Derivative Thermogravimetry Research Articles

Optimization of MgO-GGBS Cementitious Systems Using Thermo-Chemical Approaches

The current study investigated the development of a sustainable thermo-chemical approach to effectively optimize MgO-waste activated GGBS formulations, using four types of magnesium oxide (MgO) waste materials with ground granulated blast-furnace slag (GGBS) to develop binary cementitious systems (MgO-GGBS). This stems from the expected complexity of cementitious binder optimization outcomes into a simpler analytic form, enhancing the rapid delivery of optimization results and contributing to the global awareness of sustainable approaches and use of industrial wastes. Three levels of Portland cement by weight (90, 80, and 70 wt.%) was replaced with MgO wastes including an industrial by-product (GGBS) to develop an experimental regime. Investigation was carried out by employing an experiment-based optimisation technique (thermo-chemical approach), which involved the design of an experimental regime and application of experimental tests (pH measurements, thermogravimetric and derivative thermogravimetric analysis—TG/DTG and isothermal calorimetry), establishment of design variable/parameters, measurement of the design performance of the identified design parameters, and review of the relationship between the independent (control) and dependent variables (MgO wastes and their compositions). The experimental test results successfully optimised the binder compositions, established the best performing binder system (MG1), and provided an in-depth insight into the thermal stability and hydration kinetics of the investigated binder systems.

Properties of High-Density Fiberboard Bonded with Urea-Formaldehyde Resin and Ammonium Lignosulfonate as a Bio-Based Additive.

The potential of ammonium lignosulfonate (ALS) as an eco-friendly additive to urea–formaldehyde (UF) resin for manufacturing high-density fiberboard (HDF) panels with acceptable properties and low free formaldehyde emission was investigated in this work. The HDF panels were manufactured in the laboratory with very low UF resin content (4%) and ALS addition levels varying from 4% to 8% based on the mass of the dry wood fibers. The press factor applied was 15 s·mm−1. The physical properties (water absorption and thickness swelling), mechanical properties (bending strength, modulus of elasticity, and internal bond strength), and free formaldehyde emission were evaluated in accordance with the European standards. In general, the developed HDF panels exhibited acceptable physical and mechanical properties, fulfilling the standard requirements for HDF panels for use in load-bearing applications. Markedly, the laboratory-produced panels had low free formaldehyde emission ranging from 2.0 to 1.4 mg/100 g, thus fulfilling the requirements of the E0 and super E0 emission grades and confirming the positive effect of ALS as a formaldehyde scavenger. The thermal analyses performed, i.e., differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and derivative thermogravimetry (DTG), also confirmed the main findings of the research. It was concluded that ALS as a bio-based, formaldehyde-free adhesive can be efficiently utilized as an eco-friendly additive to UF adhesive formulations for manufacturing wood-based panels under industrial conditions.

Catalytic performance and reaction mechanisms of NO removal with NH3 at low and medium temperatures on Mn-W-Sb modified siderite catalysts

Iron-based catalysts have been explored for selective catalytic reduction (SCR) of NO due to environmentally benign characters and good SCR activity. Mn-W-Sb modified siderite catalysts were prepared by impregnation method based on siderite ore, and SCR performance of the catalysts was investigated. The catalysts were analyzed by X-ray diffraction, H2-temperature-programmed reduction, Brunauer-Emmett-Teller, Thermogravimetry-derivative thermogravimetry and in-situ diffused reflectance infrared Fourier transform spectroscopy (DRIFTS). The modified siderite catalysts calcined at 450°C mainly consist of Fe2O3, and added Mn, W and Sb species are amorphous. 3Mn-5W-1.5Sb-siderite catalyst has a wide temperature window of 180-360°C and good N2 selectivity at low temperatures. In-situ DRIFTS results show NH4+, coordinated NH3, NH2, NO3− species (bidentate), NO2− species (nitro, nitro-nitrito, monodentate), and adsorbed NO2 can be discovered on the surface of Mn-W-Sb modified siderite catalysts, and doping of Mn will enhance adsorbed NO2 formation by synergistic catalysis with Fe3+. In addition, the addition of Sb can inhibit sulfates formation on the surface of the catalyst in the presence of SO2 and H2O. Time-dependent in-situ DRIFTS studies also indicate that both of Lewis and Brønsted acid sites play a role in SCR of NO by ammonia at low temperatures. The mechanism of NO removal on the 3Mn-5W-1.5Sb-siderite catalyst can be discovered as a combination of Eley-Rideal and Langmuir-Hinshelwood mechanisms with three reaction pathways. The mechanism of NO, oxidized by synergistic catalysis of Fe3+ and Mn4+/3+ to form NO2 among three pathways, reveals the reason of high NOx conversion of the catalyst at medium and low temperatures. [Display omitted]

