BET Surface Area Research Articles

Adsorption efficacy of acetone with zeolitic imidazolate frameworks–8: a mechanistic and kinetic insight

ABSTRACT The zeolitic imidazolate framework-8 (ZIF-8) has been investigated for the dynamic adsorption of acetone from the gas phase. In this study, ZIF-8 was synthesised using a cost-effective and environmentally friendly method and characterised using SEM, XRD, BET, and FTIR. The synthesised ZIF-8 possessed a BET surface area of 1212 m2. g−1 and a 0.64 µm particle size. The dynamic adsorption efficacy of acetone on the thermally pretreated ZIF-8 was investigated in a gas matrix under different operational factors. Increasing the acetone concentration through the adsorbate inlet from 300 to 800 ppm enhanced the adsorption capacity from 114 to 162 mg. g−1, while increasing flow rates from 100 to 200 mL. min−1 diminished the adsorption capacity from 120 to 114 mg. g−1. Additionally, increasing the relative humidity from 30 to 70% diminished the adsorption capacity from 130 to 87 mg. g−1. The acetone adsorption kinetics on ZIF-8 were investigated by the Elovich equation, pseudo-first order (PFO), and pseudo-second order (PSO) models. The statistical parameters indicated that the Elovich equation model is most suitable for representing the kinetic behaviour. In conclusion, ZIF-8 could be introduced as a sorbent with suitable potential for adsorbing acetone from the air in various environmental and occupational settings.

Carboxymethyl-imidazolium O-vanillin Schiff base grafted into NH2-tagged MIL-101 (Cr) for effective removal of cupric ions from aqueous effluents.

A novel adsorbent (MIL-CMIVSB) was fabricated by modification of H2N-MIL-101(Cr) with carboxymethyl-imidazolium O-vanillin Schiff base. The MIL-CMIVSB's physicochemical characteristics were examined using the pertinent characterization methods. NH2-MIL-101(Cr) has a BET surface area of 1492.4 m2g-1, while MIL-CMIVSB adsorbent had 1278.7 m2g-1. Batch adsorption experiments examined the MIL-CMIVSB's cupric ion adsorption capacity from aqueous solutions at different adsorbent doses (0.1-3mg), pH (2.0-10.0), contact times (0-240min), metal ion initial concentrations (10-300mg/L), and temperatures (298-308K). The optimum conditions were 1mg/mL of MIL-CMIVSB adsorbent, 46min adsorption time, pH 7, 100ppm initial cupric ion concentration, and 303K temperature. MIL-CMIVSB effectively and selectively removes cupric ions with an adsorption capability of 359.05 ± 12.06mg/g. The nonlinear Liu isotherm governed Cu(II) sorption performance on MIL-CMIVSB (KL = 0.257 ± 0.01mg/g, R2 = 0.99892) and pseudo-2nd-order kinetically (k2 = 0.00116 × 10-4g/mg min, R2 = 0.99721).

Oxygen vacancies promote the activation of O2 in transition metal oxide doped ε-MnO2 for low-temperature CO oxidation

Carbon monoxide (CO), a toxic pollutant usually formed from incomprehensive combustion especially at low temperature, has harmful effects on human health. Therefore, the catalytic oxidation of CO always receives widespread attention. Herein, we reported transition metal (Cu, Co, Ni, Fe) doped ε-MnO2 as CO catalysts using a hydrothermal-deposition method. Physiochemical properties for CO oxidation were meticulously analyzed employing characterization techniques such as SEM, XRD, BET, XPS, EPR, CO-TPR. The doped ε-MnO2 catalyst showed expanded BET surface area, increased oxygen vacancy defects, more active sites, enhanced adsorption, and faster electron transfer. Catalytic activity tests indicated that the ε-MnO2 catalyst doped with transition metals exhibited exceptionally high catalytic activity, with the Cu-doped catalyst showing the fastest chemical reaction rate and the lowest complete conversion reaction temperature (TOF of 9.92 × 10−3 s−1, at 65℃). Density Functional Theory (DFT) calculations indicated that Cu doping more effectively induced oxygen vacancy defects compared to Co, Ni, Fe, and raw ε-MnO2 catalysts. It identifies the CO oxidation reaction and improved the CO adsorption capacity of the catalyst. Furthermore, a novel potential reaction pathway for the M-vK mechanism in transition metal oxides was proposed.

