Presence Of Polyethyleneimine Research Articles

Electrolyte-Electrocatalyst Interfacial Effects of Polymeric Materials for Tandem CO2 Capture and Conversion Elucidated Using In Situ Electrochemical AFM.

Integrating CO2 capture and electrochemical conversion has been proposed as a strategy to reduce the net energy required for CO2 regeneration in traditional CO2 capture and conversion schemes and can be coupled with carbon-free renewable electricity. Polyethylenimine (PEI)-based materials have been previously studied as CO2 capture materials and can be integrated in these reactive capture processes. PEI-based electrolytes have been found to significantly increase the CO2 loading, and impact selectivity and rate of product formation when compared to the conventional aqueous electrolytes. However, the influence of these materials at the catalyst-electrode interface is currently not well understood. In this study, PEI-based electrolytes were prepared and their impact on the morphology of a silver electrode performing electrochemical CO2 reduction (CO2R) was studied using in situ electrochemical atomic force microscopy (EC-AFM). The presence of PEI on the electrode surface could be distinguished based on nanomechanical properties (DMT modulus), and changes were observed as negative polarization was applied, revealing a reorganization of the PEI chains due to electrostatic interactions. These changes were impacted by the electrolyte composition, including the addition of supporting electrolyte KHCO3 salt, as well as CO2 captured by the PEI-based electrolyte, which minimized the change in surface mechanical properties and degree of PEI alignment on the electrode surface. The changes in surface mechanical properties were also dependent on the PEI polymer length, with higher molecular weight PEI showing different reconfiguration than the shorter polymer brushes. The study highlights that the choice of polymer material, the electrolyte composition, and CO2 captured impact the near-electrode environment, which has implications for CO2R, and presents EC-AFM as a new tool that can be used to probe the dynamic behavior of these interfaces during electrocatalysis.

Fabrication of Highly Efficient ZIF-8@PEI Monoliths for CO2 Capture Using Phosphorylated Cellulose Nanofiber as a Binder.

This study involves the synthesis and comparison of zeolitic imidazolate frameworks (ZIFs), specifically ZIF-8 and ZIF-67 pristine with a commercial zeolite, emphasizing their CO2 affinity and sorption capability. To overcome challenges persisting in the handling and integration of these materials into industrial adsorption processes, particularly when limited to microcrystalline fine powders, we present herein an innovative manufacturing method to produce standalone monolithic supports. This process involves pseudoplastic paste formulations utilizing polyethylenimine (PEI) as a coagulant and locally fabricated phosphorylated cellulose nanofiber (PCNF) as a binding agent. Rheological investigation was conducted to anticipate the required shaping and design by means of paste flowability, consistency, and stiffness. XRD and FTIR results confirm the preservation of crystalline structure and the occurrence of amine functionalization associated with the presence of PEI, respectively. The proposed method significantly enhances the CO2 adsorption performance of the produced ZIF-8 monolith in comparison with that reached when using the pristine material, achieving a capacity of 1.25-2 mmol·g-1 at 30 °C under dry conditions in a pressure range of 1-13 bar, respectively. In other words, this work clearly highlights an effective applicability of the ZIF-8 monolith as an innovative sorbent for further designing CO2 capture industrial setups.

Evaluation of the Effect of Polyethylenimine on Boron Adsorption by Soil Minerals.

