Organic Dye Pollutants Research Articles

Insights into mixed dye pollutant degradation by oxygen and air plasma bubbling array

Abstract Synthetic organic dye pollutants pose a serious threat to the aquatic ecological environment due to their difficulty in complete degradation. This study employed a plasma bubble array reactor to degrade individual and mixed dye pollutant solutions of Sunset Yellow (SY), Methyl Orange (MO), and Methyl Violet (MV). The degradation efficiencies and mechanisms of the plasma were investigated under different working gas atmospheres. It was found that oxygen plasma degraded the target dyes and their mixtures more significantly than air plasma. Specifically, compared with air plasma, the removal of single dyes SY, MO and MV by oxygen plasma was increased by 76.6%, 13.8% and 3%, respectively, after 20 min of treatment. As for mixed dyes, after 25 min treatment, oxygen plasma removed 99.1%, which was 31.6% higher than air plasma. However, the degradation kinetic order in oxygen plasma was SY > MO > MV, while that in air plasma was MV > MO > SY. Combined with the detection of reactive oxygen-nitrogen species (RONS), the results showed that the reactive oxygen species (ROS) played an important role in the degradation of SY, and it was also important for the degradation of MO, whereas both the ROS and reactive nitrogen species (RNS) were important for the degradation of MV. Scavenger experiments revealed that hydroxyl (·OH) and superoxide anion (·O2-) played the most important roles in the degradation process. The three dyes were basically completely degraded within 14-20 minutes of treatment, with corresponding yields of 1.94-2.79 g/kWh. Possible degradation pathways for each dye were deduced based on LC-MS and the toxicities of solutions were evaluated by phytotoxicity tests and ion chromatography. The results showed that the biotoxicity of the intermediates was significantly reduced. This study may provide a feasible option for effective application of plasma technology in organic dye wastewater treatment.

Hierarchical TiO2 nanostructures sensitized with MoS2 nanosheets: an efficient and reusable heterojunction photocatalyst for sunlight-assisted degradation of organic dye pollutants

Abstract The present study reports the synthesis, characterization, and natural sunlight-driven photocatalytic activity of a novel heterojunction photocatalyst comprised of hierarchical rutile titanium dioxide (r-TiO2) nanostructures and 1T/2H molybdenum disulfide (MoS2)nanosheets. These components were synthesized by solvothermal methods and their effective integration was achieved by using 3- aminopropyltrimethoxysilane as coupling agent. The photocatalytic activity of r-TiO2/MoS2 nanohybrid was explored for the degradation of cationic dye methylene blue (MB), and anionic dye congo red (CR) under natural sunlight. The results reveal that the sunlight-driven photocatalytic activity of pristine r-TiO2 was drastically enhanced upon sensitization with 1T/2H MoS2 nanosheets. The nanohybrid could degrade 99% MB and 98% CR within 150 min with rate constants 25.6×10−3 and 13.2×10−3 min−1respectively. The r-TiO2/MoS2 nanohybrid retained more than 85% of its catalytic activity even after four cycles of reuse. The scavenger test revealed that holes and hydroxyl radicals are mainly responsible for the degradation of MB and CR. The facile synthesis, outstanding catalytic activity under natural sunlight, and excellent recyclability make r-TiO2/MoS2 a promising heterojunction photocatalyst for the degradation of environmental pollutants from wastewater. The present study can provide new insights towards the development of efficient, economical and sustainable photocatalysts for harnessing renewable solar energy for environmental remediation applications.

Highly efficient Zn(O,S)/Mo(O,S)2 oxysulfide heterostructure photocatalyst for organic pollutant degradation

