3-aminopropyl Trimethoxysilane Research Articles

Modification of Hydroxysodalite Nanoparticles by (3-aminopropyl)trimethoxysilane and Isatoic Anhydride as a Novel Composite for Efficient Sorption of Cu(II) Ions from Aqueous Media

Modification of Hydroxysodalite Nanoparticles by (3-aminopropyl)trimethoxysilane and Isatoic Anhydride as a Novel Composite for Efficient Sorption of Cu(II) Ions from Aqueous Media

Fluorescent and visual sensing of sodium dodecylbenzene sulfonate with an aminosilane self-condensation promoting and electrostatic attraction effect-based ratiometric probe

BackgroundIncreasing attention has been paid to sodium dodecylbenzene sulfonate (SDBS) detection because it could cause damage to human body and environmental water. For example, SDBS must not be detected on tableware surface according to national standard of China (GB 14934-2016). However, there is no report heretofore addressing SDBS sensing on surfaces. More importantly, the interferents often affect the sensing performance of analytical approaches. Hence, there is an urgent need to establish a method with good anti-interference ability for SDBS detection both on tableware surfaces and in water. ResultsInspired by a finding that SDBS could cause the generation of white turbidity in (3-aminopropyl)trimethoxysilane (APTMS, an aminosilane) aqueous solution, APTMS modified Mn doped ZnS quantum dots (QDs) and fluorescent (FL) whitening agent (FWA) were constructed as a ratiometric probe for FL and visual sensing of SDBS. The modified QDs aggregated and settled in presence of SDBS, which was likely to be connected to the stimulatory effect of SDBS on the APTMS self-condensation and the electrostatic attraction. The FL emission from the QDs at 605 nm then decreased dramatically, whereas that at 425 nm was virtually constant owing to FWA. SDBS sensing could be achieved by calculating the ratio change of their FL intensities. The detection limits of FL and visual methods were found to be 0.011 and 10 μg/L, respectively, making it one of the most sensitive approaches in literature. Finally, it was successfully utilized for SDBS detection on tableware surfaces and in water. SignificanceHerein, the specific interaction between SDBS and APTMS was reported and the reaction mechanisms were explored for the first time. The proposed probe based on the effect described above provided a promising potential for SDBS analysis owing to high sensitivity, selectivity, anti-interference ability, and stability (in 20 days).

Kinetic Suppression of Photoinduced Halide Migration in Wide Bandgap Perovskites via Surface Passivation.

In this work, we study the kinetics of photoinduced halide migration in FA0.8Cs0.2Pb(I0.8Br0.2)3 wide (∼1.69 eV) bandgap perovskites and show that halide migration slows down following surface passivation with (3-aminopropyl) trimethoxysilane (APTMS). We use scanning Kelvin probe microscopy (SKPM) to probe the contact potential difference (CPD) shift under illumination and the kinetics of surface potential relaxation in the dark. Our results show that APTMS-passivated perovskites exhibit a smaller CPD shift under illumination and a slower surface potential relaxation in the dark. We compare the evolution of the photoluminescence spectra of APTMS-passivated and unpassivated perovskites under illumination. We find that APTMS-passivated perovskites exhibit more than 5 times slower photoluminescence red-shift, consistent with the slower surface potential relaxation as observed by SKPM. These observations provide evidence for kinetic suppression of photoinduced halide migration in APTMS-passivated samples, likely due to reduced halide vacancy densities, opening avenues to more efficient and stable devices.

Enhancing blue phosphorescence in matrix-free carbon dots through covalent crosslinking

Room temperature phosphorescence (RTP) of carbon dots (CDs) has received extensive attention due to its excellent performance and promising application. Here, a novel kind of matrix-free CDs with blue phosphorescence emission was synthesized by a simple one-step hydrothermal method of heating (3-Aminopropyl) trimethoxysilane (APTMS) and phosphoric acid in aqueous solution. The obtained CDs show a phosphorescence lifetime of 315.73 ms, and the absolute photoluminescence quantum yield (PLQY) and the phosphorescence quantum yield (PQY) can reach up to 37.8 % and 12.4 %, respectively. From the experimental results, we speculate that the generation of RTP is attributed to the restriction effect of the covalent crosslinking structure of SiOSi, SiOC, or SiC bonds formed on the CDs surface. In addition, phosphoric acid as a crosslinking agent and heteroatom dopant can promote the formation of cross-linked structures and facilitate the intersystem crossing (ISC) process, thus enhancing room temperature phosphorescence. Finally, the CDs were successfully used in information encryption and anti-counterfeiting.