Fuel Quality Index and Fuel Quality Label: Two versatile tools for the objective evaluation of biomass/wastes with application in sustainable energy practices

EU and US implementation of the Agenda for sustainable development by 2030 has directed research in the exploration of alternative sustainable fuels together with their assessment tools of energy production. A Fuel Quality Index (FQI) and a Fuel Quality Label (FQL) could assist in expressing the overall fuel quality of biomass residues, and in general contribute to the optimal use of biomass residues/wastes. The aim of this study is to develop novel FQI and FQL in order to compare and rank solid fuels objectively. For this purpose, nine samples (eight agricultural residues and one lignite) were analysed via several techniques: Proximate analysis, calorific value analysis, thermogravimetric and derivative thermogravimetric analysis, ultimate analysis and determination of emission factors, ion chromatography analysis (S-SO4−2, Cl−) and kinetic modelling. Three FQIs were developed, based on literature concepts but also in two novel concepts: a) expressing the parameters, involved in the calculation of indices, not in absolute values but in normalized values in terms of the generated energy and b) the fuel quality parameters, were not only chemical composition characteristics (as in the literature) but also combustion characteristics (e.g. activation energy). In addition, various approaches for the estimation of the indices were tested by using one or two reference values e.g. optimum and maximum. The difficulties during a factual selection of reference values are also discussed. The use of FQI was based on the concept of relative values that ultimately simplified whilst accelerated the ranking of solid fuels by only comparing a single number (the FQI value) instead of multiple factors. The FQL, is also a novel concept introduced for labelling biomass residues/wastes. These tools proved to have potential applications in the field of sustainable energy, Waste-to-Energy (WtE) practice, and, eventually, would strengthen biomass residues market, since they are able to contribute to the development of broader approved fuel quality standards for wastes.

Fourier-Transform Infrared Spectroscopy and Thermal Investigation of Hybrid Banana/Sisal Fiber Reinforced Polyester Matrix Composite

The key focus of this work was to examine the effect of hybrid fiber reinforcement on thethermal properties of particulate based natural fiber-reinforced hybrid composites. Banana and sisal fiberswere selected as natural fiber reinforcements for the polyester matrix based composites, which wereproduced by mechanical stir mix technique. Thermo-Gravimetric Analysis (TGA) and Fourier-TransformInfrared Spectroscopy (FTIS) were conducted in accordance with American Society for Testing andMaterials (ASTM) standards for the characterization of the hybrid composites. The FTIS result shows thedisappearance of 1735 cm-1 peak, a notable evidence of NaOH treatment. The thermal analysis showedthat the hybridization significantly affected the high temperature stability of the composite, with 70%Sisal/30%Banana found to have the lowest high temperature mass loss at a temperature of 300–520oC, thushighest high temperature stability. Derivative Thermogravimetry (DTG) results shows a minor mass lossrate at a temperature range of 50–150oC as well as a major mass loss rate due to pyrolysis of key fiberconstituents such as cellulose, hemicellulose and lignin between 260 and 350oC. Also it was observed thatas the percentage of banana in the hybrid fiber increases the speed of high temperature mass loss reduces.