The removal of hazardous ions from water is crucial for safeguarding both the environment and human health. Soil minerals, integral components of soil, play a vital role as adsorbents for various contaminants, including heavy metal ions, organic dyes, and detergents. This study investigates the interaction between boron ions and soil minerals (gibbsite, kaolinite, and montmorillonite) in the presence of polyethylenimine (PEI). The minerals underwent characterization based on specific surface area, particle size distribution, zeta potential, and the presence of functional groups. The influence of PEI addition on the stability of the soil mineral suspension was evaluated by turbidimetry. Mineral-boron and mineral-boron-PEI interactions were explored under varying conditions, including pH, initial boron concentration, and mineral quantity, with all adsorption experiments conducted over 24 hours. Using the Langmuir isotherm, the maximum adsorption capacity of the studied minerals was determined for boron both without and in the presence of PEI. For gibbsite, kaolinite and montmorillonite, it was 30.63, 24.55 and 26.62 mg g-1, respectively, while in the presence of PEI, it increased to 33.11, 26.61 and 45.47 mg g-1, respectively. The addition of PEI enhanced boron adsorption from aqueous solutions, increasing the removal efficiency from 65 % to about 80 %.

Superhydrophobic fluorescent micro-/nano-composites from carbon dots encapsulated in CaCO3-SiO2

ABSTRACT In this paper, polyamine-functionalized carbon dots (CDs) were synthesized by means of low temperature (<100°C) carbonization of citric acid at the presence of polyethylenimine (PEI), resulting spherical calcium carbonate micro-particles from inverse micro-emulsion system. Nanoscaled spherical silicas were prepared by Stöber method via deposition on the surface of micron calcium carbonate. Scanning- and transmission-electron microscopic analysis confirmed a micro-/nano-complex structure, enabling the composite material coating possessed coarser surface similar to those of ‘lotus leaf’. After modification with 1 H, 1 H, 2 H, 2 H-perfluorodecanethiol, both good super hydrophobicity and good fluorescent performance were confirmed by the water contact angle of 154.1°±1.5°, their surface-free energy, and fluorescence quantum yield of 14.1%, which provides an inexpensive and easy way to fabricate superhydrophobic material with fluorescence characteristics and promotes high value application of inorganic materials.

Tailored self-assembly of semi-transparent polymer/clay nanocomposites for gas-barrier applications assisted by aqueous liquid crystalline scaffolds

A new strategy for preparing flexible and semi-transparent gas-barrier coatings was developed using tailored self-assembly of montmorillonite (MMT)/polyvinylpyrrolidone (PVP) nanocomposites assisted by aqueous liquid crystalline (LC) scaffolds. First, we established a composition wherein aqueous MMT exhibited the LC phase in the presence of polyethyleneimine (PEI) and hydrochloric acid (HCl). The viscoelastic rheological features of MMT LC enable the formation of uniform and conformal MMT coatings on various types of substrates, including flat or topographically featured surfaces. Moreover, the MMT LC serves as a structural scaffold that enables the rapid transport of PVP within the inner gallery space of the MMT LC, resulting in the formation of stacked MMT/PVP nanosheets after drying. Owing to its highly aligned layered structure, MMT/PVP exhibited flexible mechanical properties with enhanced hardness and modulus compared to neat MMT. Furthermore, the MMT/PVP can suppress gas permeation, as demonstrated by 0.1 Barrer of H2 permeability for the best coating conditions (containing 63 wt% MMT and 37 wt% PVP), while maintaining semi-transparent optical properties. Considering the aforementioned properties and that all components in MMT/PVP are bio-safe materials, this coating system has potential applications as a gas-barrier coating in conventional packaging materials, food packaging, and H2 storage tanks.

Electrodeposition of Silver in Cyanide-Free Solution Containing Pyrimidine Derivative as a Complexing Agent

Pyrimidine derivatives, for example, 2,4-pyrimidinedione (uracil), 1-methyluracil and 5-methyluracil (thymine) can bind with metal ions in alkaline solution. 5-methyluracil (thymine) as complexing agent in electroplating solution has not been investigated due to low solubility in water. The aims of this study were to determine the potential of 5-methyluracil (thymine) as complexing agent for cyanide-free silver electroplating solution. The influence of complexing agent and polyethyleneimine on the silver electrodeposition reaction were studied. Several methods which are electrochemical quartz crystal microbalance (EQCM) and electrochemical impedance spectroscopy (EIS) have been used to study the electrochemical behavior of cyanide-free silver electroplating solution. The surface morphology and brightness of silver deposits obtained from each cyanide-free silver electroplating solution were evaluated. A semi-bright deposit was obtained from thymine and uracil-complexing silver solution while matte deposit from 5,5-dimethylhydantoin-complexing silver solution. A bright silver deposit could be obtained in the presence of polyethyleneimine. The reduction current value decreases as the amount of polyethyleneimine added increases due to inhibition effect on the silver electrodeposition reaction. The results of electrochemical quartz crystal microbalance measurement showed that the addition of polyethyleneimine in thymine-complexing silver solution does not significantly affect the resonance frequency change.