Facile Fabrication of Transparent Hydrophobic Spectral Converting Thin Film of Cyclic Silica-Silane Structure

There is a growing demand for advanced coatings with remarkable physical properties such as high transparency, water resistance, spectrum conversion, and dust repellence, which can be used in a variety of applications. In this study, we built thin films using silicon quantum dots and a silane-based material composite, resulting in a unique mix of hydrophobicity, self-cleaning and the ability to convert ultraviolet (UV) to visible spectrum. The use of silicon quantum dots in the film results in spectrum conversion from UV to visible wavelengths, taking advantage of their broad UV absorption and concurrent visible light emission. Concurrently, a silica-silane based layer of tetraethyl orthosilicate, N, N dimethyl amino propyl trimethoxy silane, and 3-chloro-propyl trimethoxy silane is integrated, imparting not only water resistance but also dust resistance. The challenging synthesis chemistry exemplifies the several stages required to create a spectral-converting hydrophobic layer. Given its inherent transparency, coupled with UV-to-visible spectrum conversion capabilities, this novel layered structure have a potential in outer coating of solar photovoltaic systems and various outdoor glass applications.

Chemical vapour deposition in narrow capillaries: Electro-osmotic flow control in capillary electrophoresis

BackgroundIn capillary electrophoresis (CE), the inner surface of fused-silica capillaries is commonly covalently modified with liquid silanes to control electroosmotic flow (EOF). This liquid phase deposition (LPD) approach is challenging for long and narrow-diameter capillaries (≥1 m, ≤25 μm ID) inhibiting commercial production. Here, we use chemical vapour deposition (CVD) to covalently modify capillaries with different silanes. Using a home-built CVD device, capillaries were modified with neutral (3-glycidyloxypropyl) trimethoxysilane (GPTMS), the weak base (3-aminopropyl) trimethoxysilane (APTMS), the weak acid 3-mercaptopropyltrimethoxysilane (MPTMS) and the neutral hydrophobic trichloro(1H,1H,2H,2H-perfluorooctyl) silane (PFOCTS). Gas-phase modification of GPTMS with acid and ammonia allowed further modification of the surface prior to molecular layer deposition (MLD) of poly(p-phenylene terephthalamide) (PPTA) using the self-limiting sequential reaction between terephthalaldehyde (TA) and p-phenylenediamine (PD) vapours. ResultsCapillaries coated with GPTMS by CVD showed a greater reduction in EOF at all pH values than the conventional LPD. APTMS showed a reduction of the EOF at pH 9, with EOF reversal observed below pH 6. MPTMS provided a slightly lower EOF than an unmodified capillary at high pH, and a slightly higher EOF at lower pH. PFOCTS provided the most consistent EOF as a function of pH. The deposition of successive layers of PPTA resulted in increased surface coverage of the polymer and a greater reduction in EOF at pH higher than 5. The stability of a 10 μm ID GPTMS coated capillary was tested at pH 8.8 in a 200 mM CHES/Tris BGE for the separation of inorganic anions. Over 1.5 months of continuous operation (≈4130 runs), the reproducibility of the apparent mobilities for chloride, nitrite, nitrate and sulfate were 2.43%, 2.56%, 2.63% and 3.05%, respectively. The intra-day and inter-day column-to-column reproducibility and batch-to-batch reproducibility for all the coated capillaries ranged between 0.34% and 3.95%. SignificanceThe study demonstrates the superior performance of CVD coating for suppressing the EOF compared to LPD allowing the easy modification of long lengths of narrow capillary. The variation in silane, and the ability of MLD to modify and control the surface chemistry, provides a simple and facile method for surface modification. The stability of these coatings will allow long-term capillary electrophoresis monitoring of water chemistry, such as for monitoring fertiliser run-off in natural waters.

