And 3-aminopropyltriethoxysilane Research Articles

The effect of surface-modifier of magnetite nanoparticles on electrochemical detection of dopamine and heating efficiency in magnetic hyperthermia

The citric acid (CA), dextran (DEX) and (3-aminopropyl)triethoxysilane (APTES) are frequently used ligands for surface modification of magnetite nanoparticles to improve their colloidal stability and biocompatibility for use in biomedicine. Here we report the synthesis, surface modification of magnetite (Fe3O4) nanoparticles and analysis of the influence of coating materials on heating efficiency in magnetic hyperthermia, as well as on electrochemical sensing toward the detection of neurotransmitter dopamine (DOP). Spherical magnetite nanoparticles (~13 nm) were prepared by co-precipitation and surface-modified with CA, APTES and DEX. The hyperthermia tests revealed that Fe3O4@APTES resulted in the highest specific absorption rate (SAR) of 67.2 W/g. The engineered sensor, by surface modification of screen-printed carbon (SPC) electrodes with Fe3O4@APTES, showed linear response with DOP in the concentration range of 1−200 μM and a low detection limit of 34.3 nM. Besides, the sensor offered remarkable selectivity, repeatability and reproducibility. Application of SPC-, Fe3O4-, Fe3O4@CA- and Fe3O4@DEX-modified SPC electrode resulted in lower electrocatalytic activity compared with Fe3O4@APTES/SPC. The obtained results indicate the effects of a surface modifier especially that Fe3O4@APTES, alone and combining with SPC electrodes, can serve as an agent in various types of biomedical applications, like hyperthermia and electrochemical sensing of biologically active compounds such as DOP.

Influence of surface treatments and coupling agents on the thermal and thermo‐mechanical properties of yerba mate/post‐consumer polypropylene composites

AbstractThe main objective of this work is to evaluate an interaction between yerba mate fibers (YM) and post‐consumption polypropylene (r‐PP) using the surface treatments and coupling agent. YM fibers were submitted to two different surface treatments: alkaline solution (NaOH 10%) and 3‐aminopropyltriethoxysilane (APTS) (5 wt%). The influence of 5 wt% addition of maleic anhydride (MA)‐grafted polypropylene copolymer (PP‐g‐MA) coupling agent in the composite processing was also evaluated. YM of 30 wt% was loaded into r‐PP by extrusion, and then the specimens were prepared by injection molding. The results showed that all treatments were effective in improving thermal stability increase the maximum degradation temperature by approximately 5°C, as also confirmed by differential scanning calorimetry analysis. Composite with PP‐g‐MA presented the greater increase in thermal stability and in the crystallization index (approximately 46% in relation to the r‐PP/YM30 composite). DMA analysis revealed increases in the storage and loss moduli and a decrease in the damping factor for all composites produced with treated fibers and coupling agent. The enhancement of the analyzed properties of these composites is related to the better interfacial adhesion between YM fiber and r‐PP, which was confirmed by scanning electron microscope micrographs.

Modifying thin-film composite forward osmosis membranes using various SiO2 nanoparticles for aquaculture wastewater recovery

This paper describes the fabrication, modification, and evaluation of the performance of thin-film composite (TFC) forward osmosis (FO) membranes for lab-scale aquaculture wastewater recovery using various fumed silica (SiO2) nanoparticles. The active polyamide (PA) layers of these membranes were novelly modified using different types of pretreated SiO2 nanoparticles [virgin SiO2, dried SiO2, and 3-aminopropyltriethoxysilane (APTES)-modified SiO2] and concentrations (0.05, 0,1, 0,2, and 0.4 wt%) to improve the membrane hydrophilicity with minimum particle agglomeration. Results show that the APTES-SiO2 modified membrane had the highest water flux and selectivity, followed by the dried-SiO2 modified membrane. The APTES coupling agent notably reduced the SiO2 aggregation on the membrane surface and improved membrane hydrophilicity. Consequently, high permeate flux and an acceptable reverse solute flux were observed. The optimal SiO2 concentration for PA modification was 0.1 wt% for all the nanoparticle types. The virgin and APTES-SiO2 modified membranes were used for aquaculture wastewater recovery. The water recovery rate reached 47% in 84 h when using the APTES-SiO2 modified membrane, while it reached only 26% in 108 h when using the virgin membrane. With a suitable design of the filtration apparatus and choice of draw solution (DS), the prepared novel TFC-FO membrane containing APTES-modified SiO2 can be used for recycling aquaculture wastewater into the DS, which can then be reused for other purposes.

