3-aminopropyl Trimethoxysilane Research Articles

Effectiveness of amino-functionalized sorbents for co2 capture in the presence of Hg

The reduction of CO2 emissions is an urgent need that is acknowledged worldwide. Amino-silica sorbents are one of the most promising adsorbents for capturing CO2 from several gas streams due to their excellent textural properties and reversible reactions with CO2. However, gas streams also contain impurities that can affect the retention of CO2 by such sorbents. This study focuses on the effect of the presence of mercury in the gas stream on a series of amino sorbents developed for CO2 capture. Amino-silica adsorbents were functionalized by grafting with aminopropyl-trimethoxysilane (AP) or trimethoxysilylpropyl-diethylenetriamine (DT) and by impregnation with polyethyleneimine (PEI) or tetraethylenepentamine (TEPA). A double functionalization route that combines grafting and impregnation was also assayed. The effect of mercury on the CO2 adsorption capacity of the sorbents was evaluated in a fixed reactor at 40 °C. The double-functionalized adsorbents showed high CO2 uptakes with CO2 adsorption capacities of 5–6 mmol CO2/g (0.15 bar CO2, 40 °C). In addition, their CO2 adsorption capacity was maintained over several cycles. It was established that the presence of mercury undermined the CO2 adsorption capacity of the adsorbents by just 3–16%, demonstrating in general the good selectivity of these materials for CO2, an essential requirement for avoiding the accumulation of mercury during the regeneration process of the solid sorbent and the consequent environmental and technological problems that might ensue.

Characterization of polylactic-epoxidized natural rubber/modified cellulosic fiber biocomposites with different silane coupling agents

A purpose of this research was to investigate a potential of two differently modified cellulosic fibers for applying as reinforcing fillers in polylactic acid (PLA) and modified epoxidized rubber (ENR) base of biocomposites. Coupling agents including 3-(trimethoxysilyl) propyl methacrylate and (3-aminopropyl) trimethoxysilane were used in order to modify cellulosic fibers. These fibers were compounded with PLA-modified ENR (modified by bisphenol A diglycidyl ether) in an internal mixer and fabricated to composite sheets using a compression molding, respectively. The formulations of biocomposites were designed by weight ratio of PLA (85%): modified ENR (5%): the cellulosic fiber (10%). Accordance with the results of mechanical property analysis of their biocomposites, the modifications of cellulosic fibers with both silane types significantly improved flexural, hardness and impact properties of PLA-modified ENR based biocomposites. However, the methacrylate-silane modified cellulosic fiber provided the greatest increase in flexural properties while the amino-silane modified cellulosic fiber resulting in the highest value of hardness and impact resistance of all biocomposites. Oil absorption test of biocomposites was also investigated in this research in order to evaluate its possibility to use under oily environment. After 168 hours of experiment, the amino-silane modified composite exhibited the highest oil absorption among all materials. This result indicated the most improvement of hydrophobicity of modified cellulosic fiber by (3-aminopropyl) trimethoxysilane.

Thermal and barrier properties of poly(butylene adipate-coterephthalate) incorporated with zeolite doped potassium ion for packaging film

In this research, the works were focused on development of film packaging of poly(butylene adipate-co-terephthalate) (PBAT) incorporated with modified zeolite using (3-aminopropyl) trimethoxysilane. PBAT composites were compounded by melt mixing using twin screw extrusion then molded into film by cast film extrusion process. Effects of zeolite 13X at 1 wt% and zeolite doped potassium ion (K+) on thermal properties, permeability of gases (oxygen, carbon dioxide and water vapor) and also absorption of ethylene gas of PBAT composites films have been studied. Typically, zeolite would act as a nucleating agent. Therefore, adding zeolite would increase the degree of crystallinity of PBAT. Comparing zeolite with and without cation exchange, the degree of crystallinity in film tended to increase for the one doped with potassium ion. Either zeolite with or without potassium exchange had no impact on thermal stability of composite films. Gas permeation of PBAT/zeolite film possessed lower permeation of oxygen and carbon dioxide whereas the water vapor transmission showed relatively higher rate than the neat PBAT. After cation exchange with zeolite, the permeation of oxygen and carbon dioxide has reduced 21.04% and 21.90% respectively but the effect of K+ exchange had no effect on water vapor transmission compared with PBAT. Film of PBAT and zeolite doped with cation could absorb ethylene gas more than the one with zeolite.

