Brunauer Emmett Teller Technique Research Articles

Optimizing natural organic matter removal at the Koka water treatment plant, Ethiopia, using soil–alum composite materials

ABSTRACT Conventional water treatment methods often fail to remove natural organic matter (NOM), leading to the formation of harmful disinfection by-products in chlorinated water. This study aimed to develop a synergistic, local soil–aluminum sulfate (alum) composite material to enhance NOM removal from real water samples. Locally derived soil (chalaltu) samples were collected from selected locations and subjected to thermal treatment at elevated temperatures. The thermally treated soil was then combined with alum at varying mixing percentages to create the composite material. The synthesized composite materials were thoroughly characterized using X-ray diffraction, X-ray fluorescence, scanning electron microscopy, Fourier transform infrared, and Brunauer–Emmett–Teller techniques. The alum-treated soil, obtained through thermal treatment at 500 °C with a mixing ratio of 50%, a dosage of 25 mg/L, and a settling time of 25 min, exhibited impressive removal efficiencies. The composite material increased removal efficiency by 1.5 times for both UV254 absorbance (91.1%) and dissolved organic carbon (90%), while reducing the alum dose by 58% compared to the existing Koka water treatment plant process. Reducing alum usage could lead to cost savings and alleviate concerns about its association with Alzheimer's disease. Evaluating the thermal preprocessing is essential for the operational and economic viability of the composite material within the broader water treatment context.

Adsorption technique using new semi-IPN hydrogels for high removal of methylene blue dye from aqueous solutions

ABSTRACT Six new semi-IPN hydrogels using 2-acrylamido-methylpropane-1-sulfonic acid (AMPS) and Gelatin at different ratios through redox polymerization were prepared. Methylene-bisacrylamide and glutaraldehyde were used as the crosslinking agents for AMPS and Gelatin, respectively. The hydrogels’ swelling ratios and surface morphologies were analyzed using SEM for characterization. Porosity and specific surface area using the Brunauer–Emmett–Teller technique. DSC and Tg were also used for the thermal analysis of the prepared hydrogels, which show trans-glass temperature (Tg) higher than their raw materials AMPS and Gelatin. The prepared hydrogels were used to eliminate the cationic dye MB from the water-based solutions with an initial concentration of 600 ppm. The study discovered that the N9 and N10 hydrogels were extremely effective at removing a certain dye from aqueous solutions with an optimum pH level of 11 and an optimum temperature of 65°C. Both N9 and N10 achieved high removal efficiencies, reaching equilibrium at 90 min, whereas the other hydrogels required 120 min. N9 performed slightly better at 1078.919 mg/g and N10 at 1057.404 mg/g. The adsorption behavior of the two hydrogels followed the Langmuir model. The hydrogels exhibited pseudo-second-order kinetics. The thermodynamic study cleared that the adsorption of MB dye was endothermic and spontaneous. Results also showed that the adsorption of dyes with hydrogels N9 and N10 is chemisorption in nature. Desorption studies were conducted using 0.1 M HCl and NaOH. HCl was found to be the best eluent for dye recovery.

MXene (Ti3C2Tx)/Rh-doped SnO2 composites for improved acetone sensing properties

Rh-doped SnO2 nanofibers have demonstrated high selectivity and response in detecting acetone. However, these nanofibers operated at high temperature and exhibited a long recovery time. In this study, a two-dimensional material MXene was introduced into Rh-doped SnO2 nanofibers, and MXene (Ti3C2Tx)/Rh–SnO2 composites were synthesized via hydrothermal method. The morphology, structure and composition of MXene (Ti3C2Tx)/Rh–SnO2 were systematically characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller techniques (BET). The results indicated that MXene (Ti3C2Tx)/Rh–SnO2 composites formed compact heterostructures. The effects of adding different volumes (0.5, 1, 1.5, and 2 ml) of 5 mg/ml MXene on the sensing properties of the composites were investigated. The sensing results showed that the composite of (1 ml) MXene (Ti3C2Tx)/Rh–SnO2 achieved a response as high as 82.46 % to 100 ppm acetone gas at 100 °C and exhibited rapid response and recovery times of 3/8 s, compared to the optimal operating temperature (190 °C) and recovery time (43 s) observed with the pristine Rh-doped SnO2 nanofibers, there is a significant improvement. It also demonstrated outstanding humidity resistance and a minimum detection limit of 0.6 ppm. Moreover, the addition of MXene not only significantly affects the sensing performance of the pristine Rh-doped SnO2 nanofibers but also preserves its sensing advantages. The sensing mechanism of the MXene (Ti3C2Tx)/Rh–SnO2 composites is also discussed. Herein, MXene (Ti3C2Tx)/Rh–SnO2 composites presents a feasible strategy for enhancing the sensing properties of gas sensors.