Environment and energy are presently some of the highest priority topics for mankind that need to be addressed. Organic pollutants are toxic and carcinogenic for human and aquatic life hence their presence in water even in low concentrations can cause serious health problems. Photodegradation of organic pollutants by utilizing oxide-based heterostructure photocatalysts is the promising approach to carry out remediation efficiently ascribed to the advanced optoelectronic and structural superiority of oxide photocatalysts. The Zn(O,S)/Mo(O,S)2 composites were synthesized via a facile solvothermal method at low temperatures. Several methods were used to characterize the composite morphology, structure, electrical conductivity, chemical composition, and optical characteristics. The heterostructured Zn(O,S)/Mo(O,S)2 oxysulfide was employed successfully in the photocatalytic degradation of organic pollutants. Among the as-prepared samples, the 30-ZnMoOS composite catalyst was found to have the highest photodegradation performance on various organic dye pollutants. The photocatalytic activity of the as-synthesized Zn(O,S)/Mo(O,S)2 samples was assessed on the photodegradation of different kinds of organic dyes under visible light irradiation. The photocatalytic degradation efficiency of 30-ZnMoOS composite over 10 ppm neutral red (NR), methylene blue (MB), rhodamine B (Rh B), and methyl orange (MO) was found to be 99.6 %, 99.9 %, 99.5 %, and 98.8 % within 40, 45, 180, and 180 min, respectively, under visible light illumination. In the present photocatalytic system, the superoxide (.O2-) anions, hydroxyl (.OH) radicals, and holes (h+) are proposed to be the direct reactive species causing the photodegradation of organic dyes.

Carbon Ink Enhanced Calcium Alginate-Based Hydrogel with Response Surface Methodology Optimized for Solar-Driven Salt-Tolerant Desalination.

The global shortage of freshwater resources is becoming more and more serious; therefore, it is necessary to obtain freshwater by desalinating seawater resources. Solar-driven interfacial photothermal evaporation, which is an environmentally friendly and energy-efficient technology, has been used to desalinate seawater for water purification and production. Herein, the IPCA hydrogel with abundant pores consisting of carbon ink as a photothermal conversion material and PU sponge loaded with calcium alginate as a water transport medium was successfully prepared and used to obtain portable water. The parameters of the synthesized IPCA are optimized by Response Surface Methodology analysis, and it was found that the IPCA exhibits a high evaporation efficiency of 3.779 kg m-2 h-1 and up to 95.98% of photothermal conversion capacity under one solar intensity. It maintains a high evaporation efficiency and salt resistance after 10 cycles of evaporation in actual seawater. Moreover, IPCA shows a high removal of various organic dye pollutants in wastewater. The results suggest a new approach for the preparation of simple, efficient, and green solar evaporators in practical application.

Eco-friendly synthesis of CuO/Bi2O3 nanocomposite for efficient photocatalytic degradation of rhodamine B dye.

Plant-mediated synthesized materials are receiving more attention than conventional ones due to their wide availability, ease of access, simple preparation methods, environmental benign, and possess superior physicochemical properties. In this work, plant extract-mediated CuO, Bi2O3, and CuO/Bi2O3 nanocomposite samples were successfully synthesized using bamboo leaves extract as a capping agent. These materials were utilized for the photodegradation of Rhodamine B (RhB) dye, which served as a model organic dye pollutant. The physicochemical characterization techniques such as XRD, SEM-EDS, FTIR, and DRS-UV-vis spectrophotometry provide insight into the crystal structure, morphology, surface functional groups, and optical properties. These analyses confirm the effective formation of CuO, Bi2O3, and CuO/Bi2O3 materials. Surprisingly, upon calcination at 450°C for 4h, the color of the nanocomposite changed from pale green to gray greenish, providing evidence for the formation of the CuO in CuO/Bi2O3 nanocomposite. The photocatalytic optimization parameters such as pH (4), catalyst load (35mg), irradiation time (180min) and concentration of RhB (10 mg L-1) dye were investigated. By coupling CuO with Bi2O3 nanoparticles resulted in an improved photocatalytic property for the degradation of RhB dye under optimal conditions. As a result, CuO/Bi2O3 nanocomposite exhibited a significantly boosted photocatalytic degradation efficiency (95.6%) compared to pure CuO (40.2%) and Bi2O3 (80.5%) photocatalysts, with good reusability. For comparison purpose, the photocatalytic degradation of RhB dye using selected photocatalyst was evaluated under dark and sunlight systems. This eco-friendly approach holds great potential for synthesis new nanocomposite with modified properties, thereby enabling the practical application of high-efficiency photocatalysts. The plausible mechanism of the electrons and holes transfer was proposed.

