Polyaniline-functionalized magnetic nanoparticles for the removal of toxic dye from wastewater

Facile synthesis of a magnetic molecularly-imprinted polymer adsorbent for solid-phase extraction of diclofenac from water

Numerous pollutants endanger the safety and purity of water, making water pollution a major worldwide concern. The health of people and aquatic ecosystems are at risk from these contaminants, which include hazardous microbes, industrial waste, and agricultural runoff. Fortunately, there appears to be a viable option to address this problem with adsorptive water treatment techniques. The present study presents a magnetic adsorbent (MMIP) based on molecularly imprinted polyaniline and magnetite nanoparticles for the solid-phase extraction of diclofenac, an anti-inflammatory medication, from industrial wastewater. The adsorbent nanomaterial was characterized using dynamic light scattering, zeta potential measurement, vibrating sample magnetometry, X-ray diffraction, and scanning electron microscopy. The MMIP demonstrated a particle size of 86.3 nm and an adsorption capacity of 139.7 mg g-1 at 600 mg L-1 of diclofenac and after a 200 min incubation period. The highest %removal was attained at pH range of 3-7. The adsorption process follows the pseudo-second order kinetic model. In addition, it was found that the adsorption process is enthalpy-driven and may occur via hydrogen bonding and/or van der Waals interactions.

Utilization of ZnFe2O4-Polyaniline (PANI), ZnFe2O4-Polystyrene (PST), and ZnFe2O4-Polypyrrole (PPy) nanocomposites for removal of Red X-GRL and Direct Sky Blue dyes from wastewater: Equilibrium, kinetic and thermodynamic studies

In this study, ZnFe2O4-Polyaniline (PANI), ZnFe2O4-Polystyrene (PST), and ZnFe2O4-Polypyrrole (Ppy) nanocomposites were synthesized by the adsorption method and characterized by field emission scanning electron microscopy and Fourier transform infrared spectrometer. Batch adsorption experiments were conducted for removing two types of hazardous dyes Red X-GRL and Direct Sky Blue 51 from an aqueous solution and the effect of pH, adsorbent dosage, contact time, and initial concentration of dyes were investigated. Meanwhile, kinetic, isotherm, and thermodynamic parameters were also determined. The electrolyte and surfactant effect was also tested for the prepared nanocomposites. To test the reusability desorption study was also conducted.

A comprehensive review on sustainable greener nanoparticles for efficient dye degradation

The effluents released from textile industries mainly consist of dyes, metals and other pollutants. Dyes often are discharged in wastewater streams causing adverse effect on the environment. To eliminate these harmful dyes, various techniques are emerging out of which nanotechnology is the most reliable and safer. Nanotechnology offers convincing applications in case of environmental and economic concerns. The bio-synthesis of nanoparticles has several advantages over conventional methods and approach towards environment concern as well. Biological method of nanoparticles synthesis is concluded to be the most promising and efficient in action. Bio-synthesised nanoparticles could be used for treatment and decolourisation of dyes in an efficient manner. This review comprises the study of number of bio-synthesised nanoparticles utilised for degradation of various dyes present as pollutants in wastewater. Bio-synthesised nanoparticles such as gold, silver, iron, cobalt, zinc, titanium and molybdenum used for degradation of various dyes have been discussed in this review.

Preparation and Characterization of a Novel Activated Carbon@Polyindole Composite for the Effective Removal of Ionic Dye from Water

The present study is aimed at the synthesis and exploring the efficiency of a novel activated carbon incorporated polyindole (AC@PIN) composite for adsorptive removal of Malachite Green (MG) dye from aqueous solution. An AC@PIN hybrid material was prepared by in situ chemical oxidative polymerization. The physico-chemical characteristics of the AC@PIN composite were assessed using Fourier-transform infrared spectrometer, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, ultraviolet visible spectroscopy, and determination of point of zero charge (pH_PZC). A series of adsorption studies was conducted to evaluate the influence of operational parameters such as pH, contact time, initial dye concentration, AC@PIN dosage, and temperature on dye adsorption behavior of developed composite. A maximum dye removal percentage (97.3%) was achieved at the pH = 10, AC@PIN dosage = 6.0 mg, initial dye concentration 150 mg L⁻¹, and temperature = 20 °C. The kinetic studies demonstrated that the adsorption of MG on AC@PIN followed pseudo-second-order model (R² ≥ 0.99). Meanwhile, Langmuir isotherm model was founded to be the best isotherm model to describe the adsorption process. Finally, the recyclability test revealed that the composite exhibits good recycle efficiency and is stable after 5 cycles. The obtained results suggest that AC@PIN composite could be a potential candidate for the removal of MG from wastewater.

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.

Amino-based magneto-polymeric-modified mixed iron hydroxides for magnetic solid phase extraction of phenol residues in environmental samples

Mixed iron hydroxides (MIHs) modified with different amino-based polymeric materials, including aminopropyltriethoxysilane, polydopamine, diaminobenzoic acid, polyaniline, and polyphenylenediamine, were comparatively investigated as sorbents for the extraction of phenol compounds. Polyphenylenediamine-modified mixed iron hydroxides (MIH@PPDA) showed high adsorption capability for most target analytes. Its ferromagnetic behavior, with a magnetization of 17.38 emu g^-1, was sufficient for subsequent use in magnetic solid-phase extraction (MSPE). The functional groups, morphology, and magnetic properties of this magnetic nanomaterial were investigated using Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, X-ray diffraction, and CHN analysis. High-performance liquid chromatography with a photodiode array detector was used to quantify phenol compounds. The experimental parameters affecting the efficiency of the entire MSPE process were optimized. Good linearity in the range of 0.5-1000 µg L^-1 was obtained (depended on the compound). The detection and quantitation limits varied from 0.01 to 0.3 µg L^-1 and 0.03 to 0.9 µg L^-1, respectively. The enrichment factors for all phenol compounds were in the range of 80-285. The precision in terms of intra- and inter-day relative standard deviations were below 5.8% and 6.2%, respectively. The developed MSPE method was applied to analyze phenol compounds in diverse samples, including soil, drinking water, and fruit. Relative recoveries of 76.7-130.1% were obtained. The MIH@PPDA magneto-polymeric sorbent exhibits good stability and is reliable for a variety of phenol compounds.

