Interaction of conducting polymers, polyaniline and polypyrrole, with organic dyes: polymer morphology control, dye adsorption and photocatalytic decomposition

Future perspectives of GMO detection in agriculture: strategies for electrochemical nucleic acid detection

The uncontrolled distribution of genetically modified organisms (GMO)-based food and feed is an increasing global concern, primarily due to limited information about their potential harmful effects. The growing diversity and complexity of GMOs present significant challenges for their detection, traceability, and safety monitoring. Traditionally, GMOs are detected using molecular methods, among which PCR methods are the most explored and are considered the gold standard. However, isothermal nucleic acid amplification methods, though less explored, hold great potential, especially when integrated with biosensor platforms, enabling the development of highly efficient and versatile biosensing systems. This paper provides a comprehensive overview of the recent advances in biosensors utilizing methods of isothermal nucleic acid amplification, highlighting their current progress and future perspectives. We discuss molecular methods for GMO detection, focusing on reaction conditions, amplification efficiency, and compatibility with various detection modalities. Additionally, we investigate the integration of various nanomaterials into transducers, such as electrochemical platforms, together with the electrochemical techniques and detection mechanisms, aiming to outline their synergistic effects with molecular techniques to improve detection sensitivity and enable real-time monitoring. Furthermore, we discuss the applications of GMO biosensors across diverse fields, including food safety and environmental monitoring, while addressing existing challenges and potential strategies for improving the performance, robustness, and practicality of biosensing platforms. Overall, this review highlights the significant progress achieved in GMO biosensors and underscores their promising role in advancing diagnostic and monitoring capabilities.

Tunable physical properties and dye removal application of novel Chitosan Polyethylene glycol and polypyrrole/carbon black films

In this study, polypyrrole/carbon black (PPy/C) filler with different amounts (5, 10, 15, and 20 wt%) was immobilized in a polymer blend consisting of chitosan/polyethylene glycol (CS/PEG) to produce conductive and dye adsorbent films. The study employed various distinctive techniques, including X-ray diffraction, Fourier transform infrared, and high-resolution scanning electron microscope, indicating that composites have high complexity and good interaction. Through the implementation of the UV-Vis technique, it has been observed that the reflectance of composites experiences enhancement with an increase in PPy/C content. The discussion covers the optical constants, such as the composites' refractive index and optical conductivity. Notably, the uniform dispersion of PPy/C has caused a significant rise in the electrical conductivity of the pristine blend from 1.182 × 10-8 (Ω.cm)-1 to 1.42 × 10-5 (Ω.cm)-1 when 15% PPy/C was added. This increased conductivity is attributable to correlated barrier-hopping mechanisms. The effects of increasing PPy/C quantity, contact time (0-260 min), initial MO dye concentration (20-120 mg/L), adsorbent film dosage (0.1, 0.25, 0.5, 0.75, and 1 g/L), and the initial pH (4-10) were examined. Incorporating PPy/C up to 10% improved the removal effectiveness of the composite film. The 10% PPy/C film exhibited the maximum removal effectiveness relative to other films. Langmuir showed better conventionality than the Freundlich isotherm model with R2 of 0.999. The maximal adsorption capacity observed in monolayer adsorption was determined to be 217 mg/g. The adsorption of MO by the 10% PPy/C film is a chemisorption process, according to the parameters of the kinetic studies. (CS/PEG)- (PPy/C) films could be assigned to the synergistic dye adsorption effect of PPy/C filler and CS/PEG polymer-making material, ensuring excellent adsorption efficiency. Because of these appealing characteristics, PPy/C has the potential to be an environmentally friendly adsorbent in the treatment of dye wastewater.

Synthesis of New Copolymer and Genotoxic Effects on Triticum aestivum L. (Wheat) Root Tip Cells

In the present study, a copolymer of poly(N,N-dimethylacrylamide) and sodium acrylate was synthesized with the Solution Polymerization Technique. The purpose was to uncover the cytotoxic and genotoxic effects on root tip cells of the Triticum aestivum L. plant germinated with this polymer at different concentrations (25, 50, 100, and 200 ppm). The deposition of poly(DMAA-co-NaAc) copolymer in the study sample T. aestivum was demonstrated with the FTIR, UV-VIS spectroscopy analysis, X-Ray Diffraction (XRD) Spectroscopy, Scanning Electron Microscopy (SEM), SEM Element Map, and Energy Dispersive Spectroscopy (EDS) Spectrum. All concentrations of the poly(DMAA-co-NaAc) copolymer caused a decrease in the Mitotic Index (MI). The poly(DMAA-co-NaAc) copolymer caused various mitotic abnormalities such as loss of genetic material, deconstructed prophase, adhesion, chromosome groupings in metaphase, deconstructed metaphase, C-metaphase, chromosomal loss, chromosomal fracture, deconstructed anaphase, lagging chromosome, fragment, polar aberration, bridge, advancing, star anaphase, multipolarity, and deconstructed telophase. Study results show that poly(DMAA-co-NaAc) copolymer will cause abnormalities in mitosis as a result of its uptake by plants. These results also show that the poly(DMAA-co-NaAc) polymer, which affects organisms, must be produced in a controlled setting to reduce its accumulation in nature and ultimately disposed of in a way that will not harm the environment.

