Removal Of Organic Dyes Research Articles

Molecular Engineering Spatially Separated Redox Centers Enable Efficient Piezo-Photocatalytic H2O2 Production.

Piezo-photocatalytic production of hydrogen peroxide (H2O2) from water and air is promising but still challenging as insufficient reaction active sites and low reaction efficiency. We have ingeniously applied molecular engineering methods to design an anthraquinone molecularly grafted metal-organic framework piezo-photocatalyst (denoted as UiO-66-AQ) for H2O2 generation from water and air. The catalyst achieves a peak H2O2 yield of 7872.4 μM g-1 h-1, primarily owing to the presence of spatially separated redox sites that enable simultaneously two-step single-electron water oxidation and two-electron oxygen reduction reactions. Notably, experimental and computational simulations confirm rapid carrier separation under the ligand-to-chain charge transfer mode. Electrons transfer to the AQ part and rapidly form internal peroxides for spontaneous oxygen reduction reaction while holes direct to the UiO-66 ligand for the water oxidation reaction. Additionally, a continuous flow tubular reactor with catalytic membranes made of UiO-66-AQ affords 96% removal of organic dyes through the self-Fenton process under visible light and vibrating water flow, confirming the significant potential of the catalyst for practical applications. This work deepens the understanding of directional carrier migration at piezo-photocatalytic spatial separation sites, opening new pathways for environmentally friendly and efficient H2O2 synthesis.

Molecular Engineering Spatially Separated Redox Centers Enable Efficient Piezo‐Photocatalytic H2O2 Production

Piezo‐photocatalytic production of hydrogen peroxide (H2O2) from water and air is promising but still challenging as insufficient reaction active sites and low reaction efficiency. We have ingeniously applied molecular engineering methods to design an anthraquinone molecularly grafted metal‐organic framework piezo‐photocatalyst (denoted as UiO‐66‐AQ) for H2O2 generation from water and air. The catalyst achieves a peak H2O2 yield of 7872.4 μM g‐1 h‐1, primarily owing to the presence of spatially separated redox sites that enable simultaneously two‐step single‐electron water oxidation and two‐electron oxygen reduction reactions. Notably, experimental and computational simulations confirm rapid carrier separation under the ligand‐to‐chain charge transfer mode. Electrons transfer to the AQ part and rapidly form internal peroxides for spontaneous oxygen reduction reaction while holes direct to the UiO‐66 ligand for the water oxidation reaction. Additionally, a continuous flow tubular reactor with catalytic membranes made of UiO‐66‐AQ affords 96% removal of organic dyes through the self‐Fenton process under visible light and vibrating water flow, confirming the significant potential of the catalyst for practical applications. This work deepens the understanding of directional carrier migration at piezo‐photocatalytic spatial separation sites, opening new pathways for environmentally friendly and efficient H2O2 synthesis.

In Situ Growth of Iron‐Based MOFs on Carboxylated Cotton Fabrics for Removal of Rhodamine B by Photocatalysis

ABSTRACTThere are tremendous potential in utilizing metal–organic frameworks (MOFs) for enhancing the removal of organic dyes from wastewater. However, the recovery of powdered catalysts poses a significant challenge. In this study, four different iron‐based metal–organic frameworks (Fe‐MOFs) were synthesized by growing them in situ on carboxylated cotton fabrics. Scanning electron microscopy (SEM), X‐ray diffraction (XRD), and X‐ray photoelectron spectroscopy (XPS) were employed to conduct a comprehensive characterization of the Fe‐MOFs. The dye removal rate of Fe‐MOF@Cotton was meticulously determined by comprehensively investigating various factors including the concentration of the dye and hydrogen peroxide (H2O2), the pH value of the solution, and the temperature. Extensive catalytic degradation experiments were conducted to assess the performance of Fe‐MOF@Cotton. The results vividly demonstrated that Rhodamine B (RhB) was photocatalytically degraded by Fe‐MOF@Cotton with remarkable efficiency in the presence of H2O2. Notably, the four MOF fabric composites were capable of degrading over 97% of RhB with a concentration of 20 mg/L. Moreover, these composites exhibited excellent reusability, strongly indicating their significant potential for application in the dye wastewater treatment industry. This not only highlights the effectiveness of Fe‐MOF@Cotton in dye removal but also offers a promising avenue for addressing the challenges associated with dye‐contaminated wastewater treatment.

