Brunauer , Emmett And Teller Research Articles

Removal of methylene blue in aqueous solution using nanosilica based sorbent from volcanic ash

In this study, a mesoporous nano-SiO2 from Taal volcanic ash was successfully synthesized via sol–gel precipitation method and used effectively as adsorbent of methylene blue in aqueous solution. The silica rich volcanic ash from Taal contains 43.5% SiO2 which is the precursor of nano-SiO2 and characterized using scanning electron microscope (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray fluorescence (XRD) and Brunauer, Emmett and Teller (BET). The synthesized nano-SiO2 have an average size of 45 nm, surface area of 181.66 m2/g, pore size of 16–25 nm with purity greater than 99.9%. Characteristics bands at 3410 cm−1 attributed to OH- stretching of silanol groups, and a sharp peak at 1067 cm−1 and 801 cm−1 indicating siloxane (-Si-O-Si-) functional groups. XRD analysis revealed an amorphous nature of nano-SiO2 with crystallite size of 2.96 nm. A ∼99.9 % maximum removal was reached at pH 8, adsorbate concentration of 25 mg/L, adsorbent dose of 1.87 g/L at 22.89 min contact time and found to be reusable even after 5 cycles. Adsorption was best explained by Langmuir model having 65.5 mg/g maximum monolayer adsorption capacity. Kinetic studies showed a pseudo 2nd order with R2 of 99.9%.

New alternative for adsorption of 2,4-dichlorophenoxyacetic acid herbicide (2,4-D)

The adsorptive capacity of charcoal from the husk of the brazil nut fruit, called “ouriço” (the hard ball with nuts inside) for the herbicide dichlorophenoxyacetic acid (2,4-D) was evaluated. Activated carbons were produced from the brazil nut in a tubular oven at 800 °C and activated with CO2 or water steam. The specific surface area was determined by the Brunauer, Emmett and Teller (BET) method, demonstrating the mean density of micropores. Analysis of N2 adsorption/desorption isotherms was undertaken and the morphology of activated carbons was visualized by Scanning Microscopy (SEM). The activated carbons were successfully obtained and had a specific surface area of 395 m2.g-1 and 401 m2.g-1 after activation with either CO2 or water steam, respectively. The highest pore mean density occurred with a diameter of 1.17 nm for carbons activated in both atmospheres. The graph of the adsorption/desorption isotherms of N2 showed Type I isotherms, regardless of the activation atmosphere. The SEM analysis showed that, for both activation atmospheres, pore formation occurred in the shape of uniform honeycomb craters. Adsorption kinetics followed the pseudo-second order model, indicating chemisorption. Regardless of the activation atmosphere, the activated carbon from the brazil nut “ouriço”, was highly efficient for 2,4-D adsorption.

Synthesis and application of barium tin oxide-reduced graphene oxide nanocomposite as a highly stable heterogeneous catalyst for the biodiesel production

The potential decline in crude oil reserves and rising awareness of the detrimental environmental impacts of consuming fossil fuels promoted the creation of alternative approaches to transform waste biomass into biofuels. This research provided a simple approach for synthesizing barium tin oxide (BTO) and its decoration over the reduced graphene oxide (RGrO) to manufacture BTO@RGrO as an efficient catalyst in the process of biodiesel production from waste cooking oil (WCO). The prepared BTO and BTO@RGrO nanocomposite were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDX), BET (Brunauer, Emmett, and Teller), Temperature Programmed Desorption of NH3/CO2 (NH3/CO2- TPD), and Power X-ray diffraction (XRD). The response surface methodology (RSM) based central composition designs (CCD) was employed to optimize the influence factors, including reaction temperature (40–90 °C), reaction duration (10–50 min), catalyst quantity (1–5 wt%), and methanol to oil (MeOH/Oil) molar ratio (5−25). The optimal performance of biodiesel generated was acquired over BTO@RGrO nanocomposite at the reaction temperature of 68.83 °C, reaction duration of 27.95 min, catalyst quantity of 3.21% by weight, and MeOH/Oil molar ratio of 14.93, which led to biodiesel generation with a 97.03% purity. The finding revealed that the BTO@RGrO nanocomposite could be effectively utilized as a stable heterogeneous solid catalyst under ideal reaction conditions with outstanding catalytic performance.