Synthesis of Calix[4]arene-Based Porous Organic Cages and Their Gas Adsorption.

Two crystalline large-sized porous organic cages (POCs) based on conical calix[4]arene (C4A) were designed and synthesized. The four-jaw C4A unit tends to follow the face-directed self-assembly law with the planar triangular building blocks such as tris(4-aminophenyl)amine (TAPA) or 1,3,5-tris(4-aminophenyl)benzene (TAPB) to generate a predictable cage with a stoichiometry of [6+8]. The formation of the large cages is confirmed through their relative molecular mass measured using MALDI-TOF/TOF spectra. The protonated molecular ion peaks of C4A-TAPA and C4A-TAPB were observed at m/z 5109.0 (calculated for C336H240O24N32: m/z 5109.7) and m/z 5594.2 (calculated for C384H264O24N24: m/z 5598.4). C4A-POCs exhibit I-type N2 adsorption-desorption isotherms with the BET surface areas of 1444.9 m2 ⋅ g-1 and 1014.6 m2 ⋅ g-1. The CO2 uptakes at 273 K are 62.1 cm3 ⋅ g-1 and 52.4 cm3 ⋅ g-1 at a pressure of 100 KPa. The saturated iodine vapor static uptakes at 348 K are 3.9 g ⋅ g-1 and 3.5 g ⋅ g-1. The adsorption capacity of C4A-TAPA for SO2 reaches to 124.4 cm3 ⋅ g-1 at 298 K and 1.3 bar. Additionally, the adsorption capacities of C4A-TAPA for C2H2, C2H4, and C2H6 were evaluated.

One-Pot Synthesis of Ce-SSZ-39 Zeolite with Performance in the NH3-SCR Reaction.

Cu-SSZ-39 zeolite with 8-membered rings is regarded as a very promising catalyst in the NH3-SCR reaction, but its hydrothermal stability still remains to be improved. One of the solutions to promote hydrothermal stability is the insertion of rare earth elements in the product. Nevertheless, normal ion exchange of rare earth elements limits their contents in the zeolite product due to their large hydrated ionic radius and alkaline environment under hydrothermal conditions. Herein, we for the first time present a new method for the one-pot synthesis of Ce-SSZ-39 zeolite under solvent-free conditions. The key to success is the use of Ce-FAU zeolite as a precursor. The obtained product shows good crystallinity, sheet-like morphology, large BET surface area, and 4-coordinated Al species. Detailed investigations illustrate that Ce species in the Cu/Ce-SSZ-39 zeolite micropore can prevent the dealumination and thus formation of CuAlOx species during hydrothermal aging at 850 °C for 16 h, giving the excellent hydrothermal stability and thus showing the excellent catalytic performance in the NH3-SCR reaction. One-pot synthesis of Ce-SSZ-39 zeolite with excellent catalytic performance might open a new door for developing very efficient selective catalytic reduction (SCR) catalysts in near future.