Development of an advanced DNA biosensor for pathogenic Vibrio cholerae detection in real sample

Due to the epidemics of emerging microbial diseases worldwide, the accurate and rapid quantification of pathogenic bacteria is extremely critical. In this work, a highly sensitive DNA-based electrochemical biosensor has been developed to detect Vibrio cholerae using gold nanocube and 3-aminopropyltriethoxysilane (APTES) modified glassy carbon electrode (GCE) with DNA carrier matrix. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) experiments were performed to interrogate the proposed sensor at each stage of preparation. The biosensor has demonstrated high sensitivity with a wide linear response range to target DNA from 10−8 to 10−14 (R2= 0.992) and 10−14 to 10−27 molL−1 (R2= 0.993) with a limit of detection (LOD) value of 7.41 × 10−30 molL−1 (S/N = 5). The biosensor also exhibits a selective detection behavior in bacterial cultures that belong to the same and distant genera. Moreover, the proposed sensor can be used for six consecutive DNA assays with a repeatability relative standard deviations (RSD) value of 5% (n = 5). Besides, the DNA biosensor shows excellent recovery for detecting V. cholerae in poultry feces, indicating that the designed biosensor could become a powerful tool for pathogenic microorganisms screening in clinical diagnostics, food safety, and environmental monitoring.

Solid-state photoluminescent silicone-carbon dots/dendrimer composites for highly efficient luminescent solar concentrators

Luminescent solar concentrators (LSCs) with high performances depend on not only the luminescent materials, but their dispersed polymer matrixes. However, carbon dots (CDs)-based LSCs suffer from aggregation-caused fluorescence quenching with the increased concentration of CDs in polymer matrix. To solve this issue, a novel solid-state photoluminescent (PL) silicone-carbon dots (Si-CDs) composites was synthesized by one-step solvothermal treatment of citric acid, dicyandiamide and 3-aminopropyltriethoxysilane (APTES). The solid-state PL Si-CDs showed yellow-green emission at 525 nm under excitation of UV light. For better dispersion of Si-CDs, two types of silicone dendrimers (denoted as D1 and D2) were designed and synthesized via a transesterification and hydrosilylation reaction method. The structure differences between D1 and D2 are the contents of phenyl and methoxy groups. Remarkably, silicone dendrimers with high loading of Si-CDs (up to 35 wt%) could be obtained owing to their good compatibility. Single-layered LSCs could be prepared easily by directly casting the above mixtures on glass substrates followed by room temperature curing. The external optical efficiency (ηopt) of 7.58%, 5.38% had been achieved from D1 and D2 based LSCs (25 × 25 × 1 mm), respectively. This work provides a convenient method for preparing highly efficient LSCs, posing great potential in various specific applications.

A Label-Free Liquid Crystal Biosensor Based on Specific DNA Aptamer Probes for Sensitive Detection of Amoxicillin Antibiotic.

We developed a liquid crystal (LC) aptamer biosensor for the sensitive detection of amoxicillin (AMX). The AMX aptamer was immobilized onto the surface of a glass slide modified with a mixed self-assembled layer of dimethyloctadecyl [3-(trimethoxysilyl) propyl] ammonium chloride (DMOAP) and (3-aminopropyl) triethoxysilane (APTES). The long alkyl chains of DMOAP maintained the LC molecules in a homeotropic orientation and induced a dark optical appearance under a polarized light microscope (POM). In the presence of AMX, the specific binding of the aptamer and AMX molecules induced a conformational change in the aptamers, leading to the disruption of the homeotropic orientation of LCs, resulting in a bright optical appearance. The developed aptasensor showed high specificity and a low detection limit of 3.5 nM. Moreover, the potential application of the developed aptasensor for the detection of AMX in environmental samples was also demonstrated. Therefore, the proposed aptasensor is a promising platform for simple, rapid, and label-free monitoring of AMX in an actual water environment with high selectivity and sensitivity.