Elemental Loss, Enrichment, and Transformation as Well as Life Cycle Assessment of Torrefied Corncob

Elemental loss, enrichment, and transformation are crucial to evaluate the fuel properties of torrefied biomass, and life cycle assessment (LCA) can reflect the environmental impact of torrefaction operation. Herein, corncob is selected as the feedstock for the exploration of fuel properties variation during the torrefaction process. The obtained result implies that torrefaction operation obviously changes the macroscopic and microscopic morphologies of torrefied corncob, and leads to a higher calorific value and bigger surface area. With the development of the torrefaction process, the loss of weight percentage of elemental C, H, and O occurs and is in the order of O > C > H. The relative content of elemental C gradually increases and leads to better fuel properties. The forms of elemental N and O are stable and do not change during the torrefaction process, but the form of C gradually changes from a combined state to an elemental state. These results are confirmed by Fourier transform infrared (FT-IR) spectra, contact angle detection, and thermogravimetric and derivative thermogravimetric analysis. The LCA result infers that slight torrefaction possesses the lowest environmental impact, whereas the mild torrefaction condition of 250 °C appears to be the optimal choice for corncob upgrading.

Influence of poly(ethylene oxide) sample preparation on the results of thermogravimetric analysis

Aim: To investigate whether the sample preparation process of poly(ethylene oxide) (PEO) affects kinetic analysis of the thermal degradation process. Kinetic analysis was performed to describe the course of a chemical reaction regardless of the reaction conditions and the reaction system complexity. One differential method, the Friedman method, and one integral Kissinger-Akahira-Sunose method (KAS), were applied in this work. Methods: The PEO sample was prepared in 4 different ways. Thermogravimetric analysis was performed to determine the thermal degradation of prepared samples. Infrared spectroscopic analysis was performed during the preparation of the PEO film obtained by casting from the solution. Results: Dynamic thermal decomposition of PEO, regardless of the method of preparation, takes place through a single decomposition stage, which is manifested by the appearance of one peak on derivative thermogravimetric (DTG) curve. During the preparation of the PEO film, the procedure was carried out at a temperature higher than its melting temperature (Tm=65°C). After the cooling, the obtained sample didn’t solidify and it had an intense odor of acetic acid, which was confirmed by infrared spectroscopic analysis. Samples III and IV were re-prepared at a temperature lower than the melting point of PEO, obtaining samples of satisfactory quality. Conclusion: In order to prepare poly(ethylene oxide) films by solution casting technique, drying should be carried out at temperatures below the melting point of PEO. If TG analysis of pure PEO powder is compared with the results of hot pressed samples and solution cast samples, it can be concluded that the preparation of the sample doesn’t affect the thermal stability of the PEO. The dependence of activation energy calculated by the differential Friedman and integral KAS method on conversion is constant for all samples in a broad conversion range, regardless of how the samples were prepared. The hot pressed samples and solution cast samples have lower activation energy than the commercial PEO powder.

Hydrothermal Carbonization of Spent Coffee Grounds

With increasing coffee production and consumption, the amount of coffee by-product is also increasing. Therefore, there is growing worldwide interest in using these by-products as a renewable energy source. In this study, hydrothermal carbonization was conducted with subcritical water to improve the fuel characteristics of spent coffee grounds. The water content was varied, with the mass ratio between the dry sample and water set to 1:1.5 and 1:4. The reaction temperature was increased by 10 °C from 180 to 250 °C. The fuel and thermal characteristics of the reaction products were investigated through mass and energy yields, elemental, proximate, and heating value analysis. In analysis results, as the reaction temperature increased, carbon and fixed carbon content increased, and oxygen and volatile matter content decreased, resulting in an increase in calorific value. Thermogravimetric analysis, derivative thermogravimetry, and Fourier transform infrared spectroscopy were also conducted on the reaction products. To investigate their storage characteristics, chemical oxygen demand analysis was conducted. The results showed that with increasing reaction temperature, the fixed carbon content and heating value increased; also, the fuel characteristics became similar to those of coal. In addition, the reaction products became more hydrophobic as the reaction temperature increased.

