Nitrogen Adsorption-desorption Analysis Research Articles

Magnetic dispersive solid-phase extraction of clarithromycin and azithromycin by Fe3O4@ionic salt g-C3N4 adsorbent and HPLC-UV

In this study, Fe3O4@ionic salt g-C3N4 was synthesized as a new adsorbent for magnetic dispersive solid phase extraction (MDSPE) of two antibiotics (clarithromycin and azithromycin) in biological samples followed by HPLC-UV. The new nanocomposite was characterized by Fourier-transform infrared (FT-IR), field emission-scanning electronic microscope (FE-SEM), transmission electron microscope (TEM), nitrogen adsorption–desorption analysis, X-ray powder diffraction (XRD), and vibrating sample magnetometer (VSM). Box-Behnken design (BBD) and response surface methodology (RSM) were used for the optimization and design of experiments. The method had a suitable linear range (1–300 µg/L), a high coefficient of determination (R2; 0.9988 and 0.9993), and a low detection limit (0.33 and 0.42 µg/L) for clarithromycin and azithromycin, respectively. The applicability of the method was evaluated by estimating the recovery of analytes from urine and blood serum samples. Recovery of more than 90.0 % and RSDs of less than 5.2 % show the acceptable accuracy and precision of the proposed method.

Sustainable synthesis of spongy-like porous carbon for supercapacitive energy storage systems towards pollution control.

In this study, the fruit of Terminalia chebula, commonly known as chebulic myrobalan, is used as the precursor for carbon for its application in supercapacitors. The Terminalia chebula biomass-derived sponge-like porous carbon (TC-SPC) is synthesized using a facile and economical method of pyrolysis. TC-SPC thus obtained is subjected to XRD, FESEM, TEM, HRTEM, XPS, Raman spectroscopy, ATR-FTIR, and nitrogen adsorption-desorption analyses for their structural and chemical composition. The examination revealed that TC-SPC has a crystalline nature and a mesoporous and microporous structure accompanied by a disordered carbon framework that is doped with heteroatoms such as nitrogen and sulfur. Electrochemical studies are performed on TC-SPC using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. TC-SPC contributed a maximum specific capacitance of 145 F g-1 obtained at 1 A g-1. The cyclic stability of TC-SPC is significant with 10,000 cycles, maintaining the capacitance retention value of 96%. The results demonstrated that by turning the fruit of Terminalia chebula into an opulent product, a supercapacitor, TC-SPC generated from biomass has proven to be a potential candidate for energy storage application.

Facile encapsulation of a cobalt complex inside the micropores of ZIF-8 through the bottle around the ship method: A novel heterogeneous catalyst for epoxidation of alkenes

A novel and stable heterogeneous catalyst for alkene epoxidation reaction, named as CoDMG@ZIF-8, has been synthesized by facile encapsulation of Co(III) complex i.e. [Co(DMGH)(DMGH2)Cl2] (abbreviated as CoDMG, DMGH2 denotes for dimethylglyoxime and DMGH denotes for dimethylglyoxime mono anion) inside the ZIF-8 micropores via a solvothermal process. Based on the results of fourier transform-infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) technique and field emission scanning electron microscopy (FE-SEM), it was observed that the catalyst has maintained the structure, crystallinity and morphology of the parent ZIF-8 as well. Furthermore, CHN, DRS (diffuse reflectance spectra), energy dispersive X-ray (EDX), induced coupled plasma (ICP-OES), thermal gravimetric (TGA) and nitrogen adsorption-desorption (BET method) analyses have confirmed the encapsulation of the CoDMG complex. The epoxidation reaction was performed using tert‑butyl hydroperoxide (TBHP) in CH3CN solvent in the presence of catalyst. By optimizing the reaction parameters, a total conversion of 96 % with 82 % selectivity towards the epoxide product, was achieved. It was found that both CoDMG complex and ZIF-8 exhibited lower efficiency individually, while the encapsulation of this complex inside the ZIF-8 micropores has resulted to superior activity. Finally, the epoxidation of various alkenes such as cyclohexene, 2-norbornene, α-pinene, styrene and 1-hexene under the optimized reaction condition, have been studied and the catalytic mechanism was also proposed.