In-Situ Coating of Iron with a Conducting Polymer, Polypyrrole, as a Promise for Corrosion Protection

Iron microparticles were coated with polypyrrole in situ during the chemical oxidation of pyrrole with ammonium peroxydisulfate in aqueous medium. A series of hybrid organic/inorganic core-shell materials were prepared with 30-76 wt% iron content. Polypyrrole coating was revealed by scanning electron microscopy, and its molecular structure and completeness were proved by FTIR and Raman spectroscopies. The composites of polypyrrole/carbonyl iron were obtained as powders and characterized with respect to their electrical properties. Their resistivity was monitored by the four-point van der Pauw method under 0.01-10 MPa pressure. In an apparent paradox, the resistivity of composites increased from the units Ω cm for neat polypyrrole to thousands Ω cm for the highest iron content despite the high conductivity of iron. This means that composite conductivity is controlled by the electrical properties of the polypyrrole matrix. The change of sample size during the compression was also recorded and provides a parameter reflecting the mechanical properties of composites. In addition to conductivity, the composites displayed magnetic properties afforded by the presence of iron. The study also illustrates the feasibility of the polypyrrole coating on macroscopic objects, demonstrated by an iron nail, and offers potential application in the corrosion protection of iron. The differences in the morphology of micro- and macroscopic polypyrrole objects are described.

Valorization of polyurethane foam waste through the decoration with nano-polyaniline for dye decontamination from polluted water

Two polyurethane polyaniline nanocomposites have been synthesized using two in situ polymerization routes of dried and wet bases to valorize the polyurethane waste. The physical and chemical properties of polyurethane-based nanocomposites were compared using SEM, XRD, FTIR, and Zeta potential. SEM images showed that the average particle size of the dried-based composite was 56 nm, while the wet-based composite had an average size of 75 nm. The separation efficiency for methylene blue (MB) and Congo red (CR) dyes was evaluated against free polyurethane foam waste. It was evident that pure polyurethane (PPU) achieved only 4.79% and 16.71% removal for MB and CR, respectively. These dye decontamination efficiencies were enhanced after nano polyaniline decoration of polyurethane foam either through dried base polymerization (DPUP) or wet base polymerization (WPUP). WPUP composite records 11.23% and 85.99% for MB and CR removal, respectively, improved to 26.69% and 90.07% removal using DPUP composite for the respective dyes. The adsorption kinetics, isotherms, and thermodynamics were investigated. The experimental results revealed the pseudo-second-order kinetic model as the most accurately described kinetics model for both CR and MB adsorption. The Langmuir model provided the best fit for the data, with maximum adsorption capacities of 110.98 mg/g for CR and 26.86 mg/g for MB, with corresponding R-squared values of 0.9974 and 0.9608, respectively. Regeneration and reusability studies of PPU, WPUP, and DPUP showed effective reusability, with DPUP displaying the highest adsorption capacity. These results aid in creating eco-friendly and cost-efficient adsorbents for dye removal in environmental sanitation.

Synthesis and Dye Adsorption Dynamics of Chitosan-Polyvinylpolypyrrolidone (PVPP) Composite

One major environmental issue responsible for water pollution is the presence of dyes in the aquatic environment as a result of human activity, particularly the textile industry. Chitosan-Polyvinylpolypyrrolidone (PVPP) polymer composite beads were synthesized and explored for the adsorption of dyes (Bismarck brown (BB), orange G (OG), brilliant blue G (BBG), and indigo carmine (IC)) from dye solution. The CS-PVPP beads demonstrated high removal efficiency of BB (87%), OG (58%), BBG (42%), and IC (49%). The beads demonstrated a reasonable surface area of 2.203 m2/g and were negatively charged in the applicable operating pH ranges. TGA analysis showed that the polymer composite can withstand decomposition up to 400 °C, proving high stability in harsh conditions. FTIR analysis highlighted the presence of N-H amine, O-H alcohol, and S=O sulfo groups responsible for electrostatic interaction and hydrogen bonding with the dye molecules. A shift in the FTIR bands was observed on N-H and C-N stretching for the beads after dye adsorption, implying that adsorption was facilitated by hydrogen bonding and Van der Waals forces of attraction between the hydroxyl, amine, and carbonyl groups on the surface of the beads and the dye molecules. An increase in pH increased the adsorption capacity of the beads for BB while decreasing OG, BBG, and IC due to their cationic and anionic nature, respectively. While an increase in temperature did not affect the adsorption capacity of OG and BBG, it significantly improved the removal of BB and IC from the dye solution and the adsorption was thermodynamically favoured, as demonstrated by the negative Gibbs free energy at all temperatures. Adsorption of dye mixtures followed the characteristic adsorption nature of the individual dyes. The beads show great potential for applications in the treatment of dye wastewater.

Buckybowl Molecular Tweezers for Recognition of Fullerenes

Buckybowl tweezers are a relatively young research area closely associated with the development of non-planar polycyclic aromatic systems and supramolecular chemistry. Since the appearance of the first prototypes in the early 2000s, the tweezers have undergone evolutionary changes. Nowadays they are able to effectively interact with fullerenes and the results opened up prospects for development in the field of sensing, nonlinear optics, and molecular switchers. In the present study, examples of corannulene-based and other buckybowl tweezers for the recognition of C60 and C70 fullerenes were summarized and analyzed. The main structural components of the tweezers were also reviewed in detail and their role in the formation of complexes with fullerenes was evaluated. The revealed structural patterns should trigger the development of novel recognition systems and materials with a wide range of applications.

Insights into properties, synthesis and emerging applications of polypyrrole-based composites, and future prospective: A review

Recent advancements in polymer science and engineering underscore the importance of creating sophisticated soft materials characterized by well-defined structures and adaptable properties to meet the demands of emerging applications. The primary objective of polymeric composite technology is to enhance the functional utility of materials for high-end purposes. Both the inherent qualities of the materials and the intricacies of the synthesis process play pivotal roles in advancing their properties and expanding their potential applications. Polypyrrole (PPy)-based composites, owing to their distinctive properties, hold great appeal for a variety of applications. Despite the limitations of PPy in its pure form, these constraints can be effectively overcome through hybridization with other materials. This comprehensive review thoroughly explores the existing literature on PPy and PPy-based composites, providing in-depth insights into their synthesis, properties, and applications. Special attention is given to the advantages of intrinsically conducting polymers (ICPs) and PPy in comparison to other ICPs. The impact of doping anions, additives, and oxidants on the properties of PPy is also thoroughly examined. By delving into these aspects, this overview aims to inspire researchers to delve into the realm of PPy-based composites, encouraging them to explore new avenues for flexible technology applications.