Highly fluorescent silicon quantum dots decorated silica microspheres for selective detection and removal of Au3+ and subsequent catalytic application

Sensitive detection and efficient removal of Au3+ are important for environmental monitoring and remediation. In this study, silicon quantum dots (SiQDs) were prepared with 3-aminopropyl trimethoxysilane as the silicon source and boric acid as the doping substance to enhance fluorescence quantum yield. The obtained SiQDs possessed fluorescence sensing ability of Au3+ and were successfully decorated on the mesoporous silica microspheres (SiO2), giving SiO2-SiQDs. Owing to the high affinity for Au3+ and the relatively large surface area, the SiO2-SiQDs exhibited not only selective fluorescence detection of Au3+ in water matrix with a relatively low limit of detection (13.67μgL−1), but also efficient adsorption of Au3+ with a maximal adsorption capacity of 530.7mgg−1. Besides, the Au3+ adsorbed on the SiO2-SiQDs could be in-situ reduced into evenly dispersed small-size gold nanoparticles, showing high catalytic efficiency for the reduction of 4-nitrophenol. The remarkable performance of SiO2-SiQDs on detection, adsorption and reusability demonstrated its multi-purposed applicabilities.

Electrochemical Anodization of 2-nm-Thick Tantalum Films for Self-Assembling of Molecularly Thick Layer as a Barrier for Copper

TaN in conjunction with adhesive Ta is a key barrier component of Cu-Damascene structure. However, the limited scalability and stability of TaN pose a dire need of an alternative molecularly thick (≤1 nm) barrier. To this end, the feasibility of anodizing 2-nm-thick Ta films with a mild ethanol based solution, rather than the commonly used strongly acidic (aggressive) chemical electrolytes, to enhance the formation of (3-aminopropyl) trimethoxysilane (APTMS) monolayer barrier is studied. Performing the anodization in an H2O-containing (1%) ethanol solution results in a prompt oxidization of the Ta film surface into fully passive Ta2O5 layer with extremely smooth topography, subsequently facilitating the growth of a fully oriented monolayer serving triply as a seed adsorber (for electroless Cu plating), barrier and adhesion promoter. Using Ta (pristine)/Cu [and Ta (pristine)/SAM/Cu] as a control, Ta (anodized)/SAM/Cu exhibits markedly higher adhesion strength (25.2 vs <1 MPa) and resistance against thermal failure (>500 vs 425 °C) of Cu. H2O is heavily involved in the anodization efficiency of the Ta films and is the key underlying factor deciding orientation ordering and barrier capacity of the monolayer fabricated. This is related to H2O-enhanced surface hydroxylation and Ta2O5 passivation of Ta.

Anodization of Tantalum Films for the Enhancement of Monolayer Seeding and Electroless Copper Plating

Ta is a common barrier component for Cu metallization because of their immiscibility resulting in lack of mutual chemical reactivity and solubility. Conventionally, Cu is pre-sputtered on Ta as a seed layer, followed by Cu electroplating. Electroless metallization of Cu on Ta through self-assembled monolayer (SAM) seeding is rarely studied. Herein, electrochemical anodization of Ta films in an ethanol-based solution is performed to achieve a functionalized surface for sequential silanization of (3-aminopropyl)trimethoxysilane (APTMS), seeding, and electroless Cu plating. The SAM grown on hydrously (1% H2O) anodized Ta films is fully oriented, acting as an effective seed anchoring agent and adhesion promoter to yield high densities of Ni seeds (>5 × 1015 m−2) and tight binding of a Cu film (25.6 MPa). However, the SAM grown on anhydrously anodized Ta films has a substantially deteriorated ordering, giving poor seeding (<8 × 1014 m−2) and Cu-film adhesion (8.8 MPa). Similar deteriorations are observable from the pristine Ta film. The enhancements of SAM silanization and Ni seeding are caused by the improvement of chemical structure of anodization-induced surface tantalum oxide. The role of water in the anodization solution in enhancing anodization efficiency and SAM orientation is fully discussed.