Engineering acidic and Pt sites on WO3- doped H-mordenite supported Pt catalyst for hydrogenation of γ -valerolactone to methyl tetra hydrofuran

The selective hydrogenation of gamma valerolactone (herein after GVL) into 2-methyl tetra hydrofuran (herein after MTHF) was studied over the different tungsten oxide-loaded Pt-doped H-Mordenite catalysts in a vapour phase continuous flow reactor. These catalysts were characterized by XRD, N2 adsorption-desorption analysis, SEM, TEM, FT-IR, Raman, XPS, TPR, NH3-TPD and pyridine adsorbed FT-IR analysis. XRD analysis result suggests that the tungsten oxide was well dispersed at low tungsten oxide loadings and, the tungsten oxide crystallites were formed at higher tungsten oxide loadings and the crystalline structure related to H-mordenite was retained for all the synthesised samples. The nitrogen adsorption-desorption analysis supported this result well. The TEM analysis confirms nano-sized platinum and tungsten oxide formation at 2Pt/10W-HM samples. The ammonia TPD analysis results suggested that all the samples possess weak and strong acidic sites and the amount and strength of acidic sites varies among the samples. The Pyridine adsorbed FT-IR results suggested that all the sample possesses mainly lewis acidic sites. These catalysts were evaluated for synthesising MTHF from GVL under different reaction conditions. Among the various synthesised catalysts studied, the 2 wt% Pt/10W-HM catalyst was identified as an effective catalyst with the 97 % conversion of GVL and the 98 % selectivity of MTHF. The higher catalytic performance depended on the distribution of surface tungsten oxide species along with the suitable acidic properties of the supported system.

A Magnetic Reduced Graphene Oxide Nanocomposite: Synthesis, Characterization, and Application for High-Efficiency Detoxification of Aflatoxin B1.

(1) Background: Safety problems associated with aflatoxin B1 (AFB1) contamination have always been a major threat to human health. Removing AFB1 through adsorption is considered an attractive remediation technique. (2) Methods: To produce an adsorbent with a high AFB1 adsorption efficiency, a magnetic reduced graphene oxide composite (Fe3O4@rGO) was synthesized using one-step hydrothermal fabrication. Then, the adsorbent was characterized using a series of techniques, such as SEM, TEM, XRD, FT-IR, VSM, and nitrogen adsorption-desorption analysis. Finally, the effects of this nanocomposite on the nutritional components of treated foods, such as vegetable oil and peanut milk, were also examined. (3) Results: The optimal synthesis conditions for Fe3O4@rGO were determined to be 200 °C for 6 h. The synthesis temperature significantly affected the adsorption properties of the prepared material due to its effect on the layered structure of graphene and the loading of Fe3O4 nanoparticles. The results of various characterizations illustrated that the surface of Fe3O4@rGO had a two-dimensional layered nanostructure with many folds and that Fe3O4 nanoparticles were distributed uniformly on the surface of the composite material. Moreover, the results of isotherm, kinetic, and thermodynamic analyses indicated that the adsorption of AFB1 by Fe3O4@rGO conformed to the Langmuir model, with a maximum adsorption capacity of 82.64 mg·g-1; the rapid and efficient adsorption of AFB1 occurred mainly through chemical adsorption via a spontaneous endothermic process. When applied to treat vegetable oil and peanut milk, the prepared material minimized the loss of nutrients and thus preserved food quality. (4) Conclusions: The above findings reveal a promising adsorbent, Fe3O4@rGO, with favorable properties for AFB1 adsorption and potential for food safety applications.

Effect of calcination temperature of titanium dioxide (TiO2) on adsorption performance of doxycycline hydrochloride

In this work, titanium dioxide (TiO2) was synthesized at different calcination temperatures by sol-gel method using butyl titanate as raw material. The effect of calcination temperature on the crystallinity and adsorption properties of TiO2 were investigated at 300 °C, 450 °C and 600 °C, respectively. The characteristics of TiO2 were analysed by X-ray diffraction, field emission scanning electron microscopy, nitrogen adsorption-desorption analyzer and zeta potential tester. The results showed that the crystal type, specific surface area and zeta potential of TiO2 nanoparticles changed with the increase of calcination temperature and the best performance of anatase crystals happened at the calcination temperature of 300 °C (TiO2@300) for doxycycline hydrochloride (DCH) adsorption. The equilibrium adsorption capacities of DCH was 28.97 mg/g with DCH removal rate of 86.92% at 0.03 g TiO2@300 addition in 100 ml 10 mg/L DCH solution. TiO2@300 could be a promising adsorbent.