Biogas dry reforming over Li–Ni–Al LDH-derived catalysts

Biogas dry reforming or dry reforming of methane (DRM) is an alternative to produce hydrogen, in the context of development of sustainable routes for energy production, since this route uses CH4 and CO2, two greenhouse gases as reactants. However, the deactivation of catalysts due to carbon deposition and sintering is the main drawback of this reaction. In this work, with the aim of minimizing carbon formation and sintering during DRM, the effect of lithium as a promoter in catalysts Ni–Al derived from layered double hydroxides was investigated. The catalysts were prepared by co-precipitation and characterized by different techniques: BET surface area (SBET), X-ray diffraction (XRD), temperature-programmed reduction (TPR), CO2 and H2 temperature-programmed desorption (CO2-TPD and H2-TPD), Scanning Electron Microscopy (SEM-EDS), temperature-programmed oxidation (TPO). The catalytic tests were carried out in a fixed bed reactor using a synthetic biogas (60% CH4 and 40% CO2) in the temperature range of 500–750 °C. The incorporation of Li into the Ni–Al-LDH changed the reducibility and basicity of the catalysts. The Li2 sample containing an intermediary amount of Li (5 wt%) showed the highest reduction temperature and highest density of basic sites, which resulted in the smallest Ni crystallite size before and after the reactions. As a result, this catalyst presented the greater resistance to sintering and a lower rate of carbon produced. For the reaction carried out at 700 °C, only the Li2 catalyst remaining active during the test and reaching a maximum of 80% and a final CH4 conversion of 54% after 480 min of reaction, whereas CO2 conversion was higher than 90%. All other samples deactivated at different rates due to carbon deposition and sintering.

Three-dimensional graphene with the decoration of elemental sulfur-based sulfur-nitrogen dots for CO2 capture

Using a mild hydrothermal process, elemental sulfur was directly used to develop uniformly decorated sulfur-nitrogen (NS) dots on three-dimensional (3D) graphene. UV-Visible spectroscopy confirmed that hydrophobic elemental sulfur complexed with the primary amine in polyethylenimine (PEI) solution to form a hydrophilic sulfur-amine complex, and the resulting solution served as a nitrogen (N) and sulfur (S) source while improving dispersibility in GO solution. Hydrothermal treatment of aqueous GO and PEI-sulfur solution produces NS co-doped 3D graphene foam, while x-ray diffraction (XRD) and Raman spectroscopy results reveal GO reduction to graphene, and thermal properties are determined using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). X-ray photoelectron spectroscopy (XPS) confirms NS doping on graphene sheets in the foam structure, while scanning and transmission electron microscopy (SEM and TEM) revealed homogeneous dispersion of NS dots with an average size of 5 nm. The high dispersibility and compatibility of amine-sulfur in aqueous GO results in the formation of ultra-small, uniformly distributed NS dots on graphene layers, whereas the amount of S and N in PEI solution is easily controlled by adjusting the stoichiometric ratio. Furthermore, the textural properties of NSG-1 were determined, and the obtained BET surface area was 245 m2/g, while the pore volume and average pore size were 1.91 cm3/g and 31.1 nm, respectively. The developed NS-co-doped graphene exhibits a room-temperature adsorption capacity of 2.77 mmol/g at 1 bar, with faster kinetics and CO2/N2 capture selectivity of 16.45 and 9.19 at 0.1 and 1 bar, respectively.

Utilizing olive leaves biomass as an efficient adsorbent for ciprofloxacin removal: characterization, isotherm, kinetic, and thermodynamic analysis.

Olive leaves were utilized to produce activated biomass for the removal of ciprofloxacin (CIP) from water. The raw biomass (ROLB) was activated with sodium hydroxide, phosphoric acid, and Dead Sea water to create co-precipitated adsorbent (COLB) with improved adsorption performance. The characteristics of the ROLB and COLB were examined using SEM images, BET surface area analyzer, and ATR-FTIR spectroscopy. COLB has a BET surface area of 7.763 m2/g, markedly higher than ROLB's 2.8 m2/g, indicating a substantial increase in adsorption sites. Through investigations on operational parameters, the optimal adsorption efficiency was achieved by COLB is 77.9% within 60min, obtained at pH 6, and CIP concentration of 2mg/mL. Isotherm studies indicated that both Langmuir and Freundlich models fit the adsorption data well for CIP onto ROLB and COLB, with R2 values exceeding 0.95, suggesting effective monolayer and heterogeneous surface adsorption. The Langmuir model revealed maximum adsorption capacities of 636mg/g for ROLB and 1243mg/g for COLB, highlighting COLB's superior adsorption capability attributed to its enhanced surface characteristics post-modification. Kinetic data fitting the pseudo-second-order model with R2 of 0.99 for ROLB and 1 for COLB, along with a higher calculated qe for COLB, suggest its modified surface provides more effective binding sites for CIP, enhancing adsorption capacity. Thermodynamic analysis revealed that the adsorption process is spontaneous (∆Go < 0), and exothermic (∆Ho < 0), and exhibits a decrease in randomness (∆So < 0) as the process progresses. The ΔH° value of 10.6kJ/mol for ROLB signifies physisorption, whereas 35.97kJ/mol for COLB implies that CIP adsorption on COLB occurs through a mixed physicochemical process.