Removal of Anionic Methyl Orange Dye from Water by Poly[2-methyl-1H-indole] Derivatives: Investigation of Kinetics and Isotherms of Adsorption

The adsorption properties toward methyl orange (MO) were evaluated for poly[2-methyl-1H-indole] and its derivatives. The influence of pH, ionic strength of solution, composition, and amount of sorbent on the adsorption of MO dye was investigated; the kinetics of dye adsorption was studied. The adsorption isotherms were analyzed using different models of sorption equilibrium. The presence of chemical interaction between polyindoles and dye was proved by IR and UV spectroscopy methods. The sorption of MO with polymers is realized mainly due to the formation of electrostatic interactions between the sulfogroup of the dye and the imino group of the sorbent. Microphotographs demonstrate the change in the morphology of polyindoles after adsorption, which further confirms the structural changes in the polymers. It was found that the main factors affecting the sorption capacity of the studied materials are the position and nature of substituents in the polymers and the sorption conditions. For example, polyindoles containing a methoxy group in their structure (o-OMePIn and m-OMePIn) have the best sorption activity. These polymers are effective in adsorbing dyes, which means that they can be used in wastewater treatment.

Poly (aniline-co-aniline-2,5-disulfonic acid) / L-ascorbic acid / Ag@SiO2 / polysafranin nanocomposite: synthesis, characterization and anomalous electrical behaviour

We report the synthesis of sulfonated copolyaniline/polysafranin/L-ascorbic acid/Ag@SiO2 fine powdered nanocomposites and investigate the influence of incorporating the dye on their conductivity. The composite was characterized via IR, UV, cyclic voltammetry (CV), electric, dielectric, SEM, TEM, TGA and DSC measurements. Microscopy images revealed intensified spherical particles that were dispersed across the entire surface, and the SiO2/Ag particles were distributed on the surface. The XRD results exhibited peaks at many 2q values, and their interatomic spacing (d) and crystallite (grain) sizes were calculated. The thermal degradation curves exhibited an interesting model of stability. The cyclic voltammogram exhibited redox peaks identical to those of the reported analogues. The d.c. conductivity of the oligomer varied from 0.06 - 0.016 (s/cm), and that of the composite varied from 0.008 to 0.016 (s/cm). The material changed from a semiconductor to a metallic material. The observed conductivity is mainly attributed to self-doping between the sulfonate groups and the charged nitrogen atoms in the polymer chains. The frequency dependence of the permittivity, ε', showed a marked effect on the frequency window under consideration. The permittivity, ε', is independent of the increase in the frequency of the oligomer and the composite. This behavior supports the non-Debye dependency by confirming the occurrence of electrode polarization and space charge effects. In conclusion, the incorporation of safranin dye with a thermally stable, highly sulfonated polyaniline derivative/Ag@SO2 nanocomposite achieved improved conductivity after heating. The d.c. conductivities are comparable to those of many commercial inorganic or organic composites, and because of their attractive electrical properties, we suggest that these materials are promising for electronic field applications.

Development of ultra-high surface area polyaniline-based activated carbon for the removal of volatile organic compounds from industrial effluents

Removing volatile organic compounds (VOCs) from aqueous solutions is critical for reducing VOC emissions in the environment. Activated carbons are widely used for removal of VOCs from water. However, they show less application feasibility and low removal due to less surface area. Here, a cost-effective and high surface area activated carbonized polyaniline (ACP) was synthesized to sustainable removal of VOCs from water. The ACP microstructure, surface properties, and pore structure were investigated using Brunauer-Emmett-Teller (BET) theory, Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). The specific surface area of ACP6:1 (2988.13 m2/g) was greater than that of commercial activated carbon (PAC) (1094.49 m2/g), indicating that it has excellent VOC adsorption capacity. The effects of pH, initial VOC concentration, time, temperature, and ionic strength were studied. According to kinetic and thermodynamic studies on VOCs adsorption, it is an exothermic and spontaneous process involving rate-limiting kinetics. Adsorption isotherms follow the Freundlich isotherm model, suggesting that the adsorbent surface is heterogeneous with multilayer adsorption and maximum ACP adsorption capacities of 1913.9, 2453.3, 1635.8, and 3327.0 mg/g at 293 K for benzene, toluene, ethylbenzene, and perchloroethylene, respectively, representing a 3- to 5-fold improvement over PAC. ACP is a promising adsorbent with a high adsorption efficiency for VOC removal.

Preparation of PANI modified TiO2 and characterization under pre- and post- photocatalytic conditions