Platinum nanoparticle-decorated reduced graphene oxide nanosheets: A recyclable and highly efficient catalyst towards the reduction of para-nitrophenol and methylene blue

The present study focuses on the design and development of Pt nanoparticle (PtNPs) decorated reduced graphene oxide (RGO) nanohybrid as an efficient heterogeneous catalyst towards the reduction of p-nitrophenol (p-NP) and methylene blue (MB). The citrate reduction of chloroplatinic acid in the presence of amino-propyl trimethoxy silane (APTMS) modified graphene oxide (GO) produced RGO/PtNPs nanohybrid comprised of uniform and high-density distribution of smaller-sized PtNPs. The APTMS provide efficient nucleation points via their amino groups and thereby play a vital role in regulating the size as well as the distribution of the anchored PtNPs in the present approach. The morphological and structural characterization of RGO/PtNPs nanohybrid was done by using X-ray powder diffraction, scanning and transmission electron microscopy, Fourier transform infrared and Raman spectroscopic techniques. The homogeneous and high-density dispersion of smaller-sized PtNPs endows superior catalytic activity to RGO/PtNPs nanohybrid. The nanohybrid exhibited outstanding catalytic performance enabling rapid reduction of both p-NP and MB at ambient conditions. The estimated rate constants for p-NP and MB reduction were 15.9 × 10−3, and 187 × 10−3 s−1 respectively, which outperform the rate constants of several previously reported metal-based GO/RGO nanocatalysts. The recycling tests showed that the nanohybrid maintained good catalytic stability even after the fifth recycle run. The RGO/PtNPs nanohybrid can be exploited for sustainable and efficient catalytic reduction of other environmental pollutants also. Further, the strategy followed in the present study to achieve homogenous and high-density distribution of Pt nanoparticles could be adopted for the anchoring of other metal/metal oxide/semiconductor nanoparticles.

Graphene interleaved SiOx/C spheres Via molecular polymerization as high-stability lithium-ion battery anodes

SiOx/carbon composite materials are a promising candidate for lithium-ion battery anodes because of their high capacity. However, their widespread application is hindered by poor electrical conductivity, and stability due to the volume expansion during cycling. Herein, electrodes comprised of spherical carbon-coated silicon oxide particles, interleaved between electrochemically exfoliated graphene, were prepared via molecular polymerization followed by physical mixing. The spherical silicon oxide was obtained by the carbonization of the reaction product between dialdehyde and (3-aminopropyl) trimethoxysilane. The interleaved graphene flakes both provided electrically conductive pathways between particles and formed a porous supporting structure between the silicon oxide particles and the graphene flakes, enabling a buffering for the volume expansion. A range of SiOx/C-G anodes are obtained by adjusting the content of graphene. The assembled batteries with an optimal graphene ratio (SiOx/C: G = 2:1 (w/w)) exhibit superior Li-ion storage behavior, including high cycle stability, with capacity retention of 88.6 % and high coulombic efficiency of 99 % after 250 cycles under 0.1 A·g−1. Promisingly, it was verified that with the support from the outer robust graphene layer and the porous support structure, the volume expansion of silicon oxide particles during lithiation/delithiation processes was suppressed, leading to a more stable solid electrolyte interface (SEI) layer.

Dual-silane coupling agents co-grafted on black particles for fast response and high contrast ratio electrophoretic display

As the Internet of Things (IoT) significantly improves people's lifestyles, flexible and low-power displays will become essential to real-time human-computer interaction. Electrophoretic display (EPD) has many advantages, such as low power consumption, flexibility, and high sunlight visibility, which is necessary for IoT terminal display. However, preparing electrophoretic particles with high charge and spatial resistance is difficult. Herein, dual-silane coupling agents, (3-Aminopropyl) trimethoxysilane (APS) and vinyltrimethoxysilane (VTS), were co-grafted on the black particles to optimize the electrophoretic particles' dispersity and charge. To evaluate the charge content and dispersity of particles, we measured the particles with zeta potential, dynamic light scattering, and long-term standing treatment. Fe3O4-APS0.5VTS0.5-PLMA, selected as the black particles for EPD, had an average particle size and zeta potential of 300 nm and 25 mV, respectively. Besides, the concentration of the black and white particle would significantly affect the EPD's performance. When optimizing the white and black particle concentration to 4:1, the contrast ratio of EPD was up to 13.2. In addition, the EPD has a response time of 200 ms and exhibits an invertible black and white state under ±15 V. Finally, to improve the stability of electrophoretic particles, the particles were encapsulated in microcups and driven to the black and white state under 30 V. This work demonstrated that dual-silane coupling agent particles have the potential to achieve the fast response and high contrast ratio EPD.

