Preparation of a PANI/ZnO Composite for Efficient Photocatalytic Degradation of Acid Blue

Experimental exploration and DFT analysis of the kinetics and mechanism of malachite green photodegradation catalyzed by polyaniline-copper oxide nanocomposite

CONTEXT AND RESULTS

A nanocomposite photocatalyst consisting of polyaniline (PANI) and copper oxide (CuO) was successfully synthesized through an in-situ polymerization approach using aniline as the precursor. The synthesized nanocomposite was characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy (UV-Vis), determination of the point of zero charge (pHPZC), and scanning electron microscopy (SEM). The photocatalytic efficiency of the PANI-CuO nanocomposite was evaluated in the context of photodegrading Malachite Green (MG) dye under visible light. Malachite Green, a synthetic dye commonly used in the textile and aquaculture industries, is a significant contaminant due to its toxic, mutagenic, and carcinogenic properties, making its removal from water resources crucial for environmental and human health. Distilled water artificially contaminated with MG dye was used as the medium for testing. The parameters influencing the photodegradation efficiency were comprehensively investigated. These parameters included catalyst dosage, reaction time, initial dye concentration, and pH. The results of this study indicate that the degradation efficiency of MG dye displayed an upward trend with time, catalyst dosage, and pH while exhibiting a converse relationship with the initial dye concentration. A degradation rate of 97% was achieved with an initial concentration of 20 mg L-1, employing a catalyst dose of 1.6 g L-1 at pH 6 for a reaction time of 180 min. Furthermore, the reusability of the catalyst was assessed, revealing consistent performance over five consecutive cycles.

COMPUTATIONAL AND THEORETICAL TECHNIQUES

Density functional theory (DFT) was employed to optimize the structures of PANI, PANI-CuO, and their respective complexes formed through dye interaction, employing Gaussian software. These calculations employed the B3LYP/6-311G +  + (d,p) basis set in an aqueous environment with water serving as the solvent. The kinetics of Malachite Green degradation were analyzed using both first and second-order kinetic models.

Preparation of a polyaniline/ZnO-NPs composite for the visible-light-driven hydrogen generation

Compositions of ZnO nanoparticles and polyaniline, in the form of emeraldine salt, were manufactured as thin layers by using the spin-coating method. Then, the effect of polyaniline content on their photoelectrochemical characteristics was studied. Results indicate that all the samples are sensitive to light. Besides, with 0.30% of PANI, the composite sample demonstrates the highest photocurrent density; also, its photocurrent increment starts to increase at a voltage of ⁓ 1.23 V (vs. RHE), which is approximately in accordance with the theoretical potential of water electrolysis. Furthermore, since the rate of electron-hole recombination in this composite sample is the lowest, it possesses the highest photoelectrochemical efficiency. Main findings were analyzed with respect to UV-visible absorption and photoluminescence spectra as well as SEM micrographs of the samples and Raman spectral measurements. Besides, electrochemical impedance spectroscopy analysis was applied to both pure ZnO and the sample with the best response. Effects of drying temperature and layer thickness were also investigated.

Sunlight mediated removal of toxic pollutants from Yamuna wastewater using efficient nano TeO2-ZnO nanocomposites

We have utilised our TeO2-ZnO nanocomposites for Yamuna wastewater treatment in natural sunlight wherein the sampling site was Nigam Bodh Ghat, Kashmere Gate, Delhi. In BET isotherm, TZ NCs exhibited type IV isotherm forming a H3 like hysteric loop sustaining mesoporous characteristic with an increase in surface area, pore volume and pore diameter of 56.76 m2/g, 0.257 cc/g and 17.18 nm respectively, when compared to pristine ZnO NPs. Yamuna wastewater treatment was carried out using various concentrations of TZ NCs (range 0.1-0.3 g/500 mL) under natural sunlight. Post-treatment, all the physicochemical parameters such as DO, BOD, COD, Nitrates, Ammonia and Phenolic contents were found to be reduced to 10 times bringing Yamuna water parameters within safe limits. Our TZ NCs have shown to have high selectivity for the removal of Chromium from water. Out of all the three concentrations 0.2 g/500 mL or 0.4 mg/mL is the most optimum concentration of TZ NCs for complete Yamuna wastewater treatment. Also, the bacterial culture present in Yamuna water was killed by 90% using TZ having MIC of 0.1 mg/mL. The antibiofilm activity of TZ against K.pneumoniae MTCC 109 was also checked using Congo Red Agar Assay. The presence of heavy metals, their corresponding degradation and leaching studies were analysed using ICP-OES. TZ NCs showed a very minimal leaching rate of Zinc into the water, proving no toxicity associated with these nanocomposites. Further, to observe the safe disposal of TZ NCs into the soil, TZ NCs were utilised for ecotoxicity studies.

