Synthesis and characterization of polyaniline/γ-alumina nanocomposite: A comparative study for the adsorption of three different anionic dyes

Polypyrrole- and Polyaniline-Coated Cotton Fabrics as Efficient Adsorbents for the Pharmaceutical Water Contaminants Diclofenac and Salicylic Acid

The emerging pharmaceutical contaminants diclofenac (DCF) and salicylic acid (SA) pose potential hazards to humans and living organisms due to their persistence in water environments. In this work, the conductive polymers polypyrrole (PPY) and polyaniline (PANI) were successfully coated on cotton fabrics, as confirmed by FTIR and SEM measurements. The coated fabrics efficiently removed DCF at pH 5.3 and SA at pH 4, with removal efficiencies that exceeded 90% and 70%, respectively. Adsorption was rapid for most of the tested contaminant-fabric systems and reached equilibrium within 20-30 min. The best adsorption performance for both contaminants was shown on the PPY-coated fabrics, which yielded adsorption capacities of about 65 and 21 mg/g for DCF and SA, respectively. This could be explained by molecular modeling simulations, which mostly estimated higher total cohesive energy densities for adsorption on the PPY-coated fabrics than on the PANI-coated ones. The adsorption mechanism involved both coulombic electrostatic attractions and non-coulombic van der Waals and π-π stacking. The fabrics could be reused for three adsorption-desorption cycles. Immobilization of the conductive polymers on cotton fabrics provides a facile method for their handling and collection during adsorption and regeneration cycles while maintaining their multi-functionality in adsorbing different contaminants.

Ce(III) and La(III) ions adsorption using Amberlite XAD-7 resin impregnated with DEHPA extractant: response surface methodology, isotherm and kinetic study

In this paper, the removal efficiency of Cerium (Ce(ΙΙΙ)) and lanthanum (La(ΙΙΙ)) ions from aqueous solution using Amberlite XAD-7 resin impregnated with DEHPA(XAD7-DEHPA) was studied in the batch system. The adsorbent ( XAD7-DEHPA) was characterized by SEM-EDX, FTIR and BET analysis Techniques. The response surface methodology based on the central composite design was applied to model and optimize the removal process and evaluate operating parameters like adsorbent dose (0.05-0.065), initial pH (2-6) and temperature (15-55). Variance analysis showed that the adsorbent dose, pH and temperature were the most effective parameters in the adsorption of Ce(ΙIΙ)and La(IΙI) respectively. The results showed that the optimum adsorption condition was achieved at pH = 6, the optimum amount of absorbent and the equilibrium time equal to 0.6 gr and 180 min, respectively. According to the results, the adsorption percentage of Ce(ΙIΙ) and La(ΙΙΙ) ions onto the aforementioned resin were 99.99% and 78.76% respectively. Langmuir, Freundlich, Temkin and sips isotherm models were applied to describe the equilibrium data. From the results, Langmuir isotherm (R² (Ce) = 0.999, R² (La) = 0.998) was found to better correlate the experimental rate data. The maximum adsorption capacity of the adsorbent ( XAD7-DEHPA) for both Ce(IΙI) and La(III) was found to be 8.28 and 5.52 mg g^-1 respectively. The kinetic data were fitted to pseudo-first-order, pseudo-second-order and Intra particle diffusion models. Based on the results, the pseudo-first-order model and Intra particle diffusion model described the experimental data as well. In general, the results showed that ( XAD7-DEHPA) resin is an effective adsorbent for the removal of Ce(IΙI) and La(III) ions from aqueous solutions due to its high ability to selectively remove these metals as well as its reusability.

