Synergy of adsorption and visible light photocatalysis to decolor methyl orange by activated carbon/nanosized CdS/chitosan composite

Ag-Co ferrite-based magnetic polymeric composite film: a breakthrough in cationic dye remediation for sustainable environment

The deployment of magnetically responsive and polymeric materials to remove dyes that are hazardous in aquatic environments has profoundly revolutionized environmental sustainability. This study focuses on removing the hazardous cationic Malachite Green (MG) dye from solutions, employing a novel magnetic composite film as an adsorbent, designated as Ag0.2Co0.8 Fe2O4 (ACFCeP). The composite was synthesized via solvent casting, incorporating Ag0.2Co0.8 Fe2O4 nanoparticles and CeO2 into a cellulose acetate/polyvinylpyrrolidone (CA/PVP) polymer matrix. The Ag0.2Co0.8Fe2O4 nanoparticles were synthesized by a co-precipitation method. Comprehensive characterization of the synthesized composite was conducted using techniques, such as Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), and vibrating sample magnetometer (VSM). The Ag-doped cobalt ferrite component retained a strong hysteresis loop within the final composite, even when blended with the CA/PVP polymer, preserving the robust magnetic properties that facilitate the easy removal of the composite post-treatment without secondary pollution. Additionally, the mesoporous structure of the composite effectively aids in the adsorption mechanism. The isothermal study shows that both linear Langmuir isotherm and Freundlich isotherm are well fitted with R 2 values of 0.99 and 0.97, respectively. The linear Langmuir maximum adsorption capacity, q max, is 45.66 mg g-1 at pH 7. The kinetic studies of the composite resemble the pseudo-second-order kinetic model, reaching adsorption equilibrium within 70 min for a 100 ppm MG dye concentration. The composite film exhibits excellent reusability, maintaining high removal efficiency over three cycles. Overall, the ACFCeP composite film showcases excellent dye removal capabilities, a fast adsorption rate, and satisfactory magnetic properties and offers a sustainable solution for environmental pollution, thus contributing to ecosystem preservation through efficient recycling and reuse in dye adsorption applications.

Fabrication and synergistically enhanced photocatalytic activity of ternary kaolinite, TiO2, and Al2O3 (K65T30A5) nanocomposite for visible-light-induced degradation of methylene blue and remazol red dye

The ternary photocatalyst ((Al2Si2O5 (OH)4/TiO2/Al2O3) composites (where w/w = 65, 30, and 5 wt%) denoted K65T30A5 were successfully synthesized and examined for their efficiency in removing cationic (Methylene Blue, MB) and anionic (Remazol Red, RR) dye from aqueous medium under visible-light irradiation. A series of nanocomposites with varied wt% of kaolinite, TiO2, and Al2O3 were prepared through sonication followed by calcination at 600 °C. X-ray diffraction (XRD) analysis confirmed the crystallinity of the synthesized materials and established their average crystal size to be 83.87 nm. The morphological structure, composite molecule, and surface properties of the resulting K65T30A5 were characterized using FTIR, FE-SEM, and EDS analyses to confirm the successful fabrication of the nanocomposite. FTIR and EDS elemental mapping analyses confirmed the presence of Al, Si, Ti, and O elements in the nanocomposites. The composites exhibited photocatalytic behaviour across the UV-visible spectra, with values varying from the ultraviolet to the visible region with a sharp increase in reflectance at 510 nm. Near-complete degradation of MB (97.66 %) was achieved within 90 min at pH 9 and a 10 mg/L dye concentration, while RR removal reached 90.66 % within 120 min at pH 3.5 and the same dye concentration under visible light irradiation. The catalyst exhibited robust stability, retaining its efficiency by removing 85.09 % of MB and 80.21 % of RR dye after three reuse cycles. The composite catalyst discussed in this study emerges as a promising material for straightforward fabrication techniques, featuring a high percentage of kaolinite and proving to be a cost-effective solution for large-scale water and wastewater treatment processes.