Ornated hydrangea-like M-MO/graphitic porous carbon derived via direct carbonization of MOFs for electrooxidation of methanol in alkaline DMFC

Due to their low operating temperature, ease of storage, transportation, and low greenhouse gas emissions, direct methanol fuel cells (DMFC) are considered the best choice of fuel cells for energy conversion. Although its theoretical thermodynamic energy conversion efficiency is ~97 %, its achievable energy conversion efficiency is still in the range of 30–40 %. To improve the reaction kinetics, it is important to look for an electrocatalyst with low cost and high efficiency. In the present study, direct carbonization of [Ni, Cu, and (Ni/Cu)] metal-organic framework (MOF) was carried out under a nitrogen gas flow at 800 °C for 2.5 h, where the MOF precursor was completely converted into graphitic porous carbon well ornamented with Metal/Metal oxides (M/MO). The as-prepared nanomaterials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectric spectroscopy (XPS), Fourier transform infrared (FTIR), and the Brunauer–Emmett–Teller technique (BET). The prepared materials were used as electrocatalysts in a methanol oxidation reaction solution in an alkaline solution. The cyclic voltammetry (CV) measurements for Ni-MOF, Cu-MOF, (Ni/Cu) MOF, Ni-MOF800, Cu-MOF800, and (Ni/Cu)MOF800 showed excellent current densities of 17, 1.05, 44.25, 30, 11.56, and 53 mA∙cm−2, respectively at 0.6 V with a scan rate of 50 mV∙s−1. Whereas, the retention percent value is (96.2 %) for Ni-MOF, (93.1 %) for (Ni/Cu) MOF800, (96.7 %) for (Ni/Cu) MOF, (87.5 %) for Ni-MOF800, (97 %) for Cu-MOF, and (50.2 %) for Cu-MOF800 after an hour. Since M/MO/C800 demonstrated remarkable catalytic activity in relation to methanol oxidation and an abundance of cheap value, it is regarded as a promising candidate for future electrooxidation catalysis of MeOH in direct methanol fuel cells (DMFCs).

Facile and green synthesis of recyclable, environmentally friendly, chemically stable, and cost-effective magnetic nanohybrid adsorbent for tetracycline adsorption

Antibiotic contamination of water sources, particularly tetracycline (TC) contamination, has emerged as one of the global issues that needs action. In this research, ZnCoFe2O4@Chitosan (Ch) as a magnetic nanohybrid adsorbent was synthesized using the microwave-assisted co-precipitation method, and their efficiency for the TC adsorption process was investigated. FESEM (Field Emission Scanning Electron Microscope), EDX (Energy Dispersive X-ray), Mapping and line Scan, XRD (X-Ray Diffraction), FTIR (Fourier Transform Infrared Spectrometer), VSM (Vibrating Sample Magnetometer), Thermogravimetric analysis (TGA) and BET (Brunauer Emmett Teller) techniques were used to check and verify its physical and chemical properties. The removal of TC via the adsorption process from synthetic and real wastewater samples was investigated. The factors determining the TC adsorption process, comprising tetracycline concentration (5–30 mg/L), adsorbent dosage (0.7–2 g/L), contact time (2–45 min), and pH (3–11), were evaluated. The removal effectiveness for the synthetic sample and the real wastewater sample was 93 % and 80 %, respectively, under the ideal TC adsorption process parameters of pH 3, adsorbent dosage 1 g/L, TC initial concentration 5 mg/L, and contact time 30 min. According to kinetic and equilibrium studies, the adsorption of TC by ZnCoFe2O4@Ch follows pseudo-second-order kinetics and the Freundlich isotherm. Additionally, it was determined through the analysis of thermodynamic data that the process of exothermic adsorption is spontaneous and is followed by a decrease in disorder (ΔH = −15.16 kJ/mol, ΔS = −28.69 kJ/mol, and ΔG = −6.62 kJ/mol). After five cycles of recovery and regeneration, the ZnCoFe2O4@Ch magnetic nanocomposite was able to remove 65 % of the TC pollutant and had good chemical stability. The results showed that the magnetic nano-adsorbent ZnCoFe2O4@Ch is a novel magnetic nano-adsorbent with high adsorption capacity that can be utilized to eliminate pharmaceutical contaminants from aqueous solutions.