Removal of Hexamethyldisiloxane via a Novel Hydrophobic (3-Aminopropyl)Trimethoxysilane-Modified Activated Porous Carbon.

Volatile methyl siloxanes (VMS) must be removed because the formation of silica in the combustion process seriously affects the resource utilization of biogas. Herein, a series of APTMS ((3-aminopropyl)trimethoxysilane)-modified activated porous carbon (APC) adsorbents (named APTMS@APC) were prepared for VMS efficient removal. The as-prepared adsorbents were characterized using SEM, FTIR, Raman, X-ray diffraction analyses, and N2 adsorption/desorption. The results showed that the surface modification with APTMS enhanced the hydrophobicity of APC with the water contact angle increasing from 74.3° (hydrophilic) to 127.1° (hydrophobic), and meanwhile improved its texture properties with the SBET increasing from 981 to 1274 m2 g-1. The maximum breakthrough adsorption capacity of APTMS@APC for hexamethyldisiloxane (L2, model pollutant) was 360.1 mg g-1. Effects of an inlet L2 concentration (31.04-83.82 mg L-1) and a bed temperature (0-50 °C) on the removal of L2 were investigated. Meanwhile, after five adsorption-desorption cycles, the APTMS@APC demonstrated a superior cycling performance. This indicated that the hydrophobic APTMS@APC has a great significance to remove VMS.

Amine-grafted H-MFI zeolite precursors as acidic-basic catalysts for deacetalization-Knoevenagel condensation

Amorphous and semi-crystalline precursors of zeolites have a large number of silanols that can be used to anchor organic functionalities, like silane-based amines, resulting in formation of basic sites. This work describes the use of amorphous and semi-crystalline precursors of H-MFI zeolite reacting with aminopropyltrimethoxysilane (APTMS) to produce bifunctional acidic-basic catalysts for the deacetalization-Knoevenagel condensation. The effect of precursors crystallinity on the catalytic performance is explained by the formation of Brønsted acidic sites, which catalyze the deacetalization step, and on the propylamine anchoring capacity, controlled by the amount of external silanols present in the aluminosilicate. It is shown that the aluminosilicates with lower crystallinity provide a higher yield of the end product ethyl trans-α-cyanocinnamate due to the greater number of grafted propylamine groups. These results provide new insights into the preparation of acidic-basic catalysts for converting bulky molecules.

Amine-functionalized reduced graphene oxide-supported silver nanoparticles for superior catalytic reduction of organic pollutants.

In this work, a simple and environmentally friendly approach has been followed to synthesize amine-functionalized reduced graphene oxide (RGO)-supported silver nanoparticle (AgNPs) having superior catalytic efficiency towards the reduction of organic pollutants. RGO/AgNPs nanohybrid was synthesized by a one-pot hydrothermal reduction of silver nitrate in the presence of amino-propyl trimethoxy silane (APTMS)-functionalized graphene oxide (GO) nanosheets. The structural and morphological characterization of as-synthesized RGO/AgNPs nanohybrid was done by using XRD, SEM, TEM, FT-IR, and Raman spectroscopy techniques. APTMS plays an important role in controlling the size of anchored AgNPs on the nanohybrid in the present study. The -NH2 groups on the surface of APTMS-modified GO function as effective and well-organized nucleation centers facilitating uniform growth of discrete and smaller-sized spherical AgNPs on the surface of RGO nanosheets. In the absence of APTMS, the nanohybrid comprised of bigger-sized AgNPs with few hundred of nanometers in dimension. The catalytic efficiency of RGO/AgNPs nanohybrid was evaluated for the reduction of two model organic pollutants: 4-nitrophenol (4-NP) and methylene blue (MB). Due to the synergistic effects of RGO, APTMS, and Ag components, RGO/AgNPs nanohybrid developed in the present study exhibited superior catalytic activity towards the reduction of 4-NP and MB in comparison with previously reported graphene/graphene oxide/reduced graphene oxide-supported AgNPs catalysts. The catalytic reduction of 4-NP and MB followed pseudo-unimolecular kinetics and the rate constants were found to be 18.83 × 10-3 s-1 and 131.5 ×10-3 s-1 respectively for 4-NP and MB. Furthermore, RGO/AgNPs nanohybrid showed admirable recyclability with negligible loss in its activity until five recycle runs. The superior catalytic activity, favorable kinetic parameters, and sustained catalytic efficiency after recycling make RGO/AgNPs nanohybrid a promising catalyst for the reduction of organic pollutants in environmental remediation.