Facile synthesis of MIL-100(Fe) adsorbents for boosting organic dye removal.

Highly effective MIL-100(Fe) adsorbent material was successfully synthesized from (NH4)2Fe(SO4)2·6H2O and H3BTC precursors under mild conditions. Characteristics regarding crystal structure, functional groups, elemental composition, surface morphology, specific surface area, and surface charges revealed the formation of pure and microporous MIL-100(Fe) adsorbent with a super surface area (1916.26 m2/g). The results showed that the adsorption of tartrazine organic dye was affected by adsorption time, solution pH, adsorbent dosage, pollutant concentration, and temperature. The adsorption kinetics was best described by a pseudo-second-order model with a coefficient of determination R2 = 0.999. The Toth and Langmuir models best fitted to the experimental data, showing a maximum adsorption uptake of 104.913 mg/g, which is much better than many other adsorbents. The thermodynamic parameters revealed the adsorption process of tartrazine on MIL-100(Fe) material was exothermic, spontaneous, and mainly controlled by chemical adsorption. The desorption and reuse ability of the material was effectively performed by using ethanol (98%), which showed an adsorption efficiency still remained at 88% after five adsorption cycles. This work provides an environmentally friendly synthesis of MIL-100(Fe) material with high adsorption efficiency and opens up opportunities to develop new materials for organic dye treatment in water.

Removal of organic matters and dyes from aqueous solutions and effluent of a hybrid airlift A2O bioreactor treating milk processing wastewater using chemically derived bituminous-based activated carbons

Removal of organic matters and dyes from aqueous solutions and effluent of a hybrid airlift A2O bioreactor treating milk processing wastewater using chemically derived bituminous-based activated carbons

Hydrostable Ti-based metal-organic frameworks hybridized with attapulgite for efficient removal of cationic and anionic organic dyes

Hydrostable Ti-based metal-organic frameworks hybridized with attapulgite for efficient removal of cationic and anionic organic dyes

NH2-MIL-125(Ti)/TiO2 heterojunction with non-disturbed dual reactive centers for synchronous photocatalytic removal of Cr(VI) and organic dyes.

Chromium (VI) (Cr(VI)) generally coexists with organic dyes in industrial effluents, posing a formidable challenge in water purification. Herein, NH2-MIL-125(Ti)/TiO2 Z-scheme heterojunction with intimate interfacial contact was synthesized for synchronous removal of pollutant in coexisting Cr(VI)/dyes system under simulated solar irradiation. Structural and optical investigations indicated that a well-defined interface was formed by establishing a Ti-N-C bond, facilitating the spatial separation of the photoexcited carriers of the Z-scheme heterojunction. The optimum NH2-MIL-125(Ti)/TiO2 nanocomposites show superior performance in photocatalytic removal of the pollutants in the Cr(VI) (5mg/L, 97.2%)/MB (40mg/L, 100%) coexistence systems within 120min, which is comparable to that in the single system. The electron spin resonance (ESR) tests, radicals scavenging experiments, and density functional theory (DFT) cannulations unveiled that TiO2 could serve as oxidation centers to generate hydroxyl radicals (•OH) for MB oxidation, while the NH2-MIL-125(Ti) with exposed Ti nodes could act as reduction centers to effectively adsorb Cr2O72- and inject photo-generated electrons (e-) to accomplish the in-site photoreduction of Cr(VI) into Cr(III) under illumination. Particularly, owing to the spatial separation and non-disturbed dual reactive centers, the reduction and oxidation processes could be well accommodated, which could allow MB and Cr(VI) to be removed synchronously. This work demonstrated the great potential of applying duel reactive centers to eliminate multipollutant simultaneously in the actual scenarios for wastewater treatment.