Activated charcoal modified BaFe12O19 powder: a recyclable magnetic adsorbent for removal of methyl blue dye from aqueous solutions

ABSTRACT Use of sophisticated adsorbent materials to clean harmful dye-contaminated water is rapidly gaining popularity. Among different adsorbent, magnetic ferrites based adsorbent are gaining much attention because of their easy recyclability. In this current work, activated charcoal (AC) modified magnetic BaFe12O19 (BaM) ferrite-based novel adsorbent (BaM-AC) powder was synthesised through a sol-gel combustion route. As a model dye pollutant, methyl blue (MB) was used to estimate the adsorption efficiency of BaM-AC adsorbent. X-ray diffraction (XRD) was utilised to analyse pure BaM and BaM-AC powder phases. Fourier transform infrared spectroscopy (FTIR), Brunauer, Emmett and Teller (BET), vibrating sample magnetometer (VSM) and field emission scanning electron microscope (FESEM) were also used for the characterisation of prepared adsorbents. The surface area of BaM-AC powder determined by BET was 5.93 m2 g−1. The BaM-AC adsorbent has a saturation magnetisation (Ms) of 56.8 emu g−1 and a coercive field (Hc) of 5176 Oe. Microstructural analysis showed the porous morphology of the material. In-depth studies with BaM-AC powder investigated how pH, adsorbent dose, adsorption period, MB dye concentration, and effect of temperature affected MB dye adsorption. Conferring to the outcomes of the MB-adsorption experiment, the equilibrium was reached after around 45 minutes. Pseudo-second-order kinetics and the Sips isotherm model govern the adsorption process. BaM-AC powder exhibited a good recyclability up to five-regeneration cycle. These outcomes suggest that the composite material has the potential to serve as an effective adsorbent for dye-containing wastewater treatment.

New insights in the treatment of real oilfield produced water: Feasibility of adsorption process with coconut husk activated charcoal

Naphthenic acids are water-soluble organic compounds (WSO), present in oilfield produced water (OPW), whose removal aims to comply with environmental legislation and ensure the correct disposal of OPW. In this study, the performance of the adsorptive process for the removal of WSO in synthetic (single- and multi-component) and real OPW was evaluated. It was observed that the lower the pH of the sample, the greater the adsorption capacity of WSO. Moreover, the kinetic parameters of adsorption followed the pseudo-second order model while the equilibrium parameters were represented by the isothermal BET (Brunauer, Emmett and Teller) model. In the desorption process followed the second-order model, and the aqueous solution of sodium hydroxide (0.3 and 0.1 M) showed the highest desorption efficiency (~70 %) in the synthetic and real systems, respectively. With this protocol, the adsorbent proved to be effective for the treatment of OPW, without significant loss of efficiency, for up to three consecutive cycles of adsorption-desorption. In addition, after treatment, the real effluent was classified within the legal parameters for offshore disposal, which enhances its industrial application.

Application of Green Polymeric Nanocomposites for Enhanced Oil Recovery by Spontaneous Imbibition from Carbonate Reservoirs.