Zinc–cobalt bimetallic metal-organic framework (Zn/Co-MOF) nanoparticles as potent pH stimuli anti-corrosive agent for development of a self-healable epoxy composite coating

The impressive BET-surface area and the design versatility have made Z67(ZIF-67) MOF a potent nanomaterial for anti-corrosion applications. Despite excellent anti-corrosion features the Z67(ZIF-67) suffers poor stability in water media, making it improper for application in polymeric systems. One strategy to enhance the stability of Z67 is its structure modification via a mixed-metal organic framework approach. This study involved the synthesis of a series of Z67 nanoparticles through the incorporation of zinc cation (Zn) at different percentages. Specifically, three different compositions were synthesized: Zn10-Z67, Zn20-Z67, and Zn30-Z67 denoting the addition of 10 %, 20 %, and 30 % molar percent of Zn, respectively. FTIR, FE-SEM, XRD, TEM, ICP-OES, and XPS, as well as BET analyses, were conducted for the Zinc–Cobalt bimetallic MOF structure. Subsequently, the properties attributed to the particles' active and barrier anti-corrosion feature in solution (NaCl) as well as coating (epoxy) phases were investigated. The EIS test performed in the solution phase, after 72h of metal exposure to Zn30-Z67 containing saline media, revealed a 590 % and 30 % increase in total resistance, respectively, compared to the uninhibited sample. Due to the increased stability of Zn10-Z67 in a saline environment, the active corrosion inhibition of the scratched coating containing these particles was increased by approximately 140 % compared to the Z67-containing composite. The incorporation of zinc cations into the structure of Z67 has enhanced the stability and control release features in aqueous environments, thereby enhancing the barrier properties of the epoxy coating. The reduction rate of log|Z|0.01Hz of the Zn10-Z67/EPC was 9 % which was lower than that of the Neat EPC (epoxy coating) (24 %).

Effect of nanostructure and BET surface area on the oxygen reactivity of soot filter cakes

The oxygen reactivity of propane flame soot in a filter cake was systematically investigated, considering the morphological properties of the particles. A scanning mobility particle sizer (SMPS), high resolution transmission electron microscopy (HRTEM) and Raman spectroscopy were used to determine the initial aggregate size, the primary particle size, and the nanostructure of the soot particles. The samples were analyzed using an experimental setup, which enables oxidation and in-situ measurement of the BET surface, revealing its development as the reaction progresses. Particles with five different mobility diameters were generated using a combustion aerosol standard (CAST) soot generator. While the nanostructure of the particles was similar at four operating points, the particles with the smallest mobility diameter differed as they were more amorphous, which was consistently seen in HRTEM images and Raman spectra. The results showed that for the particles with similar nanostructure, the mobility diameter, the size of the primary particles and the initial surface area correlate. These particles have similar oxygen reactivity. The amorphous particles instead, showed a significantly higher reactivity, despite having the lowest specific surface area. The nanostructure appears to be decisive for the reactivity. Further the results clearly showed that surface area development affects the soot conversion profiles. Surface-normalized reaction kinetics for soot at each operation point were formulated.