Removal of Methyl Violet from Aqueous Solution by Adsorption onto Halloysite Nanoclay: Experiment and Theory

Methyl Violet (MV) was removed from aqueous solutions by adsorption onto halloysite nanoclay (HNC) employing equilibrium, kinetics, thermodynamic data, molecular modellingR (MD), and Monte Carlo (MC) simulations. The chosen experimental variables were pH, temperature, starting MV concentration, contact time, and adsorbent dosage. The adsorption rate was determined to increase with increasing contact time, initial dye concentration, pH, and temperature. The Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich (D-R) isotherms were utilized to determine the adsorption capacity of HNC. The Langmuir equation matched equilibrium data better than the other models, whereas the pseudo-second-order model better described kinetic data, and thermodynamic analyses revealed that the adsorption process was spontaneous, endothermic, and physisorption-based. This study focused on two distinct molecular mechanics-based theoretical approaches (MC and MD). These techniques enabled a molecular comprehension of the interaction between the MV molecule and the halloysite surface. Theoretical results were consistent with experimental findings. The outcomes revealed that HNC is an excellent dye adsorbent for industrial effluents.

Industrial performance, reusability and mechanical reliability of mesoporous gamma alumina packed bed fabricated through boehmite extrusion for removal of reactive dyes from textile wastewaters

The reusable γ-alumina packed bed was fabricated by extrusion of boehmite as rods for the removal of reactive dyes from the industrial textile wastewaters in a dynamic system. The appropriate calcination temperature, and time were determined to maximize the removal efficiency, ∼90%, in the acidic environments, pH 2-3. On the other hand, the current contribution addressed the estimation of failure probability which is a challenge for the reliable design of packed beds. Therefore, the normal, and Weibull distributions were used to evaluate the reliability of rods through Akaike information criterion (AIC), and Anderson-Darling test (ADT). The results revealed that the Weibull distribution possesses the higher accuracy in the analysis of compression strength scatter. The calcination of rods at 850 °C within 90 min not only led to fabricate a reliable packed bed with a mean strength about 860 kPa but also brought the better mesoporous structure, 8 nm, which is the main reason for the development of active sites. The thermal stability of rods provided an industrial potential for the regeneration of packed bed at 500 °C, without efficiently losing the adsorptive performance, even after reuse for ten times.

Resin immobilized gold nanocomposites assisted surface enhanced infrared absorption (SEIRA) spectroscopy for improved surface assimilation of methylene blue from aqueous solution

In the present work, we report the adsorption of the methylene blue (MB) dye from an aqueous solution employing resin immobilized gold nanocomposites (R-AuNCs) assisted surface-enhanced infrared absorption (SEIRA) spectroscopy. The appropriate adsorption isotherm models, including the Langmuir, Freundlich, and Temkin are tested to reveal the interactive behavior between the adsorbent (R-AuNCs) and adsorbed (MB). Interestingly, Fourier transform infrared spectroscopy (FTIR) in combination with R-AuNC materials could be another approach through which the analysis of adsorption-desorption of MB on the surface of nanocomposite adsorbents is possible in a more precise way with high sensitivity and adsorptivity. In addition, a 10-fold enhancement of the signal intensity of MB dye was obtained due to the electrostatic interaction and H-bonding interaction between COO^- groups of adsorbent and the positively charged active sites of the dye molecules. The value of % removal efficiency and % adsorption obtained in the present method was 77.64% and 186.61%, respectively. Desorption of MB from adsorbent surface was also carried out using 0.1 M cetylpyridinium chloride as cationic surfactant; resulting process shows for 'n' number of cyclic process. The maximum desorption capacity for MB found in the present investigation was 44.38 mg/g, The advantages of current method are its simplicity, sensitivity, rapidity, ease to fabrication and excellent adsorption efficiencies to remove MB dye from aqueous solution.

Synthesis of a functional biomass lignin-based hydrogel with high swelling and adsorption capability towards Acid Red 73

In this study, sodium lignosulfonate (LS) was used as raw material. Acrylamide (AM) and acryloxyethyltrimethylammonium chloride (DAC) were grafted onto LS through the free radical graft copolymerisation to synthesise a functional biomass terpolymer lignin-based hydrogel adsorbent (LAD). The effects of different factors on the LAD adsorption of Acid Red (AR 73) were investigated through the static adsorption method. LAD adsorbed AR 73 (C0=100mg·L-1) for 2 h to reach equilibrium, and the equilibrium adsorption capacity and removal rate were 47.59 mg·g-1 and 95.18%, respectively. The prepared LAD hydrogel swelling ratio for 2 h was 25 g·g-1, and the water loss rate in ethanol solvent in 120 min was 93.51%. The adsorption of AR 73 by LAD was consistent with the Langmuir isotherm adsorption model. This adsorption was a single-molecule adsorption with a maximum adsorption capacity of 409.84 mg·g-1. The adsorption was a process of spontaneous heat release and entropy reduction. The adsorption kinetic was in accordance with the pseudo-second-order model, and the adsorption activation energy was 2.501 kJ·moL-1. Moreover, the mechanism of adsorption was electrostatic attraction, and comprehensive effects of physical, and chemical adsorption and hydrogen bond. The LAD hydrogel adsorbent has a remarkable adsorption effect on AR 73, and can be used as an efficient and recyclable biomass adsorbent for the treatment of anionic dye wastewater.

