Modification Of Polyaniline Research Articles

An insight into PANI-TiO2 photocatalysis of refractory organic matter through molecular size fractionation.

Refractory organic matter (RfOM) is ubiquitous in aquatic environment and plays various roles in regulating the fate, transport, toxicity, and bioavailability of chemical species, such as metals, emerging organic contaminants, and nanomaterials. RfOM is mainly represented by humic acids (HA) as the acid insoluble fraction of organic matrix. Considering the complex and multicomponent characteristic of HA, a detailed study was designed to elucidate the fate of molecular size fractions (MSFrs) of humic under solar irradiation in the presence of polyaniline (PANI)-modified TiO2 composites. Humic acid as a consortium of diverse molecular size fractions with different tendencies towards oxidation requires further assessment by UV-vis and fluorescence spectroscopic parameters complementary to previous studies on the photocatalytic degradation of RfOM by using TiO2 and PANI-TiO2 composites. Absorbance-based removal efficiencies under initial and post-photocatalytic conditions showed a re-formation trend during photocatalysis in the presence of PANI and TiO2 where higher MSFrs were transformed to lower MSFrs that was apparent for < 3kDa fraction. Completely different profiles were observed for PT-41 and PT-81 indicating similar degradation pathways independent of PANI ratio in the composite. As confirmed by the investigated parameters, formation of both 450kDa and 220kDa MSFrs were evident under all conditions indicating in situ generation of higher MSFrs. The eligibility of coupled absorbance-fluorescence measurements to discern molecular size distribution of humic acid via oxidative degradation was also investigated. Excitation-emission matrix (EEM) contour plots emphasized the ratio dependency of PANI modification of TiO2 and revealed sample specific variations that were more pronounced in terms of the emergence of tyrosine- and tryptophan-like aromatic proteins.

Design of a high-performance polyaniline coated niobium dicarbide MXene nanostructure based electro-membrane system for improved nanoplastic separation

This study explores the development of advanced electro-membrane filtration by incorporating Nb-based MXene (Nb2CTx) to enhance nanoplastic (NP) separation and fouling mitigation. The presence of NPs in water results in less effective filtration, hence increasing cost, highlighting the urgent need for advanced removal technologies. Nb2CTx was incorporated at varying loadings, revealing significant alterations in their morphological, structural, and physiochemical properties. The performance evaluation using NP-rich suspensions demonstrated that the membrane with 5 % Nb2CTx loading (MS5) achieved a NP removal efficiency of 97.4 % and a water flux of 90.5 L.m−2.h−1, which was significantly higher than the pristine sulfonated polyether sulfone (SPES) membrane (18.9 L.m−2.h−1 with 94 % removal efficiency). The membrane was developed for an electro-membrane system using a sacrificial anode. The sacrificial anode allowed for multiple complex process to occur simultaneously, including electrocoagulation and membrane filtration. Polyaniline (PANI) coating was added to further increase the conductivity to allow for a more energy efficient process. The study underscores the importance of Nb2CTx loading and PANI modification in improving the filtration efficiency and fouling resistance. Furthermore, applied electric field resulted in enhanced operational sustainability of SPES membranes, offering a novel approach for water treatment applications.

Synthesis and photocatalytic properties of polyaniline modified cadmium-manganese sulfide materials

In the present paper, polyaniline modification of Mn0.5Cd0.5S composite (PANI/MCS) was fabricated by a simple electrostatic adsorption method. The introduction of PANI makes PANI/MCS composites have better visible light absorption and higher photogenerated carrier segregation efficiency, thus showing better photocatalytic performance. The results show that the 50-PANI/MCS photocatalyst has the best hydrogen production capacity, which was 2.2 times greater than neat MCS. Meanwhile, the nitrogen fixation performance of the best sample 50-PANI/MCS was 4.93 times that of pure MCS. After that, a reasonable reaction mechanism was obtained through various characterization data. A cheap and readily available composite photocatalyst has been synthesized. This paper has good reference value in the area of development of efficient composite photocatalyst.