Removal of Zn(II) and Ni(II) heavy metal ions by new alginic acid-ester derivatives materials

The present work concerns the preparation of new materials based on alginic acid (AA) and diols in a facile and efficient process by improving the adsorption properties of Zn(II) and Ni(II) metal ions on the modified AA. The materials were analysed by zeta potential, thermogravimetric analysis (TGA), derivative thermogravimetry (DTG), in addition to the Fourier Transform InfraRed spectroscopy (FTIR), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) before and after the adsorption behaviour was conducted. The results show that the esterification of AA with diols of different lengths significantly improves its adsorption efficiency of Zn(II) and Ni(II) with Qmax up to 200 mg/g and 185.185 mg/g respectively. Equilibrium and kinetic studies showed that the Langmuir and Freundlich adsorption isotherm models fit the experimental data well, and followed a pseudo-first order kinetic model and the particle diffusion model with correlation coefficients R2 ≈ 1.

Effective Adsorption of Methyl Orange on Organo-Silica Nanoparticles Functionalized by a Multi-Hydroxyl-Containing Gemini Surfactant: A Joint Experimental and Theoretical Study.

A novel multi-hydroxyl-containing gemini surfactant (G16) is first designed for modifying silica precursors (SiNPs), with the purpose of fabricating organic adsorbents targeted at methyl orange (MO). The purity of G16 and structural character of the resultant G16-SiNPs are unveiled through Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetry-derivative thermogravimetry, scanning electron microscopy, and surface analysis (BET). Compared with SiNPs, G16-SiNPs exhibit enhanced hydrophobicity, enlarged interlayer spacing, and increased thermal weight losses with the modifier availability reaching as high as 100%. Enhanced MO adsorption is obtained from the higher adsorption capacity of G16-SiNPs (401.88 mg/g) than SiNPs (64.72 mg/g), which is more effective than most of the existing silica-based adsorbents. Pseudo-second-order and Langmuir models conform to all adsorption processes, indicating that the adsorption mainly relies on the availability of adsorption sites and characterized by a homogeneous adsorption form. By combining the experimental study and theoretical calculation methods, it can be demonstrated that the as-synthesized adsorbent G16-SiNPs own multi-active sites that contribute to multi-adsorption mechanisms. The partition process, electrostatic interactions, and OH−π interactions are all responsible for the adsorption performance of G16-SiNPs. This study throws light on the exploration of the superb MO adsorbent in aspects of not only the novel structured modifier and precursor but also theoretical analysis for gaining insights into the adsorption mechanism.

Ni(II), Cu(II), Mn(II), and Fe(II) Metal Complexes Containing 1,3-Bis(diphenylphosphino)propane and Pyridine Derivative: Synthesis, Characterization, and Antimicrobial Activity

Four of the coordination compounds of the general formula, [M(DPPP)(APY)(H2O) Cl2].xH2O, where M = Ni(II), Cu(II), Mn(II), and Fe(II) and x = 0, 1, or 2 molecules of H2O, DPPP = 1,3-bis(diphenylphosphino)propane, and APY = 2-aminopyridine, have been prepared and characterized. The structure of the complexes has been confirmed by elemental analysis, FT-IR, and UV-Vis spectral data. Thermal analysis (thermogravimetry, derivative thermogravimetry, and differential thermal studies) has been used to study the thermal decomposition stages. Biological activity of all synthesized complexes was tested against five bacterial strains and three fungal strains. Bacteria and fungi strains are common contaminants of the environment in Saudi Arabia, some of which are frequently reported from contaminated water, soil, and food.

Favipiravir-Based Ionic Liquids as Potent Antiviral Drugs for Oral Delivery: Synthesis, Solubility, and Pharmacokinetic Evaluation.

