Rhodamine B Removal Research Articles

Gamma-irradiated copper-based metal organic framework nanocomposites for photocatalytic degradation of water pollutants and disinfection of some pathogenic bacteria and fungi.

Although there are many uses for metal-organic framework (MOF) based nanocomposites, research shows that these materials have received a lot of interest in the field of water treatment, namely in the photodegradation of water contaminants, and disinfection of some pathogenic bacteria and fungi. This is brought on by excessive water pollution, a lack of available water, low-quality drinking water, and the emergence of persistent micro-pollutants in water bodies. Photocatalytic methods may be used to remove most water contaminants, and pathogenic microbes, and MOF is an excellent modifying and supporting material for photocatalytic degradation. This work involved the fabrication of a unique Cu-MOF based nanocomposite that was exposed to gamma radiation. The nanocomposite was subsequently employed for photocatalytic degradation and as an antimicrobial agent against certain harmful bacteria and fungi. The produced Cu-MOf nanocomposite was identified by XRD, SEM, and EDX. Growth curve analysis, UV lighting impact, and antibiofilm potential have been carried outto check antimicrobial potential. Additionally, the membrane leakage test was used to determine the mechanism of the antimicrobial action. In an experimental investigation of photocatalytic activity, a 50 mL aqueous solution including 10.0 ppm of Rhodamine B (RB) was used to solubilize 10 mg of Cu-MOF. It has been investigated how pH and starting concentration affect RB elimination by Cu-MOF. Ultimately, RB elimination mechanism and kinetic investigations have been carried out. SEM images from the characterization techniques demonstrated the fact that the Cu-MOF was synthesized effectively and exhibited the Cu-MOF layers' flake-like form. Uneven clusters of rods make up each stratum. The primary peaks in the Cu-MOF's diffraction pattern were found at 2θ values of 8.75◦, 14.83◦, 17.75◦, 21.04◦, 22.17◦, 23.31◦, 25.41◦, and 26.38◦, according to the XRD data. After 135 min of UV irradiation, only 8% of RB had undergone photolytic destruction. On the other hand, the elimination resulting from adsorption during a 30-min period without light was around 16%. Conversely, after 135 min, Cu-MOF's photocatalytic breakdown of RB with UV light reached 81.3%. At pH 9.0, the greatest removal of RB at equilibrium was found, and when the amount of photocatalyst rose from 5 to 20mg, the removal efficiency improved as well. The most sensitive organism to the synthesized Cu-MOF, according to antimicrobial data, was Candida albicans, with a documented MIC value of 62.5µgmL-1 and antibacterial ZOI as32.5mm after 1000ppmtreatment. Cu-MOF also showed the same MIC (62.5µgmL-1)values against Staphylococcus aureus and Escherichia coli, and 35.0 and 32.0mm ZOI after 1000ppmtreatment, respectively. Ultimately, it was found that Cu-MOF (1000µg/mL) after having undergone gamma irradiation (100.0kGy) was more effective against S. aureus (42.5mm ZOI) and E. coli (38.0mm ZOI). From the obtained results, the synthesized MOFnanocomposites had promising catalytic degradation of RB dye and high antimicrobial potential which encouraging their use in wastewater treatment against some pathogenic microbes and polluted dyes. Due to the exceptional physicochemical characteristics of MOFnanocomposites, it is possible to create and modify photocatalytic nanocomposites in a way that improves their recovery, efficiency, and recyclability.

Degradation of Rhodamine B by Visible Light Driven MoO3@TiO2 Core-Shell Photocatalyst.

In this study, a MoO3@TiO2 composite core-shell material was developed to remove Rhodamine B (RhB) dye through synergistic adsorption and photocatalytic degradation. n-n heterostructures were formed by coupling n-type semiconductors to enhance the efficiency of photocarrier separation and photocatalytic performance. MoO3, which possesses strong adsorption capacity, was primarily used as a dye adsorbent. Additionally, the formation of an n-n heterojunction with TiO2 enabled MoO3 to expand the photocorresponding range of TiO2, leading to the generation of superoxide (O2•) and hydroxyl (•OH) free radicals for dye degradation. The experimental results demonstrate that the MoO3@TiO2 core-shell composite exhibits excellent performance for RhB dye removal, with adsorption and degradation rates reaching 35.7 and 70.3%, respectively, even at low catalyst concentrations. This approach offers new insights into the development of MoO3 core-shell photocatalysts.