A versatile superhydrophilic/air-superoleophobic glass fiber membrane: Fabrication and application in oil/water separation

Superwetting materials have received extensive interest owing to their potential for efficient oil/water separation. Herein, a superhydrophilic-superoleophobic glass fiber membrane was fabricated through a simple spraying coating method. The membrane was coated with a composite layer of methyltrimethoxysilane (MTMS), fluorosurfactant (FS-50) and TiO2 nanoparticles. Accordingly, both hydrophilic groups (i.e., -OH) and oleophobic groups (i.e., fluorinated groups) were distributed on the membrane, and its surface roughness was improved by TiO2. The contact angles of water and oil on the coated membrane were 0° and 156.8° in air, respectively. By virtue of its selective permeability, it demonstrated separation efficiencies larger than 99.2 % for oil/water mixtures, which remained 98.7 % after 40 separation cycles. Furthermore, its separation efficiencies for oil-in-water emulsions were over 98.3 %, which remained 98 % after 10 separation cycles. Owing to its strong superoleophobicity, it displayed prominent anti-oil-fouling performance both in air and underwater. Besides, presence of TiO2 endowed it with photocatalytic capability, enabling it to recover from organic dye pollution. Moreover, the coated membrane maintained superoleophobic after 10 sandpaper-abrading or squeezing cycles. It also exhibited excellent stability under acid/alkali/salt conditions. The study provided new insights for constructing superwetting materials and an effective strategy for oil/water separation.

Polyelectrolyte modified Ag-nanosphere: A Practical Approach for Sensitive and Selective SERS-based Detection of Organic Dye Pollutants

This study presents a cost-effective method for fabricating surface-enhanced Raman spectroscopy (SERS) substrates using Ag-nanospheres (AgNS) capped with Poly(diallyldimethylammonium chloride) (PDADMAC) and poly(styrene sulfonate) (PSS). AgNS synthesis involves immersing Ag-nanocrystals in a nonaqueous solution, mixed with PEs in an aqueous solution via ultrasonic disturbance. Resulting aggregates form stable spherical assemblies with diameters ranging from 150 nm to 450 nm, and various characterization techniques, including scanning electron microscopy with energy-dispersive X-ray, UV-visible spectrophotometry, dynamic light scattering, and zeta potential analysis, were employed to analyze their fundamental chemical and physical properties. These qualified AgNSs serve as SERS substrates for sensitive and selective identification of charged organic dye contaminants, such as rhodamine 6G (R6G) and rose bengal (RB). Sensitivity assessments with the optimized quantities of either PDADMAC or PSS-capped AgNSs demonstrate successful detection down to concentrations of 10-14 M for RB and 4 x 10-13 M for R6G. The same SERS substrates also enable electrostatically driven selective detection even in analyte mixtures, and an additional variation of the SERS substrate comprising a complex of PDADMAC-capped and PSS-capped AgNSs exhibited distinct SERS spectra influenced by both positively and negatively charged analytes. Finally, successful detection of two oppositely charged pesticides was achieved through electrostatic attraction, so theses polyelectrolytes capped AgNS-based SERS substrate presents a promising avenue for efficiently and selectively detecting charged organic contaminants.

Chiral FeNC single-atom nanozymes with multi-enzyme activity for dye degradation

The application of single-atom nanozymes in the removal of organic dye pollution by advanced oxidation process (AOPs) have been widely concerned. However, the application of single-atom nanozymes in AOPs is rarely reported. In this work, a kind of Fe-and nitrogen-codoped carbon (Fe-N-C) with peroxidase-like and laccase-like activities was prepared by calcining Fe-doped MOF, then the chiral peptides were introduced into single-atom nanozymes, and chiral single-atom nanozymes (L-Au@FeNC) were successfully prepared. The L-Au@FeNC can effectively activate PMS to degrade different kinds of organic dyes and also shows high cycle stability. In addition, the results of quenching experiment and electron paramagnetic resonance (EPR) test show that 1O2 produced during PMS activation plays an important role in the degradation of organic dyes, and O2·-, ·OH, and SO4·- are also produced during PMS activation, suggesting that the degradation of selected organic dyes include radical and non-radical pathways. It should be noted that L-Au@FeNC showed higher activity than D-Au@FeNC in enzyme-like activity (laccase-like and peroxidase-like) experiment and organic dye degradation, the results of molecular docking simulation indicated that it may be due to the better binding force of L peptide to the substrate of enzyme-like reaction and organic dye than D peptide. This chiral single-atom nanozymes provide a new idea for the application of organic dye degradation and enzyme-like catalysis design.