Application of electrochemical sensor modified by SBA-15 /Fe3O4/polyaniline nanocomposite for determination of tyrosine in milk samples

In this study, a selective SBA-15 /Fe3O4/Polyaniline /Chitosan nanocomposite was successfully electrodeposited on Screen- Printed Carbon Electrode (SPCE) and used for L-Tyrosine (Tyr) detection.Biological diagnostic probes such as artificial receptors are one of the important diagnostic layers for the identification of vital biomolecules, including essential amino acids like Tyr. A new electrochemical sensing platform based on differential pulse voltammetry was prepared for selective determination of Tyr in milk samples.SBA-15 nanoparticles were synthesized from corn leaves as a source of silica. These high-absorbance nanoparticles have been used for surface modification of SPCE. The morphology and electrochemical performance of the modified electrode were characterized by X-ray diffraction, scanning electron microscopy (SEM), transition electron microscopy (TEM), Furrier transform infrared spectroscopy (FTIR), Brunauer-Emmett–Teller techniques, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry(CV).As a novel modified electrode, the catalytic activity of the modified SPCE towards electro-oxidation of Tyr was measured by differential pulse voltammetry (DPV). The experimental conditions, including the adsorption time, scan rates, the ratio of SBA-15, pH value, and applied potential, are investigated in detail.Electrochemical sensor based on SBA-15 (SPCE/SBA-15/Fe3O4/Polyaniline /Chitosan) Compared with SPCE/Fe3O4/Polyaniline/Chitosan shows good sensitivity, repeatability, reproducibility, low detection limit and high selectivity.In addition, a linear correlation between oxidation peak current and concentration of Tyr in the ranges 0.1–250 μM with a detection limit of 0.05 μM (S/N = 3) was obtained. Eventually, the suggested sensor was used for quantification of Tyr in real samples, by adding standard solutions to the milk samples.

Solid‐phase extraction of losartan and chlordiazepoxide from biological samples using sponge‐activated carbon

AbstractIn this research, sponge‐activated carbon was applied as an effective adsorbent for simultaneous dispersive solid ultrasound‐assisted microextraction followed by high‐performance liquid chromatography for the preconcentration and determination of losartan (LOS) and chlordiazepoxide (CDP) drugs from urine and plasma samples. The synthesized adsorbent was characterized using scanning electron microscopy and Brunauer–Emmett–Teller techniques. To investigate the effects of different parameters, such as adsorbent dosage, pH, adsorption time, and volume of extraction solvent on the extraction process of LOS and CDP, a central composite design (CCD)‐based response surface methodology was applied. Using a CCD, the optimized factors achieved an adsorption time of 13 min, an adsorbent dosage of 14 mg, an extraction solvent (methanol) of 1.3 mL, and pH = 4.7 under the desirability function. Under the optimized conditions, the presented method showed a wide linear range of 0.005–10.0 μg/mL with a limit of detections of 0.0011 and 0.0018 μg/mL for LOS and CDP, respectively. Moreover, the applied method had relative standard deviations of 4.7% and 5.3% for LOS and CDP, respectively.