Mitigation of environmentally hazardous pollutants by magnetically responsive composite materials

At present, environmental contamination has become an emerging issue among researchers. These facts are due to the adverse impacts of an alarming number of recalcitrant contaminants that can affect both humans and animals. There is an urgent need to develop eco-friendly approaches to mitigate the effects of toxic pollutants from the environment. Magnetically responsive composite-based sorbents are very interesting and popular materials for pollutant abatement owing to the high specific surface area, superior adsorption capacity, and magnetic properties, which make their easy separation from sample solution/media. In this review article, we discuss various synthesis approaches, key physicochemical properties, and applications of magnetic composites for pollutant removal. Current gaps for coping with contamination are identified, and a comprehensive outlook in pollutant treatment using magnetic composites is outlined. This study unveils new horizons to researches for better understanding the properties of magnetically-composite-based sorbents and their application in environmental remediation.

Magnetic nanoparticles incorporation into different substrates for dyes and heavy metals removal-A Review

Substantial discharge of hazardous substances, especially dyes and heavy metal ions to the environment, has become a global concern due to many industries neglecting the environmental protocols in waste management. A massive discharge of contaminantsfrom different anthropogenic activities, can pose alarming threats to living species and adverse effect to the ecosystem stability. In the process of treating the polluted water, various methods and materials are used. Hybrid nanocomposites have attained numerous interest due to the combination of remarkable features of the organic and inorganic elements in a single material. In this regards, carbon and polymer based nanocomposites have gained particular interest because of their tremendous magnetic properties and stability. These nanocomposites can be fabricated using several approaches that include filling, template, hydrothermal, pulsed-laser irradiation, electro-spinning, detonation induced reaction, pyrolysis, ball milling, melt-blending, and many more. Moreover, carbon-based and polymer-based magnetic nanocomposites have been utilized for an extensive number of applications such as removal of heavy metal and dye adsorbents, magnetic resonance imaging, and drug delivery. This review emphasized mainly on the production of magnetic carbon and polymer nanocomposites employing various approaches and their applications in water and wastewater treatment. Furthermore, the future opportunities and challenges in applying magnetic nanocomposites for heavy metal ion and dye removal from water and wastewater treatment plant.

Synthesis and characterisation of novel Cu(ii)-anchored biopolymer complexes as reusable materials for the photocatalytic degradation of methylene blue

This study focused on the synthesis, photocatalytic degradation of organic dyes and biological activity of novel N, N, O-donor tridentate water soluble 4-hydroxy benzohydrazide-grafted biopolymer Schiff base Cu(ii) complexes. The eco-friendly catalysts were designed for potential application in the degradation of organic dyes. The photocatalytic degradation of methylene blue was investigated with various irradiation times (30, 60, 90 and 120 min), catalytic dosages (5, 10, 15 and 20 mg) and pH (3, 7 and 12). The as-prepared compounds were characterised via various techniques including FT-IR and FT-NMR spectroscopy; TGA-DTA, XRD, SEM-EDAX; ESR and UV-vis spectroscopy; photoluminescence, magnetic moment, and conductivity measurements; and elemental and thermal analysis. The crystallinity of the Schiff base ligands, chitosan, and their Cu(ii) complexes was analysed via X-ray diffraction (XRD) studies. The XRD patterns revealed that the polymer chitosan was more crystalline than the Schiff base ligands and their complexes. The surface morphological analysis by scanning electron microscopy (SEM) revealed that the Cu(ii) complexes were amorphous in nature compared to chitosan and the ligands. The anti-inflammatory and anti-diabetic studies of the biopolymer Cu(ii) complexes were performed using the albumin denaturation technique and McCue and Shetty method, respectively. The as-synthesized 4-hydroxy benzohydrazide-grafted O-carboxymethyl chitosan Schiff base ligands and their Cu(ii) complexes showed a good anti-inflammatory and antidiabetic effect. The photocatalytic activity proved that the aryl-substituted complex was more efficient than the aliphatic-substituted complex.