Removal of Cr(VI) from Aqueous Solution by Polypyrrole/Hollow Mesoporous Silica Particles

The removal of Cr(VI) in wastewater plays an important role in human health and environment. In this work, polypyrrole/hollow mesoporous silica particle (PPy/HMSNs) adsorbents have been newly synthesized by in-situ polymerization, which prevent the aggregation of pyrrole in the process of polymerization and exhibit highly selective and powerful adsorption ability for Cr(VI). The adsorption process was in good agreement with the quasi-second-order kinetic model and the Langmuir isotherm model. And the maximum adsorption capacity of Cr(VI) was 322 mg/g at 25 °C. Moreover, the removal rate of Cr(VI) by PPy/HMSNs was ~100% in a number of binary systems, such as Cl⁻/Cr(VI), NO₃⁻/Cr(VI), SO₄²⁻/Cr(VI), Zn²⁺/Cr(VI), Fe³⁺/Cr(VI), Sn⁴⁺/Cr(VI), and Cu²⁺/Cr(VI). Thus, the PPy/HMSNs adsorbents have great potential for the removal of Cr(VI) in wastewater.

Response surface methodology based on central composite design for simultaneous adsorption of rare earth elements using nanoporous calcium alginate/carboxymethyl chitosan microbiocomposite powder containing Ni0.2Zn0.2Fe2.6O4 magnetic nanoparticles: Batch and column studies

In this research paper, the utilization of the magnetic calcium alginate/carboxymethyl chitosan/Ni_0.2Zn_0.2Fe_2.6O₄ (CA/CMC/Ni_0.2Zn_0.2Fe_2.6O₄) was investigated for the simultaneous aqueous adsorption of Nd (III), Tb (III), and Dy (III). The magnetic products were characterized by FE-SEM, EDX, XRD, FT-IR, TGA, and VSM techniques. The saturation magnetization value for Ni_0.2Zn_0.2Fe_2.6O₄ and CA/CMC/Ni_0.2Zn_0.2Fe_2.6O₄ was found to be 45.87 and 14.14 emu/g, respectively. Using RSM, a quadratic polynomial equation was obtained to predict the adsorption efficiency of each ion. Under the conditions of pH = 5.5, adsorbent dosage of 0.1 g, initial concentration of 30 mg/L, and contact time of 53 min predicted by RSM, the adsorption efficiencies of Nd (III), Tb (III), and Dy (III) were respectively 95.72, 96.17, and 99.44%. The isotherm and kinetic data were respectively fitted well with Freundlich and pseudo-second-order (PSO) models. The desorption of the loaded ions was effectively carried out by 0.2 M HNO₃, and the adsorbent was consecutively utilized with 2.54, 1.63, and 1.16% decrease in adsorption efficiency for Nd (III), Tb (III), and Dy (III), respectively, after the forth cycle. Additionally, the adsorption behavior of the CA/CMC/Ni_0.2Zn_0.2Fe_2.6O₄ towards Nd (III), Tb (III), and Dy (III) was studied by using a fixed-bed column technique.