Preparation and sustained-release study of Litsea cubeba essential oil inclusion complex with γ-cyclodextrin-metal–organic frameworks

BackgroundLitsea cubeba essential oil (LCEO) is a food additive that requires encapsulation to delay its release due to its irritating nature. To identify an appropriate inclusion material, gamma (γ)-cyclodextrin (CD)-metal organic frameworks (MOF) were prepared, and the sustained release of the inclusion complex (IC) was studied.ResultsThe γ-CD-MOF was formed using γ-CD, potassium hydroxide (KOH), cetyltrimethylammonium bromide (CTAB), and silane coupling agents through the vapor diffusion method. The highest encapsulated rate achieved was 26.02%, with a temperature of 50 °C, a stirring time of 2.5 h, and an LCEO to γ-CD dosage ratio of 1:8. During the adsorption test, the amount of LCEO gradually increased within the first 180 min. However, after this time, there was no significant change in the adsorption amount of LCEO, indicating that the γ-CD-MOF had reached adsorption equilibrium. The average release rate of the IC reached 9.76% at 11 h. By comparison, the average release rate of the IC with γ-CD was 9.30% at 10 min, resulting in a diffusion index of 0.349. Under ultraviolet (UV) scanning, the sustained-release solution of the IC exhibited a strong characteristic citral absorption peak at 238 nm. Moreover, under infrared spectroscopy scanning, the absorption peak intensity of the IC was 1.19 times higher than that of blank γ-CD-MOF at 1676 cm−1. The IC, as observed through a scanning electron microscope, exhibited round pellets with a diameter of 40–60 μm. Energy dispersive spectroscopy images showed uniform distribution of potassium and sulfur elements. In X-Ray diffraction, the diffraction peaks of the IC were found at 5.27°, 7.45°, 10.54°, 12.08°, 14.20°, 14.92°, 15.84°, 16.68°, 19.24°, 21.80°, and 23.69°, with no significant change in the adsorption amount of LCEO. The Brunauer–Emmett–Teller (BET) testing revealed that the surface area of γ-CD-MOF was 5.089 m2/g, and the pore diameter was 3.409 nm by the Barrett–Joyner–Halenda (BJH) method.ConclusionThese data demonstrated that the sustained effect of the γ-CD-MOF was superior to that of γ-CD. The adsorption kinetics curve followed the Quasi-primary kinetics model, while the release curve adhered to the Ritger–Peppas model. Furthermore, the release behavior was primarily governed by the Fick diffusion mechanism, which was advantageous for achieving the sustained release of LCEO. The UV spectrum, infrared spectroscopy (IR), scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS), X-ray diffraction (XRD), and BET techniques confirmed the successful formation of the IC of LCEO with γ-CD-MOF. This study offers a promising technical solution for delaying the release and improving the sustained-release product of LCEO.Graphical

High-performance P2-Na0.67Mn0.85Cu0.15O2/Hard carbon full cell Na-ion battery: Pre-Sodiation of anode, p/n ratio optimizations, and Operando XAS studies

Na-ion batteries have gained significant attention as a cost-effective and efficient energy storage option for large scale applications, serving as an alternative to the Li-ion batteries. However, commercialization of these batteries is still many steps away since most cathode materials suffer from significant capacity loss and more full-cell studies are required. In this work, we report the electrochemical properties of half- and full-cells of P2-type Na0.67Mn0.85Cu0.15O2 synthesized by solid state technique. X-ray diffraction, FT-IR, and Raman spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy techniques are used to determine the structural properties. Surface properties are studied by X-ray photoelectron spectroscopy and Brunauer–Emmett–Teller techniques. Half cells and full cells were constructed with Na-metal and hard carbon, respectively. Na-ion diffusion kinetics at 10 °C, room temperature, and 50 °C were determined experimentally. Galvanostatic cycling tests on half-cells show capacity values of 165/124 mAh/g for the 1./100. cycles with 24.8 % capacity fade. Operando x-ray absorption spectroscopy measurements were utilized to study local structural modification around transition metal ions during charge/discharge. In the full-cell studies, electrode mass ratio (p/n) and parameters for presodiation of hard carbon were optimized. Using 30 mA/g current density, the unprocessed and the pre-sodiated full-cells reach capacity values of 48 mAh/g (p/n = 2.5) and 150 mAh/g (p/n = 0.75 and 1.15), respectively.