Adsorption simulation of 2,4-D pesticide on novel zinc-based 2-amino-4-(1H-1,2,4-triazole-4-yl)benzoic acid coordination complexes using machine learning approach.

The capacity of zinc-based 2-amino-4-(1H-1,2,4-triazole-4-yl)benzoic acid coordination complex (Zn(NH2-TBA)2) and modified Zn(NH-TBA)2COMe complex for removal of 2,4-dichlorophenoxyacetic acid (2,4-D) from aqueous solutions was investigated through adsorption modeling and artificial intelligence tools. Analyzing the adsorption characteristics of pesticides helps in studying the groundwater pollution by pesticides in agriculture area.In this study, Zn(NH2-TBA)2 was synthesized using Schiff base and its surface was modified using acetic anhydride group and their physical characteristics were identified using proton NMR, FTIR, and XRD. NMR results showed maximum modification yield obtained was 65% after 5days. The porous structure and surface area monitored using nitrogen isotherm and BET surface area analysis presented relatively less surface area and porosity after modification. Adsorption modelling indicated that Toth model with a maximum adsorption capacity of 150.8mg/g and 100.7mg/g represents the homogenous adsorption systems which satisfy both low- and high-end boundary of adsorbate concentration in all settings according to the optimum point, while the kinetics and rate of 2,4-D adsorption follow the pseudo-first-order kinetic model in all situations. Artificial neural network (ANN), support vector regression, and particle swarm optimized least squares-support vector regression (PSO-LSSVR) were used for the optimization and modelling of adsorbent mass, adsorbate concentration, contact time, and temperature to develop predictive equations for the simulation of the adsorption efficiency of 2,4-D pesticide. The obtained results exhibited the better performance of ANN and PSO-LSSVR for prediction of adsorption results. The mean square error values of ANN (0.001, 0.012) and PSO-LSSVR (0.121, 0.105) were obtained for Zn(NH2-TBA)2 and Zn(NH-TBA)2COMe, respectively, while their respective coefficient of determination (R2) obtained were 0.999 and 0.988 for ANN and 0.980 and 0.825 for PSO-LSSVR. The study specified that machine learning predictive behavior performed better for Zn(NH2-TBA)2 compared to Zn(NH-TBA)2COMe that is also supported by theoretical kinetics and isotherm models. The research concludes that artificial intelligence models are the most efficient tools for studying the predictive behavior of adsorption data.

Rational Design of Enzymatic Electrodes: Impact of Carbon Nanomaterial Types on the Electrode Performance

This research focuses on the rational design of porous enzymatic electrodes, using horseradish peroxidase (HRP) as a model biocatalyst. Our goal was to identify the main obstacles to maximizing biocatalyst utilization within complex porous structures and to assess the impact of various carbon nanomaterials on electrode performance. We evaluated as-synthesized carbon nanomaterials, such as Carbon Aerogel, Coral Carbon, and Carbon Hollow Spheres, against the commercially available Vulcan XC72 carbon nanomaterial. The 3D electrodes were constructed using gelatin as a binder, which was cross-linked with glutaraldehyde. The bioelectrodes were characterized electrochemically in the absence and presence of 3 mM of hydrogen peroxide. The capacitive behavior observed was in accordance with the BET surface area of the materials under study. The catalytic activity towards hydrogen peroxide reduction was partially linked to the capacitive behavior trend in the absence of hydrogen peroxide. Notably, the Coral Carbon electrode demonstrated large capacitive currents but low catalytic currents, an exception to the observed trend. Microscopic analysis of the electrodes indicated suboptimal gelatin distribution in the Coral Carbon electrode. This study also highlighted the challenges in transferring the preparation procedure from one carbon nanomaterial to another, emphasizing the importance of binder quantity, which appears to depend on particle size and quantity and warrants further studies. Under conditions of the present study, Vulcan XC72 with a catalytic current of ca. 300 µA cm−2 in the presence of 3 mM of hydrogen peroxide was found to be the most optimal biocatalyst support.