Electrodeposited polyaniline based carbon nanotubes fiber as efficient counter electrode in wire-shaped dye sensitized solar cells

Electrodeposited polyaniline over the carbon nanotubes fiber (CNTF) has been investigated as potential candidate to substitutes the Pt based auxiliary electrodes in unidimensional fibrous solar cells. CNTF, with excellent electrical and mechanical properties, modified with conducting polymer (polyaniline) via facile electrodeposition process which employed as cathodic materials showed efficient electrochemical reduction of triiodide ions in the fiber shaped dye-sensitized solar cells. Scanning electron microscopic analysis showed the efficacious integration of conducting polymer over the CNTF surface. The admirable electrocatalytic behavior of the fabricated electrode has investigated by electrochemical impedance spectroscopy and cyclic voltammetry. Current density and voltage (J–V) curves are used to quantify the photovoltaic performance of devices with different counter electrodes with fixed photoanode. With lower peak to peak separation, improved current density and better fill factor, exhibited the superior efficiency of modified electrode (PANI@CNTF). As compared to pristine fiber, polyaniline modification showed the outstanding performance with improved photovoltaics and electrochemical parameters measured by the J–V and CV curves, respectively.

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.

Detection of cadmium (II) ion in water by a novel electrochemical sensor based on modification of graphite carbon nitride and polyaniline composite

A novel electrochemical sensor was constructed based on modification of polyaniline (PANI) and graphitic-phase carbon nitride (g-C3N4) composites. Detection of Cd(II) ions in the aqueous environment using differential pulsed anodic stripping voltammetry (DPASV) technique. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), contact angle (CA), and Tafel curve analyses were used to characterize the physical and electrochemical properties of electrode. We prepared a new PANI@g-C3N4 composite material by combining the two substances based on their respective advantages. The composite material was applied to electrode detection for the first time, which significantly enhanced the transfer of free electrons on the surface of the electrode, improved the sensitivity of the electrode, increased the adsorption capacity of Cd ions, and significantly improved the detection effect of the electrode. Parameters such as the amount of PANI@g-C3N4 modification, deposition potential, deposition time and solution pH were optimized to determine the best conditions for the detection of Cd(II) ions. Under optimal conditions, our sensor achieves a best signal at −0.78 V (vs. Ag/Agcl electrode), and exhibits a wide linear concentration range of 0.1–140 μg/L with a low detection limit of 0.05 μg/L. The sensor was successful in implementing the identification of real water samples with recoveries ranging from 91 % to 106 %. The relative standard deviation (RSD) is less than 4.31 %. Besides, the sensor has outstanding anti-interference, repeatability and steadiness. The successful application of this sensor provides a new idea for efficient detection of Cd(II) ions in aquatic environments.

Polyaniline modified waste‐derived graphene/sulfur nanocomposite cathode for lithium–sulfur batteries

AbstractReduction of plastic wastes in the environment and solving the energy demands from renewable sources are two important challenging tasks of this century. Modern day lives are highly entangled with polymers, however handling the huge wastes from plastics is also a serious concern. Translating the plastic wastes to useful products such as graphene can be an alternative for nonbiodegradable polymer wastes. Efficient energy storage devices, for instance, batteries are required for storing the renewable energies. With the aim of regulating these issues, we report, for the first time, the preparation of high energy cathode materials from the nanocomposites (NCs) having polyaniline (PANI), waste‐derived graphene (WDG) derived from plastic waste and sulfur (S) for Li–S battery applications. We compare the electrochemical properties of cathodes derived from WDG/S and WDG/PANI/S in Li–S batteries. The specific discharge capacity of WDG/PANI/S at 0.1 C was obtained to be 880 mAhg−1 normalized to sulfur mass at 1st cycle, 472 mAhg−1 at 100th cycle, and 400 mAhg−1 at 160th cycle. The rate capability is also found to be good at C‐rates less than 0.5 C. We found that WDG/PANI/S showed decent electrochemical properties when compared with the reference sample, WDG/S at similar sulfur loading without PANI modification.