Generation of Giant Unilamellar Vesicles (GUVs) Using Polyacrylamide Gels.

Giant unilamellar vesicles (GUVs) are a widely used model system for a range of applications including membrane biophysics, drug delivery, and the study of actin dynamics. While several protocols have been developed for their generation in recent years, the use of these techniques involving charged lipid types and buffers of physiological ionic strength has not been widely adopted. This protocol describes the generation of large numbers of free-floating GUVs, even for charged lipid types and buffers of higher ionic strength, using a simple approach involving soft polyacrylamide (PAA) gels. This method entails glass cover slip functionalization with (3-Aminopropyl)trimethoxysilane (APTES) and glutaraldehyde to allow for covalent bonding of PAA onto the glass surface. After polymerization of the PAA, the gels are dried in vacuo. Subsequently, a lipid of choice is evenly dispersed on the dried gel surface, and buffers of varying ionic strength can be used to rehydrate the gels and form GUVs. This protocol is robust for the production of large numbers of free-floating GUVs composed of different lipid compositions under physiological conditions. It can conveniently be performed with commonly utilized laboratory reagents.

One-pot Facile Preparation of Amino-functionalized Silica Hybrid Monoliths for Mixed-mode Chromatography

Silica hybrid monolithic columns were prepared using two precursors, in which organo-functionalized trialkoxysilanes are mixed with tetraalkoxysilanes. In this study, several types of amino-functionalized silica hybrid monolithic columns were prepared via single-step “one-pot” approach, and the amount of silica precursors, porogens, as well as the reaction conditions were optimized. The preparation was carried out by mixing the silica precursors, i.e. tetraethoxysilane (TEOS) or tetramethoxysilane (TMOS) with amino precursors such as aminopropyltrimethoxysilane (APTES), aminoethylaminopropyl-trimethoxysilane (AEAPTMS), and phenylaminopropyltrimethoxysilane (PAPTMS) in a porogenic solution. The chromatographic performance of these hybrid monolithic columns was optimized by investigating several parameters through the separation of inorganic anions (IO3-, BrO3-, Br-, NO2-, NO3-, I-, SCN-) and some polar compounds (thymine, thymidine, adenosine, adenine, uridine). Results showed that the silica hybrid monolithic columns could be operated at higher flow-rate that favors rapid separation. The run-to-run repeatability of Si-APTES and Si-PAPTMS hybrid monolithic columns were satisfactory with relative standard deviations (n = 5) of less than 8% for all the analyte anions.

Diametral Tensile Strength and Reflectance Evaluation of Dental Composite Prototype Using Modified Dental Composite Procedures

Dental composite is used to restore disease or fracture tooth structure and modify tooth shape as well as color in order to enhance the aesthetic properties. This restoration should possess sufficient strength and translucency at the same time. Diametral tensile strength and reflectance of dental composite were related to the selection of three main components; filler, coupling agent and resin matrix. Quarsi-experimental. This study was a follow-up study whereby the filler silica-zirconia-alumina system were synthesized by sol-gel technique with precursors composition ratio 70:20:10. The surface of subsequent filler were modified by 3-mercaptoppropyltrimethoxysilane (MPTMS) and aminopropyltrimethoxysilane (APTES) then becoming group A and B respectively. In order to prepared the dental composite, acetone was used to reduce the viscosity of Bisphenol A Glycidyl Methacrylate (BisGMA) thus enable introducing more content of filler into resin matrix. Phase of crystalline and particle morphology were identified by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) consecutively. Universal Testing Machine (Lloyd) with crosshead speed 1mm/min was used to evaluate diametral tensile strength between two samples group. Dental composite contain filler-MPTMS coated were continuing tested to measure the reflectance values. Disc of each samples were prepared (n=3) with different thickness (1.5 mm and 3 mm) and same diameter (20 mm). Both diametral tensile strength and reflectance evaluation data were analysis by t-test unpaired. The result showed no statistically significant differences in diametral tensile strength between group A (47,6548 MPa) and B (41,4265 MPa). Reflectance evaluation also exhibited no statistically significant differences in dental composite contain filler-coated MPTMS with different thickness. Dental composite prototype based on diametral tensile strength and reflectance evaluation were potential to be used as alternative dental restoration.