Adsorptive behavior of Rhodamine B dye over hierarchical N-doped carbons from hexamine-based complexes: Equilibrium and kinetics

Pollution from water-soluble dyes is a common issue due to high toxicity and diffiulty in degradation, and its effectively removal is critical for human health and sustainability. In this work, N-doped hierarchical carbons were derived by facile pyrolysis of Co-including hexamine-based complex using glucose as a cross-linker, showing high removal ability using Rhodamine B (RhB) as a model dye. Porous architecture and N-coordination can be easily altered by pyrolysis temperature, where the GNC-900 sample obtained at 900 °C exhibits the best removal ability even outperforming several classical carbons under equal conditions, owing to synergistic effects from large surface areas, high ratio of pyrrolic-N, enhanced interaction between RhB molecules and pore walls, and possible Co-Nx active sites. Adsorptive behaviour is better fitted by pseudo-second-order kinetic model, and the maximum RhB capacity over GNC-900 determined by Langmuir model is highly up to 400.1 mg/g, following mechanisms of pore filling, π-π conjugation, electrostatic, surface complexation and H-bonding. Thermodynamics indicate that RhB removal is exothermic and spontaneous process. Moreover, GNC-900 can be readily regenerated using ethanol and reused at least six times without notable loss in capacity. This novel method facilitates synthesis of N-doped carbons from metal-based complexes, exhibiting high efficiency as adsorbents for water remediation.

In situ construction of Flowerlike bismuth oxide (BiO2-x)/N-rich carbon nitride (C3N5) S-scheme heterojunctions with enhanced structural defects for the efficient photocatalytic removal of tetracycline antibiotic and RhB

Efficient photocatalysts for the simultaneous removal of organic dyes and antibiotics are crucial for sustainable environmental management. In this study, we designed and synthesized a C3N5/BiO2-x S-type heterojunction photocatalyst with structural defects using a hydrothermal method, aimed at degrading both Rhodamine B (RhB) and tetracycline (TC). The degradation kinetic constants for RhB and TC were 0.0809 min−1 and 0.0535 min−1, respectively, showing improvements of 9.52 and 25.48 times over pure C3N5, and 2.90 and 1.49 times over BiO2-x. This enhanced performance is attributed to the unique electron transfer mechanism of the S-scheme heterojunction and the structural defects that facilitate efficient separation of electron-hole (e−-h+) pairs. Free radical trapping experiments indicated that the main reactive oxygen species (ROS) involved are ·O2− and h+. Additionally, electrochemical impedance spectroscopy (EIS) and transient photocurrent response (TPR) measurements confirmed improved separation and transfer of photogenerated e−-h+ pairs in the C3N5/BiO2-x heterojunction. The higher density of structural defects in C3N5/BiO2-x compared to individual BiO2-x counterparts enhances its ability to activate and photo-oxidize TC and degrade RhB. Consequently, C3N5/BiO2-x demonstrates significant potential as a photocatalyst for improving water quality.

The Application of TiO2/ZrO2-Modified Nanocomposite PES Membrane for Improved Permeability of Textile Dye in Water.