Coronavirus disease 2019 (COVID-19) has spread across the world, and no specific antiviral drugs have yet been approved to combat this disease. Favipiravir (FAV) is an antiviral drug that is currently in clinical trials for use against COVID-19. However, the delivery of FAV is challenging because of its limited solubility, and its formulation is difficult with common organic solvents and water. To address these issues, four FAV ionic liquids (FAV-ILs) were synthesized as potent antiviral prodrugs and were fully characterized by nuclear magnetic resonance (NMR) spectroscopy, Fourier-transform infrared (FT-IR) spectrometry, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), derivative thermogravimetry (DTG), and differential scanning calorimetry (DSC). The aqueous solubility and in vivo pharmacokinetic properties of the FAV-ILs were also evaluated. The FAV-ILs exhibited improved aqueous solubility by 78 to 125 orders of magnitude when compared with that of free FAV. Upon oral dosing in mice, the absolute bioavailability of the β-alanine ethyl ester FAV formulation was increased 1.9-fold compared with that of the control FAV formulation. The peak blood concentration, elimination half-life, and mean absorption time of FAV were also increased by 1.5-, 2.0-, and 1.5-fold, respectively, compared with the control. Furthermore, the FAV in the FAV-ILs exhibited significantly different biodistribution compared with the control FAV formulation. Interestingly, drug accumulation in the lungs and liver was improved 1.5-fold and 1.3-fold, respectively, compared with the control FAV formulation. These results indicate that the use of ILs exhibits potential as a simple, scalable strategy to improve the solubility and oral absorption of hydrophobic drugs, such as FAV.

Thermal and Kinetic Properties of Brazilian Coffea Arabica Beans

The chemical composition of green coffee beans depends on the number of parameters, such as coffee cherry processing methods, used. The quality of roasted coffee is related to the certain substances that developed during the roasting process and that are responsible for the organoleptic properties. The main objective of this study was an investigation of the thermal behaviour and the fatty acids profile of green and roasted Brazilian Santos coffee beans. The glass transition temperature was measured using modulated differential scanning calorimetry (MDSC). The thermal behaviour of coffee samples was evaluated by means of thermogravimetry (TG) and first derivative thermogravimetry (DTG). The oxidative stability and kinetic parameters were characterized with the use of differential scanning calorimetry (DSC). According to the TG and DTG curves, coffee samples showed different behaviour of thermal degradation in the atmosphere of oxygen and nitrogen. Our research shows that the thermal properties and fatty acids profile did not change during the roasting process.

Multi-distribution activation energy model on slow pyrolysis of cellulose and lignin in TGA/DSC

Developing a kinetic model to analyze the multi-step reaction of biomass pyrolysis is pivotal to elucidate the mechanism of the pyrolysis. For this purpose, a model-fitting method such as multi-distribution the Distributed Activation Energy Model (DAEM) is one of the most reliable methods. DAEM with 4 different distribution functions of Gaussian, Logarithmic, Gumbel, and Cauchy was utilized to characterize the pyrolysis of cellulose and lignin during Thermogravimetric Analysis/Differential Scanning Calorimetry (TGA/DSC) instrumentation. By comparing Derivative Thermogravimetry (DTG) and DSC profiles, determination of pseudo-components can be done more accurately. A kinetics analysis on the pyrolysis of cellulose with a single Gaussian distribution DAEM yielded a single activation energy of 178 kJ mol−1 with a narrow standard deviation. This result was justified by a single and dominant endothermic peak followed by minor exothermic peaks in the DSC result. For lignin pyrolysis, the presence of multiple peaks is characterized by four pseudo-components in DAEM with activation energies of 157, 174, 194, and 200 kJ mol−1. These pseudo-components were confirmed by the DSC result which indicated the occurrences of two exothermic peaks with two lesser exothermic or possibly endothermic peaks at the same temperature range. These findings imply the importance of DSC to support a kinetics study of thermogravimetric pyrolysis.