Synergistic effect of amine and borane in immobilized metallocene catalysts on ethylene polymerization

The effect of incorporating amines and borane into the supported metallocene catalyst systems was investigated for the polymerization of ethylene and copolymerization of ethylene-1-hexene. Two methods, the conventional method and the one-pot method, were employed to prepare immobilized metallocene catalysts. The synthesized catalysts underwent characterization using scanning electron microscopy (SEM), elemental analysis (EA), inductively coupled plasma (ICP) analysis, and X-ray photoelectron spectroscopy (XPS). The results revealed that the inclusion of polyethyleneimine (PEI) increased the Zr content in the catalyst and yielded polyethylene with higher molecular weight. PEI also exhibited the ability to enhance the comonomer response of supported metallocene catalysts. Additionally, the immobilization of both PEI and borane demonstrated a significant improvement in polymerization activity. XPS analysis demonstrated the electronic effects of amines and borane on the catalyst, indicating enhanced anionic properties of methylaluminoxane and the formation of cationic zirconocenium species. These findings suggest that the presence of PEI and borane promotes the formation of more active metallocene sites for ethylene polymerization.

Ultrafiltration study of the polysulfone membrane modified with branched polyethyleneimine

Abstract This work discussed the fabrication of polysulfone (PSF) ultrafiltration membranes with hydrophilic behaviour by adding branched polyethyleneimine (PEI) as an additive. By directly blending the base polymer and the additive in the organic solvent, the casting solution is prepared. An asymmetric ultrafiltration membrane was fabricated by the phase inversion method. The presence of PEI was confirmed by comparing the IR spectra of the plain PSF membrane and the modified PSF membrane. A scanning electron microscope was used for the comparison of morphological changes in plain and modified membranes. The membrane was characterised with respect to bovine serum albumin (BSA) adsorption, pure water flux, permeability, compaction factor, humic acid (HA) rejection, and water uptake. The fouling resistance behaviour is prompted due to the presence of hydrophilic PEI chains in the membrane. As a result, pure water flux and flux recovery ratio increased from 28.84 to 326.54 L/m2h and from 0.526 to 0.954 L/m2hkPa for the modified membrane with respect to the plain membrane, respectively.

Tailoring the phase composition of carbon-coated nickel sulfides to achieve a high specific capacitance.

As significant transition metal sulfides, nickel sulfides integrated with carbon were successfully synthesized in the presence of polyethylenimine and glutaraldehyde with a solvothermal route at 180 °C followed by carbonization. Glutaraldehyde prevented complete sulfur loss and allowed the formation of a mixed phase of nickel sulfide. The electrochemical performances of pure NiS2, NiS@C0, NiS2/NiS@C1, and NiS2/NiS@C2 electrodes were tested by a series of measurements. The specific capacitances obtained from GCD analysis were 698, 1160, 1484, and 908 F g-1 at 1 A g-1 for NiS2, NiS@C0, NiS2/NiS@C1, and NiS2/NiS@C2 electrodes, respectively. The results implied that the NiS2/NiS@C1 electrode possessed the highest specific capacitances and this study can be a good reference for the preparation of other hybrid metal sulfides as pseudocapacitive electrode materials.