Amine-functionalized metal-organic framework/graphene oxide nanocomposite for the removal of Direct Red 23 from water

Herein, MIL-53 (Fe) and MIL-53 (Fe)/graphene oxide (GO) nanocomposite were synthesized and denoted as MIL-C, and MIL-C/GO. The synthesized materials were modified using 3-amino propyl trimethoxy silane (APTMS) (amine-functionalization) with different amounts (0.1, 0.2, and 0.3 mL for preparing MIL-C/NH2(0.1), MIL-C/NH2(0.2), and MIL-C/NH2(0.3), MIL-C/GO-NH2(0.1), MIL-C/GO-NH2(0.2), and MIL C/GO-NH2(0.3), respectively) and characterized. Direct Red 23 (DR23) was used as a model pollutant. The dye adsorption followed a Langmuir isotherm and pseudo-second-order model. The MIL-C/GO and MIL-C/GO-NH2(0.3) showed the adsorption capacity of 1,371 and 4,504 mg/g, respectively. The high removal ability and reusability indicated that the synthesized MIL-C/GO-NH2(0.3) could be as an alternative adsorbent for other organic contaminant with similar chemical structures from aqueous media.

Molecular dynamics simulation on the shielding effect of aminopropyl trimethoxysilane film on corrosive media

Aminopropyl trimethoxysilane (APTMS) was used as a silane reagent, and oxygen and water were set as corrosion media, respectively. The mean square displacement (MSD) of oxygen and water molecules in silanized films with different cross-linking degrees (APTMS-OH-1, APTMS-OH-4, APTMS-OH-8, and APTMS-OH-12) were investigated by molecular dynamics simulation to characterize the corrosion inhibition effect of silanized films in different corrosion media. The results showed that compared with in air, the MSD of oxygen and water molecules in silane film was significantly reduced, which indicated that silane film could prevent the diffusion of corrosive medium, thus protecting material. Silane films with various crosslinking degrees have different shielding effects on oxygen and water molecules. The MSD of oxygen in silane films with different crosslinking degrees was: APTMS-OH-1>APTMS-OH-4>APTMS-OH-12>APTMS-OH-8, while the MSD of water in silane films with different crosslinking degrees was: APTMS-OH-1>APTMS-OH-4≈APTMS-OH-12>APTMS-OH-8. The MSD of both oxygen and water molecules was the lowest in silane films with a crosslinking degree of 8, which showed that silane films had the highest shielding effect.

Antibacterial Effect of Experimental Orthodontic Elastomeric Ligature Coated with Zinc Oxide Particles

Objectives . This study aimed to evaluate antibacterial activity of elastomeric ligatures coated with Zinc oxide particles against Streptococcus mutans. Methods. ZnO particles grafted with (3-Aminopropyl) trimethoxysilane (APTMS) were prepared in situ. The ATR-FTIR spectrum was used to analyze the APTMS grafted on ZnO surfaces. Two concentrations of ZnO-APTMS, i.e., 5 and 10 wt%, were coated on orthodontic elastomeric ligatures by the dip coating method. Antibacterial property of the ZnO-APTMS coated elastomeric ligatures against S. mutans ATCC25175 were investigated by the agar diffusion test. The effect of ligature aging on antibacterial property was evaluated by the direct contact test, in which the growth of bacteria was determined by the turbidity after exposed to the samples that had been immersed in distilled water for 0, 3, 7, 14, 28 days. The drop plate test was also performed to determine the inhibitory and the bactericidal effects. Results. The analysis of ATR-FTIR spectrum confirmed that APTMS was successfully grafted on ZnO surfaces. The agar diffusion test could not demonstrate the antimicrobial effects of the ZnO-coated elastomeric ligatures. However, results from the direct contact and the drop plate tests showed the inhibitory effects on bacterial growth compared to the positive controls (p < 0.05). The inhibitory effect of the ZnO-coated elastomeric ligatures was observed even after they had been immersed in distilled water for 28 days. Conclusions. The surface coating elastomeric ligatures with 5 and 10 wt% ZnO-APTMS exhibited antibacterial activity against cariogenic bacteria, S. mutans. The bacterial inhibitory effect was prolonged until 28-day.