Dual-functional porphyrinic zirconium-based metal-organic framework for the fluorescent sensing of histidine enantiomers and Hg2.

A novel fluorescence sensor based on a porphyrinic zirconium-based metal-organic framework, L-cysteine-modified PCN-222 (L-Cys/PCN-222), was developed to selectively recognize histidine enantiomers and sensitively detect Hg2+. The dual-functional sensor was successfully prepared via the solvent-assisted ligand incorporation method and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), 1H nuclear magnetic resonance (1H NMR) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, circular dichroism (CD), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption-desorption analyses. L-Cys/PCN-222 not only showed a higher quenching response for L-histidine than that for D-histidine with a fast fluorescent response rate of <40 s but also exhibited low detection limits for L- and D-histidine (2.48 μmol L-1 and 3.85 μmol L-1, respectively). Moreover, L-Cys/PCN-222 was employed as a fluorescent and visual sensor for the highly sensitive detection of Hg2+ in the linear range of 10-500 μmol L-1, and the detection limit was calculated to be 2.79 μmol L-1 in surface water. The specific and selective recognition of chiral compounds and metal ions by our probe make it suitable for real field applications.

Accelerated synthesis of 1,8-dioxo-octahydroxanthene and 1,8-dioxo-decahydroacridine derivatives using dendritic mesoporous nanosilica functionalized by hexamethylenetetramine: a novel nanocatalyst.

Xanthene and acridine derivatives are interesting organic compounds that are used in different research fields like biomedicine and pharmaceutical science. However, applied catalysts for their synthesis have some limitations such as long reaction times, the need for harsh conditions and low yield. So, discovery of novel catalysts for the synthesis of xanthene and acridine derivatives is highly demanded. To overcome the limitation of previous methods on the efficient synthesis of 1,8-dioxo-octahydroxanthene and 1,8-dioxo-decahydroacridine derivatives, a green heterogeneous organic nano-catalyst (Cu@KCC-1-nPr-HMTA) was synthesized by covalent attachment of hexamethylenetetramine to the cavities and channels of dendritic mesoporous nanosilica (KCC-1). The prepared nano-catalyst was identified using various spectroscopic and microscopic methods including scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), X-ray energy diffraction (EDX), EDX mapping and nitrogen adsorption-desorption analysis (BET-BJH). The prepared green nano-catalyst showed a spherical and dendritic structure with a surface area of 65.699 m2 g-1, average pore size of 40.78 nm and pore volume of 0.66 cm3 g-1. Also, Cu@KCC-1-nPr-HMTA has many chemo-active sites for the condensation reaction and was used as an efficient nano-catalyst towards one-step synthesis of 1,8-dioxo-decahydroacridine and 1,8-dioxo-octahydroxanthene derivatives from the reaction of aromatic aldehydes, dimedone, and ammonium acetate under solvent-free conditions. Short reaction times of 1 to 5 minutes for 1,8-dioxo-decahydroacridine and 30 to 55 minutes for 1,8-dioxo-octahydroxanthene derivatives, high yields and mild reaction conditions are advantages of the proposed synthetic method. It is hoped that the engineered nano-catalyst will be used for the synthesis of other organic compounds in the future.