Treated residue from aluminium lamination as adsorbent of toxic reactive dyes - a kinetic, equilibrium and thermodynamic study

The residue generated in the aluminium cold lamination (TTR) was submitted to a direct burning and then it was calcined at 500°C. BET, FTIR, SEM with EDX and TGA techniques were performed to characterize the adsorbent before and after the adsorption. BET analysis showed that TTR specific surface area was 55.37 m² g^-1 and there were no significant changes after the adsorptive process. Afterwards, the TTR was applied as adsorbent of the reactive Drimaren Blue (DB), Drimaren Red (DR) and Drimaren Gold (DG). Its employment consists in a sustainable alternative for the treatment of textile wastewater, once the TTR was used as low-cost adsorbent of textile dyes. Kinetic studies showed that the process reached the equilibrium state between 5 and 10 min. The pseudo-second-order model better fitted the adsorption kinetics, with kinetic rate constants 10.51, 34.71 and 31.51 mg min g^-1 for DB, DR and DG respectively. The equilibrium experiments were performed to obtain the adsorption parameters for each dye; moreover, the maximum adsorption capacity was 6.27, 0.42 and 1.23 mg g^-1 for DB, DR and DG, respectively. Thermodynamics studies allowed to obtain the values of enthalpy for DB, DR and DG, -7.90, 14.03 and -17.75 kJ mol^-1, respectively. Furthermore, the negative values of Gibbs free energy confirmed the spontaneity of the adsorption. The results point to the physisorption characteristic of the process, in which the temperature negatively influenced the adsorption for the DB and DG; the opposite result was observed for the DR.

Comparative Study of the Adsorption of Acid Blue 40 on Polyaniline, Magnetic Oxide and Their Composites: Synthesis, Characterization and Application

Conducting polymers (CPs), especially polyaniline (PANI) based hybrid materials have emerged as very interesting materials for the adsorption of heavy metals and dyes from an aqueous environment due to their electrical transport properties, fascinating doping/de-doping chemistry and porous surface texture. Acid Blue 40 (AB40) is one of the common dyes present in the industrial effluents. We have performed a comparative study on the removal of AB40 from water through the application of PANI, magnetic oxide (Fe₃O₄) and their composites. Prior to this study, PANI and its composites with magnetic oxide were synthesized through our previously reported chemical oxidative synthesis route. The adsorption of AB40 on the synthesized materials was investigated with UV-Vis spectroscopy and resulting data were analyzed by fitting into Tempkin, Freundlich, Dubinin-Radushkevich (D-R) and Langmuir isotherm models. The Freundlich isotherm model fits more closely to the adsorptions data with R² values of 0.933, 0.971 and 0.941 for Fe₃O₄, PANI and composites, respectively. The maximum adsorption capacity of Fe₃O₄, PANI and composites was, respectively, 130.5, 264.9 and 216.9 mg g^-1. Comparatively good adsorption capability of PANI in the present case is attributed to electrostatic interactions and a greater number of H-bonding. Effect of pH of solution, temperature, initial concentration of AB40, contact time, ionic strength and dose of adsorbent were also investigated. Adsorption followed pseudo-second-order kinetics. The activation energy of adsorption of AB40 on Fe₃O₄, PANI and composites were 30.12, 22.09 and 26.13 kJmol^-1 respectively. Enthalpy change, entropy change and Gibbs free energy changes are -6.077, -0.026 and -11.93 kJ mol^-1 for adsorption of AB40 on Fe₃O₄. These values are -8.993, -0.032 and -19.87 kJ mol^-1 for PANI and -10.62, -0.054 and -19.75 kJ mol^-1 for adsorption of AB40 on PANI/Fe₃O₄ composites. The negative sign of entropy, enthalpy and Gibbs free energy changes indicate spontaneous and exothermic nature of adsorption.

Adsorption behaviors of methylene blue on sunflower stem pith

Adsorption behaviors of methylene blue (MB) from aqueous solution using sunflower stem pith (SSP) as adsorbent were investigated. The effects of adsorption conditions such as adsorption time, initial concentration of MB and dosage of SSP on the detoxification of MB were examined. The equilibrium adsorption data were analyzed using three well-known isotherms: Langmuir, Freundlich and Temkin. The results indicated that the Langmuir isotherm fitted well to the data as compared with another isotherm model. The maximum adsorption capacity calculated by the Langmuir isotherm model was 277 mg/g at 338 K. Kinetic analyses were conducted using pseudo first order, pseudo second order and the Elovich model. The regression results showed that the MB adsorption was described by the pseudo second order model. Different thermodynamic parameters such as Gibb's free energy (ΔG^o), standard enthalpy change (ΔH^o) and standard entropy change (ΔS^o) were also evaluated. The results showed that the detoxification of MB using SSP as adsorbent was feasible, non-spontaneous and exothermic under experimental conditions.