Modification of poly (vinylidene fluoride-co-hexafluoropropylene) membranes by sulfonated poly (ether ether keton) coating for membrane distillation of textile wastewater

The textile and related industries can produce a large amount of wastewater with organic dyes pollutants which can cause uncertain environmental impacts. In this study, the improved poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) hollow fiber membranes were used in a continuous air gap membrane distillation (AGMD) operation for wastewater treatment of the Hamadan textile factory, Iran. The porous membranes were fabricated by a phase-inversion process and the inner surface was coated by a thin layer of sulfonated poly (ether ether keton) (SPEEK). After SPEEK coating, the water contact angle of the membrane decreased from about 93° to 57°. The SPEEK coated membrane presented mean pore size and overall porosity of 10 nm and 82.2%, respectively. For the wastewater treatment, the improved membrane presented the water flux and color rejection of 24.7 kg/m2 h and 99.8% during 72 h of the AGMD operation, respectively. Additionally, the treated wastewater reduced to the turbidity of ∼2 NTU, total dissolved solid (TDS) of 16 mg/L and chemical oxygen demand (COD) of 10 mg/L. The coated membrane presented a reasonable anti-fouling property with a flux recovery ratio (FRR) of 91.7% after 72 h of the operation. Hence, the improved PVDF-HFP membrane can be a potential alternative for the removal of organic dyes from wastewater via a membrane distillation process.

Dual sustainability of rGO/CuCoO2 nanocomposites with enhanced photocatalytic and antibacterial insights

New growth and photocatalytic activity of CuCoO2 and rGO/CuCoO2 nanocomposites were demonstrated for model organic pollutant (dye) and antibacterial studies. The rGO/CuCoO2 nanocomposites were designed by hydrothermal technique. CuCoO2 and rGO/CuCoO2 materials were investigated and characterized by several instrumental techniques like FT-IR spectroscopy (FT-IR), Raman spectroscopy, X-Ray diffractometer (XRD), DRS-UV Visible spectroscopy, HRTEM, FESEM analysis, Thermogravimetric analysis (TGA) and BET investigations. XRD confirmed the CuCoO2 cubic phase structure. It seems to have been evaluated for FT-IR and the Raman results were better than anything else that should be satisfied. Hence, Cu–O or Co-O (M−O−M) modes were confirmed peaks at 400 to 900 cm−1. We proposed CuCoO2 and rGO/CuCoO2 ((25/75), (50/50) & (75/25)) composite materials band gap energies at 2.8 eV to 2.0 eV. So, these results are also one of the benefits in the application area. A Sedum morganianum Burrito − Burro’s plant’s tail-like morphology was obtained in the pure CuCoO2 materials, and different weight percentages of rGO composites were also identified in FESEM-analysis as wood fungi, rods, and sheets-like structures. The rGO/CuCoO2 sheet-like morphology was confirmed by HRTEM measurements. The elemental composition of materials was investigated by EDX spectroscopy. We can prepare to suggest that the synthesis potential in the prepared matter is tbepensumed Bache formulation and much less explored, first-time declared phases and novelty of the synthetic designs, new morphologies, and bandgap energies. The synthesized rGO/CuCoO2 materials were achieved by 94 % Methylene blue (MB) dye degradation in photocatalytic applications, in which case composites were more efficient with environment-friendly when compared to CuCoO2 nanoparticles. The role of the rGO composite can be divided into three different principles such as absorbance, charge separator, and photosensitizer. This rGO material can reflect a big absorption capacity depending on the dye to rGO, with parallelly obeyed for π-π interactions. Hence, it’s favored for catalytic improvement. Secondly, rGO degradation was improved to the charge separation and may be foiling for the recombination of electron-hole pairs. Finally, transform their wide bandgap semiconductor into the catalyst to facilitate parameters. The rGO/CuCoO2 composite materials have performed well in reusability and radical abilities. The antimicrobial activity of the CuCoO2 nanoparticle was investigated on Gram-positive Staphylococcus aureus &Enterococcus faecalis and Gram-negative Escherichia coli &Pseudomonas aeruginosa bacterial strain. As promised rGO/CuCoO2 and CuCoO2 materials were examined for better degradation activities and antibacterial activities. Antibacterial efficacy studies play a major innovative role in the present work and have not been previously published. Hence, we have selected this kind of material.