Polyaniline (PANI) is a promising conducting polymer for surface modification of TiO2 to overcome limitations of the use of visible light and attain increased photocatalytic efficiency for the removal of organic contaminants. In this study, a series of polyaniline modified TiO2 (PANI-TiO2) composites were prepared by using "in-situ" chemical oxidation polymerization method. The composites were systematically characterized by Fourier transform infrared spectroscopy (equipped with an attenuated total reflection accessory, FTIR-ATR), Raman spectroscopy, X-ray diffractometry (XRD), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDAX), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflectance spectroscopy (UV-DRS), photoluminescence spectroscopy (PL), nitrogen (N2) physisorption (Brunauer - Emmett - Teller surface area (SBET) and Barrett-Joyner-Halenda (BJH) pore size analysis), thermogravimetry-derivative thermogravimetry (TG-DTG) techniques. XRD patterns of PANI-TiO2 composites confirmed both the amorphous phase of PANI and the crystalline character of TiO2. TG/DTG analysis complemented the XRD profiles that the interactions between PANI and TiO2 resulted in a more stable PANI-TiO2 matrix. SEM images displayed the dominant morphology as dandelion-like shapes of PANI being more pronounced with increasing PANI ratios in PANI-TiO2 composites. UV-DRS profiles revealed that the band gap energies of the composites were lower than bare TiO2 expressing a shift to the visible light region. Both PL and UV-DRS analyses confirmed the band-gap reduction phenomenon of PANI modification of TiO2. The incorporation of PANI into TiO2 resulted in a reduction of the surface area of TiO2. The composites were subsequently subjected to photocatalytic activity assessment tests using humic acid (HA) as a model of refractory organic matter (RfOM) under simulated solar irradiation (Uyguner-Demirel et al. Environ Sci Pollut Res 30 85626-85638, 2023). The morphological and structural changes attained upon application of photocatalysis were also evaluated by FTIR-ATR, Raman spectroscopy, XRD, and SEM-EDAX methods in a comparable manner. The FTIR-ATR spectral features of PANI, RfOM and all composites displayed peaks with slight shifts under pre- and post- photocatalytic conditions as well as following dark surface interactions. Besides exhibiting noticeable photocatalytic performance, PANI-TiO2 composites were also proven to maintain stability under non-selective oxidation conditions in the presence of a complex organic matrix. The prepared PANI-TiO2 composites overcoming the limitations of UVA light active bare TiO2 photocatalysis could possibly find a beneficial use as potential catalysts in solar photocatalytic applications.

Carbonized Leather Waste with Deposited Polypyrrole Nanotubes: Conductivity and Dye Adsorption

This paper reports the conversion of a waste to a conducting material, exploiting the ability to adsorb pollutant organic dyes. Leather waste was carbonized at 800 °C in an inert nitrogen atmosphere. The resulting biochar was used for in-situ deposition of polypyrrole nanotubes produced by the oxidative polymerization of pyrrole in the presence of methyl orange. The composites of carbonized leather with deposited polypyrrole nanotubes of various composition were compared with similar composites based on globular polypyrrole. Their molecular structure was characterized by infrared and Raman spectra. Both conducting components formed a bicontinuous structure. The resistivity was newly determined by a four-point van der Pauw method and monitored as a function of pressure applied up to 10 MPa. The typical conductivity of composites was of the order of 0.1 to 1 S cm-1 and it was always higher for polypyrrole nanotubes than for globular polypyrrole. The method also allows for the assessment of mechanical features, such as powder fluffiness. The conductivity decreased by 1-2 orders of magnitude after treatment with ammonia but still maintained a level acceptable for applications operating under non-acidic conditions. The composites were tested for dye adsorption, specifically cationic methylene blue and anionic methyl orange, using UV-vis spectroscopy. The composites were designed for future use as functional adsorbents controlled by the electrical potential or organic electrode materials.

Deformation Rate-Adaptive Conducting Polymers and Composites

Materials are more easily damaged during accidents that involve rapid deformation. Here, a design strategy is described for electronic materials comprised of conducting polymers that defies this orthodox property, making their extensibility and toughness dynamically adaptive to deformation rates. This counterintuitive property is achieved through a morphology of interconnected nanoscopic core-shell micelles, where the chemical interactions are stronger within the shells than the cores. As a result, the interlinked shells retain material integrity under strain, while the rate of dissociation of the cores controls the extent of micelle elongation, which is a process that adapts to deformation rates. A prototype based on polyaniline shows a 7.5-fold increase in ultimate elongation and a 163-fold increase in toughness when deformed at increasing rates from 2.5 to 10 000% min-1 . This concept can be generalized to other conducting polymers and highly conductive composites to create "self-protective" soft electronic materials with enhanced durability under dynamic movement or deformation.

P, Alshehri M, Shah NA. Synthesis, Characterization and Investigation of Optical and Electrical Properties of Polyaniline/Nickel Ferrite Composites

Nickel ferrite nanoparticles are prepared by using a low-temperature self-propagating solution combustion method using urea as fuel. The prepared nickel ferrite nanoparticles were doped with polyaniline in the three different weight ratios of 10%, 30% and 50% by using an in situ polymerization method and by adding ammonium persulfate as an oxidizing agent. The obtained samples were characterized by using XRD, FTIR, SEM and a UV-visible spectrophotometer. XRD examined crystalline peaks of ferrites and amorphous peak of polyaniline and confirmed the formation of the composites. FTIR examined the chemical nature of samples and showed peaks due to polyaniline and the characteristic peaks that were less than 1000 cm-1 wavenumber were due to metal-oxygen bond vibrations of ferrites. AC conductivity increased with frequency in all samples and the highest AC conductivity was seen in polyaniline/nickel ferrite 50%. DC conductivity increased in all samples with the temperature showing the semiconducting nature of the samples. Activation energy was evaluated by using Arrhenius plots and there was a decrease in activation energy with the addition of ferrite content. The UV-visible absorption peaks of polyaniline showed shifting in the composites. The optical direct and indirect band gaps were evaluated by plotting Tauc plots and the values of the optical band gap decreased with addition of ferrite in polyaniline and the Urbach energy increased in the samples with 10%, 30% and 50% polyaniline/nickel ferrite composites. The optical properties of these composites with a low band gap can find applications in devices such as solar cells.

Tuning of Morphological and Antibacterial Properties of Poly(3,4-ethylenedioxythiophene):Peroxodisulfate by Methyl Violet

This study demonstrates a one-step synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT) in the presence of the methyl violet (MV) dye. The structural properties of PEDOT:peroxodisulfate were studied using Raman and MALDI-TOF spectroscopies. The use of the MV dye in the polymerization process resulted in a change in the typical irregular morphology of PEDOT:peroxodisulfate, leading to the formation of spherical patterns. SEM and TEM analyses revealed that increasing the dye concentration can produce larger spherical aggregates probably due to the hydrophobic and π-π interactions. These larger aggregates hindered the charge transport and reduced the electrical conductivity. Interestingly, at higher dye concentrations (0.05 and 0.075 M), the PEDOT:peroxodisulfate/MV films exhibited significantly improved antibacterial activity against Staphylococcus aureus and Escherichia coli. Furthermore, the PEDOT:peroxodisulfate films with the incorporated MV dye exhibited a well-defined and repeatable redox behavior. The remarkable amalgamation of their optical, electrochemical and antibacterial properties provides the PEDOT:peroxodisulfate/MV materials with an immensely diverse spectrum of applications, including in optical sensors and medical devices.