This study experimentally investigates the effect of green polymeric nanoparticles on the interfacial tension (IFT) and wettability of carbonate reservoirs to effectively change the enhanced oil recovery (EOR) parameters. This experimental study compares the performance of xanthan/magnetite/SiO2 nanocomposites (NC) and several green materials, i.e., eucalyptus plant nanocomposites (ENC) and walnut shell ones (WNC) on the oil recovery with performing series of spontaneous imbibition tests. Scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDAX), and BET (Brunauer, Emmett, and Teller) surface analysis tests are also applied to monitor the morphology and crystalline structure of NC, ENC, and WNC. Then, the IFT and contact angle (CA) were measured in the presence of these materials under various reservoir conditions and solvent salinities. It was found that both ENC and WNC nanocomposites decreased CA and IFT, but ENC performed better than WNC under different salinities, namely, seawater (SW), double diluted salted (2 SW), ten times diluted seawater (10 SW), formation water (FW), and distilled water (DIW), which were applied at 70 °C, 2000 psi, and 0.05 wt.% nanocomposites concentration. Based on better results, ENC nanofluid at salinity concentrations of 10 SW and 2 SW ENC were selected for the EOR of carbonate rocks under reservoir conditions. The contact angles of ENC nanocomposites at the salinities of 2 SW and 10 SW were 49 and 43.4°, respectively. Zeta potential values were -44.39 and -46.58 for 2 SW and 10 SW ENC nanofluids, which is evidence of the high stability of ENC nanocomposites. The imbibition results at 70 °C and 2000 psi with 0.05 wt.% ENC at 10 SW and 2 SW led to incremental oil recoveries of 64.13% and 60.12%, respectively, compared to NC, which was 46.16%.

Moisture Sorption Behavior and Effects of Temperature, Slice Thickness, and Loading Density on Drying Kinetics of a Local Sweet Potato Cultivar Grown in Bangladesh

This study is aimed at investigating the moisture sorption behavior and thin-layer drying kinetics of local sweet potato sada (LSPS) variety slices. The sweet potato tubers were sliced at 3, 5, and 7 mm and dried at temperatures of 45, 55, and 62°C at a constant air velocity of 0.6 m/sec in a laboratory-scale cabinet dryer. The BET (Brunauer, Emmet, and Teller) and GAB (Guggenheim-Anderson-De Bore) models were applied to fit the sorption data. Fick’s diffusion equation was used to calculate the drying rate constant and effective moisture diffusivity. Our current result reveals that LSPS exhibited an isotherm with a sigmoid (type II) shape, and the GAB model was more goodness of fit than the BET model to clarify the adsorption isotherm of LSPS. The drying time increased with increasing slice thickness but reduced with increasing drying temperature. The drying rate constant for thin-layer drying decreased with an increase in slice thickness but increased with increasing drying temperature. The loading density with two different shapes (French cut and cube cut) also affected the drying rate constant, which decreased with the increase in loading density. Using statistical parameters, five thin-layer drying models were applied to fit the drying data. The findings indicated that the logarithmic model for 45-55°C and the Page model for 62°C were the most suitable models for explaining the drying behavior of LSPS slices. The effective moisture diffusivity increased with increasing slice thickness and drying temperature, ranging from 7.10 × 10 − 11 to 1.55 × 10 − 10 m2/s over the temperature range studied. The activation energy also increased with increasing slice thickness, and the values were 5.55 and 7.39 kJ/mol for 3 and 5 mm slices, respectively. The findings suggested that slice thickness, drying temperature, and sample loading density on cabinet dryer trays affect the drying kinetics of sweet potato slices.

Thiazolyl-linked conjugated microporous polymers for enhancement adsorption and photocatalytic degradation of organic dyes from water

Organic dyes and pigments are common examples of pollutants that have been drained to water resources. Subsequently, chemists searched for novel and efficient adsorbents for treatment of sewage water from coloring compounds. Conjugated microporous polymers (CMPs), which displayed high Brunauer Emmett and Teller (BET) surface area and porous morphology, beside other unique merits, solve this challenging situation by consuming dye molecules into their large and permanent pores, and degrading them in the presence of light. In this paper, we adopt a designed synthesis of new thiazolyl-linked CMPs containing bicarbazole, bifluorenylidene, and biphenylethene building blocks, namely: BC-TT, BF-TT, and BIPE-TT CMPs, respectively. All the common characterizations including chemical, physical, and photophysical were conducted for the as-synthesized CMPs. In addition to their significant surface areas that reach 522 m2/g and maximum pore volumes (up to 0.50 cm3/g), they possessed good thermal stabilities with the highest values (degradation temperature = 460 °C; char yield = 67 wt%). Furthermore, the produced polymers have been proven to have adsorption capability as well as photocatalytic degradation for both Rhodamine B (RhB) and methylene blue (MB) dyes. BC-TT CMP exhibited the highest adsorption efficiency among others toward the RhB dye with a capacity of 228.83 mg/g, as well as the maximum performance for MB dye uptake (up to 232.02 mg/g). After measuring the photocatalytic degradation of dyes using these CMPs, BC-TT-CMP also showed the top value of catalytic efficiency at all, either for RhB (rate constant: 2.5 × 10−2 min−1) or MB dye (rate constant: 3.5 × 10−2 min−1).