Enhanced photocatalytic degradation of Reactive Green 19 dye using earthworms like T-ZnO-CuO nano-composite material as a S-scheme heterojunction photocatalyst

Due to increasing organic dye pollution in the water environment, green and efficient photocatalyst are urgently needed to solve this problem. This study hypothesizes that green-synthesized nanocomposites, using plant leaf extracts, will significantly enhance the efficiency of organic dye degradation without the environmental drawbacks associated with traditional methods. Herein, enhanced degradation of Reactive Green 19 (RG 19) dye using earthworm like T-ZnO-CuO (TZC) nano-composite was reported. T-ZnO (TZ) and TZC nano-composite were synthesized using leaves extract of Thevetia peruviana plant. In the synthesis process, Thevetia peruviana leaves extract acts as a capping, stabilising and reducing agent, and additionally create a unique surface morphology of TZC nano-composite. The establishment of TZ and TZC nano-composite samples were investigated using FT-IR, XRD, FE-SEM with EDX, HR-TEM and UV–VIS DRS spectroscopy. Furthermore, band gap energy of TZ and TZC nano-composites were calculated using Tauc’s plot. The band gap energy of TZC2 nano-composite was determined to be 2.80 eV. The nano-composite photocatalyst (TZC) was utilised in the degradation of RG 19 dye with 96.89 % efficiency in 150 min at 20 mg/L dye concentration, pH=7.5, and 0.6 g/L catalyst dose. In order to investigate the tentative photocatalytic mechanism, scavenging study, recyclability experiment, and stability were also investigated. The findings show that O2− and OH radical species have higher degree of involvement in the degradation process. The kinetics of the degradation of RG 19 dye follows pseudo-first-order kinetics.

Influence of gadolinium substitution on the crystal structure of NiO and its maximized photocatalytic degradation activity on tetracycline and direct yellow pollutants

Gadolinium-substituted NiO crystal structures with excellent stability were utilized for the first time to degrade antibiotic and organic dye pollutants. A simple hydrothermal technique was used to synthesize different concentrations of Gd3+ substituted NiO, and the catalysts were thoroughly characterized using sophisticated techniques to explore the influence of Gd3+ on the crystal structure and optical characteristics of NiO. The 1.5% Gd3+ substituted NiO showed outstanding photocatalytic activity on tetracycline and direct yellow degradation, with percentages of 90.72 and 95.5%, respectively. The improvement of photocatalytic degradation efficiency is primarily due to the suppression of photoinduced electron and hole recombination via the creation of Gd3+ as the inner energy band state below the conduction band. The recycling experiments revealed that the catalyst is more stable, with no indication of loss after ten cycles. Scavenging investigations also demonstrated that superoxide and holes were responsible for the efficient degradation of pollutants.

Green-synthesized Ag hierarchical assemblies for SERS detection of rhodamine dye

This study presents a simple benchtop synthetic protocol for the fabrication of silver (Ag) hierarchical structures in aqueous media using environmentally friendly and inexpensive reagents under mild experimental conditions. Natural organic acids that are known to be present in plants were employed as reducing and morphology-directing reagents. SEM and TEM imaging revealed that the products are three-dimensional hierarchical structures that were formed from self-assembly of smaller nanoparticles. They are generally spherical in shape, measure around 1.5 to 5 μm in size, and possess highly roughened surfaces due to the interstitial gaps between their nanoparticle subunits. Their hierarchical architecture allows for strong absorption of light in a broad range of wavelengths that extends to the near-infrared region. In addition, their surface morphology has an abundance of hot spot regions, which are capable of inducing strong SERS enhancement effects. The green-synthesized Ag nanostructures showed remarkable SERS activity when used as substrates for the detection of rhodamine 6G dye, a highly toxic water contaminant, even at a concentration as low as 10–8 M. Overall, this study does not only provide a greener approach to Ag hierarchical structures, but also demonstrates the immense potential of these nano-assembled architectures in the sensitive detection of organic dye pollutants.

