Efficient removal of arsenic(III) from aqueous media using magnetic polyaniline-doped strontium-titanium nanocomposite

Recent developments in conductive polysaccharide adsorbent formulations for environmental remediation: A review

Environmental remediation is crucial for human life and ecosystems, involving the cleanup of contaminated water to protect health and restore ecological balance. However, rapid industrialization and population growth have worsened pollution, particularly in water bodies, making effective wastewater treatment a key challenge in ensuring clean drinking water, and the adsorption of toxic gases for air treatment are the main strategies for environmental remediation. Among the various treatment methods, adsorption stands out for its high selectivity, low energy and chemical use, ease of operation, and cost-effectiveness. To date, innovative, highly efficient, non-toxic, engineered adsorbent materials have received potential interest from scientific and governmental communities. Conducting polymer-modified polysaccharide formulations are crucial in wastewater treatment due to their high surface area, adsorption efficiency, excellent stability, and eco-friendly, biodegradable properties. This review offers an extensive overview of recent progress in synthesizing conducting polymer-modified polysaccharide formulations (hydrogels, aerogels, nanofibers, and nanocomposites) for capturing toxic heavy metal ions, organic dyes, pharmaceuticals, phenols as well as adsorbing different toxic gases using various adsorption mechanisms. It also emphasizes the integration of different nanofillers, including carbon-based materials, Mxenes, nanoclay, metal/metal oxides, and hybrid nanomaterials, into conductive polysaccharide chains to improve their physicochemical properties and adsorption efficiency. The reported data showed that these engineered adsorbent materials based on conductive polysaccharide formulations have immense potential for wastewater treatment applications, offering more effective and sustainable solutions.

Development of nanoscale zero-valent iron embedded on polyaniline reinforced with sodium alginate hydrogel microbeads for effective adsorption of arsenic from apatite soil leachate water

A novel polymeric nanocomposite hydrogel adsorbent was developed to enhance the efficiency of arsenic removal from apatite soil leachate. Apatite soil aqueous leachate was treated with nanoscale zero-valent iron embedded on polyaniline reinforced with sodium alginate hydrogel beads. Various analytical techniques including attenuated total reflection -Fourier transform infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy were employed to characterize these chemically synthesized hydrogel beads. The influence of different types and ratios of adsorbent materials, solution pH, adsorbent dosage, contact time, temperature, initial arsenic concentration, and the presence of co-existing ions on the adsorption process were investigated. Under optimum operating conditions; a pH range of 4-6, 80 mg of sorbent, 180 min contact time led to a remarkable arsenic removal efficiency of approximately 90.33 %. Thermodynamic, adsorption isotherm, and kinetic models provided a good description of the observed experimental results. Compared to the Freundlich and Temkin models, the Langmuir model was found to be the best fit for the experimental data, with a maximum adsorption capacity of 104.167 mg/g. Physical adsorption is mainly responsible for controlling the adsorption of arsenic ions onto the hydrogel. Thermodynamic studies verified that the adsorption process was endothermic and spontaneous.

Recent advances in conducting polymer-based magnetic nanosorbents for dyes and heavy metal removal: fabrication, applications, and perspective

Globally, treating and disposing of industrial pollutants is a techno-economic challenge. Industries' large production of harmful heavy metal ions (HMIs) and dyes and inappropriate disposal worsen water contamination. Much attention is required on the development of efficient and cost-effective technologies and approaches for removing toxic HMIs and dyes from wastewater as they pose a severe threat to public health and aquatic ecosystems. Due to the proven superiority of adsorption over other alternative methods, various nanosorbents have been developed for the efficient removal of HMIs and dyes from wastewater and aqueous solutions. Being a good adsorbent, conducting polymer-based magnetic nanocomposites (CP-MNCPs) has drawn more attention for HMIs and dye removal. Conductive polymers' pH-responsiveness makes CP-MNCP ideal for wastewater treatment. The composite material absorbed dyes and/or HMIs from contaminated water could be removed by changing the pH. Here, we review the production strategies and applications of CP-MNCPs for HMIs and dye removal. The review also sheds light on the adsorption mechanism, adsorption efficiency, kinetic and adsorption models, and regeneration capacity of the various CP-MNCPs. To date, various modifications to conducting polymers (CPs) have been explored to improve the adsorption properties. It is evident from the literature survey that the combination of SiO₂, graphene oxide (GO), and multi-walled carbon nanotubes (MWCNTs) with CPs-MNCPs enhances the adsorption capacity of nanocomposites to a large extent, so future research should lean toward the development of cost-effective hybrid CPs-nanocomposites.