Chitosan-g-polyacrylonitrile ZnO nano-composite, synthesis and characterization as new and good adsorbent for Iron from groundwater

The highly poisonous, non-biodegradable heavy metals present serious concern in wastewater environmental sustainability and human health. Using adsorption is an effective technology for the treatment of this kind of water. Therefore, developing efficient and cost-effective adsorbents considers a significant and an emerging topic in the field the water purification. Chitosan grafted polyacrylonitrile (Cs-g-PAN) was facially fabricated via graft polymerization using ammonium persulfate (APS) as the initiator. The simple ultrasonic technique was used for doping ZnO nanoparticles into the Cs-g-PAN matrix to prepare chitosan-grafted polyacrylonitrile/ZnO (Cs-g-PAN/ZnO). For comparative study, pure ZnO and nanocomposite of PAN doped with ZnO (PAN/ZnO) were also prepared. XRD, FTIR, SEM, TEM, BET, EDS, and TGA measurements were conducted to confirm the morphological and structural properties of the prepared materials. Cs-g-PAN/ZnO possesses a specific surface area of 20.23 m²/g with a pore size of 31.58 nm and pore volume of 0.16 cm³ g^-1. The adsorption behavior toward Fe(II) as a pollutant for groundwater was studied for the synthesized materials. The effect of pH (4-8), contact time (5-60 min), adsorbent dose (0.01-0.3 g), and different temperature degrees (278, 288, 298, 308, and 318 K) on the removal of iron (II) has been conducted. The removal efficiency was achieved 100 % under the optimum condition, at pH = 7, contact time 30 min, adsorbate concentration 0.93 mg/L, and adsorbent dosage 0.05 g/L at room temperature. Langmuir and Freundlich's isothermal and kinetic studies have been analyzed to determine the adsorption mechanism of Fe(II) ions on the synthesized nanomaterials. The adsorption process of Fe(II) over the surface of prepared catalysts proceeded via the Langmuir model and pseudo-second-order reaction kinetics with R² > 0.99. Suggesting the formation of Fe(II) monolayer over the adsorbent surface and the rate-limiting step is probably controlled by chemisorption through sharing the electrons between Fe⁺² and the prepared catalyst.

Detection of Salmonella Enteritidis in Milk Using Conductometric Immunosensor Coated on Polyaniline/Zinc Oxide Nanocomposite

The demand for rapid and accurate detection methods for Salmonella Enteritidis necessitates the development of highly sensitive and specific biosensors to ensure proper monitoring of food safety and quality requirements in the food sector and to secure human health. This study focused on development of a polyaniline/zinc oxide (PANI/ZnO) nanocomposite film on a gold electrode conductometric immunosensor for detection of Salmonella Enteritidis. The sensor was modified with monoclonal anti-Salmonella Enteritidis antibodies as biorecognition elements. The fabricated sensor was able to detect and quantify the target pathogen within 30 min and showed a good detection range from 10¹ to 10⁵ colony-forming units (CFU)/mL for Salmonella Enteritidis and a minimum detection limit of 6.44 CFU/mL in 0.1% peptone water. Additionally, the fabricated sensor showed good selectivity and detection limit toward the target bacterium and successfully determined Salmonella Enteritidis content in ultrahigh heat-treated skim milk samples without pretreatment of the food sample.