Study on the preparation of amine-modified silicate MCM-41 adsorbent and its H2S removal performance

A series of APTMS ((3-aminopropyl)trimethoxysilane)-modified silicate MCM-41 adsorbents ( x-APTMS/MCM-41, x is the volume of APTMS per 1 g of silicate MCM-41) with different APTMS contents was prepared, and the effects of APTMS content on the desulfurization performance of the APTMS/MCM-41 adsorbents were studied in a fixed adsorption bed using H2S and N2 mixture as a model gas. The as-prepared adsorbents were characterized by X-ray diffraction analysis, N2 adsorption–desorption, Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, and energy-dispersive spectroscopy. The results showed that all the APTMS-modified x-APTMS/MCM-41 adsorbents retained the mesoporous silica structure of MCM-41. The Brunauer–Emmett–Teller-specific surface area of x-APTMS/MCM-41 increased slightly with increasing x at first and then decreased with further increasing APTMS content. The H2S removal performances of x-APTMS/MCM-41 adsorbents decreased in the order 0.6-APTMS/MCM-41 &gt; 0.7-APTMS/MCM-41 &gt; 0.5-APTMS/MCM-41 &gt; 0.4-APTMS/MCM-41 &gt; 0.8-APTMS/MCM-41. At x = 0.6, the maximum H2S removal rate of 54.2% and H2S saturated capacity of 134.4 mg g−1 were observed. The regeneration experiment of 0.6-APTMS/MCM-41 adsorbent after three times regeneration at 423 K for 3 h in nitrogen confirmed that it possessed a good regenerability.

Highly Loaded Cellulose/Poly (butylene succinate) Sustainable Composites for Woody-Like Advanced Materials Application.

We report the manufacturing and characterization of poly (butylene succinate) (PBS) and micro cellulose (MCC) woody-like composites. These composites can be applied as a sustainable woody-like composite alternative to conventional fossil polymer-based wood-plastic composites (WPC). The PBS/MCC composites were prepared by using a melt blending of 70 wt% of MCC processed from bleached softwood. MCC was modified to enhance dispersion and compatibility by way of carbodiimide (CDI), polyhydroxy amides (PHA), alkyl ester (EST), (3-Aminopropyl) trimethoxysilane (APTMS), maleic acid anhydride (MAH), and polymeric diphenylmethane diisocyanate (PMDI). The addition of filler into PBS led to a 4.5-fold improvement of Young’s modulus E for the MCC composite, in comparison to neat PBS. The 1.6-fold increase of E was obtained for CDI modified composition in comparison to the unmodified MCC composite. At room temperature, the storage modulus E′ was found to improve by almost 4-fold for the APTMS composite. The EST composite showed a pronounced enhancement in viscoelasticity properties due to the introduction of flexible long alkyl chains in comparison to other compositions. The glass transition temperature was directly affected by the composition and its value was −15 °C for PBS, −30 °C for EST, and −10 °C for MAH composites. FTIR indicated the generation of strong bonding between the polymer and cellulose components in the composite. Scanning electron microscopy analysis evidenced the agglomeration of the MCC in the PBS/MCC composites. PMDI, APTMS, and CDI composites were characterized by the uniform dispersion of MCC particles and a decrease of polymer crystallinity. MCC chemical modification induced the enhancement of the thermal stability of MCC composites.