New Frontiers in Electrodeposition for More Sustainable Electroplating Processes

Although technological and processing advancements occurred in the past forty years, industrial firms are still struggling to provide solutions to corrosion protection as well as reduction of toxic wastes. Specifically, large-scale industrialization of electroplating techniques will continue to be limited by strict environmental regulations. Moreover, price volatility of the highly demanding electroplated materials like gold, palladium, copper and nickel will heavily impact the market in the next years. In that respect, alloy plating offers better answers in terms of economic growth and environmental sustainability due to fine tuning composition, morphology and crystallinity [1]. The main categories of alloy compounds are presented and the most important properties for the manufacturing process discussed. Particular attention is devoted to advances in industrial quality control and viable solutions for the reduction of precious metal content in electroplated accessories as well as replacement of cyanide and nickel baths with non-toxic compounds, also considering the commercial needs of wear resistance and aesthetic characteristics of gloss.The electrodeposition of Cu-Sn alloys (bronze) has earned considerable interest thanks to the chemical-physical properties of this alloy, which make it a valid substitute for nickel in fashion industry. Generally, most of the bronze coatings are electroplated starting from baths containing cyanides, and the metal precursors are selected as cyanide compounds. Free cyanide is a well-known problem in the galvanic production cycle both in terms of toxicity for the workers as well as for the environment, and in terms of costs associated with its disposal. The aim of this study is to develop an electroplating bath totally cyanide-free, therefore formulated in an innovative way and which, in addition to being free from this dangerous species, has an eco-friendly support electrolyte. To achieve this goal, methanesulfonic acid (MSA) was chosen as electrolyte, which is biodegradable as part of the natural sulfur cycle. We've studied different formulations in terms of metal precursors, organic additives and their concentrations [2-3].The same cyanide issue is present also in for the electrodeposition of silver, for this reason the influence of polyethyleneimine (PEI) as additive for cyanide-free silver bath, in combination with 5,5-dimethylhydantoin (DMH) as complexing agent, was studied [4]. Chronoamperometry was used to investigate the electrodeposition mechanism, which is found to be a three-dimensional diffusion-controlled nucleation and growth mechanism, according to the Scharifker–Mostany’s model. Smoother, brighter and blue colored silver deposits are obtained in the presence of PEI in a Hull’s cell test, at low density current. Eventually, the influence of nitrate anion is also investigated. The presence of nitrate increases the range of current density allowing for an effective Ag deposition.We also investigated the use of modulated currents to increase the throwing power of electroplating, obtaining a more uniform deposition and reducing the amount of metals but maintaining the required characteristics. Pulsed current justifies its practical application mainly through its ability to influence the mechanisms of electrocrystallisation, which in turn control the mechanical and physical properties of the deposited metal. By simply adjusting the amplitude and length of the pulses, it is possible to control not only the composition and thickness, in atomic order, of the deposits, but to improve their characteristics such as grain size, porosity and homogeneity [5].The authors acknowledge Regione Toscana POR CreO FESR 2014-2020 – azione 1.1.5 sub-azione a1 – Bando 1 “Progetti Strategici di ricerca e sviluppo” which made possible the projects “A.C.A.L. 4.0” (CUP 3553.04032020.158000165_1385), “A.M.P.E.R.E.” (CUP 3553.04032020.158000223_1538) and “GoodGalv” (3647.04032020.157000060).

Cyanide-free silver electrodeposition with polyethyleneimine and 5,5-dimethylhydantoin as organic additives for an environmentally friendly formulation

The influence of polyethyleneimine (PEI) as additive for cyanide-free silver bath, in combination with 5,5-dimethylhydantoin (DMH) as complexing agent, is studied. Cyclic voltammetry (CV) measurements are used to characterize the electrochemical behaviour of the Ag/DMH complex. The Ag electrodeposition from the cyanide-free silver-plating bath is analysed by CVs and the process is optimized varying the PEI concentration. Chronoamperometry is then used to investigate the electrodeposition mechanism, which is found to be a three-dimensional diffusion-controlled nucleation and growth mechanism, according to the Scharifker–Mostany’s model. Smoother, brighter and blue coloured silver deposits are obtained in the presence of PEI in a Hull’s cell test, at low density current. Eventually, the influence of nitrate anion is also investigated. The presence of nitrate increases the range of current density allowing for an effective Ag deposition.