Production of sludge biochar by steam pyrolysis and acid treatment: Study of the activation mechanism and its impact on physicochemical properties

This study addresses the preparation of sludge biochar through a procedure that combines steam pyrolysis in a wide range of temperature (500–900 ºC) and acid treatment with HCl (performed before or after the pyrolysis). The acid washing after the pyrolysis maximizes BET surface area due to pore unblocking, thus making visible the pore structure generated. The drawback of the acid washing is the lower yield obtained (compared to the acid pretreatment), as well as the loss of the magnetic properties of sludge biochar. The acid pretreatment requires temperatures above 700 ºC to have a beneficial effect, due to the occurrence of additional reactions of the incorporated HCl with sludge constituents. The pretreatment results in materials with a high degree of microporosity. Among the reactions favoured, of interest is the development of magnetite in the whole temperature range. The activation protocol used in this study (especially the procedure that includes the acid pretreatment) is effective to generate biochar with magnetic properties through the transformation of the Fe introduced during the water treatment process, without adding a source of Fe. The presence of magnetite is an advantage for the reuse of sludge biochars in wastewater treatment.

Enhanced stability of Cu/AC catalyst with modified hydrophobic layer for methanol oxidative carbonylation to dimethyl carbonate

The by-product water generated in the oxidative carbonylation of methanol to dimethyl carbonate (DMC) causes severe oxidation and deactivation of Cu catalysts, so how to minimize the effect of water on Cu catalysts is a great challenge. Here, we report a strategy to stabilize the Cu+ species in Cu/AC catalyst by hydrophobic modification with methyltriethoxysilane. Compared to Cu/AC catalyst, the modified Cu/ACCH3 catalyst shows that the crystalline structure and the average Cu particle size were not changed, the BET surface area was slightly decreased while the amount of adsorbed methanol was obviously increased. The catalytic stability of Cu/ACCH3 was significantly improved with a deactivation rate of only 11.9 % compared to Cu/AC catalyst (29.2 %). The spent Cu/ACCH3 shows that the water contact angle remained at 119° and Cu+ species were still present as the main component, which was attributed to the confinement effect of the hydrophobic layer that inhibited the aggregation of Cu particles and prevented the Cu+ species from oxidizing water, thus improving the catalyst stability even in the presence of water. This work provides a practical strategy for improving the stability of Cu-based catalysts in the reaction, which produces water as a by-product.

Optical behavior, TL defect center analysis and photocatalytic characterization of Ag2O doped ZnO nano crystals

The objective of the study is to prepare Ag+-dopedZnO nano crystals and to assess their structure, optical behavior, TL analysis, photocatalytic activity. Using sol–gel technique the Ag+-doped ZnO nano crystals prepared. Using the FT-IR, XRD, BET surface area, SEM, EDX characterization techniques, we have examined the structure of the developed samples. The TL analysis of samples was done under a dose of 25 kGy gamma irradiation. Trap depth parameters of the samples evaluated. Which suggested the ZnO nano crystals doped with Ag+ ions are purely TL active. The optical studies such optical absorption, photoluminescence of samples reveal their optical behavior. The optical band gap of the samples also evaluated. Which is increasing with increase in concentration of Ag+ ions in ZnO nano crystals. Using the MV (10 ppm) and CR (10 ppm) dyes, under visible light the photocatalytic activity of the samples reported. At a reaction period of 90 min, the nano powdercontaining 1.0 mol% Ag+-dopedZnO nano crystals and a band gap energy of 2.75 eV demonstrated the best photocatalyticefficiency (∼91 %) in both colors. The evaluationwas done on the impact of radical scavenger research and catalyst dosage on degrading efficiency. The rate of reaction in the presence of 1.0 mol% Ag+-dopedZnO nano crystals was four times higher than the ZnO catalyst's rate constants, and the degradation reaction follows pseudo-first-orderkinetics. The degrading process shows pseudo-first-order kinetics, and the reaction rate was four times higher than the ZnO catalyst in the presence of 1.0 mol% Ag+-dopedZnO nano crystals. It took three cycle runs for the degrading efficiency to drop by 1 %. Thus, 1.0 mol% Ag+-dopedZnO nano crystals was employed as a promising photocatalyst with strong reusability potential for the degradation of textile colors, which will be very beneficial.