Corrosion protection of silane based coatings on mild steel in an aggressive chloride ion environment

Owing to the resulting micro bonds between the interfaces, the produced hybrid composites should increased in strength, surpassing many common composites. A silane coating material was synthesized through the sol-gel method using 3-glycidyloxypropyl trimethoxy silane as the precursor and (3-aminopropyl) trimethoxysilane as the cross-linking agent. We subjected the prepared coatings to a cross-hatch tape adhesion test to display the sticking efficiency of the coatings to the substrate. The CH stretching bonds along with NH2 and NC stretching modes were identified by Fourier transform infrared spectroscopy (FTIR). The microstructures, surface topographies, and elemental constitutions of the silane coatings were analyzed with scanning electron microscopy (SEM), elemental X-ray analysis (EDX), and atomic force microscopy (AFM). Electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and neutral salt spray test were performed, and the results showed that the silane coatings had high corrosion resistance. Moreover, low wettability and high contact angle indicated the high wear index in silane coatings.

Target triggered fluorescence “turn-off” of silicon nanoparticles for cobalt detection and cell imaging with high sensitivity and selectivity

Cobalt ions (Co2+) are among heavy metals ions which cause pollution in environment because of their toxicity and improper degradation. In this work, a new fluorescent approach based on silicon nanoparticles (Si NPs) was designed for Co2+ detection. The fluorescent Si NPs were prepared by mixing 3-aminopropyl trimethoxysilane (APTES) and basic fuchsin, and under the excitation of 400 nm, they emitted green fluorescence at 515 nm. The prepared Si NPs were highly soluble in water, stable to salt and pH, and their fluorescence emission was extremely constant, with the quantum yield of 2.28%. The detailed mechanism studies showed that Co2+ effectively quenched the fluorescence of Si NPs by forming static complex. After optimizing the reaction parameters, a good linear relationship for Co2+ was observed from 0.2 to 60 μM, and the limit of detection was 0.14 μM that is lower than the guideline announced by Department of Environmental Protection for drinking water (1.7 μM). The preparation method of Si NPs was cheap, rapid and simple, and the fluorescent approach was applied to determine Co2+ in Yellow river water, drinking water, and industrial wastewater. Moreover, the Si NPs has good response to exogenous Co2+ in HepG2 cell imaging.

An impedimetric biosensor based on electrophoretically assembled ZnO nanorods and carboxylated graphene nanoflakes on anindium tin oxide electrode fordetection of the DNA of Escherichia coli O157:H7.

Aminopropyltrimethoxysilane (APTMS)-functionalized zinc oxide (ZnO) nanorods and carboxylated graphene nanoflakes (c-GNF) were used in acomposite that was electrophoretically deposited on anindium tin oxide (ITO) coated glass substrate. Themodified ITO electrodes were characterized using various microscopic and spectroscopic techniques which confirm the deposition of theAPTMS-ZnO/c-GNF composite. The electrodes have been used for the covalent immobilization of an Escherichia coli O157:H7 (E. coli)-specific DNA prob. Impedimetric studies revealed that the genesensor displays linearresponse in a wide range of target DNA concentration (10-16M to 10-6M) with a detection limit of 0.1 fM. The studies on thecross-reactivity to other water-borne pathogens show that the bioelectrodeis highly specific. Graphical abstractSchematic illustration for fabrication of nucleic acid biosensor for E. coli DNA detection using anITO electrodemodified with siloxane-functionalized zinc oxide (ZnO) nanorods and carboxylated graphene nanoflakes (c-GNFs).

Preparation of “green” carbon quantum dots coated core-shell type pearl pigment Kieselguhr@TiO2@TiO2-x