This study investigates the modification of polyethersulfone (PES) membranes with 1 wt% titanium dioxide (TiO2), zirconium dioxide (ZrO2) and a nanocomposite of TiO2/ZrO2. The aim was to efficiently remove Rhodamine B (RhB) from water using a threefold approach of adsorption, filtration and photodegradation. Among the modified membranes (TiO2, ZrO2 and TiO2/ZrO2), the TiO2/ZrO2-PES nanocomposite membrane showed a better performance in rejection of RhB than other membranes with the rejection efficiency of 96.5%. The TiO2/ZrO2-PES membrane was found to possess a thicker selective layer and reduced mean pore radius, which contributed to its improved rejection. The TiO2/ZrO2 nanocomposite membrane also showed high bulk porosity and a slightly lower contact angle of 69.88° compared to pristine PES with a value of 73°, indicating an improvement in hydrophilicity. Additionally, the TiO2/ZrO2-PES nanocomposite membrane demonstrated a relatively lower surface roughness (Sa) of 8.53 nm, which offers the membrane antifouling properties. The TiO2/ZrO2-PES membrane showed flux recovery ratio (FRR), total fouling (Rt), reversible fouling (Rr) and irreversible fouling (Rir) of 48.0%, 88.7%, 36,8% and 52.9%, respectively. For the photocatalytic degradation performance, the removal efficiency of RhB followed this order TiO2 > TiO2/ZrO2 > ZrO2 (87.6%, 85.7%, 67.8%). The tensile strength and elongation were found to be compromised with the addition of nanoparticles and nanocomposites. This indicates the necessity to further modify and optimise membrane fabrication to achieve improved mechanical strength of the membranes. At low pressure, the overall findings suggest that the TiO2/ZrO2 nanocomposite has the potential to offer significant improvements in membrane performance (water flux) compared to other modifications.

Synthesis of a novel flower-like Bi4Ti3O12/AgI Z-type heterojunction for efficient photocatalytic removal of tetracycline antibiotic and RhB

Novel Flowerlike Bi4Ti3O12/AgI (BTO/AgI) Z-type heterojunctions were fabricated via a straightforward in-situ precipitation method. Notably, BTO/AgI exhibited significantly improved photodegradation efficiency for tetracycline (TC) and Rhodamine B (RhB). The rate constants for RhB and TC photodegradation were approximately 20.8 and 2.9 times higher than those of BTO alone, respectively. Furthermore, the photocatalytic efficiency of the BTO/AgI heterojunction is 1.4 times higher than that of the mixture of the two individual photocatalysts, indicating a robust interaction between BTO and AgI. This enhancement in photocatalytic performance was mainly attributed to the effective separation of photogenerated carriers facilitated by the Z-scheme heterojunction, which can be demonstrated by the highest photocurrent density (∼0.307 μA·cm−2) of BTO/AgI, surpassing BTO (∼0.073 μA·cm−2) and AgI (∼0.161 μA·cm−2) by approximately 4.12 and 1.91 times, respectively. Furthermore, three plausible photodegradation pathways of tetracycline were proposed. This study introduces a novel approach for designing and synthesizing high-efficiency Z-scheme photocatalysts for the degradation of TC and RhB in wastewater.

Fe3O4/sugarcane bagasse magnetic composite: A low-cost and green adsorbent for enhanced adsorption of Rhodamine B from aqueous solutions

In this study, we have designed and synthesized an eco-friendly Fe3O4/sugarcane bagasse magnetic composite (Fe3O4/SCB). We investigated its application for efficiently removing Rhodamine B (RhB) from textile wastewater, a significant step towards addressing the environmental issue of textile dye pollution. The composite, made from sugarcane bagasse (SCB), a secondary product from the sugarcane industry, proved an effective adsorbent. The composite Fe3O4/SCB was characterized by PXRD, FT-IR, FE-SEM, VSM, BET N2 adsorption-desorption, and pHpzc. Results from batch adsorption studies show that the removal of RhB was 93.6 ± 1.16 % using a composite dose of 1 g/L, a RhB concentration of 10 mg/L, a contact period of 60 min, and a solution pH of 3 at 323 K of solution temperature. The kinetic studies indicate that the pseudo-second-order model most accurately describes the adsorption. Meanwhile, the equilibrium data is well-represented by the Freundlich isotherm. Further, the analysis of thermodynamic results, such as the changes in ∆Go, ∆So, and ΔHo, revealed that the adsorption was spontaneous, feasible, and endothermic. The adsorption mechanism involved chemisorption and physisorption, with significant roles played by electrostatic interactions and hydrogen bonding. Desorption studies identified 0.5 M NaOH as an effective desorbing agent, and the composite demonstrated excellent reusability over four adsorption-desorption cycles. Overall, the Fe3O4/SCB, with its easy preparation, abundance, cost-effectiveness, efficiency, and eco-friendly nature, presents a promising solution for effectively removing toxic RhB from aqueous solutions, inspiring further research and potential real-world applications.