Mangosteen pericarp extract mediated synthesis of Ag/TiO2 nanocomposite and its application on organic pollutant degradation by adsorption-photocatalytic activity

Herein, Ag/TiO2 nanocomposite was synthesized via a green chemistry approach, which is an eco-friendly, simple, and cost-effective method involving mangosteen pericarp extract as a reducing agent. The as-prepared nanocomposites were characterized using X-ray powder diffraction (XRD), Fourier transformation infrared spectroscopy (FT-IR), UV-Vis spectrophotometer, Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), Transmission electron microscopy (TEM), Zeta potential measurement, and nitrogen (N2) adsorption-desorption analysis. The performance of Ag/TiO2 nanocomposite was examined by degradation of methylene blue (MB) dye as a model of organic pollutant. The dye degradation using the Ag/TiO2 nanocomposite containing 45 mM of Ag revealed the high MB degradation, which is 85.77 % after 30 minutes under dark condition. Furthermore, complete degradation of 96.76 % was achieved after 2 hours under visible light irradiation. In contrast, bare TiO2 only achieved 41.45 % after 30 minutes dark and 2 hours visible light irradiation. This increase in degradation efficiency can be attributed to the adsorption process and the enhanced light absorption resulting from the localized surface plasmon resonance (LSPR) effect of Ag. Therefore, the green-synthesized Ag/TiO2 nanocomposite has great potential as an integrated adsorbent photocatalyst materials for remediating organic pollutants in dye effluents.

Synthesis of graphene nanocomposites integrated with 3D bimetallic magnesium/cobalt metal-organic framework as anodic material for solid-state asymmetric supercapacitors

In this study, we have grown 3D porous bimetallic Mg/Co MOF in the presence of exfoliated graphene nanoplates (EGNPs) via a one-step in-situ hydrothermal process, where 1,3,5-benzenetricarboxylic acid (BTC) was used as an effective organic linker since it is cost-effective and EGNPs served as a conductive component. Morphological characterization of Mg/Co-BTC MOF@EGNP nanohybrid confirmed the homogeneous growth of ball-shaped Mg/Co-BTC MOF around the graphene nanoplates, while nitrogen adsorption-desorption analysis revealed large surface area with a high volume fraction of mesopores. This surface features is highly favorable for rapid ion/electron transportation that ensures high specific gravimetric capacitance (838 F/g) and noticeable rate capability (81 % capacitance retention). As-synthesized nanohybrid was used as anode material to construct a prototype all-solid-state asymmetric supercapacitors (ASC) device with a significantly high energy density of 73.82 Wh kg−1, a wide potential window of 0–1.7 V, admirable capacitance retention of 95.1 % after 8000 cycles, and long self-discharge time. Moreover, these capacitance performances also demonstrates the reliability of the as-synthesized poly vinyl alcohol (PVA)-Li2SO4 membrane as a separator-cum-electrolyte for fabrication of future leakage-proof ASCs for wearable electronics. This work can lead to manufacting innovation in the future.

Optimization Conditions of Malachite Green Adsorption onto Almond Shell Carbon Waste Using Process Design.

Almond shell-based biocarbon is a cheap adsorbent for the removal of malachite green, which has been investigated in this work. FT-IR, DRX, and BET were used to characterize almond shell-based biocarbon. The nitrogen adsorption-desorption isotherms analysis results showed a surface area of 120.21 m2/g and a type H4 adsorption isotherm. The parameters of initial dye concentration (5-600 mg.L-1), adsorbent mass (0.1-0.6 mg), and temperature (298-373 K) of adsorption were investigated. The experiments showed that the almond shell could be used in a wide concentration and temperature range. The adsorption study was fitted to the Langmuir isotherm and the pseudo-second-order kinetic model. The results of the FT-IR analysis demonstrated strong agreement with the pseudo-second-order chemisorption process description. The maximum adsorption capacity was calculated from the Langmuir isotherm and evaluated to be 166.66 mg.g-1. The positive ∆H (12.19 J.mol-1) indicates that the adsorption process is endothermic. Almond shell was found to be a stable adsorbent. Three different statistical design sets of experiments were taken out to determine the best conditions for the batch adsorption process. The optimal conditions for MG uptake were found to be adsorbent mass (m = 0.1 g), initial dye concentration (C0 = 600 mg.L-1), and temperature (T = 25 °C). The analysis using the D-optimal design showed that the model obtained was important and significant, with an R2 of 0.998.