Polymer Coated Functional Catalysts for Industrial Applications

Surface engineering of conventional catalysts using polymeric coating has been extensively explored for producing hybrid catalytic material with enhanced activity, high mechanical and thermal stability, enhanced productivity, and selectivity of the desired product. The present review discusses in detail the state-of-the-art knowledge on surface modification of catalysts, namely photocatalysts, electrocatalysts, catalysts for photoelectrochemical reactions, and catalysts for other types of reactions, such as hydrodesulfurization, carbon dioxide cycloaddition, and noble metal-catalyzed oxidation/reduction reactions. The various techniques employed for the polymer coating of catalysts are discussed and the role of polymers in enhancing the catalytic activity is critically analyzed. The review further discusses the applications of biodegradable and biocompatible natural polysaccharide-based polymers, namely, chitosan and polydopamine as prospective coating material.

Green nanocomposite: fabrication, characterization, and photocatalytic application of vitamin C adduct-conjugated ZnO nanoparticles

Recently, the conjugation of metal oxide nanoparticles with organic moieties has attracted the attention of many researchers for various applications. In this research, the green and biodegradable vitamin C was employed in a facile and inexpensive procedure to synthesize the vitamin C adduct (3), which was then blended with green ZnONPs to fabricate a new composite category (ZnONPs@vitamin C adduct). The morphology and structural composition of the prepared ZnONPs and their composites were confirmed by several techniques: Fourier-transform infrared (FT-IR) spectroscopy, field-emission scanning electron microscopy (FE-SEM), UV-vis differential reflectance spectroscopy (DRS), energy dispersive X-ray (EDX) analysis, elemental mapping, X-ray diffraction (XRD) analysis, photoluminescence (PL) spectroscopy, and zeta potential measurements. The structural composition and conjugation strategies between the ZnONPs and vitamin C adduct were revealed by FT-IR spectroscopy. The experimental results for the ZnONPs showed that they possessed a nanocrystalline wurtzite structure with quasi-spherical particles with a polydisperse size ranging from 23 to 50 nm, while the particle size appeared greater in the FE-SEM images (band gap energy of 3.22 eV); after loading with the l-ascorbic acid adduct (3), the band gap energy dropped to 3.06 eV. Later, under solar light irradiation, the photocatalytic activities of both the synthesized ZnONPs@vitamin C adduct (4) and ZnONPs, including the stability, regeneration and reusability, catalyst amount, initial dye concentration, pH effect, and light source studies, were investigated in detail in the degradation of Congo red dye (CR). Furthermore, an extensive comparison between the fabricated ZnONPs, composite (4), and ZnONPs from previous studies was performed to gain insights to commercialize the catalyst (4). Under optimum conditions, the photodegradation of CR after 180 min was 54% for ZnONPs and 95% for the ZnONPs@l-ascorbic acid adduct. Moreover, the PL study confirmed the photocatalytic enhancement of the ZnONPs. The photocatalytic degradation fate was determined by LC-MS spectrometry.

A Review on Polyaniline: Synthesis, Properties, Nanocomposites, and Electrochemical Applications

The development in the use of polyaniline (PANI) in advanced studies makes us draw attention to the presented research and combine it into one study like this one. The unique composition of PANI qualifies it for use in electrochemical applications in addition to many other applications whose use depends on its mechanical properties. Based on this, it is necessary to limit the reactions that produce PANI and the cheapest cost, and then limit the current uses in the formation of nanocomposites with metals, their oxides, and/or carbon nanocomposites in order to determine what is missing from them and work on it again to expand its chemistry. The development in the use of PANI in advanced studies makes us draw attention to the research presented on PANI and combine it into one study. One of the very important things that made PANI possess a very huge research revolution are preparation in a variety of ways, easy and inexpensive, from which a daily product can be obtained with very high purity, as well as its distinctive properties that made it the focus of researchers in various scientific departments. The unique structure of PANI, which is easy to prepare in its pure form or with various chemical compounds including metals, metal oxides, and carbon nanomaterials (such as carbon nanotubes, graphene, graphene oxide, and reduced graphene oxide), qualifies it for use in electrochemical applications. The various studies reviewed showed that PANI gave good results in the applications of super capacitors. In some of the studies mentioned later, it gave a specific capacitance of 503 F/g, cycle stability 85% at 10,000 cycles, energy density 8.88 kW/kg, and power density 96 W h/kg. It was also noted that these values improved significantly when using PANI with its nanocomposites. Because of its good electrical conductivity and the possibility of preparing it with a high surface area with nanostructures in the form of nanowires, nanofibers, and nanotubes, PANI was used as a gas sensor. We have noticed, through the studies conducted in this field, that the properties of PANI as a basic material in gas sensors are greatly improved when it is prepared in the form of PANI nanocomposites, as explained in detail later. From this review, we tried with great effort to shed light on this attractive polymer in terms of its different preparation methods, its distinctive properties, its nanocomposites, and the type of polymerization used for each nanocomposites, as well as its applications in its pure form or with its nanocomposites in the supercapacitor and gas sensor applications.