In this paper, the green and environmentally friendly pearlescent pigment particles of the core-shell type kieselguhr@TiO2@TiO2-x composite were prepared via sol-gel deposition method, the surface of kieselguhr coated by TiO2, and then the surface of the composites was coated with TiO2-x by the technique of co-precipitation and the route of pyrolysis of the hydrazine salt. Orthogonal design method was employed to study the effects of different operating parameters on properties of the core-shell type kieselguhr@TiO2@TiO2-x composite. Due to characteristics of large specific surface with a lot of hydroxyl groups, the composite pigment were coated with Carbon dots with the assistance of (3-aminopropyl)trimethoxysilane (APS). Thus, the prepared composite pigment was mixed with citric acid and APS followed by hydrothermal reaction at 180 °C to generate carbon quantum dots coated composite pigment (kieselguhr@TiO2@TiO2-x@CDs).The obtained kieselguhr@TiO2@TiO2-x@CDs composite were characterized by X ray powder diffraction (XRD), element analysis, Raman spectra analysis, Hitachi s4800 field emission scanning electron microscopy (FESEM), X ray photoelectron spectroscopy (EDS) and TG-DTA respectively. And the color instrumental measurement was used to determine L*, a* and b* value of a pigment to evaluate the color brightness of the core-shell type kieselguhr@TiO2@TiO2-x composite. In addition, the MTT method, also known as MTT colorimetry, is a way of detecting cell survival and growth, which was employed to study in vitro cytotoxicity of their composite particles against mouse peritoneal macrophages for evaluation of their green application.

Titania Laden Liquid Crystal Based Sensor as Photocatalyst.

The present research work elucidates the photocatalytic effect of titania on liquid crystal based sensor used to detect sodium arsenate in water. The titania nanoparticles with an average size of 18-20 nm were synthesized by hydrothermal method and calcined up to 500 °C to obtain pure anatase phase. The catalytic activity of titania nanoparticles was enhanced by surface modification with (3-aminopropyl) trimethoxysilane. The sensing experiment was performed under visible light irradiation while keeping the concentration of substrate, analyte, the thickness of the liquid crystal layer, temperature and pH values constant. In addition, span 80 (a non-ionic surfactant) was used to obtain homeotropic alignment of liquid crystals. The TiO₂ nanoparticles gave dark to bright texture within 53 min while the functionalized titania responded in less than 25 min under similar sensing condition. The detection results showed that the functionalized titania nanoparticles possess greater photocatalytic activity under visible light and enhanced the sensing response than unfunctionalized titania nanoparticles.

Study on interfacial adhesion of the aramid fibers/rubber matrix by grafting mercapto hyperbranched polysiloxane

In order to improve the interfacial adhesion between aramid fiber (AF) and rubber matrix, the mercapto hyperbranched polysiloxane (HPSi) was grafted onto the AFs via a novel in-situ growth strategy, which combines the formation of polydopamine (PDA) precursor layer and the co-dehydration condensation between (3-aminopropyl) trimethoxysilane and (3-mercaptopropyl) trimethoxysilane. Based on the results of characterizations including morphology observations and chemical structure analyses, the growth process of mercapto HPSi with the reaction time was investigated and discussed. The pull-out force tests of AFs/rubber composites, which were carried out by universal testing machine, showed that the modification strategy proposed in this study could increase the interfacial adhesion up to approximately 96.5%, and the key factor could be inferred to be the covalent interaction between mercapto groups and double bonds. It is also worth mentioning that the phenomenon of excessive surface modification will occur with the overlong growth time, which would result in the reduction of the interfacial adhesion.

Highly efficient dark to transparent electrochromic electrode with charge storing ability based on polyaniline and functionalized nickel oxide composite linked through a binding agent

Here in this work, a black to transparent efficient electrochromic electrode based on nickel oxide (NiO) functionalized polyaniline (PANI) composite has been prepared. To ensure strong interaction among NiO and PANI, NiO nanoparticles were first functionalized with (3-Aminopropyl) trimethoxysilane (3-APTS) followed by subsequent attachment to monomer. This linking agent 3-APTS makes a bridge between NiO and PANI. Prepared PANI-fNiO composite exhibits extended contrast throughout the visible spectrum as well as in near-IR and near-UV regions with superior coloration efficiency of 138 cm2C-1. The composite PANI-fNiO was found to have improved cyclic stability of 7000 cycles. Thus with such kind of attachment both components synergistically favor each other’s coloration and bleaching, rendering dark (almost) black to transparent electrochromism. Observed hexagonal nanoparticles with ion diffusion channels were observed to give a fast response of 1.5s/2s for coloration and bleaching respectively. Moreover, PANI-fNiO shows pseudocapacitive behaviour with a large areal capacitance of 1.1 F cm−2. Both electronic and ionic charge transport mechanisms in such bonded PANI-fNiO composite have been studied using temperature dependent dc conductivity studies, cyclic voltammetery and electrochemical impedance spectroscopy. The observed results present the strong potential of PANI-fNiO composite as an integrated electrochromic electrode with charge storing ability.