Heterogeneous photocatalytic degradation of sulfamethoxazole in water using a biochar-supported TiO2 photocatalyst

The present study reports an effective heterogeneous photocatalytic degradation of sulfamethoxazole (SMX) in water using a biochar-supported TiO2 (biochar/TiO2). The biochar was used as a low cost and effective support for TiO2 to lower the recombination rate of electrons and electron holes during photocatalysis, allow efficient attachment of TiO2, increase adsorption capacity and help easy separation of the photocatalyst after use. The biochar/TiO2 showed much higher adsorption of SMX than the commercial TiO2 powder due to the hydrophobic interaction between the biochar and SMX. Particularly this study focused on the effects of water quality and operating conditions on the photocatalytic oxidation of SMX. The addition of low concentration of bicarbonate made drastic enhancement in SMX removal and mineralization while the final effluent showed high biotoxicity. On the contrary, the presence of nitrate exhibited slight enhancement in SMX removal efficiency. The photocatalyst loading and UV irradiation time also played their important roles in enhancement of SMX removal and mineralization. In overall the photocatalytic oxidation of SMX using the biochar/TiO2 at the selected catalyst loading and irradiation time (5 g biochar-supported TiO2 L(-1), 6 h) resulted in the high removal and mineralization of SMX and negligible toxicity.

Synergic Effect between Adsorption and Photocatalysis of Metal-Free g-C3N4 Derived from Different Precursors

Graphitic carbon nitride (g-C₃N₄) used in this work was obtained by heating dicyandiamide and melamine, respectively, at different temperatures. The differences of g-C₃N₄ derived from different precursors in phase composition, functional group, surface morphology, microstructure, surface property, band gap and specific surface area were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-visible diffuse reflection spectroscopy and BET surface area analyzer, respectively. The photocatalytic discoloration of an active cationic dye, Methylene Blue (MB) under visible-light irradiation indicated that g-C₃N₄ derived from melamine at 500°C (CN-M500) had higher adsorption capacity and better photocatalytic activity than that from dicyandiamide at 500°C (CN-D500), which was attributed to the larger surface area of CN-M500. MB discoloration ratio over CN-M500 was affected by initial MB concentration and photocatalyst dosage. After 120 min reaction time, the blue color of MB solution disappeared completely. Subsequently, based on the measurement of the surface Zeta potentials of CN-M500 at different pHs, an active anionic dye, Methyl Orange (MO) was selected as the contrastive target pollutant with MB to reveal the synergic effect between adsorption and photocatalysis. Finally, the photocatalytic mechanism was discussed.

Functionalized Activated Carbon Derived from Biomass for Photocatalysis Applications Perspective

This review highlighted the developments of safe, effective, economic, and environmental friendly catalytic technologies to transform lignocellulosic biomass into the activated carbon (AC). In the photocatalysis applications, this AC can further be used as a support material. The limits of AC productions raised by energy assumption and product selectivity have been uplifted to develop sustainable carbon of the synthesis process, where catalytic conversion is accounted. The catalytic treatment corresponding to mild condition provided a bulk, mesoporous, and nanostructure AC materials. These characteristics of AC materials are necessary for the low energy and efficient photocatalytic system. Due to the excellent oxidizing characteristics, cheapness, and long-term stability, semiconductor materials have been used immensely in photocatalytic reactors. However, in practical, such conductors lead to problems with the separation steps and loss of photocatalytic activity. Therefore, proper attention has been given to develop supported semiconductor catalysts and certain matrixes of carbon materials such as carbon nanotubes, carbon microspheres, carbon nanofibers, carbon black, and activated carbons have been recently considered and reported. AC has been reported as a potential support in photocatalytic systems because it improves the transfer rate of the interface charge and lowers the recombination rate of holes and electrons.