A simple and portable vacuum assisted headspace solid phase microextraction device coupled to gas chromatography based on covalent organic framework/metal organic framework hybrid for simultaneous analysis of volatile and semi-volatile compounds in soil

Various microextraction methods have demonstrated a positive effect when assisted by vacuum. However, working with such systems is often laborious, they often require expensive and non-portable vacuum pumps, and may even suck off some sample vapor or solid particles during the evacuation process. To address these issues, a simple, and affordable vacuum-assisted headspace solid-phase microextraction (HS-SPME) device was developed in this study. The device, named In Syringe Vacuum-assisted HS-SPME (ISV-HS-SPME), utilizes an adjustable 40 mL glass syringe as a vacuum provider and sampling vessel. A new fiber coating, made from a hybrid of covalent triazine-based frameworks and metal-organic frameworks (COF/MOF), was prepared and characterized by Fourier transform infrared spectrometry, field emission scanning electron microscopy, energy dispersive X-ray, X-ray diffraction, thermogravimetric analysis, and Brunauer–Emmett–Teller techniques for use in the ISV-HS-SPME. By optimizing parameters such as extraction temperature, extraction time, desorption temperature, desorption time, and, humidity using a simplex method, the ISV system was found to increase the extraction efficiency of polycyclic aromatic hydrocarbons (PAHs) and benzene, toluene, ethylbenzene, and xylenes (BTEX) in solid samples by up to 175%. The determinations were followed by GC-FID measurements. Compared to three commercially available fibers, the ISV-HS-SPME device with the COF/MOF (2DTP/MIL-101-Cr) fiber exhibited significantly higher peak areas for PAHs and BTEX. The linear dynamic ranges for BTEX and PAHs were 7.1–9000 ng g−1 and 0.23–9000 ng g−1, respectively, with limits of detection ranging from 2.1–5 ng g−1 for BTEX and 0.07–1.6 ng g−1 for PAHs. The relative standard deviation of the method was 2.6–7.8% for BTEX and 1.6–6.7% for PAHs. The ISV-HS-SPME was successfully used to simultaneously determine PAHs and BTEX in polluted soil samples with recoveries ranging from 80.4 to 108%.

SnO2-Based Porous Nanomaterials: Sol-Gel Formation and Gas-Sensing Application

Porous nanocomposites using two (tin dioxide-silica dioxide) and three (tin dioxide-indium oxide-silica dioxide)-component systems for gas sensors were created with the sol-gel method. To understand some of the physical-chemical processes that occurred during the adsorption of gas molecules on the surface of the produced nanostructures, two models-the Langmuir model and the Brunauer-Emmett-Teller theory-were used to carry out calculations. The results of the phase analysis concerning the interaction between the components during the formation of the nanostructures were obtained through the use of X-ray diffraction, thermogravimetric analysis, the Brunauer-Emmett-Teller technique (to determine the surface areas), the method of partial pressure diagrams in a wide range of temperatures and pressures and the results of the measurement of the nanocomposites' sensitivity. The analysis allowed us to find the optimal temperature for annealing nanocomposites. The introduction of a semiconductor additive into a two-component system based on tin and silica dioxides significantly increased the sensitivity of the nanostructured layers to reductional reagent gases.

Ar permeability through densified single-walled carbon nanotube-based membranes

Single-walled carbon nanotube (SWCNT)-based membranes (pellicles) and gas counterflows are used as a debris mitigation system in extreme ultraviolet (EUV) lithography. Densification with volatile liquids is a well-known approach to tune the performance of SWCNT membranes. However, densification can change the gas permeability through SWCNT membranes, violating the circulation of buffer gas counterflows. In the present work, we investigate the Ar permeability through SWCNT membranes before and after densification with isopropyl alcohol in the pressure drop test. The effective diffusivity of Ar through pristine and densified SWCNT membranes is, respectively, calculated to be Deffpristine = 330 × 109 m2 s−1 and Deffdensified = 4 × 109 m2 s−1. We developed a probabilistic model of gas penetration through SWCNT membranes. On the basis of the experimental data, the probabilities of Ar atoms penetrating through pristine and densified SWCNT membranes are estimated to be 8% and 0.1%, respectively. Structural changes in SWCNT membranes after densification with scanning electron microscopy and the Brunauer–Emmett–Teller technique are demonstrated. The bulk density of SWCNT membranes, measured using x-ray reflectometry, is found to be 0.38 and 0.89 g/cm3 before and after densification, respectively. The temporal dynamic of isopropyl alcohol evaporation from the volume of SWCNT membranes is analyzed using Fourier-transform infrared spectroscopy (FTIR). Results obtained using EUV and FTIR spectroscopy show that isopropyl alcohol is present in the volume of the SWCNT membrane even after the membrane has been left in vacuum (P < 0.01 Pa) for 22 h.