SnO2-x/CD-MOF S-Scheme heterostructure photocatalysts synergized by oxygen vacancies and highly porous for rhodamine B and tetracycline degradation: Process, and mechanism analysis

To enhance the performance of environmentally friendly cyclodextrin metal-organic framework (CD-MOF) materials for more effective removal of organic pollutants and wastewater treatment, also the composites underwent optimization, and the adsorption-enhanced photocatalytic mechanism was thoroughly investigated. This study presents the synthesis of novel SnO2-x/CD-MOF (SCM) photocatalysts were prepared by a simple solvothermal method, which were characterized by oxygen vacancies (OVs), high specific surface area and heterojunction. SCM exhibited outstanding photodegradation performance for rhodamine B (RhB) and tetracycline (TC) when exposed to visible light. Specifically, the RhB removal efficiency was an impressive 93.5 %, achieved with a degradation rate constant of 0.0484 min−1, while the removal efficiency of TC was 83.1 %, with a degradation rate constant of 0.0246 min−1. The photodegradation activity of SCM was predominantly influenced by ·O2-, h+, and ·OH. The mechanism of action involves three phases: adsorption, photocatalysis, and desorption-diffusion. The exceptional performance of SCM in terms of photocatalysis can be gave the credit to the synergistic effect of the high specific surface area of γ-CD-MOF and the oxygen vacancy-induced enhancement of SnO2-x catalytic activity. TC degradation intermediates and possible degradation pathways were analyzed and the toxicity of the intermediates was assessed. This study introduces a novel approach to designing CD-MOF-based photocatalysts.

Advanced Processes in Water Treatment: Synergistic Effects of Hydrodynamic Cavitation and Cold Plasma on Rhodamine B Dye Degradation

The increasing pollution of water bodies, due to the constant release of highly toxic and non-biodegradable organic pollutants, requires innovative solutions for environmental remediation and wastewater treatment. In this study, the effectiveness of different Advanced Oxidation Processes (AOPs) for the purification of water contaminated with Rhodamine B (RhB) dye at a concentration of 5 mg/L were investigated and compared. Using the classical ozonation strategy as a benchmark treatment, the research showed over 99% degradation of RhB within 4 min in a laboratory-scale batch setup with a capacity of 0.2 L. In contrast, a “chemical-free” process exploiting ultrasound (US) technology achieved a 72% degradation rate within 60 min. Further experiments were conducted using a pilot-scale rotor-stator hydrodynamic cavitation (HC) reactor on a 15 L solution leading to 33% of RhB removal in the presence of hydrogen peroxide (H2O2) at 75 mg/L. However, the use of an innovative cavitational reactor, which hybridizes HC with cold plasma, showed remarkable efficiency and achieved 97% degradation of RhB in just 5 min when treating a 5 L solution at an inlet pressure of 20 bar in a loop configuration. In addition, a degradation rate of 58% was observed in a flow-through configuration, emphasising the robustness and scalability of the HC/electrical discharge (ED) plasma technology. These results underline the potential of hybrid HC/ED plasma technology as an intensified and scalable process for the purification of water, as it offers a catalyst- and oxidant-free protocol.

Simultaneous desalination and removal of organic pollutants in a novel bifunctional FCDI system: The enhancement by in-situ reutilization of chloride ions

A new system of flow electrode capacitive deionization coupled with in situ electro-oxidation (FCDI-EO) was constructed to achieve the degradation of organic pollutants while maintaining high desalination efficiency. The effects of different parameters of potential difference, electrolyte, and pH on the chloride removal performance of FCDI-EO and the removal performance of rhodamine B (RhB) were investigated. Under the optimal conditions of potential difference = 4 V, [Cl−] = 500 mg/L, and pH = 4, the removal of chloride ions, RhB and total organic carbon (TOC) was as high as 88.74 %, 99.02 %, and 87.82 %, respectively. The quenching experiments showed that hydroxyl radicals (OH) and reactive chlorine species (RCS) were involved in the FCDI-EO system. The liquid chromatography-mass spectrometry (LC-MS) analysis suggested the possible mineralization pathway of RhB. Furthermore, toxicity assessment analysis showed that the toxicity of the degradation intermediates of RhB decreased during the treatment. Overall, this study provides a promising process that reducing the generation of high-concentration saline water in desalination and in situ utilizing the Cl− gathered from the feed water. The findings of this study could provide useful guidance for the development of flow electrode capacitive deionization technology and organic pollutant control.