Engineering the surface chemical microenvironment over CuO nanowire arrays by polyaniline modification for efficient ammonia electrosynthesis from nitrate

Electrochemical nitrate reduction into ammonia offers an attractive alternative to value-added ammonia (NH3) production under benign conditions. The critical to achieve satisfactory NH3 production rate from nitrate electroreduction that can compare with industrial Haber–Bosch route is the development of highly efficient electrocatalysts. In this work, we descript a post-modification strategy for synthesizing polyaniline (PANI)-modified CuO nanowire arrays (CuO@PANI) for selective electrocatalytic nitrate-to-ammonia transformation. Surface modification of CuO with PANI can not only well-retain the nanowire array structure and large specific surface area, but also modulate the surface chemical microenvironment of catalyst, which promotes nitrate enrichment and hydrogenated species accumulation, and thus facilitates selective nitrate-to-ammonia transformation. As a result, the CuO@PANI exhibits high Faradaic efficiency (93.88%) and excellent NH3 selectivity (91.38%) for NH3 electrosynthesis from nitrate. The strategy is worthy for designing high-efficiency electrocatalysts by surface modification with organic molecular or polymers for selective nitrate reduction into ammonia.

Creating 3 dimensional foam morphology of lead dioxide on the polyaniline film for improving the performance of lead flow batteries

In the present study, we investigate the effect of polyaniline as a conductive surface modifier on the morphology of the lead dioxide, PbO2, as a positive active material of lead-acid redox flow batteries. We used cyclic voltammetry to electrodeposit PbO2 on the surface of the bare and polyaniline-modified graphite substrates. We characterized the morphology and crystal structure of the electrodeposited PbO2 film using X-ray diffraction and scanning electron microscopy. In addition, we used electrochemical polarization and electrochemical impedance spectroscopy techniques to investigate the kinetics of the lead dioxide charge transfer in the presence and absence of polyaniline. To analyze the effect of the polymer film on the battery performance, we discharged the cells at different rates, and studied the cycle life of the cells. The results show that lead dioxide adopts an interconnected 3D fiber-like morphology on the surface of the polyaniline-modified graphite, resulting in a higher surface area, a better cycle life, and a higher coulombic efficiency, along with a retarded short-circuit problem. Besides, polyaniline modification increased the electron transfer rate of lead dioxide, reduced the internal resistance, enhanced the discharge plateau with less oscillation in the voltage range from 1.4 to 1.6 V, and increased the average specific power up to 367 mWg−1, resulted in a generally boosted battery performance.

Photoelectrocatalytic activity of highly ordered TiO2 nanotube arrays modified with polyaniline for tetrabromobisphenol A degradation in water.

Polyaniline (PANI) is a useful conductive polymer material, and has good adsorption property, which makes it a good modification material. In this work, for the sake of highly enhancing the utilization of visible region in sunlight and accelerating photocatalytic degradation of tetrabromobisphenol A (TBBPA), a typical polybrominated flame retardant, titanium dioxide nanotube arrays (TiO2 NTAs) were modified with PANI by chemical and electrochemical polymerization. The coated amount of PANI was controlled via adjusting the polymerization time and the amount of aniline in the electrochemical method. The results demonstrate that the EC-PANI/TiO2 NTAs (synthesized electrochemically) exhibit higher catalytic activity than bare TiO2 NTAs and C-PANI/TiO2 NTAs (synthesized chemically) in photoelectrocatalytic degradation of TBBPA under visible light, and the degradation efficiency for TBBPA could reach 94.37% within 120min. The improved performance was contributed to the synergetic effect of PANI modification which integrated the broad absorption of PANI in visible light region and high catalytic property of TiO2 NTAs. Interestingly, it was also found that the degradation efficiency of TBBPA by EC-PANI/TiO2 was further enhanced by up to 95.74% when the ethanol was present in the reaction system as the hole scavenger. Furthermore, the EC-PANI/TiO2 exhibited excellent stability after 10 cycling experiments. All the results indicated that this new modified material presented strong potential as a photoelectrocatalyst and had great practical applications in the future.