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.

Electrocoagulation using commercial grade aluminium electrode for the removal of crystal violet from aqueous solution

The current research work studies the removal of crystal violet (also known as gentian violet), a kind of dye, from simulated wastewater by electrocoagulation using scrap aluminium roofing sheet as electrode in a batch electrochemical cell. Optimization of different operational parameters - pH, current density, time, initial concentration - was carried out experimentally. The equilibrium was attained at 1 hour and at pH 11. After suitable optimization, a removal of above 90% was achieved at an optimum current density of 20 mA/m². Also, the adsorption behaviour of crystal violet in electrocoagulation was also studied and the isothermal and kinetic models were proposed to be the Dubinin-Radushkevich model and pseudo-first order model. The mechanism involved during the process was suggested as chemisorption. The adsorption thermodynamic studies were a clear indication that the process is spontaneous and endothermic as well as thermodynamically favourable too. Both chemical and physical characterization of the flocs generated during the electrolysis was explained by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) respectively.

Synthesis of poly(acrylamide-co-itaconic acid)/MWCNTs superabsorbent hydrogel nanocomposite by ultrasound-assisted technique: Swelling behavior and Pb (II) adsorption capacity

In this research, the poly (acrylamide-co-itaconic acid)/multi-walled carbon nanotubes (P(AAm-co-IA)/MWCNTs) as a novel superabsorbent hydrogel nanocomposite was synthesized by graft copolymerization of acrylamide (AAm) and itaconic acid (IA) mixture in the presence of the MWCNTs using ammonium persulfate (APS) as a free radical initiator and methylenebisacrylamide (MBA) as a crosslinker under ultrasound-assisted condition. The blank P(AAm-co-IA) hydrogel and its composite with the MWCNTs were characterized by means of SEM, FTIR, XRD and TGA methods. The effects of different parameters such as pH, time, the MWCNTs content and salt solutions on swelling behavior were investigated. The stability of the hydrogel increased by any increase in the MWCNTs content, which might be attributed to the hydrophobic nature of the MWCNTs as well as the increase of the crosslinker density. The water retention capacity (WRC) of the P(AAm-co-IA) hydrogel increased in the presence of the MWCNT (10 wt%). The synthesized hydrogel nanocomposite was studied for Pb (II) adsorption from aqueous solution. The effects of different parameters such as contact time (5-90 min), Pb (II) initial concentration (25-175 mg/L) and initial pH (1.5-4.5) of solution on Pb (II) adsorption were investigated by batch method. In comparison to P(AAm-co-IA) hydrogel, the P(AAm-co-IA)/MWCNTs hydrogel nanocompoite showed better adsorption behavior toward Pb (II). One of the most important aspects of this research was to investigate the effects of ultrasonic waves on polymer matrix and its ability.

Mechanism of aniline adsorption on post-crosslinked resins: pore structure and oxygen content

A series of post-crosslinked resins were synthesized from macroporous chloromethylated styrene-divinylbenzene copolymer by controlling post-crosslinked reaction conditions. Adsorption study towards aniline showed that the three resins, ST-DVB-WH5, ST-DVB-WH6, and ST-DVB-WH7, prepared at different temperatures, and which had nearly identical static adsorption capacity, displayed great disparity in kinetic behavior. The rate constant of ST-DVB-WH7 by the pseudo-first-order model was 1.50 and 1.19 times higher than that of ST-DVB-WH5 and ST-DVB-ST-DVB-WH6. Further analysis of the diffusion model showed that the three resins exhibited different diffusion rates due to the difference in oxygen content and pore structure of each resin. The results showed that the adsorption capacity was mainly decided by the pore volume within 1.14 and 3.42 nm and the adsorption rate was mainly decided by the oxygen content of the resin. In addition, as the best synthetic resin for aniline adsorption, the equilibrium adsorption capacity of ST-DVB-WH7 was 1.57 times and 1.44 times higher than that of H-103 and NKA-II, respectively.