Integrating machine learning with experimental investigation for optimizing photocatalytic degradation of Rhodamine B using neodymium-doped titanium dioxide: a comprehensive approach with toxicity assessment.

In this study, neodymium-doped titanium dioxide (Nd-TiO2) nanoparticles were synthesized via a hydrothermal method for the photocatalytic degradation of Rhodamine B (RhB) under UV and sunlight conditions. The properties of these NPs were comprehensively characterized. And optimization of RhB degradation was conducted using control-variable experiment and artificial neural networks (ANN) under various operational conditions and in the presence of competing compounds. The acute toxicity of both NPs, RhB, and the environmental impact of the photocatalytic treatment effluent on Danio rerio were evaluated. The Nd modification increased the catalyst's specific surface area and thermal stability. X-ray diffraction confirmed the tetragonal anatase phase in undoped TiO2, while Nd-doped TiO2 exhibited shifts in peaks and the presence of brookite and rutile phases. Nd (1mol%) doped TiO2 demonstrated superior RhB photocatalytic degradation efficiency, achieving 95% degradation and 82% total organic carbon (TOC) removal within 60min under UV irradiation. Optimization under sunlight conditions yielded 95.14% RhB removal with 0.28g/L photocatalyst and 1% doping. Under UV light, 98.12% RhB removal was optimized with 0.97% doping, along with the presence of humic acid and CaCl2. ANN modeling achieved high precision (R2 of 0.99) in modeling environmental photocatalysis. Toxicity assessments indicated that the 96-h LC50 values were 681.59mg L-1 for both NPs, and 23.02mg L-1 for RhB. The treated dye solution exhibited a significant decline in toxicity, emphasizing the potential of 1% Nd-TiO2 in wastewater treatment.

New recyclable and functionalized chitosan-based polyurethane foams for effective and incessant removal of Orange II (OII) and Rhodamine B (RhB) dyes from water

The development of new efficient materials for the removal of water-soluble toxic organic dyes has been one of the focused research areas in the recent past. There is a strong demand for the new materials as most of the reported techniques/materials suffer from serious limitations. In this regard, a series of flexible chitosan-based task-specific polyurethane foams (PUCS-GP, PUCS-CA-GP, PUCS-TA-GP, and PUCS-GA-GP) associated with naturally available hydroxycarboxylic acids was developed. The basis for the preparation of these task-specific and functionalized PU foams is to possess amine groups for trapping the anionic dyes (example: Orange II denoted as OII) and carboxylic acid groups for attracting the cationic dyes (example: Rhodamine B denoted as RhB) under specified pH conditions. Batch adsorption experiments were conducted to assess and improve various parametric conditions. The experimental results revealed that the adsorption kinetics closely agree with the pseudo-second-order model having a maximum sorption capacity of 38.3 mg/g at pH 3 for OII on PUCS-GP and 48.4 mg/g at pH 6 for RhB on PUCS-CA-GP. Furthermore, the adsorption process was described by isotherms, kinetic equations and thermodynamic parameters (ΔG°, ΔH° and ΔS°). Notably, the regeneration of OII and RhB dyes from the exhausted PUCS-GP and PUCS-CA-GP materials was effectively accomplished. The recovered PUCS-GP shows >90 % OII and PUCS-CA-GP displays >70 % RhB removal efficiency even after twelve adsorption–desorption processes under mild conditions, demonstrating excellent recyclability/durability. The advantages of these functionalized foam materials are facile preparation, high adsorption capacity, good reusability, and very efficient removal of organic dyes from wastewater streams.

Removal of Rhodamine-B dye from Aqueous Solutions Using Alkaline-Modified Activated Carbon from Cocoa Pod Husk.