Dual-functional marine algal carbon-based materials with highly efficient dye removal and disinfection control

The design and simple, green preparation of dual-functional materials for the decontamination of both hazardous dyes and pathogenic microorganisms from wastewater remain challenging currently. Herein, a promising marine algal carbon-based material (named C-SA/SP) with both highly efficient dye adsorptive and antibacterial properties was fabricated based on the incorporation of sodium alginate and a low dose of silver phosphate via a facile and eco-friendly approach. The structure, removal of malachite green (MG) and congo red (CR), and their antibacterial performance were studied, and the adsorption mechanism was further interpreted by the statistical physics models, besides the classic models. The results show that the maximum simulated adsorption capacity for MG reached 2798.27 mg/g, and its minimal inhibit concentration for Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was 0.4 mg/mL and 0.2 mg/mL, respectively. The mechanistic study suggests that silver phosphate exerted the effects of catalytic carbon formation and pore formation, while reducing the electronegativity of the material as well, thus improving its dye adsorptive performance. Moreover, the MG adsorption onto C-SA/SP showed vertical orientation and a multi-molecular way, and its adsorption sites were involved in the adsorption process with the increase of temperature. Overall, the study indicates that the as-made dual-functional materials have good applied prospects for water remediation.

4-Cyanophenol herbicide sensor using multi-walled carbon nanotube embedded dual-microporous polypyrrole nanoparticles as metal-free and environmentally friendly hybrid electrode

A highly sensitive 4-cyanophenol (4-CP) sensor was fabricated using multi-walled carbon nanotube (MWCNT)-embedded dual-microporous polypyrrole nanoparticle-modified screen-printed carbon electrodes (SPCE/DMPPy/MWCNT). The well-defined dual pores of DMPPy and MWCNT (~ 0.53 and ~ 0.65 nm) acted as good analyte absorption agents (shortening the ion diffusion path) and conducting agents (reducing the internal electron-transfer resistance). This enhanced electrical conductivity resulted in the improved electro-oxidation of 4-CP. A higher sensitivity (19.0 μA μM^-1 cm^-2) and lower limit of detection (0.8 nM) were achieved with a wide detection range of 0.001-400 µM (R² = 0.9988). The proposed sensor exhibited excellent recovery of 4-CP in real-world samples. Therefore, the SPCE/DMPPy/MWCNT sensor is regarded highly suitable for rapidly detecting 4-CP.

Highly-efficient peroxydisulfate activation by polyaniline-polypyrrole copolymers derived pyrolytic carbon for 2,4-dichlorophenol removal in water: Coupling mechanism of singlet oxygen and electron transfer

Carbonization of N-containing aromatic polymers is a promising route to prepare N-doped carbon materials with low cost, easy regulation, and no external N source. However, there are relatively few studies applying these materials for persulfate activation, and the catalytic mechanisms of the existing reaction systems are divergent. In this paper, a series of N-doped carbon materials were prepared by carbonizing polyaniline (PANI), polypyrrole (PPy), and PANI-PPy copolymers. The copolymer-derived carbon materials exhibit superior peroxydisulfate (PDS) catalytic activity compared to some commercially available and reported carbon materials. Combing quenching experiments, EPR analysis, chemical probe analysis, and various electrochemical analysis methods identified the singlet oxygen (¹O₂) and electron transfer as the main reaction pathways of all systems, but the contribution of each pathway was influenced by the types of precursors. The structure-activity relationship indicated that the carbonyl group (CO) was the main active site for the ¹O₂ pathway, while the electron transfer ability of the reaction system and the potential of the complex formed by catalyst and PDS jointly determined the electron transfer pathway. This paper provides a new strategy for obtaining excellent N-doped carbon-based persulfate activators and deepens the insight into the mechanism of PDS activation by N-doped carbon materials.

Carbonized Leather Waste: A Review and Conductivity Outlook

The carbonization of collagen-based leather waste to nitrogen-containing carbon is reviewed with respect to the preparation, characterization of carbonized products, and applications proposed in the literature. The resulting nitrogen-containing carbons with fibrous morphology have been used as adsorbents in water pollution treatment, in electrocatalysis, and especially in electrodes of energy-storage devices, such as supercapacitors and batteries. Although electrical conductivity has been implicitly exploited in many cases, the quantitative determination of this parameter has been addressed in the literature only marginally. In this report, attention has been newly paid to the determination of conductivity and its dependence on carbonization temperature. The resulting powders cannot be compressed into pellets for routine conductivity determination. A new method has been used to follow the resistivity of powders as a function of pressure up to 10 MPa. The conductivity at this pressure increased from 9.4 × 10^-8 S cm^-1 for carbonization at 500 °C to 5.3 S cm^-1 at 1000 °C. The conductivity of the last sample was comparable with conducting polymers such as polypyrrole. The carbonized leather thus has the potential to be used in applications requiring electrical conduction.

