pH and adsorbent dosage. Kinetic and isotherm adsorption tests were conducted for both AACP and AA-ZnCl₂. The results showed that AACP achieved fluoride removal efficiencies of 65.4 % in synthetic solutions and 38.6 % in groundwater. The AA-ZnCl₂ demonstrated superior performance, removing over 98 % of fluoride in synthetic solutions and 55.4 % in groundwater, across a pH range of 4 to 10, with an optimal solid dosage of 3 g.L−1. For an initial fluoride concentration of 5 mg.L−1, a removal efficiency of 97.4 % was achieved within 5 min of contact time. The kinetic adsorption data were best described by the pseudo-second-order model, while the Freundlich isotherm model provided the best fit for the adsorption isotherm data. The findings in this work indicate hat ZnCl₂-modified activated alumina, synthesized with ultrasonic assistance, is highly effective for defluoridating groundwater for safe human consumption being an alternative method to be implemented in an industrial scale.

Functionalized Cyclodextrin/Carboxymethyl Cellulose Composite Hydrogel with Double Network Structure for Adsorption of Heavy Metal Ions in Wastewater.

Heavy metal ions in industrial wastewater pose significant environmental and ecological threats. In this work, a hydrogel featuring a double network structure was synthesized via radical polymerization and cross-linking of β-cyclodextrin (CD) and carboxymethylcellulose (CMC) with acrylic acid (AA). The hydrogel's functional groups and microstructure were characterized using Fourier transform infrared spectroscopy (FTIR-ATR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Mechanical properties were evaluated through rheological and compression tests. The study examined the impact of initial metal ion concentration, adsorbent-ion contact time, and solution pH on adsorption capacity. The maximum adsorption capacities of the functionalized CD/CMC-PAA-MBA hydrogel for Cu2+, Pb2+, and Cd2+ ions were 158.12, 393.56, and 290.12 mg/g, respectively. Notably, the hydrogel exhibited the highest selectivity for Pb2+ in mixed solutions. The adsorption kinetics of the metal ions were modeled using the pseudo-second-order rate equation and the Langmuir adsorption isotherm.

Evaluation of ZnO/NiO/kaolin nanocomposite as a sorbent/photocatalyst in hybrid water remediation process

The colored effluents causing environmental pollution pose a threat to the world. This study aims to assess the effectiveness of nickel oxide/zinc oxide/kaolin nanocomposite (NiO/ZnO/Ka) in removing methylene blue (MB) from water. Furthermore, it aims to examine the impact of synergetic adsorption/photocatalytic degradation (APCD) on the MB adsorption capacity as well as the suitability of the nonlinear adsorption isotherm and kinetic modeling in analyzing the process. The composites ZnO/Ka and NiO/ZnO/Ka were synthesized by the sol–gel method and were characterized by X-ray diffraction, Fourier transform infra-red, field emission scanning electron microscopy, and Brunauer–Emmett–Teller. The impacts of various parameters, such as pH, initial concentration of MB, dose, ionic strength, and temperature, on MB removal were studied using adsorption and APCD. The results showed that ZnO/Ka had the maximum adsorption capacity of MB (39.31 mg/g) and the maximum removal (78.61%) under optimal conditions of pH 10, clay dosage of 0.1 g/25 mL, initial concentration of MB 200 mg/L, contact time of 15 min, and 298 K, while NiO/ZnO/Ka showed the maximum adsorption capacity of MB (40.88 mg/g) and maximum removal (83.74%) at pH 7. It was also noticed that Temkin and Fritz–Schlunder models are the best isotherm models, with the highest R2 (1 and 0.842) for ZnO/Ka and NiO/ZnO/Ka, respectively. Moreover, the data of adsorption and photodegradation of MB onto ZnO/Ka and NiO/ZnO/Ka were revealed to follow pseudo-first-order and Avrami kinetic models with R2 (0.897) for ZnO/Ka and (0.986) for NiO/ZnO/Ka. Overall, NiO/ZnO/Ka showed better removal of MB than ZnO/Ka, and the hybrid process (photodegradation process after adsorption) enhanced the overall efficiency of MB removal than adsorption alone.