Rhodamine-B (RhB) dye in wastewater poses health and environmental risks due to respiratory and eye infections, neurotoxicity, and carcinogenicity, necessitating proper disposal for risk mitigation. This study investigates RhB removal from water using NaOH-modified activated carbon derived from cocoa pod husk (CPHAC). Employing a face-centered central composite design, operational variables were optimized to achieve maximum RhB dye removal efficiency. The study reveals a removal efficiency of 98.87 ± 0.84% under optimized conditions: adsorbent dose of 1.34g, contact time of 71.59min, and an initial RhB concentration of 6.61 ppm. The Freundlich isotherm model demonstrated a good fit, suggesting that RhB removal is governed by heterogeneity and multilayer adsorption. Kinetic experiments revealed that adsorption follows a pseudo-second-order model, indicating likely irreversible adsorption with dye molecules forming chemical bonds on CPHAC's surface. Overall, this study demonstrates the effectiveness of CPHAC as an efficient adsorbent for RhB removal from water.

Study of machine learning on the photocatalytic activity of a novel nanozeolite for the application in the Rhodamine B dye degradation

Contamination of wastewater with organic dyes has caused a serious threat to humans and aquatic life due to the hazardous effect of these contaminants. In this context, the present work aims to carry out a Machine Learning (ML) study to evaluate the photocatalytic activity of a nanozeolite (nANA) in the degradation of Rhodamine B (RhB) dye. Three machine learning algorithms (Random Forest, Artificial Neural Network and Xtreme Gradient Boosting) were used in the regression model development. The dataset used in the machine learning and data correlation was generated by Central Composite Rotational Design (CCRD 2²). Regarding the machine learning study, the ANN with structure 3:6:1 showed the best performance as a predictive model (R² = 0.98 and 0.9 for training and testing, RMSE < 5.0), resulting in the 50.37 ± 1.01 % RhB removal at pH 5.7, [RhB] = 200 mg L−1 and [nANA] = 2.75 g L−1 after 180 min under visible light. Feature importance revealed that all parameters (pH, [RhB], [nANA]) were relevant to the response. Therefore, this work confirms the potentiality of machine learning algorithms to develop predictive models as well as a good starting point for the scale-up of advanced oxidation processes.

Removal of Rhodamine B from water using natural clay: a study on adsorption kinetics, thermodynamics, and environmental impact

ABSTRACT This study investigates the adsorption capabilities of natural clay for the removal of Rhodamine B (RhB) from water, emphasising its potential as a cost-effective and sustainable solution for water treatment. The adsorption process was studied at three temperatures, focusing on kinetics, thermodynamics, and equilibrium. UV Vis spectrophotometry confirmed that natural clay achieved a remarkable RhB removal efficiency exceeding 97%. Factors such as initial concentration, adsorbent dosage, and temperature significantly influenced the adsorption efficiency. Thermodynamic analysis revealed negative Gibbs free energy values (−26.27, −27.50, and −28.80 kJ/mol) across the tested temperatures (14°C, 24°C, and 34°C), indicating the spontaneous and favourable nature of RhB adsorption onto clay surfaces, which is further enhanced by higher temperatures due to its endothermic nature. Equilibrium data fitting favoured the Freundlich isotherm model, suggesting heterogeneous adsorption, while kinetics were best described by the pseudo-second-order model. Optimal conditions for maximum RhB removal were identified as 40 minutes contact time, initial pH 3.71, and 0.5 grams of adsorbent. These findings underscore natural clay’s potential for large-scale water treatment applications, offering both environmental benefits and economic viability as a sustainable solution to mitigate industrial dye contamination in water sources.

In-Situ Hydrothermal Fabrication of ZnO-Loaded GAC Nanocomposite for Efficient Rhodamine B Dye Removal via Synergistic Photocatalytic and Adsorptive Performance.