Low cost MXene synthesis for regenerative adsorption of benzene, toluene, ethylbenzene and xylene (BTEX)

MXenes, a group of emerging 2D metal carbides with unique properties and expanding potential applications, have attracted researchers’ interests. However, high synthesis costs and safety concerns have imposed limitations on their research and development. Here, we report a low-cost and safer synthesis method for a titanium-MXene, which we then test for its efficacy as an adsorbent for organics contamination in water. For the synthesis, we examine how different carbon forms (graphite and activated charcoal (AC)) impact the MXene properties and application. Instead of expensive and high-risk pure titanium as a precursor, cheap and easy-to-handle titanium oxide was used, while achieving lower-temperature synthesis through the molten-salt shielded synthesis approach. The resulting 3D MAX phases were separately etched into 2D-MXenes and characterized extensively. The synthesised MXenes were tested as adsorbents in adsorption experiments under various conditions. The data obtained were fitted to isotherm and kinetic models to understand the adsorption mechanisms. Although the AC-based MXene exhibited a much larger BET surface area compared to the graphite-based MXene (24 m2/g vs 2 m2/g respectively), other characterization results indicated that both materials had remarkably similar morphological and functional properties. Additionally, both MXenes effectively removed at least 80 % of the initial contaminant concentration. However, AC-based MXene is cheaper to produce and demonstrated superior regenerative capabilities over three cycles of regeneration and reuse. Also, its reuse potential is less affected by oxidation during the regeneration process. This study concludes that MXenes can be synthesized at a lower cost and highlights the crucial role of the carbon form used in synthesis for the MXene subsequent application. Specifically, AC-based MXenes show great potential for clean water recovery applications and could be a good candidate for analytical chemistry purposes.

Hydrophobic UiO-66 composite: Surface energy modelling for oil-water interactions

Oil spill is considered as the serious threat to aquatic ecosystem and it is quite a challenge to clean such oil spills. In order to cure this problem, we introduced a novel hydrophobic composite material making use of metal organic framework (MOF) i.e., UiO-66 and polyurethane (PU) foam. PU foam was utilized for oil absorption by incorporation of Fe3O4 particles via in-situ approach and dip coating it with polydimethylsiloxane (PDMS) and hydrophobic UiO-66 (hUiO-66) resulting into the formation of hydrophobic composite foam. The decrease in hydrophilic character and increase in hydrophobic character of PU foam was deduced using FTIR and contact angle analysis. PDMS being a low surface energy polymer accounted for the hydrophobicity of the composite material, the coating of PDMS on the material gave contact angle of 122.1°. Furthermore, Fe3O4 provides surface roughness on the surface of PU foam which is clearly visible in FESEM analysis leading to decrease in surface energy of the composite thereby increasing the hydrophobicity and absorption capacity. In order to study the surface area, pore size and pore type of the material, BET surface area analyzer was used depicting surface area of 1049.90 m2g−1 for UiO-66 and 431 m2g−1 for hUiO-66@Fe3O4@PDMS. To gain insight into the surface energy of the composite, various models such as Zisman model, OWRK model and Neumann model were utilized to determine. Moreover, the composite resulted in excellent reusability maintaining the separation efficiency of about 78.4 g/g even after 36 cycles. This shows a substantial improvement in the area compared to previous research and opens the door for the production of hydrophobic foams for purposes like oil-spill cleanup in challenging circumstances. The proposed approach efficiently helpful in oil-spill cleanup, making it promising for oil leakages.