Preparation of straw-reinforced grafted starch composite adsorbent for the treatment of textile printing and dyeing wastewater

A straw-reinforced grafted starch composite resin (SSCR) was prepared via grafting and cross-linking co-polymerization with multi-monomers, using raw starch as a matrix and reed straw fine particles as a reinforcing material to the starch matrix. Its structures were characterized by carbon-13 nuclear magnetic resonance, scanning electron microscopy, X-ray diffraction, and the Brunauer–Emmett–Teller technique. The SSCR had enhanced physico-chemical stability due to the formation of a “sea–island” structure, including enhanced resistance to acid/alkali effects and flow abrasion. The introduction of positively charged graft chain segments on SSCR significantly improved its adsorption capacity to active and direct dyes. In the static adsorption experiment, the decolorization rate (DR) of SSCR for the simulated textile printing and dyeing wastewater was up to 85.42%, which had advantage over 201 × 7 ion exchange resin (DR = 38.53%) and activated carbon (DR = 60.19%). In the dynamic adsorption experiment, the SSCR was used as packing material for the column bed. The DR of the SSCR bed for the simulated textile printing and dyeing wastewater was up to 99.95%, and after six dynamic adsorption–regeneration circulations the DR was not lower than 95%.

Fabrication of mesoporous zirconia and titania nanomaterials for bone regeneration and drug delivery applications

Mesoporous materials have reached a significant milestone in the last twenty years in the field of drug delivery, and they continue to be an important part of development and innovation in pharmacodynamics and pharmacokinetics. In addition, their applications in the regeneration of hard tissues were greatly explored in recent decades due to their exponential biomineralization capabilities. They are the perfect candidates for active uptake and loading medicinal substances due to their unique chemical-physical properties. In this research, mesoporous zirconia (MZNs) and titania (MTNs) nanopowders were prepared by polymer sacrificial method as amoxicillin delivery systems. They were investigated using several characterization techniques including X-rays diffraction (XRD), Fourier transform infrared (FTIR), Transmittance electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) surface area measurements. These techniques assist in evaluating the appropriate pore size and diameter, with emphasis on the safety of the released drugs. Amoxicillin release form MZNs and MTNs was conducted in Phosphate buffer saline (PBS) up to 28 days. The possibility of using these antibacterial agents against different strains of gram-positive and gram-negative bacteria has been evaluated. Finally viabilities of the human bone osteosarcoma cell line (MG-63) were tested. MZNs and MTNs demonstrate particle diameters in range of (8–25 nm) and they were confirmed as mesoporous particles by TEM and BET techniques. Amoxicillin loaded nanopowders showed good antibacterial and antifungal activities alongside with proliferation behavior after 24 h (124 and 110%) for MZNs & MTNs, respectively, and (189 and 114%) for amoxicillin loaded MZNs & MTNs, respectively. Therefore, the developed nanomaterials are of high potentiality to be implemented as medication delivery systems for bone regeneration.

Development of Stable, Efficient, and Recyclable Amine-Containing Microspheres for Gold(I) Thiosulfate Complex Recovery