High-performance photocatalytic membranes for water purification in relation to environmental and operational parameters

Growing technologies, increasing population and environmental pollution lead to severe contamination of water and require advanced water treatment technologies. These aspects lead to the need to purify water with advanced smart materials. This paper reviews the recent advances (during the last 5 years) in photocatalytic composite membranes used for water treatment. For this purpose, the authors have reviewed the main materials used in the development of (photocatalytic membranes) PMs, environmental and operational factors affecting the performance of photocatalytic membranes, and the latest developments and applications of PMs in water purifications. The composite photocatalytic membranes show good performance in the removal and degradation of pollutants from water.

An Overview of Polymer-Supported Catalysts for Wastewater Treatment through Light-Driven Processes

In recent years, alarm has been raised due to the presence of chemical contaminants of emerging concern (CECs) in water. This concern is due to the risks associated with their exposure, even in small amounts. These complex compounds cannot be removed or degraded by existing technologies in wastewater treatment plants. Therefore, advanced oxidation processes have been studied, with the objective of developing a technology capable of complementing the conventional water treatment plants. Heterogenous photocatalysis stands out for being a cost-effective and environmentally friendly process. However, its most common form (with suspended catalytic particles) requires time-consuming and costly downstream processes. Therefore, the heterogeneous photocatalysis process with a supported catalyst is preferable. Among the available supports, polymeric ones stand out due to their favorable characteristics, such as their transparency, flexibility and stability. This is a relatively novel process; therefore, there are still some gaps in the scientific knowledge. Thus, this review article aims to gather the existing information about this process and verify which questions are still to be answered.

Conducting polymers/zinc oxide-based photocatalysts for environmental remediation: a review

The accessibility to clean water is essential for humans, yet nearly 250 million people die yearly due to contamination by cholera, dysentery, arsenicosis, hepatitis A, polio, typhoid fever, schistosomiasis, malaria, and lead poisoning, according to the World Health Organization. Therefore, advanced materials and techniques are needed to remove contaminants. Here, we review nanohybrids combining conducting polymers and zinc oxide for the photocatalytic purification of waters, with focus on in situ polymerization, template synthesis, sol-gel method, and mixing of semiconductors. Advantages include less corrosion of zinc oxide, less charge recombination and more visible light absorption, up to 53%.

Photodegradation and kinetics of edible oil refinery wastewater using titanium dioxide

Edible oil refinery wastewater (EORW) is one source of environmental pollution in Nigeria. The treatment of EORW before discharge into the environment remains a significant challenge in the edible oil refinery industries. This research was aimed at photocatalytic treatment of EORW using a batch photocatalytic reactor with titanium dioxide photocatalyst. We investigated the physicochemical parameters: chemical oxygen demand (COD), biological oxygen demand (BOD5), oil and grease, phenol, chloride (Cl-), total suspended solids, sulfate (SO42-), and phosphate (PO43-) using American Public Health Association methods. The results showed that the reduction efficiency of the treated EORW with TiO2 catalyst ranged between 65.8% (PO43-) and 87.0% (COD), and the improvement in efficiency was 54.1% (pH) and 60.8% dissolved oxygen. However, the results showed no significant difference (p<0.05) in the control treatment without catalyst. The biodegradability of EORW increased from 0.196 to 0.32. It was observed that the optimum values were an initial EORW concentration of 100 mL/L, irradiation time of 90min, catalyst dose of 1.25 g/L, and an agitation speed of 900 rpm. The kinetics of the photodegradation process was well described by the pseudo-first-order equation (R2>0.96) and pseudo-second-order equation (R2>0.98). The intra-particle diffusion model fairly represented the diffusion mechanism with an R2 value of 0.806. The treated EORW met the most acceptable water quality standards for discharged effluent according to the maximum permissible limits of the Nigerian National Environmental Standards and Regulations Enforcement Agency.