Agricultural waste valorisation – Novel Areca catechu L. residue blended with PVA-Chitosan for removal of chromium (VI) from water – Characterization, kinetics, and isotherm studies

Arecanut, an industrial crop prevalent in tropical regions such as India, Sri Lanka, and parts of Southeast Asia, generates significant agricultural waste during processing. This study explores a waste-to-wealth approach by incorporating arecanut organic residue into Polyvinyl alcohol (PVA) - Chitosan blends via an eco-friendly continuous stirring method to develop an adsorbent film for removing chromium (VI) from water. Morphological analyses confirmed enhanced surface area, porosity, and roughness in the blended films. XRD and FTIR analyses indicated a semi-crystalline nature with a decrease in the characteristic peak intensity of PVA and chitosan, confirming the incorporation of arecanut residue. Optimal conditions identified OR-4 film, using 0.4 g of adsorbent, achieving 88.68 % removal of 173 mg/L chromium (VI) at pH 9.0, within 45 minutes at 40°C. SEM images demonstrated significant surface roughness reduction before and after adsorption, confirming chromium adsorption. Kinetic studies revealed a pseudo-second-order model and adsorption isotherms confirmed film surface heterogeneity. This research advances eco-friendly materials for water purification and offers a sustainable solution for managing agricultural residues.

Enhanced VOCs adsorption over ZSM-5 nanosheets with different thicknesses along the b-axis

A systematic study was conducted on the effect of the b-axis thickness on the adsorption/desorption properties of representative VOCs (toluene and dichloromethane) by varying the diffusion resistance over ZSM-5 nanosheets. ZSM-5 nanosheets with about 30 nm thickness along the b-axis (Z5-3) presented a 1.3-fold higher adsorption capacity (83.9 mg/g) and 27 % enhancement in breakthrough times for toluene (38 min) compared with conventional ZSM-5 (Z5-4). Dichloromethane adsorption capacity on Z5-3 (micropore volume of 0.12 cm3/g) was approximately 53 % higher than that on Z5-4 (micropore volume of 0.08 cm3/g) and only weekly correlated to the b-axis thickness due to its small molecular size. The adsorption isotherms and molecular dynamic simulations indicated that a shorter b-axis thickness enhanced the diffusion of toluene (3.9 × 10-5 cm2/s) and dichloromethane (7.2 × 10-5 cm2/s), as well as the toluene adsorption capacities over ZSM-5 samples. The toluene and dichloromethane physisorption mechanism was verified by adsorption kinetics. Additionally, the toluene and dichloromethane adsorption capacities of all samples decreased by about 33 % and 21 % at a relative humidity (RH) of 50 % at 298 K, respectively. This indicated that the structure of ZSM-5 samples did not significantly affect their hydrophobicity. Moreover, according to the competitive adsorption test results, toluene and dichloromethane underwent successive co-adsorption, competitive adsorption, and equilibrium adsorption. These findings are useful for designing high-performance and cost-effective zeolite adsorbents to efficiently remove volatile organic compounds from industrial sources.

One‐Step Green‐Synthesized UiO‐66‐NH2 /Alginate Composite Hydrogels with Improved Methylene Blue Adsorption

AbstractZirconium‐based metal‐organic frameworks (Zr‐MOFs) represent an important class of MOFs with high stability and outstanding properties, the green preparation and shaping of which are still challengeable works to hinder their real‐world applications. In this presentation, UiO‐66‐NH2 MOFs were in‐situ grown accompanied by alginate (Alg) hydrogelation under aqueous conditions, achieving UiO‐66‐NH2/Alg composite hydrogels. Relevant characterizations demonstrate the in‐situ generated UiO‐66‐NH2 MOFs were evenly distributed in hydrogel networks by attaching on Alg fiber surfaces. The network structure became denser, but both specific surface area and pore volume were augmented due to the presence of MOFs, which in turn increased active sites to interact with adsorbates. Thus, the adsorption capacity to methylene blue (MB) of composite hydrogels became higher with more dosage of MOF ligand, and the pH sensitivity of Alg adsorption to MB in the pH range of 4 to 10 was eliminated. Furthermore, the study of adsorption kinetics and isotherm reveals MB adsorption on the obtained hydrogels belong to rate controlling chemisorption mechanism. In summary, this manuscript presents a facile approach to realizing the green synthesis and shaping of Zr‐MOFs by one‐step compositing of UiO‐66‐NH2 with Alg‐based hydrogels in aqueous system, achieving MOFs‐based composite hydrogels with enhanced MB adsorption.