Antibacterial Activity of Polyaniline Coated in the Patterned Film Depending on the Surface Morphology and Acidic Dopant.

We have fabricated poly(ε-caprolactone) (PCL) films with flat and honeycomb-patterned (HCP) structures to coat polyaniline (PANI) on the film surface. In addition, the effect of chemical modification of PANI by sulfuric acid (H2SO4) was also studied for antibacterial activity. The flat and HCP PCL films were obtained by simple evaporation of the solvent and via the breath figure (BF) method, respectively. The morphology and chemical composition of PANI coated on the film surface were evaluated by scanning electron microscopy (SEM) and X-ray spectroscopy (EDX). Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analyses (TGA) were obtained to identify the PANI coating. The wettability and conductivity of the films were also measured. Applicational aspects were evaluated by assessing antibacterial and antibiofilm activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The EDX, TGA, and FT-IR findings indicated chemical modification of PCL film by PANI and H2SO4. The conductivity of the films was increased by the coating of PANI to the patterned surface and additionally increased by the chemically modified PANI. The antibacterial activity was 69.79%, 78.27%, and 88% against E. coli, and 32.73%, 62.65%, and 87.97% against S. aureus, for flat PANI, HCP PANI, and H2SO4-treated HCP films, respectively. Likewise, the PANI coated flat, HCP, and H2SO4-treated HCP films inhibited E. coli biofilm formation by around 41.62%, 63%, and 83.88% and S. aureus biofilm formation by 17.81%, 69.83%, and 96.57%, respectively. The antibacterial activity of the HCP film was higher than that of flat PANI films, probably due to the higher coating of PANI on the HCP surface. Moreover, sulfonation of the HCP film with H2SO4 might have improved the wettability, thereby enhancing the antibacterial and antibiofilm properties. Our results showed that topographical changes, as well as doping, offer simple and cost-effective ways to modify the structural and functional properties of films.

Three-Dimensional Nano Polyaniline Modification Graphite Fiber as High-Capacity Electrode Material for Uranium (VI) Electrosorption

To improve the adsorption performance of graphite felt, aniline was directly polymerized on the surface of graphite felt by electrochemical method. The material test results showed that the electropolymerized polyaniline presented a three-dimensional nanofiber structure and the specific surface area of the electrode increased from 24.23 to 42.17 m2 g−1 after modification. The electrochemistry test results showed that the electrode had a large specific capacitance 144.6 F g−1 in 1 M NaCl at a sweep speed of 5 mV s−1. When pH = 4 and E = −0.9 V (vs SCE), the adsorption capacity of the electrode can reach 187.8 mg g−1. 94.6% adsorbed uranium can be eluted by 0.1 M hydrochloric acid. After 7 cycles, the performance loss was only 25%, which indicated that the electrode had a good regeneration performance. The uranyl ions combined with the amino and imino groups of polyaniline on the electrode surface, and were partially reduced to U (V), which greatly improved the adsorption capacity of electrode. All the results show that the electrode had exceptional potential applications in the extraction of U(VI) from aqueous solution, and it provides a feasible method for U(VI) environmental pollution cleanup in uranium mining and fuel processing.