Conductometric Immunosensor for Escherichia coli O157:H7 Detection Based on Polyaniline/Zinc Oxide (PANI/ZnO) Nanocomposite

A conductometric immunosensor was developed for the detection of one of the most common foodborne pathogens, Escherichia coli O157:H7 (E. coli O157:H7), by conductometric sensing. The sensor was built based on a polyaniline/zinc oxide (PANI/ZnO) nanocomposite film spin-coated on a gold electrode. Then, it was modified with a monoclonal anti-E. coli O157:H7 antibody as a biorecognition element. The fabricated nanostructured sensor was able to quantify the pathogens under optimal detection conditions, within 30 min, and showed a good detection range from 10¹ to 10⁴ CFU/mL for E. coli O157:H7 and a minimum detection limit of 4.8 CFU/mL in 0.1% peptone water. The sensor efficiency for detecting bacteria in food matrices was tested in ultra-heat-treated (UHT) skim milk. E. coli O157:H7 was detected at concentrations of 10¹ to 10⁴ CFU/mL with a minimum detection limit of 13.9 CFU/mL. The novel sensor was simple, fast, highly sensitive with excellent specificity, and it had the potential for rapid sample processing. Moreover, this unique technique for bacterial detection could be applicable for food safety and quality control in the food sector as it offers highly reliable results and is able to quantify the target bacterium.

Advanced Photocatalysts Based on Conducting Polymer/Metal Oxide Composites for Environmental Applications

Photocatalysts provide a sustainable method of treating organic pollutants in wastewater and converting greenhouse gases. Many studies have been published on this topic in recent years, which signifies the great interest and attention that this topic inspires in the community, as well as in scientists. Composite photocatalysts based on conducting polymers and metal oxides have emerged as novel and promising photoactive materials. It has been demonstrated that conducting polymers can substantially improve the photocatalytic efficiency of metal oxides owing to their superior photocatalytic activities, high conductivities, and unique electrochemical and optical properties. Consequently, conducting polymer/metal oxide composites exhibit a high photoresponse and possess a higher surface area allowing for visible light absorption, low recombination of charge carriers, and high photocatalytic performance. Herein, we provide an overview of recent advances in the development of conducting polymer/metal oxide composite photocatalysts for organic pollutant degradation and CO2 conversion through photocatalytic processes.

CuO-ZnO-PANI a lethal p-n-p combination in degradation of 4-chlorophenol under visible light

Recent interest and responsibility to retain the water resources rose among people. Scientists have been engaged to develop the mechanism that involves the freely available sunlight - a sustainable resource - to remove the pollutants from water to make it again suitable for life. Ample research was reported in the removal of dye pollutants present in water. For this they have utilized p type and n type semiconductors or combination of both (p-n type) under the excitation of a wide range of electromagnetic band energy. Most of the interest lies in emerging out of the mechanism with hybrid semiconductors to remove the previously reported flaws. Toward this regard, this manuscript aims to develop unique material using the underlying p-n-p model for harnessing visible light in catalysis. Initially, p-n structure was developed with copper oxide (p-type) and zinc oxide (n-type), then polyaniline (p-type) conjugated at different concentrations (0.5 M, 0.7 M & 1.0 M), to yield p-n-p models, using precipitation followed by sonication techniques. Detailed physicochemical investigations were conducted on the resultant p-n-p material to elucidate its characteristics. Furthermore, the mechanism was advocated for the best photocatalytic activity under visible light excitation for the degradation of 4-chlorophenol and compared with the performance of a standard p-n (CuO/ZnO) combination.