Constructing p-n heterojunction in CoO@TiO2 photocatalytic material to enhance the performance of catalytic degradation of Rhodamine B

Traditional Fenton reactions suffer from slow reaction rates and energy wastage degrade dye contaminant. By constructing a heterojunction interface between quantum dots and titanium dioxide, a CoO@TiO2 photocatalyst is prepared to extend the photoresponse range to longer wavelengths. Under infrared light irradiation, RhB is degraded by over 97 % after 120 min. CoO@TiO2 possesses a large surface area, loaded with a substantial amount of quantum dots, forming a p-n heterojunction, significantly enhancing the photocatalytic rate. This study provides a new approach for the efficient preparation of photocatalysts for the degradation of organic dye pollutants.

Standalone Highly Efficient Graphene Oxide as an Emerging Visible Light-Driven Photocatalyst and Recyclable Adsorbent for the Sustainable Removal of Organic Pollutants.

Carbon-based nanostructures are promising eco-friendly multifunctional nanomaterials because of their tunable surface and optoelectronic properties for a variety of energy and environmental applications. The present study focuses on the synthesis of graphene oxide (GO) with particular emphasis on engineering its surface and optical properties for making it an excellent adsorbent as well as a visible light-active photocatalyst. It was achieved by modifying the improved Hummers method through optimizing the synthesis parameters involved in the oxidation process. This controlled synthesis allows for systematic tailoring of structural, optical, and surface functionality, leading to improved adsorption and photocatalytic properties for the sustainable removal of organic pollutants in water treatment. Several spectroscopic and microscopic characterization techniques, such as XRD, SEM, Raman, UV-visible, FTIR, TEM, XPS, BET, etc. were employed to analyze the degree of oxidation, surface chemistry/functionalization, morphological, optical, and structural properties of the synthesized GO nanostructures. The analyses showed excellent surface functionality with surface active sites for better adsorptive removal and a tunable band gap from 2.51 to 2.76 eV exhibiting excellent natural sunlight activity (>99%) for photocatalytic removal of the organic pollutant. Various adsorption isotherms have been studied with excellent adsorption capability (Qmax = 454.54 mg/g) as compared to the literature. The study introduces GO both as a proficient stand-alone (sole) nanoadsorbent as well as a nanophotocatalyst for the efficient removal of organic dye pollutants in water treatment. Additionally, the article highlights the sustainable solar light-induced green chemistry aspects of GO as an excellent recyclable adsorbent as a result of its self-cleaning ability under natural sunlight, demonstrating its potential in real eco-friendly environmental and practical applications.

Photocatalytic degradation of toxic basic blue 41 and reactive orange M2R dyes using green synthesized zinc oxide nanoparticles

Zinc oxide nanoparticles (Cm-ZnO NPs) were synthesized to eliminate organic dye pollutants from textile dye effluents. The present study reports Cucumis maderaspatanus L. leaves utilized as a green reducing/stabilizing agent for Cm-ZnO NPs synthesis. The nanoparticles underwent thorough analysis using techniques such as XRD, UV–vis, TEM, and FT-IR. Photocatalytic degradation of toxic basic blue 41 (BB41) and reactive orange M2R (ROM2R) dyes using Cm-ZnO NPs, showed a degradation rate of 97.69 % and 94.30 % respectively under optimized conditions. The kinetics of photocatalytic degradation of BB41 and ROM2R dyes followed first-order kinetics. The scavenger studies were conducted to identify the photogenerated reactive species involved in dye degradation. The singlet oxygen (1O2) and hydroxyl radicals (●OH) are mainly responsible for the degradation of BB41 and ROM2R dye respectively. LC-MS analysis was used to identify the photocatalytic degraded products, and ECOSAR software assessed their toxicity. The recyclability was performed up to four cycles and the stability of Cm-ZnO NPs was confirmed by XRD analysis. Thus, the as-synthesized Cm-ZnO NPs are suitable for industrial textile wastewater treatment.

Tailoring structural and optical properties of Cu(II)-induced MgAl2O4 nanoparticles and their response to toxic dyes under solar illumination.