Antitumoral action of carvedilol–a repositioning study of the drug incorporated into mesoporous silica MCM-41

We have studied repositioning of carvedilol (an antihypertensive drug) incorporated into MCM-41 mesoporous silica. The repositioning proposes a reduction in the slow pace of discovery of new drugs, as well as toxicological safety and a significant reduction in high research costs, making it an attractive strategy for researchers and large pharmaceutical companies. We obtained MCM-41 bytemplatesynthesis and functionalized it by post-synthesis grafting with aminopropyltriethoxysilane (APTES) only or with folic acid (FA), which gave MCM-41-APTES and MCM-41-APTES-FA, respectively. We characterized the materials by scanning and transmission electron microscopy, zeta potential (ZP) measurements, Fourier transform infrared absorption spectroscopy, x-ray diffractometry, nitrogen gas adsorption, and CHNS elemental analysis. We quantified the percentage of drug that was incorporated into the MCM-41 materials by thermogravimetric analysis and evaluated their cytotoxic activity in non-tumor human lung fibroblasts and the tumor human melanoma and human cervical adenocarcinoma cell lines by XTT salt reduction (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-arboxanilide). The x-ray diffractograms of the MCM-41 materials displayed low-angle peaks in the 2θrange between 2° and 3°, and the materials presented type IV nitrogen adsorption isotherms and H2 hysteresis typical of the MCM-41hexagonal network. The infrared spectra, the charge changes revealed by ZP measurements, and the CHN ratios obtained from elemental analysis showed that MCM-41 was amino-functionalized, and that carvedilol was incorporated into it. MCM-41-APTES incorporated 23.80% carvedilol, whereas MCM-41 and MCM-41-APTES-FA incorporated 18.69% and 12.71% carvedilol, respectively. Incorporated carvedilol was less cytotoxic to tumor and non-tumor cells than the pure drug. Carvedilol repositioning proved favorable and encourages further studies aimed at reducing its cytotoxicity to non-tumor cells. Such studies may allow for larger carvedilol incorporation into drug carriers or motivate the search for a new drug nanocarrier to optimize the carvedilol antitumoral activity.

Mn3O4-MnOOH nanocomposites for the adsorption-based removal of nickel ions from wastewater.

The removal of nickel from wastewater is a significant environmental concern because of its potential hazards to environment. Adsorption is known as an efficient water treatment strategy and there is a growing interest in the development of new adsorbent materials providing rapid adsorption kinetics, cost-effectiveness, and high adsorption capacity. In this study, the feasibility of Mn3O4-MnOOH nanocomposites was evaluated as the adsorbent material for the removal of nickel ions from wastewater. The nanocomposites were prepared using a modified sonochemical method and characterized by XRD analysis and SEM images. Batch adsorption experiments were carried out under different experimental conditions obtained by varying solution pH, adsorbent amount, and contact period. Under the optimum adsorption conditions, the %RE value was recorded around 80% for 10mg/L Ni(II) ions. The adsorption characteristics were investigated with respect to adsorption isotherms and kinetics. Langmuir and Freundlich isotherm models were used to fit the adsorption data and the results indicated that adsorption of nickel ions onto nanocomposite could be complex and obey both monolayer adsorption and heterogeneous surface. Accordingly, maximum adsorption capacity of nanocomposites were calculated as 12.387mg/g. Research works comparing the kinetic models of pseudo-first-order, pseudo-second-order, and Elovich revealed that chemical sorption plays an important role as the rate-limiting step in the adsorption of nickel ions.