Controlled release of molasses melanoidin-like product from hybrid organic-inorganic silica xerogels and its application to the phytoextraction of lead through the Indian mustard.

In this study, we investigate the release of melanoidin-like product (MLP) from hybrid silica xerogels to control the quantity of MLP in the medium for lead phytoextraction. In the preparation of the hybrid organic-inorganic xerogels with MLP, tetraethoxysilane (TEOS), methyltriethoxysilane (MTES), propyltriethoxysilane (PTES), and 3-aminopropyltriethoxysilane (APTES) were used as precursors. The experimental results suggest that the release of MLP can be easily controlled by partially substituting TEOS with the organosilanes. The addition of the organosilanes lowered the release rate of MLP in the following order of xerogels: TEOS, MTES/TEOS, PTES/TEOS, and APTES/TEOS. Furthermore, a novel phytoextraction of lead through the Indian mustard was conducted using the MLP-doped TEOS xerogel. Results show that the addition of TEOS xerogel did not have any influence on the growth of the mustard, whereas the lead uptake significantly increased in a nutrition medium with 1-mM Pb(NO3)2. In conclusion, the beneficial effect of the MLP-doped TEOS xerogel on lead phytoextraction was confirmed.

Synthesis of magnetic core-shell amino adsorbent by using uniform design and response surface analysis (RSM) and its application for the removal of Cu2+, Zn2+, and Pb2+

The magnetic Fe3O4 was synthesized by using a one-step solvothermal method. Then, anhydrous ethanol as a solvent, tetramethyl ammonium hydroxide (TMAOH) as an auxiliary agent, tetraethyl orthosilicate (TEOS) as a silicon source, and (3-aminopropyl) triethoxysilane (APTES) as amino source were used to prepare Fe3O4@mSiO2-NH2 by using the sol-gel method. Uniform design U14*(145) and the response surface method (RSM) were used to optimize the synthesis ratio. According to the results of TEM, SEM, N2 adsorption-desorption test, VSM, and XRD, it found that the best coating effect obtained when the relative molar ratio of TMAOH:TEOS:APTES:Fe3O4 was 5:4:6:0.45. The results of EDS and elemental analysis confirmed the success of amino group coating; VSM magnetization after surface modification was 32emu/g; BET results show that specific surface area is 236m2/g, size 5nm, and the pore volume is 0.126cm3/g. The removal of Cu2+, Zn2+, and Pb2+ by Fe3O4@mSiO2-NH2 was studied at the optimal initial pH value 6 of the adsorption test system. The isothermal adsorption results show that the Langmuir model and Redlich-Peterson model are more suitable than the Freundlich model to describe the adsorption behavior, and Cu2+, Zn2+, and Pb2+ adsorption is mainly single molecular layer. The maximum adsorption capacity qm of the Langmuir model for Cu2+, Zn2+, and Pb2+ removal was 48.04mg/g, 41.31mg/g, and 62.17mg/g, respectively. The adsorption kinetic rates of Cu2+, Zn2+, and Pb2+ on Fe3O4@mSiO2-NH2 relatively more suitable for pseudo-second-order kinetic model, i.e., R2, were ranged between 0.995 and 0.999, and the suitable reaction time was 60min. These results proved that Fe3O4@m-SiO2-NH2 prepared by using this method is easy to synthesize, has easy recovery, is ecofriendly, and can be potential adsorbent for Cu2+, Zn2+, and Pb2+ removal.

Mechanism of Adhesion of Natural Polymer Coatings to Chemically Modified Siloxane Polymer.