Cellulose-in-cellulose 3D-printed bioaerogels for bone tissue engineering

Nanostructured scaffolds based on cellulose with advanced performances and personalized morphologies for bone tissue engineering are under technological development. 3D-printing and supercritical carbon dioxide (scCO2) technologies are innovative processing strategies that, when combined, allow the precise fabrication of highly porous aerogel scaffolds. Novel sterile cellulose-in-cellulose aerogels decorated with superparamagnetic iron oxide nanoparticles (SPIONs) are synthesized in this work by an integrated technological platform based on 3D-printing and scCO2. Methylcellulose (MC) and bacterial nanocellulose (BC) are two versatile cellulosic polysaccharides with remarkable physicochemical and biological performances, whereas SPIONs are commonly used to functionalize biomaterials aimed at tissue engineering. Aerogels with hierarchical porosity and high structural resolution were obtained according to nitrogen adsorption–desorption analysis, confocal, scanning and transmission microscopies (SEM and TEM). The magnetic properties of SPIONs-doped aerogels confirmed the correct functionalization of the nanostructures. Finally, NIH/3T3 fibroblast cell viability, hemocompatibility with human blood and safety tests (in ovo with HET-CAM and in vivo with Artemia salina) indicate the biocompatibility of the cellulose-in-cellulose aerogels.Graphical abstract

Photocatalytic oxidative desulfurization of model fuel using iron-molybdenum nanocatalyst based on cerium oxide (FeyMox/CeO2) under visible light

Iron and molybdenum-activated CeO2 nanoparticles were utilized in a photocatalytic oxidation reaction in order to eliminate sulfur compounds from a model fuel. The catalyst was synthesized through a two-step process and then calcined for 3 h at 600 °C. The physicochemical properties of the synthesized nanophotocatalyst were characterized using a range of techniques, including X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS), photoluminescence spectroscopy (PL), nitrogen adsorption–desorption, and thermogravimetric analysis (TGA). The sample of Fe1Mo2/CeO2 exhibited superior performance in the photocatalytic oxidative desulfurization (PODS) reaction. The PODS reaction parameters, such as the initial sulfur concentration, photocatalyst dosage, temperature, solvent-to-fuel volume ratio (S/F), and oxidant-to-sulfur molar ratio (O/S), underwent optimization. Under ideal circumstances (T = 50 ℃, photocatalyst dosage = 2 g/L, O/S = 6, and S/F = 1), a 100% conversion rate of DBT was achieved. The kinetic studies showed that the PODS reaction follows the pseudo-first order kinetic model, and the activation energy measured was 39.44 kJ/mol−1.

Eggshell-Derived Copper Calcium Hydroxy Double Salts and Their Activity for Treatment of Highly Polluted Wastewater.

By using methyl orange (MO) removal as a model reaction, the best temperatures for processing eggshells are 750 °C and above to obtain biobased CaO materials, a raw material for producing CuCa hydroxy double salt (HDS) materials with high efficiency in treatments of highly polluted wastewater (the initial concentration of MO is 500 ppm). Characterization techniques employed in this study include power X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, nitrogen adsorption-desorption analysis, and the colorimetric method, as well as energy-dispersive X-ray, infrared-, and electron spin resonance spectroscopies. Complete MO removal and high chemical oxygen demand (COD) efficiencies (>90%) can be achieved after 3 min treatments of the aqueous MO with the calcined eggshell-derived CuCa HDS materials. The spent, deactivated HDS materials can be regenerated by an acid wash method. The activity of CuCa HDS materials in MO removal is unaffected by eggshell sources, implying that sorting steps may be unnecessary when eggshell food waste (duck, quail, and hen eggshells) is collected to produce biobased CaO. The findings of this study demonstrated that eggshells can be used in place of limestone and could be a more sustainable, renewable, and cost-effective source for material development and other applications.

Expanding the Potential of Self-Assembled Silk Fibroin as Aerogel Particles for Tissue Regeneration.