It is desirable to develop a highly stable, cost-effective, and recyclable adsorbent to adsorb Au(I) from thiosulfate solutions. In this study, reliable aminated microspheres (PS–TETA) were synthesized via a one-pot method that profited from active chloromethyl group-induced nucleophilic substitution between chloromethylated polystyrene (PS–Cl) and triethylenetetramine (TETA). These microspheres were used to recover a gold(I) thiosulfate complex. Scanning electron microscopy, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller technique, and X-ray photoelectron spectroscopy were adopted to analyze the surface elements and structure of PS–TETA. Additionally, influencing parameters, such as pH, thiosulfate concentration, and temperature, were investigated. The results indicated that the synthetic process and gold-adsorption behavior of PS–TETA was directly related to the surface chlorine and amine groups. The adsorption process was exothermic and consistent with the Freundlich isotherm model and pseudo-second-order kinetics. Complete adsorption of Au(I) was achieved with a maximum capacity of 23.79 kg t–1. Na2SO3 proved to be an effective desorbent and exhibited a satisfactory adsorption ability of the adsorbent even after five cycles. Anion exchange as a reasonable Au(S2O3)23– adsorption mechanism of PS–TETA is proposed. This study offers a practical method for synthesizing aminated microspheres with excellent properties to recover Au(I) from thiosulfate solutions.

Immobilization of EreB on Acid-Modified Palygorskite for Highly Efficient Degradation of Erythromycin.

Erythromycin is one of the most commonly used macrolide antibiotics. However, its pollution of the ecosystem is a significant risk to human health worldwide. Currently, there are no effective and environmentally friendly methods to resolve this issue. Although erythromycin esterase B (EreB) specifically degrades erythromycin, its non-recyclability and fragility limit the large-scale application of this enzyme. In this work, palygorskite was selected as a carrier for enzyme immobilization. The enzyme was attached to palygorskite via a crosslinking reaction to construct an effective erythromycin-degradation material (i.e., EreB@modified palygorskite), which was characterized using FT-IR, SEM, XRD, and Brunauer–Emmett–Teller techniques. The results suggested the successful modification of the material and the loading of the enzyme. The immobilized enzyme had a higher stability over varying temperatures (25–65 °C) and pH values (6.5–10.0) than the free enzyme, and the maximum rate of reaction (Vmax) and the turnover number (kcat) of the enzyme increased to 0.01 mM min−1 and 169 min−1, respectively, according to the enzyme-kinetics measurements. The EreB@modified palygorskite maintained about 45% of its activity after 10 cycles, and degraded erythromycin in polluted water to 20 mg L−1 within 300 min. These results indicate that EreB could serve as an effective immobilizing carrier for erythromycin degradation at the industrial scale.

Adsorption of tetracycline using CuCoFe2O4@Chitosan as a new and green magnetic nanohybrid adsorbent from aqueous solutions: Isotherm, kinetic and thermodynamic study

Utilizing a new microwave-assisted method, CuCoFe 2 O 4 @Chitosan (Ch) was synthesized as a very strong, magnetically separable nano-adsorbent. The magnetic nanohybrid adsorbent was characterized by FESEM (Field emission scanning electron microscopy ) , EDS (energy dispersive X-ray), Mapping & Linescan, BET (Brunauer-Emmett-Teller), FTIR (Fourier-transform infrared spectroscopy), XRD (X-ray diffraction analysis), TGA (Thermogravimetric analysis), and VSM (Vibrating Sample Magnetometer) techniques. Then, the adsorption process of Tetracycline (TC) was investigated. The highest percentage of pollutant adsorption on the synthetic and real samples was recorded at an initial concentration of 5 mg/L, pH 3.5, contact time of 20 min, the dose of 0.4 g/L, and temperature of 25 °C, 93.07 %, and 67%, respectively. The TC adsorption process via the synthesized magnetic nanocomposite was consistent with the Freundlich isotherm model (R 2 = 0.992) and pseudo -second-order kinetic (K 2 = 0.267). The outcomes of thermodynamic analyses, which included entropy changes (ΔS = 10.122 J/mol.k), enthalpy changes (ΔH = −1.975 kJ/mol), and the Gibbs negative free energy (ΔG = −4.992 kJ/mol), revealed that the adsorption process was spontaneous, favorable, and exothermic. The good magnetic properties allow easy separation after the adsorption operation. Finally, the efficiency of the nano-adsorbent in the removal process was 82.16% after four adsorption–desorption cycles. Some advantages of this research are a fast and green method for synthesis of adsorbent, fast kinetic, and magnetic properties to easy separation.