Preparation of PANI Modified ZnO Composites via Different Methods: Structural, Morphological and Photocatalytic Properties

Polyaniline modified zinc oxide (PANI-ZnO) photocatalyst composites were synthesized by focusing on dissolution disadvantage of ZnO. In-Situ chemical oxidation polymerization method was performed under neutral conditions (PANI-ES) whereas in hybridization method physical blending was applied using emeraldine base of polyaniline (PANI-EB). PANI-ZnO composites were prepared in various ratios of aniline (ANI) to ZnO as 1%, 3%, 6% and 9%. The alterations on the structural and morphological properties of PANI-ZnO composites were compared by Fourier Transform Infrared (FT-IR), Raman Spectroscopy, X-ray Diffraction (XRD) and Scanning Electron Microscopy-Energy Dispersive X-ray Analysis Unit (SEM-EDAX) techniques. FT-IR and Raman spectroscopy confirmed the presence of PANI in all composites. SEM images revealed the morphological differences of PANI-ZnO composites based on PANI presence and preparation methods. Photocatalytic performances of PANI-ZnO specimens were investigated by following the degradation of methylene blue (MB) in aqueous medium under UVA irradiation. The effects of catalyst dose and initial dye concentration were also studied. MB degradation was followed by both decolorization extents and removal of aromatic fractions. PANI-ZnO composites expressed enhanced photocatalytic performance (~95% for both methods) as compared to sole ZnO (~87%). The hybridization method was found to be more efficient than the In-Situ chemical oxidation polymerization method emphasizing the significance of the neutral medium.

Preparation of solar-enhanced AlZnO@carbon nano-substrates for remediation of textile wastewaters

Photoactive aluminum doped ZnO (AlZnO) was synthesized by sol-gel method. After that, AlZnO photocatalyst was deposited on five carbon-based materials (CBMs) using ultrasonic route followed by solid-state mixing using ball mill. The CBMs used were polyaniline (PANI), carbon nitride (CN), carbon nanotubes (CNT), graphene (G), and carbon nanofibers (CNF). The crystal phases, elemental compositions, morphological, and optical properties of the AlZnO@CBMs composites were investigated. Experimental results revealed that two of AlZnO@CBMs composites exhibited superior bleaching efficiency (100% removal) and photocatalytic stability (three cycles) for 50 μmol/L Methylene Blue (MB) contaminated water after 60 min irradiation in visible light at pH 6.5, 0.7% H₂O₂, and 5 g/L inorganic salts. Under optimum conditions, AlZnO@CBMs nanocomposites were employed for the treatment of mixed dyestuffs composed of MB, Methyl Orange (MO), Astrazone Blue FRR (BB 69), and Rhodamine B (RhB) dyes under dark, ultraviolet, visible, and direct sunlight. For mixed dyestuffs, the AlZnO@G achieved the highest dye sorption capacity (60.91 μmol dye stuffs/g) with kinetic rate 8.22 × 10^-3 min^-1 in 90 min via multi-layer physisorption (Freundlich isotherm) on graphene sheet. In additions, AlZnO@CN offered the highest photo-kinetic rate (K_photo) of ~54.1 × 10^-3 min^-1 (93.8% after 60 min) under direct sunlight. Furthermore, the selective radical trapping experiment confirmed that the holes and oxidative superoxide radicals are crucial on dyes photodegradation pathway. Owing to their superior performance, AlZnO@G and AlZnO@CN nanocomposites can offer an effective in-situ solar-assisted adsorption/photocatalytic remediation of textile wastewater effluents.

The Impact of In Situ Polymerization Conditions on the Structures and Properties of PANI/ZnO-Based Multiphase Composite Photocatalysts

We have synthesized polyaniline/ZnO-based (PANI/ZnO) multiphase composite photocatalysts from acid media by a newly proposed two-step in situ polymerization. The first step of synthesis yielded PANI salt required for the PANI/ZnO synergistic effect. In the second step, the aniline oxidation continued, without ZnO dissolution, and it produced PANI base. Thus, both PANI salt and base phases in the composites were detected by FTIR and UV/Vis, while the presence of both ZnO and PANI polymer was confirmed by XRD. Additionally, XRD also showed Zn5(OH)8(NO3)2·2H2O and Zn(SO4)(H2O) phases in PANI/ZnO-based multiphase composites. Furthermore, the impact of the synthesis conditions on the morphology of the composites was investigated by FE-SEM. The images displayed that ZnO particles were encapsulated in PANI sheets that were formed by the aniline oligomers. Photocatalytic evaluation of PANI/ZnO-based catalysts (i.e., degradation of Acid Blue 25 dye) was conducted and the obtained results confirmed that all the studied composites experienced the PANI/ZnO synergistic effect. It was observed that the best photocatalytic properties were held by the PANI/ZnO_2 sample due to its optimal particle size.