Synthesis of graphene oxide-modified porous chitosan cross-linked polyaniline composite for static and dynamic removal of Cr(VI)

A novel ternary composite was synthesized comprising graphene oxide-modified porous chitosan cross-linked polyaniline (GO@CS-PANI) by improved Hummers method, followed by cross-linking and grafting. The morphological, structural, and electrical properties of the composite were characterized by FESEM, BET, XRD, RAMAN, FTIR spectra, and zeta potential. It was found that the composite shows excellent Cr(VI) removal performance both in static and dynamic adsorption. The optimal adsorption parameters were solution at pH of 2.0, adsorbent dosage of 0.4 g/L, time of 45 min, and temperature of 35 °C. The Langmuir isotherm model was the best-fitted model, indicating homogeneous adsorption with maximum uptake of 539.83 mg/g. Pseudo-second-order was the best-fitted kinetic model, and the rate was controlled by film diffusion. Thermodynamic data demonstrated that the process was spontaneous, endothermic, and feasible. From the dynamic study, it was witnessed that a lower flow rate and a higher bed height were suitable for maximum adsorption performance. The Thomas model was the best-fitted model for data obtained from the dynamic study. Competition from interfering ions showed that anions have little effect on Cr(VI) removal, whereas cations have no such effect. The adsorption mechanism involved electrostatic attraction, π-π interaction, ion exchange, and metal ion complexion. After five cycles of adsorption-desorption study, the composite still removed 76% Cr(VI). These findings of the present study and the reusable nature of GO@CS-PANI composite signify the innovative and excellent adsorbent for wastewater treatment.

Magnetic nanocomposite adsorbents for abatement of arsenic species from water and wastewater

The presence of high concentrations of arsenic species in drinking water and other water bodies has become one of the most critical environmental concerns. Therefore, decontamination of arsenic-containing water is essential for improved health and environmental concern. In recent years, nano-adsorbents have been widely used for the adsorptive removal of arsenic from water. Separating existing nano-adsorbents from treated waters, on the other hand, is a critical issue for their potential applications in natural water treatment. To address these issues and to effectively remove arsenic from water, researchers looked at iron oxide-based magnetic nanocomposite adsorbents. The magnetic nanoadsorbents have the benefit of surface functionalization, making it easier to target a specific pollutant for adsorption, and magnetic separation. In addition, magnetic nanoparticles have a large surface area, high chemical inertness, superparamagnetic, high magnetic susceptibility, small particle size, and large specific surface area, and are especially easily separated in a magnetic field. Magnetic nano-adsorbents have been discovered to have a lot of potential for eliminating arsenic from water. The recent advances in magnetic nano-absorbents for the cleanup of arsenic species from water are summarized in this paper. Future perspectives and directions were also discussed in this article. This will help budding researchers for the further advancement of magnetic nanocomposites for the treatment of water and wastewater contaminated with arsenic.

Magnetic Beads of Zero Valent Iron Doped Polyethersolfun Developed for Removal of Arsenic from Apatite-Soil Treated Water

The drop immerses calcium chloride aqueous solution was utilized to prepare the zero valent iron-doped polyethersulfone beads (PES/ZVI) for the efficient removal of arsenic from apatite-soil treated waters. The proposed beads can assist in promoting uptake efficiency by hindering ZVI agglomeration due to a high porosity and different active sites. The PES/ZVI beads were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and vibrating sample magnetism (VSM). The main objective of this study was to investigate the function of new PES/ZVI beads with an increased removal efficiency for the remediation of arsenic ions from the apatite-soil treated waters. A maximum adsorption removal of 82.39% was achieved when the experiment was performed with 80 mg of adsorbent for a contact time of 180 min. Based on the results, a removal efficiency >90% was obtained after 300 min of shaking time with an arsenic concentration of 20 mg·L^-1. The experimental process was fitted with the Langmuir model due to the high R² (0.99) value compared to the Freundlich model (0.91) with an adsorption capacity of 41.32 mg·g^-1. The adsorption process speed was limited by pseudo-second-order (R² = 0.999) and the adsorption mechanism nature was endothermic and physical.