Surface coatings play an important role in improving the performance of biomedical implants. Polydimethylsiloxane (PDMS) is a commonly used material for biomedical implants, and surface-coated PDMS implants frequently face problems such as delamination or cracking of the coating. In this work, we have measured the performance of nano-coatings of the biocompatible protein polymer silk fibroin (SF) on pristine as well as modified PDMS surfaces. The PDMS surfaces have been modified using oxygen plasma treatment and 3-amino-propyl-triethoxy-silane (APTES) treatment. Although these techniques of PDMS modification have been known, their effects on adhesion of SF nano-coatings have not been studied. Interestingly, testing of the coated samples using a bulk technique such as tensile and bending deformation showed that the SF nano-coating exhibits improved crack resistance when the PDMS surface has been modified using APTES treatment as compared to an oxygen plasma treatment. These results were validated at the microscopic and mesoscopic length scales through nano-scratch and nano-indentation measurements. Further, we developed a unique method using modified atomic force microscopy to measure the adhesive energy between treated PDMS surfaces and SF molecules. These measurements indicated that the adhesive strength of PDMS-APTES-SF is 10 times more compared to PDMS-O2-SF due to the higher number of molecular linkages formed in this nanoscale contact. This lower number of molecular linkages in the PDMS-O2 indicates that only fewer numbers of surface hydroxyl groups interact with the SF protein through secondary interactions such as hydrogen bonding. On the other hand, a larger number of amine groups present on PDMS-APTES surface hydrogen bond with the polar amino acids present on the silk fibroin protein chain, resulting in better adhesion. Thus, APTES modification to the PDMS substrate results in improved adhesion of nano-coating to the substrate and enhances the delamination and crack resistance of the nano-coatings.

Crosslinked Proton Exchange Membranes with a Wider Working Temperature Based on Phosphonic Acid Functionalized Siloxane and PPO

A series of proton exchange membranes were prepared by incorporating phosphonic functionalized siloxane into sulfonic poly(2,6-dimethyl-1,4-phenyleneoxide) (SPPO) and imidazole functionalized poly(2,6-dimethyl-1,4-phenyleneoxide) grafted with siloxane (IPPO-Si). Phosphonic acid functionalized siloxane was synthesized from amino trimethyl phosphonic acid (ATMP) and (3-aminopropyl)triethoxysilane (APTES). FTIR results showed that 1-methylimidazole and APTES were successfully grafted onto polyphenylene oxide, and APTES successfully formed Si-O-Si crosslinked networks through hydrolytic crosslinking. The membranes were thermally stable up to 220 °C and exhibited excellent oxidative stability and mechanical performance. We also measured the proton conductivity of the membranes. The results showed that the proton conductivities of the composite membranes increased with the increasing of SPPO content at different degrees under high (100 °C–160 °C) and low (25 °C–80 °C) temperature conditions. Furthermore, the IPPO-SI-P/SPPO-30 has the best conductivity, reaching to 0.1131 S cm−1 at 80 °C, 100%RH and 0.1049 S cm−1 at 160 °C, 5%RH, respectively. Therefore, this novel membrane acts as a potential candidate for proton exchange membranes with a wider applicable temperature (25 °C–160 °C).

Comparison of Structure and Adsorption Properties of Mesoporous Silica Functionalized with Aminopropyl Groups by the Co-Condensation and the Post Grafting Methods.

The adsorptive potential has been evaluated for the aminopropyl functionalized mesoporous silica materials obtained by co-condensation and post grafting methods. Nitrogen sorption, small angle neutron and X-ray scattering (SANS and SAXS) demonstrated high surface area and well-ordered hexagonal pore structure suitable for applications as adsorbents of metals from waste waters. A comparison of Cr(VI) adsorption properties of the materials prepared by different functionalization methods has been performed. The obtained results demonstrated the adsorption capacity due to the affinity of the chromium ions to the amino groups, and showed that co-condensation of tetraethoxysilane (TEOS) and 3-aminopropyl triethoxysilane (APTES) resulted in higher metal sorption capacity of the materials compared to post-synthesis grafting of aminopropyl groups onto the mesoporous silica particles.

Enhanced corrosion inhibition of low carbon steel in aqueous sodium chloride employing sol–gel-based hybrid silanol coatings