Investigation of the effect of PAn and PAn/ZnO photocatalysts on 100% degradation of Congo red under UV visible light irradiation and lightless environment

PAn (polyaniline) and PAn/ZnO photocatalysts were synthesized using chemical polymerization of aniline. The structure characterization of the synthesized samples was analysed by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-Vis spectroscopy measurements, and thermal gravimetric analysis (TGA). The photocatalytic activities of PAn and PAn/ZnO (0.1g/100ml) on the degradation of the Congo red (CR) dye were studied under the UV visible light irradiation and the lightless environment and the efficiency of catalysts have been explained in details. Contribution of UV visible light irradiation on the 100% degradation of CR dye for the PAn and PAn/ZnO photocatalyst is determined. The reaction kinetics and effect of pH (pH 4 and pH 10) were investigated by using first order kinetic model. According to the experimental results, photocatalytic reaction rate of Congo Red increased in acidic environment and under UV visible light irradiation.

Polyaniline-TiO2 composite photocatalysts for light-driven hexavalent chromium ions reduction

In order to develop efficient photocatalysts, great efforts have been made to reduce hexavalent chromium to trivalent chromium. The photocatalytic efficiency of this reduction depends largely on the adsorption and diffusion of hexavalent chromium ions on the surface of the photocatalyst. In this paper, polyaniline-TiO₂ composite can effectively improve the photocatalytic reduction performance and stability of hexavalent chromium ion. The effect of polyaniline (PANI) thickness on Cr(VI) activity and stability of photocatalytic reduction was studied by adjusting the content of PANI on Mesoporous TiO₂ (MT) surface. Under the irradiation conditions, the reaction results showed that the reduction rate was 100%, and the maximum reaction rate reached 0.62 min^-1 when the PANI modification was 3.0%. Moreover, the results showed that the reduction performance remained 100% after ten cycles. The main reason is that the PANI modified on the surface of TiO₂ is rich in positively charged amino group, which can efficiently adsorb the reactant Cr(VI), and make the product Cr(III) leave the reaction interface quickly, thus ensuring the performance of photocatalyst.

Synthesis and Characterization of Nanostructured Polyaniline Thin Films with Superhydrophobic Properties

Polyaniline (PANI) thin films incorporated with TiO2 or ZnO nanoparticles were synthesized via an electrochemical polymerization technique. Cyclic voltammetry (CV) was used to synthesize PANI from a strongly acidic medium (0.5 M H2SO4). The effects of different deposition cycles on the morphology, thickness, color, and properties of electrodeposited PANI thin films nanocomposites were investigated. Furthermore, the effects of the nanoparticles concentration on the morphology and water contact angle (CA) of the produced coating were investigated. Field-emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) were used to investigate the morphological structure. X-ray photoelectron spectroscopy (XPS) was used to study the surface composition of the formed film. The results reveal that the CA of the prepared coating reached 146°. A granular morphology of PANI with a moderate concentration of nanoparticles was obtained. In addition, XPS analysis confirmed the incorporation of the oxide nanoparticles in the matrix.

One-pot synthesis of propargylamines using magnetic mesoporous polymelamine formaldehyde/zinc oxide nanocomposite as highly efficient, eco-friendly and durable nanocatalyst: optimization by DOE approach

Magnetic mesoporous polymelamine formaldehyde nanocomposite-incorporating ZnO nanoparticles were successfully synthesized using solvothermal and sol-gel methods. Fourier-transform infrared spectrometry (FT-IR), X-ray diffraction, Brunauer-Emmett-Teller, vibrating sample magnetometer, thermogravimetric analysis, elemental analysis, transmission electron microscopy and field emission scanning electron microscopy techniques were then utilized for evaluation of nanocomposites. The as-prepared nanocomposite can be used as heterogeneous nanocatalyst with remarkable performance for A³ coupling reaction toward one-pot synthesis of propargylamine and its derivatives under solvent-less condition. In order to maximize the product yield, the variables, i.e., reaction time, temperature and catalyst amount, were optimized by using a statistical approach. The synthesized nanocomposite can be easily separated from the reaction medium and reused over and over, without significant changes in its catalytic activity.