A Comprehensive Review on Adsorption, Photocatalytic and Chemical Degradation of Dyes and Nitro-Compounds over Different Kinds of Porous and Composite Materials

Dye and nitro-compound pollution has become a significant issue worldwide. The adsorption and degradation of dyes and nitro-compounds have recently become important areas of study. Different methods, such as precipitation, flocculation, ultra-filtration, ion exchange, coagulation, and electro-catalytic degradation have been adopted for the adsorption and degradation of these organic pollutants. Apart from these methods, adsorption, photocatalytic degradation, and chemical degradation are considered the most economical and efficient to control water pollution from dyes and nitro-compounds. In this review, different kinds of dyes and nitro-compounds, and their adverse effects on aquatic organisms and human beings, were summarized in depth. This review article covers the comprehensive analysis of the adsorption of dyes over different materials (porous polymer, carbon-based materials, clay-based materials, layer double hydroxides, metal-organic frameworks, and biosorbents). The mechanism and kinetics of dye adsorption were the central parts of this study. The structures of all the materials mentioned above were discussed, along with their main functional groups responsible for dye adsorption. Removal and degradation methods, such as adsorption, photocatalytic degradation, and chemical degradation of dyes and nitro-compounds were also the main aim of this review article, as well as the materials used for such degradation. The mechanisms of photocatalytic and chemical degradation were also explained comprehensively. Different factors responsible for adsorption, photocatalytic degradation, and chemical degradation were also highlighted. Advantages and disadvantages, as well as economic cost, were also discussed briefly. This review will be beneficial for the reader as it covers all aspects of dye adsorption and the degradation of dyes and nitro-compounds. Future aspects and shortcomings were also part of this review article. There are several review articles on all these topics, but such a comprehensive study has not been performed so far in the literature.

MXenes and MXene-supported nanocomposites: a novel materials for aqueous environmental remediation

Water contamination has become a significant issue on a global scale. Adsorption is a cost-effective way to treat water and wastewater compared to other techniques such as the Advanced Oxidation Processes (AOPs), photocatalytic degradation, membrane filtration etc. Numerous research experts are continuously developing inexpensive substances for the adsorptive removal of organic contaminants from wastewater. A fresh and intriguing area of inquiry has emerged as a result of the development of MXenes. This article aims to provide a preliminary understanding of MXenes from synthesis, structure, and characterization to the scope of further research. The applications of MXenes as a new generation adsorbent for remediation of various kinds of organic pollutants and heavy metals from wastewater are also summarized. MXenes with altered surfaces may make effective adsorbents for wastewater treatment. Lastly, the mechanism of adsorption of organic contaminants and heavy metals on MXenes is also discussed for a better understanding of the readers.

Recent Advances in the Removal of Organic Dyes from Aqueous Media with Conducting Polymers, Polyaniline and Polypyrrole, and Their Composites

Water pollution by organic dyes, and its remediation, is an important environmental issue associated with ever-increasing scientific interest. Conducting polymers have recently come to the forefront as advanced agents for removing dye. The present review reports on the progress represented by the literature published in 2020-2022 on the application of conducting polymers and their composites in the removal of dyes from aqueous media. Two composites, incorporating the most important polymers, polyaniline, and polypyrrole, have been used as efficient dye adsorbents or photocatalysts of dye decomposition. The recent application trends are outlined, and future uses also exploiting the electrical and electrochemical properties of conducting polymers are offered.

Polypyrrole-based nanomaterials: A novel strategy for reducing toxic chemicals and others related to environmental sustainability applications

Aqueous contaminants such as pharmaceuticals, dyes, personal care products, etc., are the common water contaminants that show adverse health effects. Photocatalysis is one of the well-known techniques to treat these water contaminants. Currently, most inorganic photocatalysts show a poor balance between adsorption and photocatalytic activity. In addition, heavy metal pollution and low biosafety are significant concerns in photocatalysis. Thus, environmentally friendly photocatalysts are required to avoid the secondary pollution caused by some inorganic semiconductor-photocatalysts. Organic polymer-based photocatalysts are low-cost, stable, non-toxic, and can utilize visible and NIR light for photocatalysis. In this review, we have discussed polypyrrole as a photocatalyst. Polypyrrole is a conducting organic polymer photocatalyst that is highly stable with high charge mobility and strong binding sites for photocatalytic reactions. Besides these advantages, polypyrrole has limitations, such as high charge recombination due to a small bandgap and poor dispersity. So we have explored the modifications to polypyrrole photocatalysts, such as doping and heterojunctions. Further, we have explained the applications of polypyrrole in photocatalysis as an adsorbent, sensitizer, degradation of pollutants, and energy production. Finally, the future aspects of polypyrrole photocatalysis are also explored to improve the path of future research.

Microstructure Evolution and Its Correlation with Performance in Nitrogen-Containing Porous Carbon Prepared by Polypyrrole Carbonization: Insights from Hybrid Calculations

The preparation of nitrogen-containing porous carbon (NCPC) materials by controlled carbonization is an exciting topic due to their high surface area and good conductivity for use in the fields of electrochemical energy storage and conversion. However, the poor controllability of amorphous porous carbon prepared by carbonization has always been a tough problem due to the unclear carbonation mechanism, which thus makes it hard to reveal the microstructure-performance relationship. To address this, here, we comprehensively employed reactive molecular dynamics (ReaxFF-MD) simulations and first-principles calculations, together with machine learning technologies, to clarify the carbonation process of polypyrrole, including the deprotonation and formation of pore structures with temperature, as well as the relationship between microstructure, conductance, and pore size. This work constructed ring expressions for PPy thermal conversion at the atomic level. It revealed the structural factors that determine the conductivity and pore size of carbonized products. More significantly, physically interpretable machine learning models were determined to quantitatively express structure factors and performance structure-activity relationships. Our study also confirmed that deprotonation preferentially occurred by desorbing the dihydrogen atom on nitrogen atoms during the carbonization of PPy. This theoretical work clearly reproduces the microstructure evolution of polypyrrole on an atomic scale that is hard to do via experimentation, thus paving a new way to the design and development of nitrogen-containing porous carbon materials with controllable morphology and performance.