Development of novel alginate‐polyethyleneimine cell‐laden bioink designed for 3D bioprinting of cutaneous wound healing scaffolds

AbstractIn this work, the novel bioink composed of alginate and polyethyleneimine were prepared with different concentrations of alginate and polyethyleneimine (PEI) and used to measure printability, rheological behavior, and cellular functions. The results indicated that viscosity tends to increase about 1.3 times with increasing the alginate and PEI content, which gradually affected structural fidelity. The presence of PEI can create a bioink that is partially gelled with higher storage modulus, high shape fidelity, and printability than alginate. Increasing in the mechanical strength and decreasing in the swelling rate for alginate/PEI bioink demonstrated the strong effect of PEI on the enhancing of structure rigidity in the alginate‐based bioinks. Finally, the cell viability and cell proliferation of the 3D alginate/PEI scaffolds were examined using live/dead and 40,6‐diamidino‐2‐phenylindole staining to select the best bioink formulation. Fibroblast‐laden bioink of 6% alginate and 7% PEI indicated the high proliferation of the printed cells via increasing in hydrophilicity of the surface. The in‐vivo evaluations on the wound rat model indicated that the 3D scaffold effectively accelerated the wound healing process and promoted tissue regeneration by activation of vimentin along with cytokeratin as well as collagen synthesis. Hair follicles started to form at Day 7 in alginate/PEI scaffold.

Nanocomposites based on polylactide and silver nanoparticles and their antimicrobial and antiviral applications

Novel antimicrobial and antiviral silver-containing nanocomposites (PLA-Ag-PEI) based on polylactide (PLA) have been created by the thermochemical reduction of Ag+ ions in the polymer films. Structure-properties relationships of nanocomposites were investigated using FTIR, WAXS, TEM, DSC, TGA. It was found that thermochemical reduction of Ag+ ions in presence of polyethyleneimine as a reducing agent and stabilizer occurred above 100 °C for 5 min. The optimal parameters of the Ag+ ions reduction process in the polymer films were determined, i.e. 160°С for 5 min. The average size of Ag nanoparticles in the PLA-Ag-PEI was defined to be 6.7 nm. The nanocomposites have demonstrated strong antimicrobial activity against S. aureus and E. coli strains, as well as antiviral activity against herpes simplex virus type 1, influenza A virus and adenovirus serotype 2.

Antibacterial ultrafiltration membrane with silver nanoparticle impregnation by interfacial polymerization for ballast water

AbstractInterfacial polymerization technology was employed to immobilize silver (Ag) nanoparticles on the surface of commercial polyethersulfone (PES) membrane to develop antibacterial and antifouling ultrafiltration membrane. Ag nanoparticles were prepared from the reduction of silver nitrate (AgNO3) by sodium borohydride in the presence of polyethyleneimine (PEI) as the stabilizer. The encapsulated Ag nanoparticles in the PEI solution were embedded into the PEI membrane when trimesoyl chloride solution was used to crosslink the PEI solution with the PES membrane, forming Ag‐polyamide (PA) networks through the interfacial polymerization reaction. Experimental results showed that the membrane prepared with 50 mmol/L of AgNO3 and 20 mmol/L of PEI had the optimized antibacterial effect against Escherichia coli. Bacterial concentration and species were also investigated. Exiguobacterium aestuarii and Staphylococcus aureus which are gram‐positive bacteria, needed significantly more time for the Ag‐PA/PES membrane to kill the bacteria completely when compared to E.coli and Vibrio coralliilyticus which are gram‐negative bacteria. This study showed that Ag nanoparticles impregnated in membrane surfaces were 100% effective in killing various types of marine bacteria and bacteria in the seawater collected off Sentosa Island in Singapore. These membranes exhibit excellent antibacterial and antifouling properties which can be used to kill bacteria in ballast water and seawater.