The anti-corrosion properties of sol–gel-based hybrid silanol coatings incorporated with span tea leaves extract employed on low carbon steel in saline solution was explored by electrochemical and surface analyses. Hybrid sol–gel matrices were prepared by copolymerizing tetraethyl orthosilicate (TEOS) and 3-aminopropyltriethoxysilane (APTES). Corrosion protective hybrid sol–gel coatings were dip-coated on low carbon steel substrates and sintered to ensure the formation of metallo-siloxane bonds. Inhibition efficiency of 85.66% was achieved with the doping concentration of 75 ppm of water extract into hybrid sol–gel at 30 °C. Polarisation studies demonstrated that the hybrid coatings incorporated with water extract of span tea leaves operate as a mixed-type inhibitor. The Nyquist impedance plots depicted that on increasing the concentration of span tea leaves extract, charge transfer resistance (Rct) increased, and double-layer constant phase element (CPEdl) decreased. A comparison of the corrosion resistance of the coated and uncoated low carbon steel substrates was presented. Electrochemical noise analysis substantiated that the optimum corrosion-resistant coating formulation endured a much lower current noise fluctuation. Moreover, wettability analysis established the hydrophobic nature of the optimum corrosion protective coating.

(3-Aminopropyl)triethoxysilane and iron rice straw biochar composites for the sorption of Cr (VI) and Zn (II) using the extract of heavy metals contaminated soil

Heavy metals like Cr (VI), when released into the environment, pose a serious threat to animal and human health. In this study, iron and (3-Aminopropyl)triethoxysilane (APTES) biochar composites were prepared from the biochar, which was produced through the pyrolysis of rice straw at 400 and 600 °C, using the chemical processes with an aim that the doping of pristine biochar structure with the Fe and NH2 radicals would enhance the removal of Cr (VI) and Zn (II) adsorption in both aqueous solution and soil. Both biochar composites were mixed at a rate of 3% (w/w) with the mine soil for the soil incubation test, and after completion of the test, a soil fertility index (SFI) was calculated. Results showed that both iron and APTES biochar composites followed the Langmuir-Freundlich isotherm showing the maximum removal capacity of 100.59 mg/g for Cr (VI) by APTES/SiBC 600 and maximum adsorption capacity of 83.92 mg/g for Zn2+ by Fe/BC 400. The SFI of the mine-soil amended with both Fe and APTES biochar composites were 16.67 and 13.04%, respectively higher than the controlled study. The mitotic index of the A. cepa cells that grew up in the soil amended with Fe/BC and APTES/SiBC were 40.47 and 44.45%, respectively, higher than the controlled study. The results indicated that the incorporation of the Fe and APTES biochar composites in the soil effectively reduced the metal toxicity and improved the soil physicochemical properties. This study opens up the prospects of using biochar composites in contaminated soil and water treatments.

Intermolecular interactions in composites of organically-modified silica aerogels and polymers: A molecular simulation study

Two types of ORMOSIL-based composite systems have been studied by all-atom molecular dynamics simulations: (i) tetramethylorthosilicate (TMOS) and vinyltrimethoxysilane (VMTS) with polydimethylsiloxane (PDMS); and (ii) tetraethylorthosilicate (TEOS) and 3-aminopropyltriethoxysilane (APTES) or TEOS/(3-glycidyloxypropyl)trimethoxysilane (GLYMO) with the polyimides/polyamic acids of 3,3’,4,4’-biphenyltetracarboxylic dianydride – 4,4’-oxydianiline (BPDA-ODA) and pyromellitic dianhydride – 3,5-diaminobenzoic acid (PMDA-DBA). For systems (i) it was concluded that an increase in the % mol of PDMS leads to the formation of smaller aggregates of silica primary particles, which is explained by the reduction in the number of silica–silica H-bonds in favor of silica-PDMS H-bonds; both electrostatic and van der Waals interactions contribute significantly for the overall attractive forces between the two phases. In the case of systems (ii), the silica hydroxyl and amine groups form H-bonds with anhydride, carbonyl, carboxyl and terminal amine groups in the polyimides/polyamic acids, whereas for the TEOS/GLYMO the most prevalent H-bonds are those developed between hydroxyl silica groups and carboxyl or terminal amine groups of the polymer chains; in the latter composite systems, van der Waals forces play a more significant role in the adhesion between silica particles and the polymer.