Ammonia removal from industrial effluent using zirconium oxide and graphene-oxide nanocomposites

The present study developed and evaluated nano-adsorbents based on zirconium oxide and graphene oxide (ZrO₂/GO) as a novel adsorbent for the efficient removal of ammonia from industrial effluents. Fourier transform infrared (FTIR) spectroscopy, Field Emission Scanning Electron Microscope, Energy-dispersive X-ray Spectroscopy, and X-ray diffraction were used to evaluate and identify the novel adsorbent in terms of morphology, crystallography, and chemical composition. The pH (7), adsorbent quantities (20 mg), adsorbent contact time (30 min) with the sample, and initial ammonia concentration were all tuned for ammonia uptake. To validate ammonia adsorption on the ZrO₂/GO adsorbent, several kinetic models and adsorption isotherms were also utilized. The results showed that the kinetics of ammonia adsorption are of the pseudo-second order due to high R² (>0.99) value as compared first-order (R² = 0.52). The chemical behavior and equilibrium isotherm were analyzed using the isotherm models and Langmuir model provided high R² (>0.98) as compared Freundlich (>0.96). Hence, yielding a maximum uniform equilibrium adsorption capacity of 84.47 mg g^-1. The presence of functional groups on the surface of graphene oxide and ZrO₂ nanoparticles, which interact efficiently with ammonia species and provide an efficient surface for good ammonia removal, is most likely to be responsible.

Chitosan magnetic graphene grafted polyaniline doped with cobalt oxide for removal of Arsenic(V) from water

The present study reports the successful functionalization/magnetization of bio-polymer to produce chitosan-magnetic graphene oxide grafted polyaniline doped with cobalt oxide (ChMGOP-Co₃O₄). Analytical techniques furrier transform infra-red (FT-IR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) were used to confirm the formation of ChMGOP-Co₃O₄. The effects of several experimental factors (solution pH, adsorbent dosage and coexisting ions) on the uptake of As(V) ions using ChMGOP-Co₃O₄ were examined through batch experiments. As(V) removal process was validated by experimentally and theoretically investigating the adsorption capacity, rate, and thermal effects. Thermodynamic parameters such as free energy (ΔG°), entropy (ΔS°) and enthalpy (ΔH°) were also calculated and were used to explain the mechanism of adsorption. Based on the results, the sorbent showed a high adsorption capacities (90.91 mg/g) at favorable neutral pH and superior removal efficiencies as high as 89% within 50 min. In addition, the adsorption isotherm followed the Langmuir isotherm in compare to the Freundlich, due to its higher R² value (0.992 < 0.941). Meanwhile, the kinetic data revealed that the of As(V) adsorption was controlled by pseudo-second-order. Overall, the adsorption mechanism studies revealed a spontaneous endothermic nature with predominance of physisorption over chemisorption. This study indicated that ChMGOP-Co₃O₄ is an exceptional novel adsorbent material for the efficient isolation of As(V) from aqueous media.

Dispersive clean-up process based on a magnetic graphene oxide nanocomposite for determination of 2-glycerol monopalmitate in olive oil prior to GC-FID and GC-MS analysis

BACKGROUND

Recently, methods have been developed for the better quality control, fraud detection and analytical investigation of olive oil. Magnetic graphene oxide (GO) material is known for its reusability, high adsorption capability and stability in food sample preparation. Monopalmitine or 2-glycerol monopalmitate (2-GMP) is one of the main parameters in the quality assay and classification of olive oil, which can be classified as extra virgin ≤ 0.9% and olive pomace ≤ 1.2. Hence, newly synthesized magnetic GO (MGO) and commercial silica-gel were used as a dispersive solid-phase clean-up (d-SPE) sorbent to determine 2-GMP value in olive oil samples prior to gas chromatography (GC) analysis. The d-SPE method is validated with olive oil certified reference material (CRM) with respect to silica-gel and a MGO nanocomposite.