Corrosion Inhibition of Mild Steel in Hydrochloric Acid Environments Containing Sonneratia caseolaris Leaf Extract

Sonneratia caseolaris leaf extract was characterized for its mitigation of the electrochemical corrosion of steel in naturally aerated hydrochloric acid environments by electrochemical methods and surface analysis. The presence of S. caseolaris leaf extract (SCLE) in the hydrochloric acid medium ameliorated the corrosion resistance of steel via the adsorption of SCLE species to form a barrier layer. The improved inhibition effectiveness was demonstrated to be independent of the SCLE concentration and the corrosive environment. The highest inhibition performance of approximately 98% was reached for steel in a 1 M HCl medium containing 2500 ppm SCLE. The performance significantly decreased with a decrease in the HCl concentration from 1.00 to 0.01 M with the same SCLE concentration. In addition, severe corrosion occurred on the uninhibited steel surface but was significantly reduced on the inhibited steel surface. The analyzed results also indicated the existence of electronegative functional groups in SCLE, which could promote the adsorption process for the self-formation of the barrier layer on the steel surface. The work reported herein suggested a powerful strategy to mitigate electrochemical corrosion by adding an effective new inhibitor to achieve a green inhibitor system.

A comprehensive review on preparation, functionalization and recent applications of nanofiber membranes in wastewater treatment

The direct discharge of significant amounts of polluted water into water bodies causes adverse ecological and human health effects. This severe deterioration in water quality creates significant challenges to meet the growing demand for clean water. Therefore, the world urgently needs environmentally friendly advanced technology to overcome this global crisis. In this regard, nanofiber-based membrane filtration is a promising technique in wastewater remediation because of their huge surface area, extremely porous structure, amenable pore size/pore size distribution, variety of material choices, and flexibility to modification with other functional materials. However, despite their unique properties, fouling, poor mechanical properties, shrinkage, and deformation are major drawbacks of nanofiber membranes for treating wastewater. This review presents a comprehensive overview of nanofiber membranes' fabrication and function in water purification applications as well as providing novel approaches to overcoming/alleviating the mentioned disadvantages. The review first presents nanofiber membrane preparation methods, focusing on electrospinning as a versatile and viable technique alongside discussing the parameters controlling nanofiber morphology. Afterward, the functionalization of nanofiber membranes by combining them with other nanomaterials, such as metal and metal-oxide nanoparticles, carbon nanotubes, metal-organic frameworks, and biomolecules, were demonstrated and discussed. In addition, nanofiber membranes functionalized with microorganisms were highlighted. Finally, we introduced and discussed in detail the most relevant and recent advances in nanofiber applications in wastewater treatment in the context of removing different pollutants (e.g., heavy metals, nutrients, radioactive elements, pharmaceuticals, and personal care products, dyes, and pesticides). Moreover, the promising antimicrobial ability of nanofiber membranes in removing microorganisms from wastewater has been fully underscored. We believe this comprehensive review could provide researchers with preliminary data and guide both researchers and producers engaged in the nanofiber membrane industry, letting them focus on the research gaps in wastewater treatment.

Application of polypyrrole-based adsorbents in the removal of fluoride: a review

When fluoride levels in water exceed permitted limits (>1.5 mg L−1), water pollution becomes a major concern to humans.

Phytic acid-doped poly-N-phenylglycine potato peels for removal of anionic dyes: investigation of adsorption parameters

In this work, we report on enhanced adsorption of anionic dyes, Reactive Blue 49 (RB 49) and Direct Blue 199 (DB 199), using a phytic acid-doped poly-N-phenylglycine@potato peel (PA-PPG@PP) nanocomposite material.

The Adsorption Performance of Polyaniline/ZnO Synthesized through a Two-Step Method

Polyaniline/Zinc oxide (PANI/ZnO) were prepared using a two-step method, and the morphology and the structure of PANI/ZnO composites were characterized through a scanning electron microscope (SEM) and X-ray diffraction (XRD). Factors such as the content of ZnO, the adsorption time and the mass of the adsorbent, and the kinetic equation of PANI/ZnO as adsorbents for the adsorption of methyl orange solution were studied. The results showed that the adsorption efficiency of methyl orange by polyaniline with the increase of adsorbent mass firstly increased and then decreased. Among the composites with the same quality, PANI composites with 8% ZnO have a better adsorption effect for methyl orange, and the maximum adsorption ratio can reach 69% with the increase of adsorption time at 0.033 g; With the increase of adsorbent mass, the adsorption efficiency of PANI composites with 8% ZnO increased continuously. When the mass increased from 0.033 g to 0.132 g, the adsorption rate increased from 69% to 93%, and the adsorption of the methyl orange solution by PANI/ZnO composites was more in line with the quasi-second-order kinetic equation.

Adsorption of methylene blue dye on sodium alginate/polypyrrole nanotube composites

Nanomaterials have recently come to the fore as potential adsorbents due to their high surface, high efficiency, and adsorption capacity. This study the performance of polypyrrole nanotube incorporated sodium alginate (SA/PPyNT) on the adsorptive removal of methylene blue dye from an aqueous solution was investigated. Firstly, polypyrrole nanotubes were synthesized by oxidative chemical polymerization. Then, polypyrrole nanotubes were added to the sodium alginate gel and the composite beads were prepared by a crosslinking process in a 3% CaCl₂ solution. The composite beads were characterized using Fourier transform infrared-attenuated total reflectance (FTIR-ATR), scanning electron microscope (SEM), and atomic force microscopy analyzes. In the adsorption studies, to determine the optimum conditions, experiments were carried out at different conditions namely temperature (25-45 °C), contact time, initial pH (2-12), adsorbent dosage (1-5 g/L), dye concentrations (10-50 mg/L). The studies indicated that the removal percentage of MB reached up to 90.5% at pH = 7 and 25 °C. Furthermore, different isotherm models such as Freundlich, Langmuir, D-R, and Harkins-Jura were applied. Considering the correlation coefficients, the Langmuir isotherm model was found to be the most suitable model (r² = 0.9974). The adsorption capacity showed the maximum at 666.7 mg/g in pH = 7 at 25 °C. As a result of the kinetic studies, it was seen that adsorption followed the pseudo-second-order kinetic model (r² = 0.9976). When thermodynamic parameters were examined, it was seen that the adsorption occurred exothermically (∆H_A = - 68.1 kJ/mol) and spontaneously (∆G_A²⁹⁸ = - 27.4 kJ/mol). From the data obtained, it was concluded that the SA/PPyNT composites are promising material as an adsorbent.