Synthesis of manganese doped β-FeOOH and MnFe2O4 nanorods for enhanced drug delivery and hyperthermia application.

Preparation of manganese ferrite (MnFe2O4) nanorods by the reduction of akaganeite seeds in the presence of oleylamine is reported. The Mn-doped β-FeOOH akaganeite seeds have been processed by the hydrolysis of metal-chloride salts in the presence of polyethylenimine (PEI) surfactant. The hydrophobic oleylamine capped nanorods are made hydrophilic using trisodium citrate as a phase transferring agent. The nanorods form with an aspect ratio of 5.47 and possess a high magnetisation value of 69 emu/g at an applied magnetic field of 1.5 T. The colloidal water dispersion of nanorods exhibits superior heating efficiency by the application of alternating magnetic field (AMF). A specific absorption rate value of 798 W/g is achieved at an applied AMF of field strength 500 Oe and frequency 316 kHz. Further, the citrate functionalised nanorods are capable of attaching with doxorubicin (DOX) electrostatically with a loading efficiency of 97% and the drug release is pH responsive. The DOX loaded nanorods show a promising effect on the apoptosis of MCF-7 as experimented in vitro.

Electrochemical and thermodynamic study on the corrosion performance of API X120 steel in 3.5% NaCl solution

The present work studied the effect of temperature on the corrosion behavior of API X120 steel in a saline solution saturated with CO2 in absence and presence of polyethyleneimine (PEI) as an environmentally safe green inhibitor. The effect of PEI on the corrosion behavior of API X120 steel was investigated using destructive and non-destructive electrochemical techniques. The overall results revealed that PEI significantly decreases the corrosion rate of API X120 steel with inhibition efficiency of 94% at a concentration of 100 μmol L−1. The adsorption isotherm, activation energy and the thermodynamic parameters were deduced from the electrochemical results. It is revealed that the adsorption of PEI on API X120 steel surface follows Langmuir adsorption isotherm adopting a Physi-chemisorption mechanism. Finally, the samples were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques to elucidate the effect of aggressiveness of corrosive media on the surface morphology and the corrosion performance of API X120 steel. The surface topography result indicates that the API X120 steel interface in PEI presence is smoother than CO2 with Cl− ions or Cl− ions only. This is attributed to the compact protective film limits the aggressive ions transfer towards the metallic surface and reduces the corrosion rate. Moreover, PEI inhibition mechanism is based on its CO2 capturing ability and the PEI adsorption on the steel surface beside the siderite layer which give the PEI molecules the ability to reduce the scale formation and increase the corrosion protection due to capturing the CO2 from the brine solution.

Effect of secondary polymer on self‐precipitation of pH‐sensitive polymethylmethacrylate derivatives Eudragit E100 and Eudragit L100

Interpolyelectrolyte complexes or polyplexes can be seen as interesting alternatives in the purpose of active ingredients encapsulation. Working on polymethylmethacrylate derivatives with special focus on controlled oral drug delivery, the influence of charged polyelectrolytes (polyacrylic acid, polyethylenimine, and amino‐dextran) and noncharged ones (polyvinyl alcohol, dextran 40, and Pluronic F68) has been investigated on the precipitation of two pH‐sensitive Eudragit polymers, namely, L100 and E100. Moreover, the possibility of preparing polyplexes involving the two polymethylmethacrylate derivatives with different charged and noncharged secondary polyelectrolytes has been studied. The obtained dispersions have been characterized in terms of mean particle size, size distribution, zeta potential, and morphology. Direct precipitation of Eudragit L100 by medium acidification in a batch process and in the presence of polyethylenimine allowed the production of particles with a narrow size distribution. The mean size was around 200 nm. In this case, the zeta potential was found to be +45 mV at pH = 7 in 1mM aqueous NaCl solution, and the produced suspension was stable in time since no aggregation and sedimentation have been observed. A precipitation pH of 8.16 allows us to suggest the preparation of a polyplex based on Eudragit L100 and polyethylenimine. In contrary, polyvinyl alcohol has shown ability to induce an increase in particle mean size whereas other polyelectrolytes showed no significant effect. Moreover, it was observed that polyethylenimine and polyacrylic acid solutions were able to directly induce Eudragit E100 precipitation whereas amino‐dextran and noncharged polyelectrolytes showed no effect on its precipitation and on particle size distribution.