Biomass-based flexible fire warning sensor with excellent flame retardancy and sensitivity

Traditional fire warning sensors usually work under directly fire attack or relatively high temperature with short service life and poor sensitivity. Therefore, the preparation of thermosensitive sensors with excellent fire resistance, sustainability and sensitive fire detection function is critical. In this work, biomass-based carbon nanofibers (CNFs) are designed and constructed by phosphating treatment and polyaniline modification co-functionalization strategy. The introduction of lignin molecules significantly improves the compatibility and spinnability of polyaniline and biomass-based spinning aid, thus effectively reducing the generation of the bead like defects and fine fibrous morphologies. The optimized CNFs exhibit good structure stability, electrical conductivity and sensitivity (responsive temperature 100 ℃, thermosensitive sensor response about 2 s, and sustained working time at least 5 min in the flame). Furthermore, the specific capacitance of biomass-based CNFs reaches 358F/g, energy density of 49.7 Wh/kg at a power density of 542.4 W/kg. This work provides a novel strategy and paradigm for achieving excellent flame resistance and ideal fire warning sensor of biomass-based materials. The resulting biomass-based carbon nanofibers can be processed into intelligent thermosensitive sensor with various shapes and have a broad application prospect in flexible devices and wearable electrodes fields.

Selective adsorption-involved formation of NMC532/PANI microparticles with high ageing resistance and improved electrochemical performance

Abstract Surface modification offers an alternative strategy to improve both ageing resistance and electrochemical performance of cathode materials for lithium-ion batteries. From the viewpoint of real application, surface modification of the cathode materials should be designed with scientificity, effectiveness, low cost, less Li+ leaching, and remained tap density. In this contribution, a selective adsorption-involved in-situ growth of polyaniline (PANI) nanoparticles on LiNi0.5Mn0.3Co0.2O2 (NMC532) has been designed through a room-temperature-and-pressure chemical vapor deposition technique. The selective growth of PANI on NMC532 is based on theoretical computation results that multivalent Ni, Mn, and Co are capable of specifically conjugating and activating aniline molecules and, hence, initiating in-situ oxidation polymerization. With only trace amount of aniline monomer, the resulting PANI nanoparticles-inlaid NMC532 microparticles can endure four-month ageing in ambient atmosphere and exhibit improved electrochemical performance at both room temperature and 55 °C, compared with pristine NMC532. The improved electrochemical performance of NMC532/PANI is attributed to the enhanced structural stability of NMC532 and inhibited side reactions related to Li2CO3 formation, PVDF degradation, electrolyte decomposition, and transition-metal dissolution, owing to PANI modification.

Improved Simultaneous Decolorization and Power Generation in a Microbial Fuel Cell with the Sponge Anode Modified by Polyaniline and Chitosan.

In recent years, microbial fuel cell (MFC) has been regarded as a promising technology for dye wastewater treatment. Compared with traditional anaerobic reactors, MFC has better decolorization effect while producing electricity simultaneously. In this paper, a double-chamber MFC with the sponge anode modified by polyaniline and chitosan-NCNTs was employed for simultaneous azo dye decolorization and bioelectricity generation. The influence of dye concentration, co-substrate concentration, and operating temperature on the performance of MFC with the modified anodes were studied. The results showed that a high decolorization efficiency (98.41%) and maximum power density (2816.67 mW m-3) of MFC equipped with modified bioanodes were achieved due to the biocompatibility and bioelectrocatalysis of modified material. And the biomass on the modified anode's surface was increased by 1.47 times. Additionally, microbial community analysis revealed that the modification of polyaniline and chitosan-NCNTs improved the selective enrichment of specific communities and the main microorganism was the electroactive and decolorizing bacteria Enterobacter (62.84%). Therefore, the composite anode is capable of fully utilizing the synergistic role of various materials, leading to superior performance of dye decolorization in MFCs. This work provided a strategy for the research on the recovery of biomass energy and decolorization in wastewater treatment. Graphical Abstract.

Effect of Cobalt Phthalocyanine on the Chemical Polymerization of Aniline

AbstractThe synthesis of polyaniline (PANI) using organic metal complexes, for example, cobalt phthalocyanine (CoPc), is currently one of the promising approaches for PANI modification. Compounds of this kind favor the improvement of the properties of the target material and participate in the oxidative polymerization of aniline as catalysts. To fully understand the effect of CoPc on the synthesis and properties of PANI, the oxidative polymerization of aniline was monitored by measuring the open‐circuit potential (OCP) and pH, as well as by UV spectroscopy. Combining these techniques allows one to estimate the effect of the catalyst and assume the likely scheme of aniline oxidative polymerization with participation of the catalyst, as well as determine the extent of process acceleration.