A sensitive electrochemical sensor based on metal cobalt wrapped conducting polymer polypyrrole nanocone arrays for the assay of nitrite

The conducting polymer polypyrrole nanocones wrapped by metal cobalt (Co/PPy) are a promising platform for the detection of sodium nitrite, which can be obtained by an electrochemical deposition technique under a mild condition. Co/PPy nanocone arrays combined the high conductivity and large specific surface area of PPy nanocones with the redox properties of metal cobalt, and their 3D structure can provide more active sites for nitrite detection. Owing to the microstructure and excellent electrical properties of the nanocomposite, Co/PPy nanocone arrays were convenient to construct a high-performance nitrite sensor. The microscopic morphology and composition of Co/PPy nanocone arrays were characterized by SEM, FT-IR, XPS, and XRD, and their electrochemical performances were also investigated. The experimental results showed that Co/PPy nanocones exhibited excellent performance for nitrite determination. The sensors were used for the determination of nitrite in pickled Chinese cabbage and water samples, and the results were consistent with those of spectrophotometry. Hence, the synthesized Co/PPy nanocone arrays have a broad application prospect in food safety, environmental protection, and industrial manufacturing.

Recent Advances in Functional Polymer Materials for Energy, Water, and Biomedical Applications: A Review

Academic research regarding polymeric materials has been of great interest. Likewise, polymer industries are considered as the most familiar petrochemical industries. Despite the valuable and continuous advancements in various polymeric material technologies over the last century, many varieties and advances related to the field of polymer science and engineering still promise a great potential for exciting new applications. Research, development, and industrial support have been the key factors behind the great progress in the field of polymer applications. This work provides insight into the recent energy applications of polymers, including energy storage and production. The study of polymeric materials in the field of enhanced oil recovery and water treatment technologies will be presented and evaluated. In addition, in this review, we wish to emphasize the great importance of various functional polymers as effective adsorbents of organic pollutants from industrial wastewater. Furthermore, recent advances in biomedical applications are reviewed and discussed.

Conductive Polymers and Their Nanocomposites as Adsorbents in Environmental Applications

Proper treatment and disposal of industrial pollutants of all kinds are a global issue that presents significant techno-economical challenges. The presence of pollutants such as heavy metal ions (HMIs) and organic dyes (ODs) in wastewater is considered a significant problem owing to their carcinogenic and toxic nature. Additionally, industrial gaseous pollutants (GPs) are considered to be harmful to human health and may cause various environmental issues such as global warming, acid rain, smog and air pollution, etc. Conductive polymer-based nanomaterials have gained significant interest in recent years, compared with ceramics and metal-based nanomaterials. The objective of this review is to provide detailed insights into different conductive polymers (CPs) and their nanocomposites that are used as adsorbents for environmental remediation applications. The dominant types of CPs that are being used as adsorbent materials include polyaniline (PANI), polypyrrole (Ppy), and polythiophene (PTh). The various adsorption mechanisms proposed for the removal of ODs, HMIs, and other GPs by the different CPs are presented, together with their maximum adsorption capacities, experimental conditions, adsorption, and kinetic models reported.

Anionic Dye Removal by Polypyrrole-Modified Red Mud and Its Application to a Lab-Scale Column: Adsorption Performance and Phytotoxicity Assessment

In this study, polypyrrole-modified red mud (PRM) was prepared for the efficient removal of anionic dyes (methyl orange and Congo red) from aqueous solutions. The phytotoxicity (bean sprouts) of the dye solution before and after dye removal was investigated. Adsorption kinetics confirmed that the adsorption of methyl orange (MO) and Congo red (CR) on PRM was controlled by chemical reactions between the functional groups of polypyrrole and dyes. From Langmuir isotherm fitting, we found the theoretical adsorption capacities of MO and CR on PRM were 194.1 and 314.9 mg/g, respectively. The adsorption progress of MO and CR on PRM was found to be spontaneous and endothermic. The column studies demonstrated that, under dynamic flow, the PRM can efficiently remove MO and CR from aqueous solution, with adsorption capacities of 31.08 and 55.04 mg/g, respectively. In the toxicity test, the phytotoxicity of the column effluents (after dye removal) was significantly lowered compared to the initial dye influents. After the removal of MO and CR, the average root length of bean sprouts was increased from 3.30 cm to 5.18 cm and from 3.01 cm to 7.00 cm, respectively. These findings highlighted the efficient removal of dyes by PRM from aqueous solution, demonstrating the possible application of PRM for the removal of dye from dye-contaminated wastewaters.

Pressure-Sensitive Conducting and Antibacterial Materials Obtained by in Situ Dispersion Coating of Macroporous Melamine Sponges with Polypyrrole

Melamine sponges were coated with polypyrrole during the in situ polymerization of pyrrole. The precipitation polymerization was compared with the dispersion mode, that is, with the preparation in the presence of poly(N-vinylpyrrolidone) and nanosilica as colloidal stabilizers. The coating of sponges during the dispersion polymerization leads to the elimination of the undesired polypyrrole precipitate, improved conductivity, and increased specific surface area. The sponges were tested with respect to their conductivity and as pressure-sensitive conducting materials with antibacterial performance.