Enhancement of acid dyestuff salt-free fixation by a cationizing sol-gel based coating for cotton fabric

In the last years, several technologies have been investigated to introduce cationic sites onto cotton fibres to enhance anionic dyestuff uptake properties. However, several limitations of proposed technologies, such as fabric yellowing, high cost, inadequate reactivity, and toxicity of used chemicals, have still restricted the development of cationizing functional coatings. Herein, a new non-conventional sol-gel treatment of cellulose-based fabrics was investigated to introduce positive electrical charges as useful sites for binding acid dyestuffs, characterized by a featuring extensive colour range and bright shades. As proved by zeta potential and surface charge measurements as well as Fourier-Transform Infrared spectroscopy, the two-step procedure achieved using tetraethylorthosilicate (TEOS) and (3-Aminopropyl)triethoxysilane (APTES) sol-gel precursors promoted the functionalization of cotton fibres introducing amino groups, able to counteract the negative charge of cellulose during the dyeing procedure under acidic conditions. The dyestuff affinity for treated samples, compared to untreated cotton and polyamide references, was measured by competitive fixation of an acid dyestuff, namely Acid Yellow 114, from a non-electrolyte aqueous solution. The results showed that protonated amino groups, obtained at the highest APTES concentration, can reverse fibres charge enhancing anionic dye uptake properties without the addition of electrolytes. Compared to untreated cotton, the colour strength of cationized cotton was improved by nearly 90 %, depending on the APTES concentration, reaching performances obtained using a polyamide reference. The findings make sol-gel a reliable and promising method for cationizing cotton fibres for eco-friendly dyeing processes of cotton using acid dyestuffs.

Innovative application of facile single pot green synthesized CuO and CuO@APTES nanoparticles in nanopriming of Vigna radiata seeds.

Nanopriming is an emerging field of science which uses nanoparticles in solution to improve parameters of seed vigor. This leads to an initial advantage to the crop plant at the germination phase of its life cycle, which is also the most vulnerable phase and may lead to an improved yield. In this study, we have synthesized copper oxide (CuO) and (3-Aminopropyl) triethoxysilane (APTES)-coated CuO (CuO@APTES) nanoparticles via environmentally friendly green synthesis using the extract of Coriandrum sativum (coriander) herb. The synthesized nanoparticles were used as nanoprimers on Vigna radiata (moong bean), a model legume, to promote seed vigor via increase in germination. This was followed by characterization and comparison of both types of nanoparticles using various physicochemical techniques; UV-Visible (UV-Vis), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), dynamic light scattering (DLS), zeta potential, and transmission electron microscopy (TEM). All characterization techniques pointed out to the successful synthesis and coating of CuO nanoparticles. Seed imbibition and germination assays were performed, which indicated increased imbibition potential and germination promotion at low nanoparticle concentration. Such studies can be used in the development of simple prepackaged nanoprimer products, which can be used by farmers before sowing to provide a boost to their crops and productivity.

A SERS aptasensor based on AuNPs functionalized PDMS film for selective and sensitive detection of Staphylococcus aureus

In this study, a sensitive biosensor was developed based on aptamer functionalized polydimethylsiloxane (PDMS) film for the detection of Staphylococcus aureus (S. aureus) using surface-enhanced Raman scattering (SERS) technology. Initially, the surface of PDMS film was chemically modified by piranha solution and 3-Aminopropyltriethoxysilane (APTES), and then AuNPs-PDMS film was prepared by coating gold nanoparticles (AuNPs) through electrostatic interaction. Next, the aptamers were immobilized on the AuNPs-PDMS membrane via gold-sulfur bond to form the capture substrate. Meanwhile, gold-silver core-shell nanoflowers (Au@Ag NFs) modified with mercaptobenzoic acid (4-MBA) and aptamers were applied as a signal probe. In the presence of the target, the signal molecular probe and the capturing substrate specifically combined with the target and resulted in a sandwich structure “capture substrate-target-signal molecular probe”. Under the optimized experimental condition, the signal of 4-MBA at 1085 cm-1 was linearly related to the S. aureus concentration in the range of 4.3 × 10 cfu mL−1-4.3 × 107 cfu mL−1 (y = 326.91x-117.62, R2 = 0.9932) with a detection limit of 13 cfu mL−1. The method was successfully applied to spiked actual samples and a 92.5–110% recovery rate was achieved.