Effect of synthesis conditions on the structural properties of CNT-doped carbon aerogels

Resorcinol-formaldehyde (RF) sol-gels have attracted much attention in the last decade. Carbon aerogels with very light and porous structures can be produced by controlled drying and subsequent pyrolysis of these organic gels under a neutral atmosphere. In general, it is indispensable to tailor the aerogel pore structure according to the application. In this study, some parameters affecting the structure, like the carbon nanotubes doping, heating rate during carbonization process, and temperature of carbonization have been investigated by measuring N2 adsorption/desorption isotherms at 77 K. It was observed that by increasing the amount of carbon nanotubes (CNTs) from 0 mg to 100 mg, the Brunauer, Emmett and Teller (BET) surface area and the total pore volume showed a decreasing trend and then increased again at 180 mg. By increasing the heating rate from 5 °C/min to 15 °C/min, the surface of meso pores showed an increasing trend. With the increase of carbonization temperature from 600 °C to 1200 °C, the micro pore volume decreased. At low carbonization temperature (600 °C), meso pore surface was dominant, whereas at high carbonization temperature (1200 °C), micro pore surface prevailed. According to simultaneous thermal analysis (STA), the carbonization efficiency of the CNT-doped organic gel was about 45 %.

Flax fiber based semicarbazide biosorbent for removal of Cr(VI) and Alizarin Red S dye from wastewater

In the present study, flax fiber based semicarbazide biosorbent was prepared in two successive steps. In the first step, flax fibers were oxidized using potassium periodate (KIO4) to yield diadehyde cellulose (DAC). Dialdehyde cellulose was, then, refluxed with semicarbazide.HCl to produce the semicarbazide functionalized dialdehyde cellulose (DAC@SC). The prepared DAC@SC biosorbent was characterized using Brunauer, Emmett and Teller (BET) and N2 adsorption isotherm, point of zero charge (pHPZC), elemental analysis (C:H:N), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses. The DAC@SC biosorbent was applied for the removal of the hexavalent chromium (Cr(VI)) ions and the alizarin red S (ARS) anionic dye (individually and in mixture). Experimental variables such as temperature, pH, and concentrations were optimized in detail. The monolayer adsorption capacities from the Langmuir isotherm model were 97.4 mg/g and 18.84 for Cr(VI) and ARS, respectively. The adsorption kinetics of DAC@SC indicated that the adsorption process fit PSO kinetic model. The obtained negative values of ΔG and ΔH indicated that the adsorption of Cr(VI) and ARS onto DAC@SC is a spontaneous and exothermic process. The DAC@SC biocomposite was successfully applied for the removal of Cr(VI) and ARS from synthetic effluents and real wastewater samples with a recovery (R, %) more than 90%. The prepared DAC@SC was regenerated using 0.1 M K2CO3 eluent. The plausible adsorption mechanism of Cr(VI) and ARS onto the surface of DAC@SC biocomposite was elucidated.