Development of Ratiometric Fluorescence Sensors Based on CdSe/ZnS Quantum Dots for the Detection of Hydrogen Peroxide.

In this study, carboxyl group functionalized-CdSe/ZnS quantum dots (QDs) and aminofluorescein (AF)-encapsulated polymer particles were synthesized and immobilized to a sol–gel mixture of glycidoxypropyl trimethoxysilane (GPTMS) and aminopropyl trimethoxysilane (APTMS) for the fabrication of a hydrogen peroxide-sensing membrane. CdSe/ZnS QDs were used for the redox reaction of hydrogen peroxide (H2O2) via a reductive pathway by transferring electrons to the acceptor that led to fluorescence quenching of QDs, while AF was used as a reference dye. Herein, the ratiometric fluorescence intensity of CdSe/ZnS QDs and AF was proportional to the concentration of hydrogen peroxide. The fluorescence membrane (i.e., QD–AF membrane) could detect hydrogen peroxide in linear detection ranges from 0.1 to 1.0 mM with a detection limit (LOD) of 0.016 mM and from 1.0 to 10 mM with an LOD of 0.058 mM. The sensitivity of the QD–AF membrane was increased by immobilizing horseradish peroxidase (HRP) over the surface of the QD–AF membrane (i.e., HRP–QD–AF membrane). The HRP–QD–AF membrane had an LOD of 0.011 mM for 0.1–1 mM H2O2 and an LOD of 0.068 mM for 1–10 mM H2O2. It showed higher sensitivity than the QD–AF membrane only, although both membranes had good selectivity. The HRP–QD–AF membrane could be applied to determine the concentration of hydrogen peroxide in wastewater, while the QD–AF membrane could be employed for the detection of α-ketobutyrate.

Biocompatible Fe3O4@SiO2-NH2 nanocomposite as a green nanofiller embedded in PES-nanofiltration membrane matrix for salts, heavy metal ion and dye removal: Long-term operation and reusability tests.

High purity amorphous silica (95.55%) was simply extracted from rice husk and used as a shell for Fe3O4 magnetic nanoparticles. The obtained eco-friendly nanomaterial was functionalized by (3-Aminopropyl)trimethoxysilane and characterized by SEM, FT-IR, XRD, VSM, TEM and zeta potential analyses. The synthesized Fe3O4@SiO2-NH2 nanocomposite was embedded into the polyethersulfone membranes with different concentrations via phase inversion method. The effects of Fe3O4@SiO2-NH2 on various properties of the prepared nanofiltration membranes including membrane morphology, hydrophilicity, porosity, and mechanical stability were investigated using SEM image, water contact angle test, porosity measurement and mechanical property analysis, respectively. The performance of Fe3O4@SiO2-NH2 nanocomposite modified membranes was evaluated by measuring the pure water flux, salts rejection, Cd(II) ions removal, MR dye retention, and antifouling property. The results showed that the pure water flux was significantly increased in Fe3O4@SiO2-NH2 modified membranes due to the presence of hydrophilic functional groups on the Fe3O4@SiO2-NH2 surface. In addition, the significant enhancement in efficiency of modified membranes for removal of Cd(II) ions and MR dye was observed due to the adsorption properties of Fe3O4@SiO2-NH2 nanocomposite. Among the modified membranes with different concentrations of Fe3O4@SiO2-NH2, the 0.5 wt% concentration of nanocomposite showed the highest efficiency for the removal of Cd(II) ions (93%) and MR dye (97%). Membrane reusability study indicated a slightly decrease (≈7%) in Cd(II) ions removal after five continuous cycles. Membrane long-term filtration study showed a little reduction in permeate flux with unchanged MR dye retention during long-term filtration, which confirmed the stability of modified membrane.