Application of polyaniline-based adsorbents for dye removal from water and wastewater-a review

Several industries release varying concentration of dye-laden effluent with substantial negative consequences for any receiving environmental compartment. The control of water pollution and tighter restriction on wastewater discharge directly into the environment to reduce the potential ecotoxicological effect of dyes is forcing processors to retreat and reuse process water and chemicals. Among the different available technologies, the adsorption process has been recognized to be one of the finest and cost-effective wastewater treatment technologies. Various adsorbents have been utilized to remove toxic dyes from water and wastewater. Here, we review the application of polyaniline-based polymeric adsorbent for the adsorption of dyes which have been received considerable attention. To date, various modifications of polyaniline have been explored to improve the adsorption properties. Review on the application of polyaniline for adsorption of dyes has not been present till date. This article provides relevant literature on the application of various polyaniline composites for removing dyes, and their adsorption capacities with their experimental conditions have been compiled. It is evident from the literature survey that polyaniline provides a better opportunity for scientists for the effective removal of various dye.

Convenient pH-responsive removal of Acid Black 1 by green l-histidine/iron oxide magnetic nanoadsorbent from water: performance and mechanistic studies

This study was aimed at developing green histidine-modified Fe₃O₄ nanoparticles (His-MNPs) for the adsorptive removal of Acid Black 1 (AB1) from aqueous solution. The His-MNPs were characterized by atomic force microscopy, scanning electron microscopy-energy dispersive X-ray spectrometry, infra-red spectra and thermogravimetry. These MNPs were spherical (average diameter 11–28 nm) with polydispersity index of 1.40 and about 13% mass coating of histidine. To optimize AB1 adsorption on His-MNPs and understand its mechanism, the influences of different operational variables (pH, adsorbent amount, temperature, initial AB1 concentration, contact time, ionic strength, etc.) on adsorption were examined with adsorption isotherms, kinetics and thermodynamic studies. The AB1 adsorption from water was fast with equilibrium time ≤ 45 min. The adsorption equilibrium was best fitted to the Langmuir isotherm model (q_max = 166.7 mg g⁻¹ at the adsorbent dose of 0.2 g L⁻¹, temperature 30 °C and pH 4). The linearity order for other isotherms was as follows: Dubinin–Radushkevich (D–R) < Temkin < Freundlich. The kinetics of the AB1 adsorption demonstrated the best compliance with the pseudo-second-order model, predominantly controlled by film diffusion as compared to intraparticle diffusion. Thermodynamic parameters (ΔH° and ΔG°) reflected the exothermic and spontaneous adsorption process. The values of ΔG°, ΔH°, activation energy and D–R free adsorption energy were all consistent with the physisorptive removal of AB1. The spectral (electronic and IR) and pH studies further corroborated the mechanism of AB1 removal by His-MNPs. The His-MNPs showed efficient adsorption, easy regeneration and excellent reusability, assisted by their pH-responsive properties. The prepared adsorbent can provide a safe, effective and economical alternative strategy for removing azo dyes from wastewater.

Effective and eco-friendly separation of Acid Black 1 dye from water by electrostatic adsorption onto reusable Histidine-Fe₃O₄ nanoparticles, credited to their pH-responsiveness.

Selective removal of cationic micro-pollutants using disulfide-linked network structures

Micropollutants are found in all water sources, even after thorough treatments that include membrane filtration. We have developed swellable di-sulfide covalent organic polymers (COPs) with great affinity towards cationic textile micropollutants.

One-pot synthesis of carbon dot-entrenched chitosan-modified magnetic nanoparticles for fluorescence-based Cu2+ ion sensing and cell imaging

In this work, a new synthetic approach is developed for the synthesis of fluorescent magnetic nanoparticles which are explored for the detection of mostly abundant transition metal Cu²⁺ ions and cell imaging.

Kinetic and thermodynamic study of polyaniline functionalized magnetic mesoporous silica for magnetic field guided dye adsorption

An eco-friendly magnetic mesoporous silica iron oxide (MS@Fe₃O₄) nanoparticles with a high surface area was fabricated using a colloidal chemical method.

Polyaniline/reduced graphene oxide/Fe3O4 nano-composite for aqueous Hg(II) removal

To ease the adsorbent recovery and to increase the adsorption capacity of polyaniline (PANI), aniline was polymerized in the presence of a solvothermally prepared nano-composite of reduced graphene oxide and Fe3O4 (RGO/Fe3O4). The polyaniline was formed along the RGO/Fe3O4 composite in transmission electron microscope (TEM). The thus formed PANI/RGO/Fe3O4 adsorbent was tested and applied in removing Hg(II) in aqueous solution. The initial adsorption rate as well as the adsorption capacity increases with the incorporation of RGO/Fe3O4. The magnetic separation of PANI/RGO/Fe3O4 was easy, and its regeneration can be carried out at the optimal pH of 2. Test results proved the competence of the prepared adsorbent in pollution remediation applications for safer water quality and environmental protection.

Hydroxyapatite conjugated graphene oxide nanocomposite: a new sight for significant applications in adsorption

Hydroxyapatite was conjugated with GO to synthesized GO/HAP nanocomposite which demonstrated an enhanced adsorption efficiency for removal of cationic dye from aqueous phase through electrostatic interaction.