Influence of albumin interaction on corrosion resistance of sintered iron biomaterials with polyethyleneimine coating

Bioresorbable biomaterials are expected to degrade or to be resorbed within the body at an appropriate degradation rate rather than removing the implant after fulfilling its function. Adsorption of proteins on the metal surface and its subsequent detachment can affect the degradation mechanism and induce health complications. The iron samples were produced from carbonyl iron powder by powder metallurgy and coated by thin layer of polyethyleneimine (PEI). The effect of both PEI coating and bovine serum albumin (BSA) interaction on corrosion resistance of iron biomaterials in Hanks’ solution was investigated. Adsorption of BSA onto Fe + PEI was more rapid in comparison to adsorption onto bare Fe due to the electrostatic nature of BSA adsorption to polymeric layer. The corrosion behavior of sintered samples in Hanks’ solution without and with protein was investigated. Alteration of degradation mechanism was observed in the presence of PEI and/or BSA. PEI was observed to avoid the pitting corrosion while presence of BSA resulted in surface-induced complexation. The extensive pitting with high extent of metal release was observed in the presence of PEI and BSA. The additional spectroscopic and microscopic methods were used to prove the suggested alteration of corrosion mechanism.

A polyethylenimine/salicylaldehyde modified cellulose Schiff base for selective and sensitive Fe3+ detection

We describe a new solid-state colorimetric sensor synthesized by micro-crystalline cellulose (MCC) in the presence of polyethylenimine (PEI) and salicylaldehyde (SA) via an oxidation process and two successive Schiff base reactions. The formation of the Fe3+ complex led to color change detectable by eye, as well as an absorption peak at 501 nm causing fluorescence quenching. The signal was linear with the concentration ranging from 4 to 20 ppm; the detection limit is 0.01 ppm, making this a sensitivity and reliable monitoring platform for Fe3+ detection. Orbital electron distribution and computational studies were also carried out using density functional theory (DFT) to better supplement the sensor’s detection performance. Finally, the sensing mechanism is discussed in detail.

Inhibitor loaded calcium carbonate microparticles for corrosion protection of epoxy-coated carbon steel

pH-sensitive calcium carbonate microparticles were loaded with polyethyleneimine (PEI), a corrosion inhibitor, and used as anti-corrosion additive in epoxy coatings applied on carbon steel. The presence of PEI in the CaCO3 particles was confirmed by Fourier-Transform Infra-Red Spectroscopy (FTIR) and the loading was quantified by Thermal Gravimetric Analysis (TGA). The protective performance of the modified coatings applied on carbon steel was investigated by Electrochemical Impedance Spectroscopy (EIS) and the results evidenced that the modified coatings provided high corrosion protection and very stable barrier properties over time. The self-healing ability was investigated by Localized Electrochemical Impedance Spectroscopy (LEIS) and by the Scanning Vibrating Electrode Technique (SVET) on coated samples artificially damaged and immersed in NaCl solutions. The results revealed an important corrosion inhibition effect, stable over time, in the coatings modified with the PEI loaded particles. The corrosion inhibition effect involves the dissolution of the calcium carbonate microparticles in the local acid media formed at the anodic sites and subsequent release of the corrosion inhibitor that forms a protective film on the steel surface.