Optimisation and characterisation of KOH-activated carbon obtained from Baijiu spent grains for the mitigation of risk factors in alcoholic beverages

This study aims to repurpose waste grain from the Baijiu brewing process into activated carbon for mitigating risk factors in alcoholic beverages, enhancing quality and ensuring safety. For attaining the most effective activated carbon, tailored carbon synthesis conditions were identified for diverse alcoholic beverages, optimising strategies. For beverages with low flavour compound content, optimal conditions include 900 °C calcination, 16-hour activation and a 1:2 activation ratio. In contrast, for those with abundant flavour compounds, 800 °C calcination, 16-hour activation and a 1:1 activation ratio are recommended. Post-synthesis analyses, employing nitrogen physisorption–desorption isotherms, FT-IR and SEM, validated a significant BET surface area of 244.871 m2/g for the KOH-activated carbon. Critical to adsorption efficiency, calcination temperature showcased noteworthy micro-porosity (0.8–1 nm), selectively adsorbing higher alcohols (C3–C6) and acetaldehyde while minimising acid and ester adsorption. Sensory evaluations refined optimal parameters, ensuring efficient spent grain management and heightened beverage safety without compromising aroma.

Facile construction of Bi2WO6/TiO2 microspheres heterojunction for boosting photocatalytic degradation of organic dyes

Flower-like Bi2WO6 microspheres and TiO2 spherical particles were prepared by a facile hydrothermal method without any surfactant or template. A unique Z-Scheme Bi2WO6/TiO2 heterojunction was successfully synthesized via a simple physical mixing method. The effect of mass ratio on the structure, morphology, optical properties, BET surface area and photocatalytic performance evaluated by degradation of organic dyes including Rhodamine B (RhB), methylene blue (MB) and methyl orange (MO) under solar irradiation was systemically investigated. When the mass ratio of Bi2WO6 to TiO2 was 1:4, the Bi2WO6/TiO2 composites exhibited the highest photocatalytic degradation efficiency, the highest degradation efficiency of RhB and MB reached 95.2 % and 89.3 %, which could be attributed to the construction of heterojunction structure between TiO2 and Bi2WO6. The optical absorption capacity of Bi2WO6/TiO2 composites was stronger than pure TiO2. Furthermore, the radicalquenching experiments proved that ·O2– and h+ played crucial roles in the photocatalytic reaction. The suitable band structure of Bi2WO6 and TiO2 revealed the Z-Scheme pathway and possible photocatalytic mechanism of Bi2WO6/TiO2 composites for organic dyes degradation. Thus, the direct Z-scheme Bi2WO6/TiO2 heterojunction effectively promoted separation of photogenerated electron-hole pairs, resulting in higher photocatalytic activity.

Enhanced detection of heavy metal ions using Ag nanoparticles and single-walled carbon nanotubes within Cu-based metal-organic frameworks

Heavy metal ions (HMIs) are major water pollutants, and their toxicity for humans is a great concern for scientists and environmentalists. They are harmful to health even at trace levels; therefore, identifying and removing heavy metals from water is critical. Herein, we report highly selective and sensitive multi-analyte detection of HMIs in water using an electrochemical sensor probe based on Ag nanoparticles and single-walled carbon nanotubes incorporating copper benzene tri-carboxylate metal–organic frameworks (Ag/SWNTs@CuBTC-MOFs). The materials were characterized using FTIR, XPS, XRD, and FE-SEM with EDX mapping, TEM, TG-DTA, BET surface area, CV, and EIS. The Ag/SWNTs@CuBTC-MOF electrochemical sensor was tested by differential pulse voltammetry over a pH range of 3–10 for various HMIs. It shows high pH-dependent sensitivity towards Hg2+ (pH-5.0), Ni2+ (pH-7.0), and Fe3+ (pH-10.0) ions and a limit of detection of 1.39 nM, 2.6 nM, and 3.03 nM, respectively. The fabricated sensor probe exhibits high selectivity, good linearity, and a limit of detection below the maximum contamination limit, as the US Environmental Protection Agency suggested.