Beneficial effect of Sn doping on bismuth ferrite nanoparticle-based sensor for enhanced and highly selective detection of trace formaldehyde

Pure and sn-doped bismuth ferrite (BFO) nanoparticles were synthesized via facile sol–gel technique. Structural and morphological analysis of the nanoparticles were systematically carried out by using X-ray powder diffraction, field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, photoluminescence spectroscopy and Brunauer–Emmett–Teller techniques. The gas sensing properties of the sensors based on prepared nanoparticles towards formaldehyde in the temperature range from 200 °C to 400 °C revealed that the doping of Sn enhances the formaldehyde sensing performance of BFO nanoparticle by few folds. Prepared sensors demonstrate p-type behaviour and high selectivity towards formaldehyde. It was observed that the sensor based on 1.5 % Sn doped BFO nanoparticles exhibited maximum sensing response of 3.05 (Rg/Ra) to 1 ppm formaldehyde. Prepared sensors were ultra-fast (response/recovery time of 2.71 s/25.22 s) and very stable having low detection limit of 100 ppb. The enhancement of formaldehyde sensing property due to sn-doping is a combined effect of variation of charge carriers due to valency mismatch and enhanced oxygen defects as confirmed from X-ray photoelectron spectroscopy study. sn-doped BFO nanoparticles could be a potential candidate for the detection of trace formaldehyde gas towards the monitoring of both indoor and outdoor environmental air quality.

Cu2O-Decorated Marigold Hollow Alumina Microsphere Nanoparticles as a Robust and Efficient Catalyst for the Synthesis of Isoquinolones

The design of a heterogeneous catalyst involving plentifully accessible transition metal-based nanoparticles for the sustainable synthesis of valuable N-heterocycles has attracted much attention in recent years. The isoquinolone moiety is one of the privileged pharmacophores found in various natural products and drug molecules, so development of its synthetic methodology has always been in demand. Herein, we report a novel Cu2O-decorated marigold hollow alumina microsphere nanocatalytic system for the synthesis of isoquinolones using 2-bromobenzonitriles and ketones under neat condition. The prepared nanocatalyst was well characterized by scanning electron microscopy, high-resolution transmission electron microscopy, powder X-ray diffraction, energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller techniques. The present method is facile and showed better green chemistry metrics such as low E-factor, high reaction mass efficiency, and high turnover number and can be reused for five cycles without any loss in its catalytic activity.

Functionalized copper metal-organic framework with peroxidase-mimetic activity as an adsorbent for efficient removal of noxious organic dye from aqueous solution

We show that Cu-BDC-NH 2 could be employed as a peroxidase-mimetic catalyst for Fenton-like degradation of methylene blue (MB) in water. The three-dimensional copper-based MOF was constructed solvothermally by dissolving CuCl 2 .2H 2 O and 2-amine-1, 4-benzenedicarboxylic acid (1, 4-BDC-NH 2 ) in DMF. Transmission electron microscopy, Fourier transform infrared spectroscopy, Powder X-ray diffraction, the Brunauer–Emmett–Teller technique, Thermal Gravimetric Analysis, X-ray Photoelectron Spectroscopy, UV–Vis, and fluorescence spectroscopy were used to characterize the material. The influence of pH, temperature and concentration dose of Cu-BDC-NH 2 on MB degradation was examined. According to the results, not only does Cu-BDC-NH 2 sustain a reasonably high level of activity at pH 3, but it also work efficiently in a neutral to basic pH range, showing good stability and endurance. Under ideal conditions, full removal of MB was accomplished in 60 min. The peroxidase activity provided an advantage in removing the dye in a short period of time. Selective adsorption of dyes over Cu-BDC-NH 2 were also conducted by combining two cationic dyes. The elimination of MB was above 80% after four cycles, demonstrating the high recyclability. The results show that Cu-BDC-NH 2 not only significantly adsorbs the dye but also exhibits photocatalytic activity. Because of their good activity in broader pH range, higher temperature endurance and greater recyclability for MB removal, the treatment technique may be simplified for practical use and thereby lowering treatment costs. • Cu-MOF with peroxidase-like activity is used for removal of MB dye in water. • Complete removal of MB could be achieved in 60 min. • High selectivity towards MB was achieved in 10 min even under mixed dye conditions. • Cu-MOF showed good activity in different pH, higher temperature and are recyclable.