A newly produced silk fibroin (SF) aerogel particulate system using a supercritical carbon dioxide (scCO2)-assisted drying technology is herein proposed for biomedical applications. Different concentrations of silk fibroin (3%, 5%, and 7% (w/v)) were explored to investigate the potential of this technology to produce size- and porosity-controlled particles. Laser diffraction, helium pycnometry, nitrogen adsorption-desorption analysis and Fourier Transform Infrared with Attenuated Total Reflectance (FTIR-ATR) spectroscopy were performed to characterize the physicochemical properties of the material. The enzymatic degradation profile of the SF aerogel particles was evaluated by immersion in protease XIV solution, and the biological properties by cell viability and cell proliferation assays. The obtained aerogel particles were mesoporous with high and concentration dependent specific surface area (203-326 m2/g). They displayed significant antioxidant activity and sustained degradation in the presence of protease XIV enzyme. The in vitro assessment using human dermal fibroblasts (HDF) confirm the particles' biocompatibility, as well as the enhancement in cell viability and proliferation.

Effects of Biosorption Technique Using Various Fruit Waste Activated Carbon in Improving Chenderiang River Water Quality

The release of heavy metals from industries and other human-made activities into waterways is the primary cause of environmental pollution. Heavy metals are very toxic and once ingested through the mouth and nose; they can accumulate in the organs inside the human body and poison the internal organs with serious illnesses and even can cause death. Hence, in order to determine the water quality, biosorption technique using low-cost, eco-friendly fruit or agricultural wastes i.e., banana and orange peel activated carbon were prepared and characterized using FT-IR spectroscopy and nitrogen adsorption-desorption analysis. The adsorbents were then used to treat and identify the physicochemical parameters of Chenderiang River water, Tapah, Perak, Malaysia. Physicochemical analysis of river water sample such as DO, BOD5, pH, Temperature, EC, Turbidity, Hardness, Alkalinity, TSS, (PO4)3−, AN, Cu, Cr, Fe, and Zn before and after treatment were measured using Multiprobe system, EC meter, Lamotte Smart3® Colorimeter, and AAS. The results showed that orange peel (OP) activated carbon is more effective than banana peel (BP) activated carbon in reducing most of the pollutants including heavy metals in Chenderiang river water. The findings of this study showed that the biosorption technique using fruit waste is a low-cost, biodegradable and eco-friendly alternative method to remove pollutants including heavy metals in water and indirectly can reduce municipal solid waste. Therefore, can reduce water pollution and ensure good water quality.

Preparation of chemically and thermally modified water caltrop epicarp (Trapa natans L.) adsorbent for enhanced adsorption of Ni(II) from aqueous solution

The present study aims to prepare waste water caltrop (Trapanatans L.) epicarp (WCS)-based adsorbents such as raw WCS (WCS-Raw), citric acid-grafted WCS (WCS-CA), acrylamide-grafted WCS (WCS-AM), and calcined WCS (WCS–Si) for Ni(II) removal from aqueous solution in batch adsorption process. The physical and chemical properties of the prepared adsorbents were investigated by different characterization techniques such as scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, nitrogen adsorption-desorption analyses, and pH at the Point of Zero Charge (pHpzc) in order to assess the suitability and effectiveness of the adsorbents for the removal of Ni(II) by understanding their surface morphology, chemical composition, porosity, and surface charge properties. The experimental Ni(II) adsorption data followed both the Langmuir isotherm and the pseudo-second-order kinetic model suggesting the adsorption process on the prepared adsorbents is well-described by these models. The modified adsorbents WCS-CA, WCS-AM, and WCS-Si exhibited a maximum adsorption capacity of 52.08, 40.32, and 158.73 mg/g, respectively, while WCS-Raw had a capacity of 29.06 mg/g. The thermodynamic study revealed that the adsorption process was feasible, spontaneous, and endothermic. The desorption study demonstrated that the adsorbents could be reused for multiple cycles with minimal loss of activity. The present work evidenced the potential practical applicability and sustainability of the WCS-based adsorbents as promising adsorbents in treating and removing Ni(II) from wastewater.