Application of sulfonated biochar-based magnetic catalyst for biodiesel production: Sensitivity analysis and process optimization

The sulfonated magnetic porous biochar-based solid catalysts have a significant potential to replace homogeneous acid catalysts in order to decrease corrosion issues and the environmental risks brought on by homogeneous acid catalysts. For this purpose, produced biochar from the rice husk pyrolysis at 700 °C was employed for the synthesis of a biochar-based magnetic acid catalyst. The base structure of the catalyst was modified and magnetized using different ratios of ZnCl2 and FeCl3. The magnetic porous biochar was sulfonated with two sulfonation agents including H2SO4 and ClSO3H. Characteristic analyzes of BET (Brunauer, Emmett, and Teller), Scanning Electron Microscopy, vibrating-sample magnetometer, Fourier Transform Infrared Spectroscopy, Energy-Dispersive X-ray Spectroscopy, and elemental analysis were used to investigate the physicochemical properties of the synthesized catalysts. The magnetic biochar-sulfonated with ClSO3H was evaluated as the selected catalyst in the biodiesel generation process from oleic acid (OA) as a representative of bio-oils. The central composite design (CCD) based on the response surface methodology (RSM) was used to optimize the process and examine the effectiveness of various parameters, including catalyst concentration based on the OA weight (3–15 wt.%), experiment duration (1–5 h), MeOH: Oil molar ratio (5–25), and reaction temperature (40–100 °C), on the efficiency of biodiesel generation. The optimum yield was achieved at 98.11% under the optimal condition, which included an experiment duration of 4.8 h, catalyst concentration of 9.9 wt.%, MeOH: Oil ratio of 16:1, and reaction temperature of 74.8 °C.

Recycling waste by manufacturing biomaterial for environmental engineering: Application to dye removal

There are several disposal and governance difficulties due to rapid bio-waste growth. Therefore, recycling and repurposing them for environmental purposes is garnering increasing attention. Hydrothermal carbonization (HTC) followed by phosphoric acid activation was used in this investigation to synthesize a novel activated hydrochar (AHPP) from pomegranate peels. X-Ray Diffraction, Fourier-transform infrared spectroscopy, Scanning electron microscopy with energy dispersive X-ray spectroscopy, Brunauer, Emmett and Teller (BET) surface area analysis and Barrett-Joyner-Halenda (BJH) pore size distribution, and pH of zero charge were exploited to define the characteristics of AHPP, which was then used to assess the uptake of Basic Red 46 (BR46) dye in the batch mode. Isothermal and kinetic investigations were accomplished with pH = 6, 0.5 g.L−1 of adsorbent, 400 rpm at 298 K upon 60 min. The Freundlich model accurately presented the equilibrium curves with an adsorption capacity of 998.95 mg g−1, while the PSO kinetic model adequately corresponded to the experimental data. Furthermore, thermodynamic data disclosed that the process was spontaneous, endothermic, and linked to a growing disorder at the adsorbent-adsorbate interface. Lastly, the reuse investigation using HCl ascertained that AHPP might be recycled ten times, whereas a probable adsorption mechanism was proffered. Overall, it is possible to conclude that activated hydrochar generated from pomegranate peels as cost-effective waste could be employed as an alternative sorbent in dining substantial effluents retaining BR46.

Influence of nanopores volumes in hydrogen absorption properties of B4C and WC carbide-derived carbon nanomaterials