Ion beam modification of polyaniline: Optical and electrical properties of Cu+ ion implanted thin films

Ion implantation of thin nanometre scale films is believed to facilitate better control of the material modification process in thin films when compared to mainstream chemical and electrochemical methods. In this work emeraldine base polyaniline (PANI) films on Indium Tin Oxide coated Polyethylene Terephthalate (ITO/PET) substrates were implanted with 50 keV Cu+ ions at liquid nitrogen temperature to fluences between 0.5 × 1016 and 5.0 × 1016 ions/cm2 to form Cu-PANI nanocomposite sublayer regions in the films. UV–vis, PL and I-V measurements were used to investigate changes in optical and electrical properties of the films post ion implantation. UV–vis data shows red shifting of the optical band gap as a function of fluence from 3.12 eV down to 1.41 eV. At higher fluences Local Surface Plasmon Resonance (LSPR) effects are observed due to formation of Cu nanoparticles ((NPs) in the PANI matrix. Photoluminescence spectra show an increase in the emission peak intensity with fluence, suggesting a corresponding increase in the number of available charge carriers due to radiation induced carbon clustering. This is corroborated by I-V data, which shows a decrease in the DC resistance of the films as a function of fluence.

Enhanced methanol electro-oxidation activity of electrochemically exfoliated graphene-Pt through polyaniline modification

Pt and Pt-based catalysts are deemed as the popular anode catalysts for direct methanol fuel cells due to their high electrocatalytic activity for methanol oxidation. The structure of the catalyst support is critical to the electrocatalytic performance of the catalysts. In this work, a kind of high-quality graphene (electrochemically exfoliated graphene) with the intact surface is exploited as the catalyst support instead of the popularly used reduced graphene oxide. Pt nanoparticles are successfully synthesized on electrochemically exfoliated graphene and exhibit better methanol electro-oxidation activity than those on reduced graphene oxide. To further raise the electrocatalytic performance of Pt catalysts, the substrate surface is modified by conductive polyaniline. It is found that the interaction of electrochemically exfoliated graphene with polyaniline is much different from the interaction of reduced graphene oxide with polyaniline. The intact surface structure of electrochemically exfoliated graphene is favorable for the combination with polyaniline by π-π interactions, which releases more N species for the growth of Pt nanoparticles. The synergistic interaction of Pt and N species can facilitate the dispersion of Pt nanocrystals as well as the electron transport through Pt-based hybrids, thereby further promoting the electrocatalytic properties of Pt catalysts for methanol oxidation.

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.

Adsorption Behaviour of Reactive Black Dye 5 by Magnetically Separable Nano-adsorbent

Dyes in the textile industry are the most significant source of pollutants, which cause damaging effects to people’s health. Reactive black 5 (RD5) is an anionic color that is currently used in the textile industry. This study is designed to provide the strategies to synthesize and characterize the new family of functionalized magnetite nanoparticles via a chemical co-precipitation method with polyaniline modification groups on the surface. The effect of various parameters including pH, the initial concentration of RD5, the mass of adsorbent, contact time, temperature and ionic strength has been studied. Under optimal conditions, 10 mL of RD5 solution with a concentration of 30 mg/L, 20 mg of adsorbent, pH of 7 and contact time of 10 minutes, the color was completely removed. The results also showed that adsorption followed Langmuir isotherm (R2=0.998) and the maximum adsorption capacity was 63.69 mg/g. The results of kinetic studies also showed that the RD5 removal followed the pseudo-second-order equation with the correlation coefficient of R2=0.9984. The ΔG0 was negative at all temperatures which shows that the adsorption process was spontaneous. Conforming to our results, adsorption process by designed magnetic nano-adsorbent is an efficient and affordable method for eliminating RD5 from the industry.