Cadmium cation uptake through amine and acid post‐functionalized Santa Barbara Amorphous materials; comprehensive adsorption studies

AbstractIn this research, a novel adsorbent, nitrilotriacetic acid anhydride (NTAA) and 3‐aminopropyltriethoxysilane (APTES) modified Santa Barbara Amorphous materials (SBA‐15) as a mesoporous silica was synthesized and applied for the adsorption of cadmium solution. X‐ray diffraction, transmission electron microscopy, scanning electron microscopy, nitrogen adsorption–desorption isotherms and Fourier transform infrared analysis were used. The adsorption experiments were performed during batch system containing different concentrations of cadmium solution (60–120 mg/L) in pH range of 2–10, adsorbent dosage of 100–600 mg/L with contact time interval of 15–120 min. The maximum cadmium removal was achieved at pH 6 with 250 mg/L of adsorbent after 60 min. The proposed mechanisms for the removal and capture of Cd+2 ions by adsorbent are electrostatic interactions and chelation. The equilibrium studies prove that the experimental data are compatible with the Langmuir isotherm model well with the maximum adsorption capacity of 500 mg/g. Kinetic and thermodynamic studies also indicate that pseudo‐second order kinetic model is the predominant model and the adsorption process is exothermic. This study reveals a high capability of novel nano‐adsorbent for the efficient removal of hazardous heavy metal cations and anions from wastewater.

Synthesis and characterization of dialdehyde cellulose/amino‐functionalizedMCM‐41 core‐shellmicrospheres as a new eco‐friendly flame‐retardant nanocomposite

AbstractUsing proper flame‐retardant materials when constructing buildings or fabricating devices is the most important fire safety guidelines. The halogen and phosphorus‐based compounds are among the most effective flame retardants. However, most of these compounds are recognized to have a harmful effect on human body and the environment during combustion. In this context, we designed and synthesized a new eco‐friendly flame‐retardant nanocomposite by combining dialdehyde cellulose (DAC) and amino‐functionalized mesoporous silica MCM‐41 (N‐M41). Spherical N‐M41 nanoparticles have been successfully prepared in one‐pot reaction using tetraethyl orthosilicate and (3‐aminopropyl)triethoxysilane (APTES), and then coated with different amounts of DAC through Schiff base reaction between the carbonyl group of DAC and NH2of APTES. The resulted DAC@N‐M41 nanocomposite was characterized by XRD, Fourier transform infrared, scanning electron microscopy, transmission electron microscopy, differential thermal analysis (DTA) and thermogravimetry analysis (TGA). TEM micrographs revealed that this nanocomposite was made up of core‐shell nanospheres structure with narrow size distribution (ca. 140 nm). DTA and TGA analysis revelated that the presence of silica within the nanocomposite can effectively increase the char yield, decrease the heat release, and improve the fire performance of the prepared nanocomposite. A mechanism of the reduction in flammability of this nanocomposite has been proposed.

Water management improvement in PEM fuel cells via addition of PDMS or APTES polymers to the catalyst layer.

Water management is one of the obstacles in the development and commercialization of proton exchange membrane fuel cells (PEMFCs). Sufficient humidification of the membrane directly affects the PEM fuel cell performance. Therefore, 2 different hydrophobic polymers, polydimethylsiloxane (PDMS) and (3-Aminopropyl) triethoxysilane (APTES), were tested at different percentages (5, 10, and 20 wt.%) in the catalyst layer. The solution was loaded onto the surface of a 25 BC gas diffusion layer (GDL) via the spraying method. The performance of the obtained fuel cells was compared with the performance of the commercial catalyst. Characterizations of each surface, including different amounts of PDMS and APTES, were performed via scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) analyses. Molecular bond characterization was examined via Fourier transform infrared spectroscopy (FTIR) analysis and surface hydrophobicity was measured via contact angle measurements. The performance of the fuel cells was evaluated at the PEM fuel cell test station and the 2 hydrophobic polymers were compared. Surfaces containing APTES were found to be more hydrophobic. Fuel cells with PDMS performed better when compared to those with APTES. Fuel cells with 5wt.% APTES with a current density of 321.31 mA/cm 2 and power density of 0.191 W/cm 2 , and 10wt.% PDMS with a current density of 344.52 mA/cm 2 and power density of 0.205 W/cm 2 were the best performing fuel cells at 0.6V.