Sustainable energy development is needed to meet rising energy demands and reduce fossil fuel risks. Hydrogen generation is a crucial study area for sustainable energy. This study examines hydrogen adsorption on carbide-derived carbon nano-porous (CDC nP) nanomaterials. B4C CDC nP and WC-CDC nP Nanomaterials were produced by reacting chlorine gas with boron carbide (B4C) and tungsten carbide (WC) at 1200 °C and 980 °C in a high-pressure quartz stationary bed reactor. A CDC nP Nanomaterials was activated by heating it to 900 °C for 1 h in hydrogen to produce A-B4C-CDC nP Nanomaterials, which were characterized using Small-angle X-ray scattering (SAXS), nonlocal density functional theory (NLDFT), X-ray diffractometers (XRD), transmission electron microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), energy dispersive spectroscopy (EDS), and Scanning Electron Microscopy. Before treatment, the BET (Brunauer, Emmett, and Teller) surface area of activated B4C CDC nP material was 2240 m2/g, non-activated WC-CDC nP was 1240 m2/g, and A-B4C-CDC Nanomaterials was 1580 m2/g. This novel study examines CDC pore size and absorption on CDCs. Nitrogen adsorption isotherms showed better pore volume and distribution than raw material. High linearity allows an incompressible adsorbed hydrogen phase at ambient temperature. The isotherms match IUPAC (International Union of Pure and Applied Chemistry) Type I isotherms and confirm nano-porous materials. The equal temperature matches IUPAC Type I isotherms, indicating nano-porous material. H2 adsorption of Sample A peaked at 6.75 wt% at pressures above 125 MPa. Since all three carbide-derived carbons had the same maximum adsorbate density, overall pore volume is a major determinant.

Thermodynamic behavior of bioactive glass in relationship with high fluorine content

Fluoride (F) is important for enhancing illogical activity of bioceramics. To increase fluoride content of derived Hench bioactive glass (BaG), bioactive fluorosilicate glasses (BaG-Fx) were synthesized by using melting method and characterized using different physico-chemical analyses. Fluoride-containing BaGs were synthesized at a temperature of 1350°C. Structural and thermal effect of calcium fluoride (CaF2) insertion into the glass network in the BaG: SiO2–CaO–Na2O–P2O5 quaternary system was studied. Indeed, the incorporated amounts of fluorine (CaF2) (from 5% to 20% by mass) induced significant physico-chemical changes. Through the structural study by X-ray diffraction (XRD), the amorphous character of our fluorosilicate glasses is proven. Infrared (IR) spectroscopy proved the incorporation of fluorine into the glass matrix. In the microstructural framework, we revealed the morphological changes of the glass powders as a function of the CaF2 content. These results were confirmed by Brunauer, Emmett and Teller (BET) measurements. Through Differential Scanning Calorimetry (DSC) thermal analysis we established the impact of fluoride ions on the structural dynamics and thermodynamic properties of these newly developed bioactive glasses. Accordingly, it was possible for the first time to incorporate as much as 20 wt% of CaF2 in BaG respecting the conditions of bioactivity and biodegradability required by Hench. After detailed analyses of the transformation entropies of BG-Fx as a function of the added CaF2 content, it can be stated that the intermolecular movements within the fluorosilicate network are more limited as a function of the added CaF2 amount. This slows down the ion exchange phenomena and subsequently the dissociation of the material in vitro, which can be anticipated to occur after implantation in vivo.

Multi-application of fennel (Foeniculum vulgaris) seed composites for the adsorption and photo-degradation of methylene blue in water

This work reports on synthesis of fennel-based composites and their feasibility to remove and photo-degrade methylene blue dye from aqueous solution. Pristine fennel seeds (PFS) was impregnated with iron(III) oxide nanoparticles (Fe2O3 NP) and iron(III)-1,2,3,4-tetracarboxylic acid (Fe-TCA) to yield the composites fennel seeds-nanoparticles (FS-NP) and fennel seeds-tetracarboxylic acid (FS-TCA), respectively. Scanning electron microscope (SEM) images revealed that the surface of the adsorbents appeared to have a rough texture with cavities. Fourier transform infrared spectroscopy (FTIR) spectra confirmed the presence of −OH, −C=O, −COC, −COOH and −CO groups that could easily bind to the dye. The physicochemical characteristics such as cation exchange capacity (CEC) and Brunauer, Emmett and Teller (BET) surface area were enhanced after impregnation compared with PFS. The maximum adsorption capacity recorded at pH 10 for PFS was 13.2 mg/g while for FS-NP and FS-TCA was 32.8 and 42.9 mg/g, respectively This was ascribed to chemical interaction such as hydrogen bond, electrostatic attraction and π-π stacking. The isotherm and kinetic data were best described by Freundlich and pseudo-first order models. Thermodynamic parameters (∆Ho and ∆Go) showed spontaneity and endothermicity respectively. The positive values of ΔSo suggests that there was increased level of freedom at solid/liquid interface. PFS showed no activity for photocatalytic degradation properties while PF-NP and PF-TCA recorded 58.9 and 48.6% efficiencies, respectively. The data revealed that pseudo-second order described the photocatalytic processes of MB better than pseudo-first order kinetics.