An innovative nanocomposite for sustainable organic dye removal: Sodium titanate/carbon

An innovative nanocomposite for sustainable organic dye removal: Sodium titanate/carbon

Dicobalt orthosilicate-graphitic carbon nitride nanocomposites as promising visible-light nanocatalysts for removal of water-soluble organic dyes

This paper reports the preparation of cobalt silicate (Co2SiO4, CSO) first by a cost-effective and simple sonochemical route, followed by the fabrication of Co2SiO4/g-C3N4 (CSO/CN) nanocomposites with different mass ratios by ultrasonic-assisted co-precipitation. We have investigated the photocatalytic performance of Co2SiO4, g-C3N4, and different Co2SiO4/g-C3N4 nanocomposites for the degradation of eriochrome black T (EB). This initial instance of CSO integrated with CN demonstrates a superior function in photocatalysis. The outcomes indicated that multiple parameters affected effectiveness, including the amount of CSO, catalyst, and EB. As a result, CSO/CN with a weight ratio of 0.1:1 is the most efficient, which means that 0.07 g of CSO/CN (0.1:1) is capable of degrading 90.0% of 10 ppm EB. Photodegradation reactions were demonstrated by the scavenger tests to be largely influenced by superoxide radicals. The kinetic investigation showed that a bigger rate constant (k = 0.0166 min‒1) leads to higher efficiency (90.0%). The combination of CSO and CN as composites shows great potential for efficient photocatalytic dye degradation applications. Advanced materials for environmental treatment procedures may be developed as a result of further research and development in this field.

Chitosan/Acid Modified Olive Tree (Olea europaea) Leaves as Sustainable Adsorbent for Organic Dye Removal from Water: Adsorption Modeling and Optimization by Box-Behnken Design

Chitosan/Acid Modified Olive Tree (Olea europaea) Leaves as Sustainable Adsorbent for Organic Dye Removal from Water: Adsorption Modeling and Optimization by Box-Behnken Design

Chemically Modified Gelatin/Chitosan as a Chemosensor Adsorbent for Detection of Toxic Metals and Removal of Organic Dyes

ABSTRACTDue to the vast amounts of toxic metals, oils, and dyes containing wastewater, water pollution is currently a serious health issue for human beings and animals. Adsorption of these pollutants using a biopolymeric‐based hydrogel from wastewater is one of the potent methods due to its biodegradability and low cost. Herein, a porous and biodegradable hydrogel (CS–GL–IL) was synthesized from gelatin (GL), chitosan (CS), and ionic liquid (IL), acting as an excellent adsorbent for water pollutants. The maximum percentage swelling obtained for the synthesized CS–GL–IL hydrogel was 480% ± 3% for 0.5 g of the ionic liquid, 0.05 g of APS, and 35 mL of water at 65°C for 1.5 h of reaction. The process of eliminating methyl orange (MO) and methylene blue (MB) from a dye containing water was done using the CS–GL–IL hydrogel. Numerous methods, including PXRD, SEM, FTIR, and rheology, have been used for the characterization of the CS–GL–IL hydrogel. The obtained data indicate that the Freundlich adsorption isotherm with pseudo‐second‐order kinetics was followed for adsorption of dyes. The hydrogel exhibits excellent adsorption capacities of 1171 mg/g and 1062 mg/g for MO and MB, respectively. Furthermore, the hydrogel also exhibited efficiency in detection and adsorption of Ni2+ and Pb2+ with adsorption capacities of 315 mg/g and 370 mg/g, respectively. Dye removal efficiency remained above 82% even after eight iterations of dye adsorption and desorption experiments. Due to its high adsorption potential and regeneration capabilities, the CS–GL–IL hydrogel acts as an excellent material for remediation of wastewater.

Combining porous organic polymers with chelating agents: a facile strategy to develop effective and multi-purpose absorbents for wastewater treatment

A type of multifunctional absorbent for the concurrent and efficient removal of dyes and heavy metal ions from water was prepared by coupling carbamate-based porous organic polymer and chelating agent N-(2-hydroxyethyl) ethylenediaminetriacetic acid.

A pillararene-based supramolecular polymer hydrogel for removal of organic dyes from water

Organic dyes in industrial wastewater are posing significant threats to global water resources and have raised concerns about negative impacts on human health. Hydrogels have attracted much attention among various...