Melamine functionalized mesoporous silica SBA-15 for separation of chromium (VI) from wastewater

In this study, a Melamine-functionalized mesoporous silica-SBA-15 (Melamine-MS-SBA-15) adsorbent was synthesized to remove Cr(VI) from wastewater. The mesoporous silica-SBA-15 adsorbent was first synthesized using the hydrothermal method and post-synthesis under toluene reflux. Then, 3-aminopropyl trimethoxy silane was added to the adsorbent surface and it was further modified by melamine to obtain the final product. SBA-15 well-performed after Melamine functionalization against the Cr(VI) removal due to the conversion of physisorption to chemisorption adsorption. The adsorption of Cr(VI) using the Melamine-MS-SBA-15 was studied. XRD, BET, SEM, FTIR, TGA, and zeta potential analyses were used to characterize the adsorbent. Parameters affecting adsorption including pH (3–9), initial concentration (20–200 ppm), contact time (1–24 h), adsorbent dose (1.5–15 mg L−1), and temperature (18–30 °C). Optimal results were pH = 3, an initial concentration of 20 ppm, an adsorbent dose of 4 mg L−1, a contact time of 6 h, and a temperature of 18 °C. The results of isotherm and kinetics model studies were consistent with Temkin and pseudo-second-order models, respectively. The thermodynamics parameters confirmed the spontaneous reaction. Experimental results showed that functionalization of the adsorbent surface of MS-SBA-15 with melamine increased the adsorption efficiency and adsorption capacity. The highest adsorption capacity for Cr(VI) was about 50 mg/g. The maximum adsorption efficiency for solutions containing Cr(VI) was about 84%. Increasing the adsorption concentration in a fixed value of the heavy metal concentration increased the adsorption capacity and increasing the heavy metal concentration, increased the adsorption capacity.

Chiral organic-silica hybrid monolithic HPLC column with dynamic grafting BSA for the enantiomeric separation

BSA functionalized hybrid monolithic column prepared by in-situ dynamic grafting on traditional stainless steel column for enantiomeric separation. A hybrid silica monolithic column (HMC) was prepared using a single precursor (methytrimethoxysilane) in stainless steel HPLC column (50 mm × 4.6 mm) by sol–gel method. The chiral hybrid monolithic column (CHMC) was prepared by grafting 3-aminopropyl trimethoxysilane onto HMC, and then reacting bovine serum albumin (BSA) with Glutaraldehyde. The preparation conditions were optimized, and the maximum grafting amount of BSA was 48.6 mg g−1. The CHMC was characterized and its chromatographic performance was tested. The results showed that the CHMC has a homogeneous network skeleton structure, good stability and reproducibility. The CHMC was combined with HPLC, under optimized chromatographic conditions, the baseline separation of tryptophan and pidotimod enantiomers were successfully achieved.

Determination of Al(III), Pb(II), and Cu(II) in Gunshot Residue Using Amino-Functionalized Silica Adsorbents in Dispersive Solid Phase Microextraction (DSPME) with Capillary Electrophoresis (CE)

Here is reported the design, synthesis, and application of an amino silica adsorbent for the extraction and determination of Al(III), Pb(II), and Cu(II) in gunshot residue (GSR) from the dorsal and palmar zones by capillary electrophoresis. The extraction procedure was used to determine the adsorbent composition by varying the molar ratio of the cross-linking agent tetramethyl orthosilicate (TMOS) and the functional monomer 3-aminopropyl trimethoxysilane (APTMS). (5.0:0.0 to 0.0:5.0). The optimal composition (3.0:2.0) was characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and adsorption isotherm analysis. A univariate method was used to optimize critical factors in dispersive solid phase microextraction (DSPME), including the adsorbent mass, contact time, sample volume, and elution solution. Using the optimal conditions (adsorbent, 10 mg; contact time, 10 min; sample volume, 5 mL; eluent solution, methanol/10−1 mol L−1 HNO3), the method provides limits of detection of 0.06 mg L−1 for Pb(II), 0.08 mg L−1 for Cu(II), and 0.11 mg L−1 for Al(III). The precision and accuracy were evaluated in terms of inter- and intra-day repeatability (n = 3) with a relative standard deviation below 10%. The developed method was applied for gunshot residue analysis, providing concentrations from 12.6 to 702 mg L−1 for Al(III), 11.8 to 280 mg L−1 for Pb(II), and 29.8 to 395.6 mg L−1 for Cu(II).