Platinum-Functionalized Graphene Oxide: One-Pot Synthesis and Application as an Electrocatalyst.

This paper presents the preparation of platinum on a reduced graphene oxide matrix (PtrGO) using the microwave-assisted method with three different pH solutions. The platinum concentration determined by energy-dispersive X-ray analysis (EDX) was 4.32 (weight%), 2.16 (weight %) and 5.70 (weight%), corresponding to pH 3.3, 11.7 and 7.2, respectively. Pt functionalization of reduced graphene oxide (rGO) decreased the rGO specific surface, as shown by Brunauer, Emmett and Teller (BET) analysis. An XRD spectrum of platinum-decorated reduced graphene oxide (rGO) showed the presence of the associated phases of rGO and centered cubic platinum peaks. An oxygen reduction reaction (ORR) electrochemical characterization performed using the rotating disk electrode (RDE) method showed that in PtGO1 synthetized in an acidic environment, with 4.32 Pt (weight%) determined by EDX, platinum is much more dispersed, which explains its better electrochemical oxygen reduction reaction performance. Koutecky-Levich (K-L) plots calculated at different potentials prove a good linear relationship. Electron transfer numbers (n) determined from the K-L plots are between 3.1 and 3.8, which confirms that the ORR for all the samples can be regarded as first-order reaction kinetics of O2 concentration formed on the Pt surface during ORR.

Simultaneous and selective removal of diclofenac and ibuprofen from aqueous matrices by a hybrid TiO2-dual-template molecularly imprinted polymer

ABSTRACT Dual-template molecularly imprinted polymer based on TiO2 nanoparticles (NPS) (TiO2-MIP) was synthesised by surface molecularly imprinted method to achieve the simultaneous and selective removal of diclofenac and ibuprofen in aqueous media. The characterisation results of Fourier Transformed Infrared spectroscopy (FTIR), X-ray Diffractometry (XRD), Brunauer, Emmett and Teller (BET) and Field Emission Scanning Electron Microscopy (FE-SEM) revealed the successful imprinting process on the surface of titania. The effects of operating parameters including pH, initial concentration of target pollutants and dosage of nanocomposite were first investigated. Then, TiO2-MIP nanocomposites were prepared at different TiO2 NPS to imprinted polymer mass ratios, and the optimal value was determined. The best treatment performance was obtained at pH = 4, 10 mg/L of target pollutants, 1 g/L of the nanocomposite, and 1:4 mass ratio, in which the simultaneous and selective removal efficiency of diclofenac and ibuprofen was 86.6% and 75.0%, respectively. The adsorption capacity of synthesised TiO2-MIP nanocomposites for DCF and IBP was 5.22 and 4.38 mg/g, respectively. The pseudo-second-order model (R2 ≥ 0.99) and Langmuir isotherm model (R2 = 0.99) demonstrated the best fitting with experimental data. The adsorption capacity, photodegradation activity, selectivity and reusability of polymeric nanocomposite were also studied. The results revealed that the synthesised TiO2-MIP nanocomposite had higher adsorption capacity, enhanced photodegradation performance and better selectivity for target pollutants than non-imprinted TiO2 nanocomposite. The results further showed that the selection factor of TiO2-MIP for diclofenac and ibuprofen was 5.4 and 3.8 times of the competitive pollutant, respectively, indicating stronger and more specific interactions for the target molecules. The brilliant adsorption and photodegradation performance, simultaneous removal of contaminants, good stability and selectivity towards target pollutants in the presence of competitive compounds are the advantages of the as-prepared TiO2-MIP nanocomposite. Thus, a hybrid TiO2-molecularly imprinted polymer can play an influential role in the treatment of persistent environmental insults in complex aquatic environments.