Nanosized MCM-41 silica from rice husk and its application for the removal of organic dyes from water.

A novel synthesis of a nanometric MCM-41 from biogenic silica obtained from rice husk is here presented. CTABr and Pluronic F127 surfactants were employed as templating agents to promote the formation of a long-range ordered 2D-hexagonal structure with cylindrical pores and to limit the particle growth at the nanoscale level thus resulting in a material with uniform particle size of 20-30 nm. The physico-chemical properties of this sample (RH-nanoMCM) were investigated through a multi-technique approach, including PXRD, 29Si MAS NMR, TEM, Z-potential and N2 physisorption analysis at 77 K. The results were compared to those of a nanometric MCM-41 synthesized from a silicon alkoxide precursor. The adsorption capacity of RH-nanoMCM towards the cationic dye rhodamine B from aqueous phase was investigated at different initial dye concentrations by means of UV-vis spectroscopy. Insight into the non-covalent interactions between the dye molecules and the adsorbent surface was gained by means of 1H and 13C MAS NMR spectroscopy and FT-IR spectroscopy.

Fluorinated Conjugated Microporous Polymers Based on Pillar[n]arenes for Removal of Water Pollutants and Their Cation Selective Adsorption.

Organic dyes are widely used in many applications. However, the leakage of organic dyes into the natural environment has become a severe and worldwide problem owing to their high toxicity and nonbiodegradability. Therefore, the development of effective removal technologies for organic dyes is required. In this article, we report the synthesis and adsorption properties of highly fluorinated conjugated microporous polymers based on pillar[n]arenes. The polymers exhibited large Brunauer-Emmett-Teller surface areas of up to 1063 m2 g-1 and selective adsorptive removal of cationic organic dyes from aqueous solutions. Comparison with the nonfluorinated polymers indicated that the adsorption mechanism mainly relies on the fluorine-cation electrostatic interaction. The maximum adsorption capacity reached 313 mg g-1 for crystal violet, which is higher than those of conventional adsorbents. Additionally, the fluorinated polymers could function as proton channels when they were embedded into lipid membranes.

Green and Eco-Friendly Egg White–TiO2 Hydrogel with Enhanced Antimicrobial, Adsorptive, and Photocatalytic Properties

The design of multi-purpose decontaminants with environmentally friendly characteristics, low cost, and high efficiency in removing pollutants from the environment is an effective and economic strategy for maintaining the long-term development of the ecosystem. Based on the strategy of killing two birds with one stone, an egg white (EW)/TiO2 hydrogel with a porous structure is devised as a bio-adsorbent using waste eggs nearing their expiration date for simultaneously achieving the efficient removal of organic dyes and the inactivation of microorganisms from industrial wastewater. The characterizations of its morphology and composition using scanning electron microscopy (SEM), the Brunauer–Emmett–Teller (BET) theory, energy-dispersive spectrometry (EDS), Fourier transform infrared spectroscopy (FTIR), and a thermogravimetric analyzer (TGA) validate the successful synthesis of EW/TiO2. The maximum adsorption capacity of EW/TiO2 is 333.172 mg∙mL−1 according to the Langmuir model. The photodegradation of a methyl blue (MB) solution under irradiation via a xenon lamp is used to assess the photocatalytic behavior of EW/TiO2. Among the different samples, the 5 wt% TiO2-doped EW/TiO2 hydrogel shows an efficiency of 99% for 120 min of irradiation. Finally, the antibacterial properties of the EW/TiO2 hydrogel are evaluated by calculating its bacterial survival rate against Escherichia coli (E. coli). The EW/TiO2 photocatalyst exhibits a photocatalytic inactivation efficiency of 90.4%, indicating that the EW/TiO2 hydrogel possesses positive antibacterial activity via effectively inhibiting the growth of the bacteria, which is suitable for industrial wastewater treatment over a long period of time.