Synthesis of a novel visible light responsive γ-Fe2O3/SiO2/C-TiO2 magnetic nanocomposite for water treatment

This work investigates the preparation of a magnetically recoverable photocatalytic nanocomposite of maghemite nanoparticles coated with silica and carbon doped titanium dioxide. The novel nanocomposite boasts the advantages of efficient photocatalytic degradation of organic pollutants in water and ease of recovery of the fine particles after water treatment. The photocatalytic nanocomposite was successfully synthesized through a stepwise approach via co-precipitation and sol-gel methods. Characterisation by Fourier transform infrared (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) substantiated the existence of the intended structure of the nanocomposite and the particles were found to be in the size range of 15-22 nm with a quasi-spherical shape. Brunauer-Emmett-Teller (BET) surface area analysis revealed an average surface area of 55.20 m²/g, which is higher than that of commercial TiO₂ (Degussa P25, 50.00 m²/g), and an average pore diameter of 8.36 nm. A 5 ppm methylene blue solution was degraded with an efficiency of 96.8% after 3 h of solar irradiation, which was 19.7% greater than using the same photo-catalyst under strict UV light irradiation. Photo-catalysis using these nanoparticles was observed to be very effective. The prepared novel visible light active nanocomposite has great potential for incorporation into water treatment systems because it exhibits good stability and magnetism, as well as high photocatalytic efficiency.

Rapid degradation of malachite green by CoFe2O4-SiC foam under microwave radiation

This study demonstrated rapid degradation of malachite green (MG) by a microwave (MW)-induced enhanced catalytic process with CoFe₂O₄-SiC foam. The catalyst was synthesized from CoFe₂O₄ particles and SiC foam by the hydrothermal method. X-ray diffraction and scanning electron microscopy techniques were used to confirm that CoFe₂O₄ particles were settled on the surface of SiC foam. In this experiment, a novel fixed-bed reactor was set up with this catalyst for a continuous flow process in a MW oven. The different parameters that affect the MW-induced degradation rate of MG were explored. The MW irradiation leads to the effective catalytic degradation of MG, achieving 95.01% degradation within 5 min at pH 8.5. At the same time, the good stability and applicability of CoFe₂O₄-SiC foam for the degradation process were also discussed, as well as the underlying mechanism. In brief, these findings make the CoFe₂O₄-SiC foam an excellent catalyst that could be used in practical rapid degradation of MG.

Preparation and Characterization of WS₂@SiO₂ and WS₂@PANI Core-Shell Nanocomposites

Two tungsten disulfide (WS₂)-based core-shell nanocomposites were fabricated using readily available reagents and simple procedures. The surface was pre-treated with a surfactant couple in a layer-by-layer approach, enabling good dispersion of the WS₂ nanostructures in aqueous media and providing a template for the polymerization of a silica (SiO₂) shell. After a Stöber-like reaction, a conformal silica coating was achieved. Inspired by the resulting nanocomposite, a second one was prepared by reacting the surfactant-modified WS₂ nanostructures with aniline and an oxidizing agent in an aqueous medium. Here too, a conformal coating of polyaniline (PANI) was obtained, giving a WS₂@PANI nanocomposite. Both nanocomposites were analyzed by electron microscopy, energy dispersive X-ray spectroscopy (EDS) and FTIR, verifying the core-shell structure and the character of shells. The silica shell was amorphous and mesoporous and the surface area of the composite increases with shell thickness. Polyaniline shells slightly differ in their morphologies dependent on the acid used in the polymerization process and are amorphous like the silica shell. Electron paramagnetic resonance (EPR) spectroscopy of the WS₂@PANI nanocomposite showed variation between bulk PANI and the PANI shell. These two nanocomposites have great potential to expand the use of transition metals dichalcogenides (TMDCs) for new applications in different fields.