CuSO4 nanoparticles loaded on carboxymethylcellulose/polyaniline composites: A highly efficient catalyst with enhanced catalytic activity in the synthesis of propargylamines, benzofurans, and 1,2,3‐triazoles

AbstractA novel and efficient heterogeneous CuSO4 nanoparticles (CuSO4 NPs) immobilized on carboxymethylcellulose/polyaniline (CuSO4NPs@CMC/PANI) composites were prepared via one‐pot and one‐step interfacial oxidative polymerization of aniline with sodium carboxymethylcellulose (CMC) as soft template and CuSO4 as catalyst. The in situ formed CuSO4 NPs were dispersed uniformly and firmly on the resultant composites and stabilized by complexation with hydroxyl groups (─OH), carboxylate groups (─COO−), nitrogen atoms, and delocalized π‐π conjugate benzenoid and quinoid moieties of CMC/PANI composites. The morphology, composition, and structure of the as‐fabricated composites were systematically characterized by X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), and derivative thermogravimetry (DTG) techniques. The CuSO4NPs@CMC/PANI composites were successfully applied as catalysts in aldehyde‐alkyne‐amine (A3) coupling reactions, A3‐cycloisomerization tandem reactions, and Cu‐catalyzed azide‐alkyne cycloaddition (CuAAC) reactions. All reactions proceeded smoothly and afforded the desired products in excellent yields. Moreover, no significant decrease in catalytic ability was observed in A3 model reaction after 15 recycles, indicating CuSO4NPs@CMC/PANI composites exhibited easy separability and high reusability. Tolerance of wide scope of substrate, excellent catalytic activity, easy operation, recycling of catalyst, and environmental benign are the salient features of these catalytic process.

Mechanical and Microstructural Characteristics of Calcium Sulfoaluminate Cement Exposed to Early-Age Carbonation Curing.

The early-age carbonation curing technique is an effective way to improve the performance of cement-based materials and reduce their carbon footprint. This work investigates the early mechanical properties and microstructure of calcium sulfoaluminate (CSA) cement specimens under early-age carbonation curing, considering five factors: briquetting pressure, water–binder (w/b) ratio, starting point of carbonation curing, carbonation curing time, and carbonation curing pressure. The carbonization process and performance enhancement mechanism of CSA cement are analyzed by mercury intrusion porosimetry (MIP), thermogravimetry and derivative thermogravimetry (TG-DTG) analysis, X-ray diffraction (XRD), and scanning electron microscope (SEM). The results show that early-age carbonation curing can accelerate the hardening speed of CSA cement paste, reduce the cumulative porosity of the cement paste, refine the pore diameter distribution, and make the pore diameter distribution more uniform, thus greatly improving the early compressive strength of the paste. The most favorable w/b ratio for the carbonization reaction of CSA cement paste is between 0.15 and 0.2; the most suitable carbonation curing starting time point is 4 h after initial hydration; the carbonation curing pressure should be between 3 and 4 bar; and the most appropriate time for carbonation curing is between 6 and 12 h.

Thermal reduction of graphene oxide in the presence of carbon suboxide

This work focused on the kinetic analysis of the thermal reduction reaction of graphene oxide (GO) both with and without carbon suboxide (C3O2) by using Borchardt-Daniels, Kissinger, and Ozawa models. The effect of C3O2 on the thermal decomposition of GO was investigated by thermogravimetry (TG), derivative thermogravimetry (DTG), and differential scanning colorimetry (DSC) analysis. It was noticed that C3O2 tends to increase the chemical reactivity of GO due to the decreasing of the reaction activation energy Ea. The apparent reaction order is determined to be 0.7 for the thermal decomposition of both studied samples. This value evidences the complex mechanism of the thermal decomposition of GO that includes consecutive zero-order and first-order processes. Finally, by comparing the enthalpy values of GO thermal decomposition, it was determined that GO sample with the additive of C3O2 releases a lower amount of energy comparing to that of pure GO during the thermal reduction.