Resistive switching characteristics of methyl-ammonium lead iodide perovskite during atmosphere degradation

Methylammonium lead iodide (MAPbI3) with extraordinary optoelectronic properties has recently been explored for memristors. Despite significant studies on its susceptibility to air, there has been limited attention towards the impact of ambiance on resistive switching (RS), specifically, the nanoscale electrical properties of interest. We used scanning probe microscopy (SPM) to study local current-voltage (I-V) characteristics, time-scale evolution of hysteresis, current maps, and topography to profoundly understand the ambient degradation. The local and macroscopic current-voltage characteristics are studied by interface modulation with (3-Aminopropyl)trimethoxysilane (APTMS) in devices, i.e., ITO/APTMS/MAPbI3 and ITO/ MAPbI3/APTMS. We report three stages of degradation based on quantitative nano-mechanical (QNM) characterizations and local I-V properties: stage 1 comprising of increased Young’s modulus accompanied by the appearance of hysteresis; stage 2 with decreased Young’s modulus when RS and negative differential resistance (NDR) happen with the evolution of lead iodide (PbI2); stage 3 when RS disappears with enhanced Young’s modulus and densification of PbI2. The enhanced nanoscale and macroscale RS characteristics of ITO/MAPBI3 and ITO/APTMS/MAPbI3 could be attributed to the humidity-induced degradation of MAPbI3 into PbI2 indicated by XRD. These characteristics at the nanoscale however diminish on Day 7 showing the nano-scale RS devices requires the prompt attention of researchers.

Superparamagnetic Spinel-Ferrite Nano-Adsorbents Adapted for Hg2+, Dy3+, Tb3+ Removal/Recycling: Synthesis, Characterization, and Assessment of Toxicity.

In the present work, superparamagnetic adsorbents based on 3-aminopropyltrimethoxy silane (APTMS)-coated maghemite (γFe2O3@SiO2-NH2) and cobalt ferrite (CoFe2O4@SiO2-NH2) nanoparticles were prepared and characterized using transmission-electron microscopy (TEM/HRTEM/EDXS), Fourier-transform infrared spectroscopy (FTIR), specific surface-area measurements (BET), zeta potential (ζ) measurements, thermogravimetric analysis (TGA), and magnetometry (VSM). The adsorption of Dy3+, Tb3+, and Hg2+ ions onto adsorbent surfaces in model salt solutions was tested. The adsorption was evaluated in terms of adsorption efficiency (%), adsorption capacity (mg/g), and desorption efficiency (%) based on the results of inductively coupled plasma optical emission spectrometry (ICP-OES). Both adsorbents, γFe2O3@SiO2-NH2 and CoFe2O4@SiO2-NH2, showed high adsorption efficiency toward Dy3+, Tb3+, and Hg2+ ions, ranging from 83% to 98%, while the adsorption capacity reached the following values of Dy3+, Tb3+, and Hg2+, in descending order: Tb (4.7 mg/g) > Dy (4.0 mg/g) > Hg (2.1 mg/g) for γFe2O3@SiO2-NH2; and Tb (6.2 mg/g) > Dy (4.7 mg/g) > Hg (1.2 mg/g) for CoFe2O4@SiO2-NH2. The results of the desorption with 100% of the desorbed Dy3+, Tb3+, and Hg2+ ions in an acidic medium indicated the reusability of both adsorbents. A cytotoxicity assessment of the adsorbents on human-skeletal-muscle derived cells (SKMDCs), human fibroblasts, murine macrophage cells (RAW264.7), and human-umbilical-vein endothelial cells (HUVECs) was conducted. The survival, mortality, and hatching percentages of zebrafish embryos were monitored. All the nanoparticles showed no toxicity in the zebrafish embryos until 96 hpf, even at a high concentration of 500 mg/L.