Worldwide environmental challenges pose critical problems with the growth of the global economy. Addressing these issues requires the development of an eco-friendly and sustainable catalyst for degrading organic dye pollutants. In this study, copper-doped magnesium aluminates (CuxMg1-xAl2O4) with x = 0.0-0.8 were synthesized using a citrate-based combustion route. The inclusion of Cu(II) significantly impacted the structural, microstructural, optical, and photocatalytic activity of the catalyst. Rietveld analysis of X-ray diffraction powder profiles revealed single-phase spinels crystallized in the face-centered cubic unit cell with space group. Chemical states of the ions, surface morphology, and elemental investigation were analyzed by X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy, respectively. UV-visible and diffuse reflectance spectroscopies confirmed the reduction of the band gap due to Cu(II) doping, validated by first-principle investigations using the WIEN2k code. The catalyst with x = 0.8 showed higher photocatalytic efficacy (90% and 93%) for removing two azo organic dye pollutants, rhodamine B and methyl orange, respectively, within 120min. Degradation kinetics followed a pseudo-first-order mechanism. The doped (0.8) sample was structurally and morphologically stable and reusable under visible irradiation, retaining performance after three runs. Scavenger studies confirmed hydroxyl and superoxide radicals' involvement in the degradation. This work presents an effective approach to enhancing CuxMg1-xAl2O4 catalysts' photodegradation performance, with potential applications in pharmaceuticals and wastewater remediation.

Eco-Friendly g-C3N4/Carboxymethyl Cellulose/Alginate Composite Hydrogels for Simultaneous Photocatalytic Degradation of Organic Dye Pollutants.

The presented study was focused on the simple, eco-friendly synthesis of composite hydrogels of crosslinked carboxymethyl cellulose (CMC)/alginate (SA) with encapsulated g-C3N4 nanoparticles. The structural, textural, morphological, optical, and mechanical properties were determined using different methods. The encapsulation of g-C3N4 into CMC/SA copolymer resulted in the formation of composite hydrogels with a coherent structure, enhanced porosity, excellent photostability, and good adhesion. The ability of composite hydrogels to eliminate structurally different dyes with the same or opposite charge properties (cationic Methylene Blue and anionic Orange G and Remazol Brilliant Blue R) in both single- and binary-dye systems was examined through adsorption and photocatalytic reactions. The interactions between the dyes and g-C3N4 and the negatively charged CMC/SA copolymers had a notable influence on both the adsorption capacity and photodegradation efficiency of the prepared composites. Scavenger studies and leaching tests were conducted to gain insights into the primary reactive species and to assess the stability and long-term performance of the g-C3N4/CMC/SA beads. The commendable photocatalytic activity and excellent recyclability, coupled with the elimination of costly catalyst separation requirements, render the g-C3N4/CMC/SA composite hydrogels cost-effective and environmentally friendly materials, and strongly support their selection for tackling environmental pollution issues.

Visible Light-Triggered Chitosan Supported Ternary Ferrite for Efficient Removal of Organic Dye Pollutants from Wastewater

Visible Light-Triggered Chitosan Supported Ternary Ferrite for Efficient Removal of Organic Dye Pollutants from Wastewater

Optimizing malachite green adsorption with Co-PTC metal organic framework: Insights into mechanisms and performance

The removal of organic pollutants from aqueous environments has garnered significant attention in environmental science and engineering. Metal-organic frameworks (MOFs) have emerged as promising materials for this purpose due to their intriguing structures, high surface area, and perpetual porosity. In this study, we investigate the adsorption performance of Co-based MOF for the removal of malachite green (MG), a common organic dye pollutant. The MOF, abbreviated as Co-PTC is synthesized via a one-pot green approach using perylene-3,4,9,10-tetracarboxylic dianhydride (PTC) as the ligand at room temperature. Basic to advanced characterization techniques are employed to elucidate the structure and interactions within the MOF. Through a comprehensive analysis, the underlying mechanisms governing the adsorption process are explored, and optimization studies have been carried out. Co-PTC in minute amounts exhibits an adsorption capacity of 79.3 % selectively for MG in 50 min. The kinetics and isotherm models governing the adsorption process are well investigated.