The Influence of Potassium Hydroxide Concentration and Reaction Time on the Extraction Cellulosic Jute Fibers

ABSTRACT A common method used to obtain cellulosic fibers is alkalinization with NaOH. Depending on NaOH content, treatments remove significant quantities of lignin and hemicellulose as small molecules. In biorefineries, where the preservation of components is needed, KOH may prevent hemicellulose chain formation. Here, we studied the efficacy of obtaining cellulosic fibers from jute using KOH. Jute fibers are about 84.2% holocellulose, which corresponds to 59.5% alpha cellulose and 24.7% hemicellulose. To obtain high cellulosic fiber yields from jute, effects of pulping with different KOH concentrations and altering reaction times were studied using factorial planning (22). Afterward, in natura and treated fibers were characterized via Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG) and derivative thermogravimetry. Holocellulose sample components were obtained by removing lignin. Factors including concentration and reaction time individually significantly affected cellulose yield. Alpha cellulose was produced when higher levels of the factorial planning conditions were applied. Ideal parameters for cellulose extraction included the addition of 10% (w/v) KOH for 3 h. FTIR analysis was used to ensure that lignocellulosic components were removed by fiber treatment. TG showed that treated fibers were thermally stable at temperatures close to, or higher than, in natura fibers.

Synthesis and characterisation of MCM-41@SiO2-NH-pydc as a new nano mesoporous sorbent: application for the simultaneous preconcentration of cationic dyes previous spectrophotometric determination, using taguchi experimental design

ABSTRACT In this study, a new nano mesoporous MCM-41@SiO2-NH-pydc was successfully synthesised and was used as a new and low-cost adsorbent for the simultaneous influential clean-up, preconcentration and determination of crystal violet (CV) and auramine O (AO) dyes. The as-synthesised sorbent was characterised by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDX), thermogravimetric (TGA) and derivative thermogravimetric (DTG) and Brunauer–Emmett–Teller (BET) techniques. The extraction performance was evaluated by dispersive solid phase micro extraction (DSPME) of CV and AO from real samples. The analysis was carried out by UV-Vis spectrophotometric. The analytical results confirmed that theMCM-41@SiO2-NH-pyd could be an appropriate candidate as asorbent forDSPME. The maximum recoveries (95.95% and 92.95% for CV and AO, respectively) was obtained at 0.015 g MCM-41@SiO2-NH-pydc sorbent, pH = 8.0, 500 μL DMF as eluent solvent, 20 and 10 min extraction and centrifuge time, respectively, and 50 second desorption time. After the optimum conditions, the limit of detection (LOD), quantification (LOQ) and linear range were obtained, 0.0010, 0.0033 and 0.008–0.6 mg L−1 for CV and 0.0056, 0.0187 and 0.03–1.5 mg L−1for AO, respectively. The relative standard deviations (RSD) for five analyses were 4.2% for CV and 4.6% for AO. In comprising with the previous reported methods, the developed method provided a relatively in expensive, time-saving and environmentally friendly advantages. The developed analytical method can be applied for the determination of CV and AO with sufficient sensitivity as well as acceptable reproducibility.

Physicochemical and Thermal Properties of Cellulosic Fiber Extracted from the Bark of Albizia Saman

ABSTRACT The environmental threats posed by manmade composites during their disposal and depletion of fossil fuel resources have necessitated the application of ecofriendly materials for composite making. In the recent decades, many plant fibers with promising potentials required for reinforcing composites have been identified and used for various applications. In this paper, physical, mechanical, and thermal properties in addition to chemical composition of novel lignocellulosic fiber extracted from the bark of Albizia saman (AS) have been reported. Chemical tests on ASFs revealed the presence of high cellulose and lignin contents (60.76% and 14.64%), which contributes significantly to the strength and rigidity of the AS fiber. FT-IR and X-ray diffraction study confirmed the presence of cellulose with high degree of crystallinity (57.69%) and crystallite size (2.85 nm). Thermal stability of ASFs studied through Thermogravimetric, Derivative Thermogravimetric, and Differential Scanning Calorimetry curves revealed the maximum degradation of ASFs as 306.19°C with kinetic activation energy (KAE) of 64.01 kJ/mol. The tensile strength and tensile strain of ASFs was found to be to be in the range 381–1092 MPa and 1.65–4.42%, respectively, and the value of tensile modulus was found to be 9.68–42.31 GPa. From the results, it can be concluded that ASFs possess the essential characteristics required for reinforcing composites and hence can be suitably used for making green composites.