NbCl5 Functionalized Perlite: A Potent and Recyclable Catalyst for Synthesis of Pyrans

Niobium pentachloride functionalised perlite was prepared via a solid state dispersion technique, which was utilized as an efficient heterogeneous catalyst for the synthesis of pyrans. The immobilisation of NbCl5 over perlite was examined by Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), Thermogravimetric analysis (TGA), scanning electron microscope (SEM) with energy dispersive spectra (EDS), and Brunauer, Emmett and Teller (BET) surface area measurements. The wt% of NbCl5-loaded perlite was optimized based on the adequacy with respect to the yield of the pyrans in various solvents. The recyclability of the catalyst was validated in synthesizing pyrans and the results marked its efficiency up to five runs. The efficacy of the NbCl5/perlite catalyst was found to be comparable and better with respect to the other heterogeneous catalysts reported. The structures of pyrans were confirmed by FT-IR, 1H and 13C NMR spectral techniques. The proposed recyclable heterogeneous NbCl5/perlite catalyst simplifies the protocol, and has minimal chemical waste, a lower reaction time and a high-yield.

Hydrothermally obtained β-MnO2 nanoparticles/activated carbonized coconut fibers composites, electrochemical properties study for future energy storage devices

Pure β-MnO2 (M) nanoparticles (Nps) and M Nps/activated carbonized coconut fiber (ACCF) composites (Cps), (M@ACCF Cps), with ACCF loadings 2.5, 5, 10 and 15% were hydrothermally synthesized. The phase, structure and morphology of ACCF, β-MnO2 Nps and M@ACCF Cps were characterized using X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The chemical surface for oxidation state analysis of samples was studied using X-ray photoelectron spectroscopy (XPS). Specific surface area and pore structure were investigated using a Brunauer, Emmett and Teller (BET) technique. Electrochemical studies revealed a maximum specific capacitance (Csc), 320.15 ± 0.12F g−1, at 1 A g−1 for the M@ACCF10% Cps electrode with the excellent retention, 90.87%, at the 4000th cycle of a GCD test. Symmetric M@ACCF10% Cps coin cells demonstrated an outstanding capacitance value of 38.1 ± 0.2 F g−1 at 0.5Ag−1 over a voltage range of 0.0 – 1.8 V.

Effect of reactant ratio and nanofillers type on the microstructural properties, porosity fluctuations and heavy metal removal ability of chitosan-clay hybrid materials

The structure, porosity, and functionality of synthesized chitosan-clay nanocomposites (NCs) are examined throughout this work in relation to the initial stoichiometry and octahedral cavity occupation of the clay fraction. Dioctahedral and trioctahedral smectite are selected as starting materials. X-Ray Diffraction analysis (XRD) confirms the accomplishment of the NCs synthesis process. The stoichiometry fluctuation implies a crystallite exfoliation process provided that the clay fraction contribution must not reach twice the organic ones. From 1:3 stoichiometry ratio, The intercalation process is enhanced by the interlamellar space (IS) closures, and crystallite size increases with crystallinity degree. According to transmission electron microscopy-energy dispersive X-ray (TEM-EDX) investigations, the exfoliation of "clay-particles" wrapping the organic fraction and the intercalation process occurred as the clay fraction abundance increased. Despite the low proportion approved from the synthesis beginning process, Fourier transform infrared spectroscopy (FTIR) reveals the polymer fraction characteristics absorption bands. The Brunauer, Emmett and Teller (BET) analysis of specific surface area and Barrett-Joyner-Halenda (BJH) Analysis of pore size distribution (PSD) supports the findings from TEM/EDX. For slightly saturated soil solution with Pb2+ or Cd2+ cation, Atomic absorption spectroscopy (AAS) evaluate the NCs adsorption capacity. The outcomes are extremely positive for dioctahedral smectite.