Fuzzy logic modeling of Pb (II) sorption onto mesoporous NiO/ZnCl2-Rosa Canina-L seeds activated carbon nanocomposite prepared by ultrasound-assisted co-precipitation technique

In this study, NiO/Rosa Canina-L seeds activated carbon nanocomposite (NiO/ACNC) was prepared by adding dropwise NaOH solution (2mol/L) to raise the suspension pH to around 9 at room temperature under ultrasonic irradiation (200W) as an efficient method and characterized by FE-SEM, FTIR and N₂ adsorption-desorption isotherm. The effect of different parameters such as contact time (0-120min), initial metal ion concentration (25-200mg/L), temperature (298, 318 and 333K), amount of adsorbent (0.002-0.007g) and the solution's initial pH (1-7) on the adsorption of Pb (II) was investigated in batch-scale experiments. The equilibrium data were well fitted by Langmuir model type 1 (R²>0.99). The maximum monolayer adsorption capacity (q_m) of NiO/ACNC was 1428.57mg/L. Thermodynamic parameters (ΔG°, ΔH° and ΔS°) were also calculated. The results showed that the adsorption of Pb (II) onto NiO/ACNC was feasible, spontaneous and exothermic under studied conditions. In addition, a fuzzy-logic-based model including multiple inputs and one output was developed to predict the removal efficiency of Pb (II) from aqueous solution. Four input variables including pH, contact time (min), dosage (g) and initial concentration of Pb (II) were fuzzified using an artificial intelligence-based approach. The fuzzy subsets consisted of triangular membership functions with eight levels and a total of 26 rules in the IF-THEN approach which was implemented on a Mamdani-type of fuzzy inference system. Fuzzy data exhibited small deviation with satisfactory coefficient of determination (R²>0.98) that clearly proved very good performance of fuzzy-logic-based model in prediction of removal efficiency of Pb (II). It was confirmed that NiO/ACNC had a great potential as a novel adsorbent to remove Pb (II) from aqueous solution.

Synthesis and Characterization of Nano-Conducting Copolymer Composites: Efficient Sorbents for Organic Pollutants

Nano-conducting copolymers of aniline (ANI) and pyrrole (Py) with silica of different starting monomer ratios are prepared by oxidative chemical polymerization. X-ray diffraction (XRD) data showed that polyaniline (PANI) is the predominant phase in copolymer composites with a higher starting ANI monomer ratio while polypyrrole (PPy) is the major phase for other prepared samples. Transmission and scanning electron microscope images ascertained XRD results where hexagonal-shaped particles are assigned to PANI/SiO₂ and poly(9ANI-co-1Py)/SiO₂ samples; the cauliflower morphology can be observed for PPy/SiO₂, poly(1ANI-co-9Py)/SiO₂, poly(1ANI-co-2Py)/SiO₂, and poly(1ANI-co-1Py)/SiO₂ samples. One-dimensional nano-fibers can be obtained by using a starting monomer ratio of 2ANI:1Py during synthesis. Thermal analysis showed that copolymerization increases the thermal stability as compared with PANI/SiO₂ and PPy/SiO₂ composites. All prepared samples were applied as sorbents for Congo red dye from aqueous solutions. It was found that the sorption capacity value was affected by the starting monomer ratio; poly(2ANI-co-1Py)/SiO₂ has the highest sorption capacity; the q_m value is 142.9 mg g⁻¹ due to its highly-stabilized nano-structure.

A holistic review of hydrogel applications in the adsorptive removal of aqueous pollutants: Recent progress, challenges, and perspectives

Due to the unique physical and chemical characteristics of hydrogels, such as hydrophilicity, swellability, and modifiability, there is increasing research interest in the development and application of novel hydrogels in water and wastewater treatment. Hydrogels have exhibited superior performance in the adsorptive removal of a wide range of aqueous pollutants including heavy metals, nutrients, and toxic dyes. However, there remain certain challenges which need to be addressed in order to evolve hydrogel based treatment systems from the lab-scale to practical applications. This review provides a coverage of the latest developments in the application of hydrogels for the adsorptive removal of aqueous pollutants. A holistic overview of different steps involved in the hydrogel based treatment systems is provided, and the influencing factors and mechanisms of pollutants removal are reviewed. Major challenges pertaining to adsorption kinetics, operational pH range, interference, and hydrogel recovery are examined. Important considerations such as stability and reusability of hydrogels and resource recovery are also discussed, for economic and sustainability concerns.