In this work, zinc oxide (ZnO)/granular activated carbon (GAC) composites at different ZnO concentrations (0.25M-ZnO@GAC, 0.5M-ZnO@GAC, and 0.75M-ZnO@GAC) were prepared by an in-situ hydrothermal method and demonstrated synergistic photocatalytic degradation and adsorption of rhodamine B (RhB). The thermal stability, morphological structure, elemental composition, crystallographic structure, and textural properties of developed catalysts were characterized by thermal gravimetric analysis (TGA/DTG), scanning electron microscopy equipped with energy dispersive-x-ray (SEM-EDS), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) analysis. The successful loading of ZnO onto GAC was confirmed by SEM-EDS and XRD analysis. The BET surface areas of GAC, 0.25M-ZnO@GAC, 0.5M-ZnO@GAC, and 0.75M-ZnO@GAC were 474 m2/g, 450 m2/g, 453 m2/g, and 421 m2/g, respectively. The decrease in GAC could be attributed to the successful loading of ZnO on the GAC surface. Notably, 0.5M-ZnO@GAC exhibited the best photocatalytic degradation efficiency of 82% and 97% under UV-A and UV-C light over 120 min, attributed to improved crystallinity and visible light absorption. The photocatalytic degradation parameters revealed that lowering the RhB concentration and raising the catalyst dosage and pH beyond the point of zero charge (PZC) would favor the RhB degradation. Photocatalytic reusability was demonstrated over five cycles. Scavenger tests revealed that the hydroxyl radicals (•OH), superoxide radicals (O2-•), and photoinduced hole (h+) radicals play a major role during the RhB degradation process. Based on the TOC results, the RhB mineralization efficiency of 79.1% was achieved by 0.5M-ZnO@GAC. Additionally, GAC exhibited a strong adsorptive performance towards RhB, with adsorption capacity and the RhB removal of 487.1 mg/g and 99.5% achieved within 90 min of equilibrium time. The adsorption characteristics were best described by pseudo-second-order kinetics, suggesting chemical adsorption. This research offers a new strategy for the development of effective photocatalyst materials with potential for wider wastewater treatment applications.

Dye wastewater treatment through adsorption-photocatalysis using electroplating sludge-derived NiFe2O4@C catalyst

Electroplating sludge (ES) is classified as HW46 hazardous waste, and its high-value utilization offers superior economic and environmental benefits compared to traditional methods such as thermal treatment, solidification, and landfill. This paper exploits ES's inherent properties while preserving its carbon structure, and a NiFe2O4@C heterojunction catalyst with high adsorption and excellent photocatalytic capabilities is innovatively developed through a novel “one-step” approach. This catalyst is used to activate peroxymonosulfate (PMS) for the degradation of rhodamine B (RhB). Characterization techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), and the Brunner-Emmet-Teller (BET) method, confirm that the NiFe2O4@C prepared under low-oxygen concentration exhibits a remarkably larger surface area and heterogeneous structure. In dark adsorption experiments lasting 60 min, the NiFe2O4@C achieves an adsorption capacity (Qe) of 295.65 mg/kg. During the subsequent 120-minute photoreaction stage, RhB removal efficiency reaches 96.98 %. Quenching experiments reveal that several active radicals (SO4−, ∙OH, and O2−) play a predominant role in RhB degradation, while nonradicals (1O2 and charge transfer) and high-valent metals also contribute to RhB removal. Density functional theory (DFT) calculations predict RhB molecular sites susceptible to attacks by reactive species. The identification of intermediates using liquid chromatography-mass spectrometry (LC-MS), combined with these theoretical insights, confirmed the main degradation pathways of RhB.

Synergistic effects of barium and PVP-doped Zn–Al layered double hydroxide for catalytic and antibacterial applications with molecular docking studies

Zinc-aluminum layered double hydroxide (Zn–Al LDH) doped with 3 wt% of polyvinyl pyrrolidone (PVP) and various concentrations (2 and 4 wt%) of barium (Ba) doped PVP-LDH were synthesized by co-precipitation method to effectively remove rhodamine-B (RhB) dye from wastewater and investigate its antibacterial properties against S. aureus. The composition and morphology of the layered structure were confirmed employing several characterization techniques: X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM). Dopants into LDH enhanced oxygen vacancies, increasing the number of active sites and demonstrating superior capability to degrade RhB dye. The results also revealed that doped LDH effectively inhibits the biofilm formation of S. aureus bacteria. The 4 wt% Ba doped sample exhibited a maximal degradation (93.92 %) in basic medium and 72.66 % antimicrobial efficiency against S. aureus. To confirm the effectiveness of PVP and Ba-doped LDH as antimicrobial agents, molecular docking investigations were carried out targeting the DNA gyrase and tyrosyl-tRNA synthetase enzymes of S. aureus.