RESULTS

The developed d-SPE method was applied for various virgin, refined and pomace olive oil samples to determine the value of 2-GMP%. The presence of 2-GMP in the samples was confirmed by GC-mass spectrometry analysis based on silylation derivatives of the analyte. Finally, the d-SPE-MGO method was determined 2-GMP% as 1.9% for pomace olive oil, 0.6% for refined olive oil, 0.4% for virgin olive oil and 3.1% for CRM. The MGO provided satisfactory clean-up recovery (124%) in the acceptable data range for CRM2018, and silica-gel also provided satisfactory recovery (83%) for CRM2018. The proposed method performed with higher sensitivity and efficiency for screening 2-GMP% in olive oil.

CONCLUSION

The MGO based d-SPE method was applied for clean-up purposes to determine 2-GMP%. It proved superior via its advantageous features of super quickness, easy isolation with an external magnet and the highly efficient exclusion of all the coexisting interfering peaks conventionally generated with a standard silica-gel material. These methods based on MGO and silica-gel are reflected in the dispersive mode of extraction and can be used as alternatives to conventional methods. Considering the benefits of the consumption of significantly fewer sorbents and less time required regarding the dispersive methods, the methods can be utilized as alternatives in contrast to conventional techniques. © 2021 Society of Chemical Industry.

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.

Nitrile-calixarene grafted magnetic graphene oxide for removal of arsenic from aqueous media: Isotherm, kinetic and thermodynamic studies

A novel adsorbent was developed based on nitrile functionalized calix [4]arene grafted onto magnetic graphene oxide (N-Calix-MGO) for remediation of arsenic (III) ions from aqueous media. The nanocomposite was characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The effective parameters on adsorption efficiency such as pH, adsorbent dosage, contact time, initial concentration, and temperature were studied. The adsorption process was provided with a high removal efficiency up to (90%) at pH 6 which followed by IUPAC Type II pattern. The mathematical models of kinetics and isotherm validated the experimental process. The adsorption kinetic is followed pseudo-first-order model with R² > 0.9. The adsorption equilibrium was well fitted on the Freundlich model (R² ∼ 0.96) as compared Langmuir model (R² ∼ 0.75). Hence, the Freundlich model suggested a multilayer sorption pattern with a physisorption mechanism for arsenic (III) uptake ono developed nanocomposite with a sorption capacity of 67 mg/g for arsenic. The Gibbs free energy (ΔG° < -20 kJ/mol) showed As(III) uptake ono N-Calix-MGO nanocomposite was the physical adsorption mechanism.

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.

Adsorption and in vitro release study of curcumin form polyethyleneglycol functionalized multi walled carbon nanotube: kinetic and isotherm study

Polyethylene glycol functionalized with oxygenated multi-walled carbon nanotubes (O-PEG-MWCNTs) as an efficient nanomaterial for the in vitro adsorption/release of curcumin (CUR) anticancer agent. The synthesized material was morphologically characterized using scanning electron microscopy, Fourier transform infrared spectroscopy and transmission electron microscopy. In addition, the CUR adsorption process was assessed with kinetic and isotherm models fitting well with pseudo-second order and Langmuir isotherms. The results showed that the proposed O-PEG-MWCNTs has a high adsorption capacity for CUR (2.0 × 10³ mg/g) based on the Langmuir model. The in vitro release of CUR from O-PEG-MWCNTs was studied in simulating human body fluids with different pHs (ABS pH 5, intestinal fluid pH 6.6 and body fluid pH 7.4). Lastly, to confirm the success compliance of the O-PEG-MWCNT nanocomposite as a drug delivery system, the parameters affecting the CUR release such as temperature and PEG content were investigated. As a result, the proposed nanocomposite could be used as an efficient carrier for CUR delivery with an enhanced prolonged release property. Graphical Abstract ᅟ.