Comprehensive functionality analysis of spent coffee grounds activated using a microwave-assisted method

Despite the immense number of research on the activated carbon (AC) preparation for wastewater treatment, fewer fractions have been devoted to the microwave-assisted activation route, which is unfortunate considering its advantageous features. In regards, this study explores the feasibility of a simple and rapid microwave-assisted activation method to generate AC from the spent coffee ground (SCG) under various microwave powers (100-450 W). The physicochemical properties of the generated ACs were studied by Fourier transform infrared spectroscopy, scanning electron microscopy, nitrogen adsorption-desorption, and X-ray diffraction analysis. As attained, lower microwave powers generated ACs with higher surface areas, pore volumes, and pore size as well as dominant OH and C=O spectral bands, which can correspond to higher adsorption sites for a more effective methylene blue (MB) removal process. In parallel, the adsorption tests demonstrated that the lowest microwave power sample (SCG-100) exhibited the highest MB adsorption at equilibrium (35 ± 1.75 mg g−1) in the optimum conditions of 25 mg L−1 MB solution, pH 8, 6 hour duration, and 0.025 g adsorbent. The kinetic and isotherm studies revealed the MB adsorption onto SCG-100 was defined by the pseudo-first-order (R2 =0.9462) and Langmuir isotherm (R2 = 0.9617) models respectively. Thermodynamically, the adsorption process occurred in an exothermic, and spontaneous manner. The water quality analysis data further found that the total organic compound, biological, and chemical oxygen demand were successfully decreased in a 6-hour period. Therefore, it can be concluded that the microwave activation method was capable of generating highly functional absorbent material for pollutant adsorption application.

Soft-templated mesostructured TiO2 - SiO2 composites with high thermal stability

To overcome the drawbacks of pure mesostructured titania and in particular the low thermal stability, in this study we have investigated in detail the effect of Si4+ addition on the properties of mesostructured TiO2 prepared by combining the sol-gel process and the surfactant templating mechanism. Obtained materials have also been tested for the photodegradation of methyl orange, used as a model dye.From the SAXS and the manometry nitrogen adsorption-desorption analyses, it can be concluded that the presence of Si4+ delays the collapse of the mesopores network. Compared to the bare mesostructured TiO2, the XRD and Raman results show that the anatase and the rutile phases appear at higher temperature. The higher the Si4+ content, the higher the amorphous-anatase and rutile anatase-phase transition temperatures. The delay in the crystallization also allows the detection of the TiO2-β phase, which is an anatase phase with oxygen vacancies. These phenomena have been attributed to the « glass effect ». In that case, amorphous SiO2, which is formed during the synthesis, surrounds the titania particles and inhibits their growth, when the heating temperature is increased. By this way, the thermal stability of the mesostructured titania containing Si4+ is enhanced.Photocatalytic experiments highlight the importance of the presence of the anatase phase for the discoloration efficiency of the dye solution. Indeed, the increase of Si4+ leads to a clear decrease of the photodegradation efficiency.

Enhanced atmospheric water harvesting efficiency through green-synthesized MOF-801: a comparative study with solvothermal synthesis

Adsorption-based atmospheric water harvesting has emerged as a compelling solution in response to growing global water demand. In this context, Metal–organic frameworks (MOFs) have garnered considerable interest due to their unique structure and intrinsic porosity. Here, MOF 801 was synthesized using two different methods: solvothermal and green room temperature synthesis. Comprehensive characterization indicated the formation of MOF-801 with high phase purity, small crystallite size, and excellent thermal stability. Nitrogen adsorption–desorption analysis revealed that green-synthesized MOF-801 possessed an 89% higher specific surface area than its solvothermal-synthesized counterpart. Both adsorbents required activation at a minimum temperature of 90 °C for optimal adsorption performance. Additionally, green-synthesized MOF-801 demonstrated superior adsorption performance compared to solvothermal-synthesized MOF-801, attributed to its small crystal size (around 66 nm), more hydrophilic functional groups, greater specific surface area (691.05 m2/g), and the possibility of having a higher quantity of defects. The maximum water adsorption capacity in green-synthesized MOF-801 was observed at 25 °C and 80% relative humidity, with a value of 41.1 g/100 g, a 12% improvement over the solvothermal-synthesized MOF-801. Remarkably, even at a 30% humidity level, green-synthesized MOF-801 displayed a considerable adsorption capacity of 31.5 g/100 g. Importantly, MOF-801 exhibited long-term effectiveness in multiple adsorption cycles without substantial efficiency decline.