Peroxydisulfate-based Non-radical Oxidation of Rhodamine B by Fe-Mn Doped Granular Activated Carbon: Kinetics and Mechanism Study.

While numerous persulfate-based advanced oxidation processes (AOPs) have been studied based on fancy catalysts, the practical combination of Fe or Mn modified granular activated carbon (GAC) has seldom been investigated. The present study focused on a green and readily synthesized Fe-Mn bimetallic oxide doped GAC (Fe-Mn@GAC), to uncover its catalytic kinetics and mechanism when used in the peroxydisulfate (PDS)-based oxidation process for degrading Rhodamine B (RhB), a representative xenobiotic dye. The synthesized Fe-Mn@GAC was characterized by SEM-EDS, XRD, ICP-OES and XPS analyses to confirm its physicochemical properties. The catalytic kinetics of Fe-Mn@GAC+PDS system were evaluated under varying conditions, including PDS and catalyst dosages, solution pH, and the presence of anions. It was found Fe-Mn@GAC exhibited robust catalytic performance, being insensitive to a wide pH range from 3 to 11, and the presence of anions such as Cl-, SO4 2-, NO3 - and CO3 2-. The catalytic mechanism was investigated by EPR and quenching experiments. The results indicated the catalytic system processed a non-radical oxidation pathway, dominated by direct electron transfer between RhB and Fe-Mn@GAC, with singlet oxygen (1O2) playing a secondary role. The catalytic system also managed to maintain a RhB removal above 81 % in successive 10 cycles, and recover to 89.5 % after simple DI water rinse, showing great reusability. The catalytic system was further challenged by real dye-containing wastewater, achieving a decolorization rate of 84.5 %. This work not only provides fresh insight into the kinetics and mechanism of the Fe-Mn@GAC+PDS catalytic system, but also demonstrates its potential in the practical application in real dye-containing wastewater treatment.

Designing strategically functionalized hybrid porous polymers with octavinylsilsesquioxane/dibenzo[g,p]chrysene/benzo[c]-1,2,5-thiadiazole units for rapid removal of Rhodamine B dye from water

Because of their large surface area and persistent pores that have exceptional adsorption capabilities, porous organic/inorganic polymers (POIPs) with octavinylsilsesquioxane (OVS) units have attracted much interest recently. In this study aimed at removing Rhodamine B (RhB) from wastewater, we utilized OVS nanoparticles synthesized through the Heck coupling process to produce two distinct types: OVS-DBC-PO and OVS-DBC-BT POIPs. OVS and a variety of chemical compounds containing Br, such as tetrabromodibenzo[g,p]chrysene (DBC-Br4), 2,6-bis(4-bromophenyl)pyridine 1-oxide (PO-Br2), and 4,7-dibromobenzo[c][1,2,5]thiadiazole (BT-Br2) were involved in the reactions. Thermogravimetric analysis (TGA) results revealed that the high thermal decomposition temperature (Td10) of OVS-DBC-PO and OVS-DBC-BT POIPs were 447 °C and 543 °C, respectively. Additionally, the OVS-POIPs demonstrated significant porosity, with the OVS-DBC-BT POIP exhibiting the highest specific BET surface area (SABET) of 386 m2 g−1. OVS-DBC-PO and OVS-DBC-BT POIPs exhibit exceptional porosity character. Based on dye adsorption measurements, RhB interacts with functional groups on the OVS-POIP samples' surface and penetrates their pores, enhancing the number of contact sites and the effectiveness of adsorption. Both OVS-DBC-PO and OVS-DBC-BT POIPs demonstrated maximum adsorption capacities of 65 and 66 mg g−1, respectively, at a pH of 4 and a temperature of 25 °C. As a result, OVS-DBC-PO and OVS-DBC-BT POIP materials could be viewed as efficient absorbents for removing RhB from aqueous solutions and this study presents a novel way of making POIPs, which are adsorbents used in the filtration and treatment of water.