Phytoextract-assisted synthesis of Fe2O3/MgO nanocomposites for efficient photocatalytic degradation of gentian violet

Organic-based pollutants are extensively released from various industries and they potentially harm the environment and human health. Photocatalysis is regarded as one of the most promising techniques for removal of organic contaminants from wastewater. Therefore, in this study, iron oxide-based nanocomposites were synthesized by an emerging green and sustainable method using Ethiopian endemic plant extract, Echinops kebericho M. as a capping and stabilizing agent. The phytoextract-assisted synthesized nanoparticles (NPs) α-Fe2O3 and nanocomposites (NCs) α-Fe2O3/MgO calcinated at a temperature of 400°C were characterized and used for their photocatalytic activities toward gentian violet (GV) dye degradation using ultraviolet–visible spectroscopy (UV-vis) at optimized catalyst dose, initial GV concentration, pH, and time conditions. The X-ray diffraction (XRD) analysis result revealed that the mean crystal size of α-Fe2O3 and α-Fe2O3/MgO is 11.2 and 15.4 nm, respectively. Characterization results of scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS) clearly showed the successful deposition of MgO on α-Fe2O3. The maximum degradation of GV, 96.2%, was observed by using α-Fe2O3/MgO after 60 min under visible light irradiation. Thus, synthesized NCs were shown to have better GV degradation efficiency in a shorter time as compared to the previously reported nanomaterials. The results revealed photocatalytic degradation using endemic plant extract-assisted synthesized NCs, α-Fe2O3/MgO, is considered a greener, simple, and more efficient method for the removal of organic dyes.

Study on adsorption characteristics of biochars and their modified biochars for removal of organic dyes from aqueous solution

Abstract To address organic dye pollution and agricultural waste comprehensive utilization, the biochar (ZB) was prepared using Rosa roxburghii residue as the material for preparation. Three modified biochars (ZBO, ZBS, and ZBH) were created using NaOH, Na2S, and H3PO4 as modifying agents. The morphology, structure, pore size, and elemental composition of biochars were characterized and analyzed by a combination of FTIR, SEM-EDS, and N2 adsorption–desorption techniques. Furthermore, the adsorption performance of the as-prepared biochars was investigated in the adsorption of RhB and MB dye process. The experimental findings showed that adsorption equilibrium for these dyes was achieved in 180 min. Moreover, the dye adsorption on biochars followed a pseudo-second-order kinetic equation. For the biochar (ZB), the Langmuir equation proved to be more appropriate than the Freundlich equation. In contrast, the Freundlich equation was more apt for the modified biochars. More importantly, Pearson's correlation analysis revealed that the adsorption rate and capacity of RhB positively correlated with the specific pore volume, t-plot micropore area, and BET surface area, but a negative one with the pore size. The MB adsorption showed the opposite correlations. This study reveals a novel biochar for adsorbing organic dyes, which provides a strategy for the treatment of Rosa roxburghii residue.

Hazelnut Shells as a Tenable Biosorbent for Basic Red 18 Azo Dye Removal

The increasing pollution from the textile industry, particularly organic azo dyes, presents a significant environmental challenge, necessitating the development of effective and sustainable treatment methods. This study investigates the adsorption potential of hazelnut shells (raw—RHSs; modified—MHSs) for the removal of organic azo dyes from aqueous solutions. As biomass, hazelnut shells are biodegradable and represent a sustainable alternative to synthetic adsorbents, thereby reducing the ecological footprint. Through a series of batch adsorption experiments, the influence of various parameters, including pH, contact time, concentration, and temperature, on adsorption capacity was examined. Characterization of the hazelnut shells was conducted using optical microscopy and ATR-FTIR, XRF, and XRD spectroscopy, confirming its suitability as a biosorbent. The analyzed isotherms showed that adsorption onto RHSs was best fitted by the Freundlich model, while adsorption onto MHSs was best fitted by the Temkin model. Kinetic studies demonstrated that the adsorption process is well described by the pseudo-second-order model, suggesting that chemical adsorption plays a significant role. The maximal adsorption capacity was 62.11 mg/g for RHSs and 80.65 mg/g for MHSs, highlighting the potential of hazelnut shells as an abundant, low-cost, and eco-friendly adsorbent. Furthermore, recycling studies indicated the feasibility of the adsorbent, underscoring its practical applicability in real scenarios.

(Digital Presentation) Camellia sinensis Biochar as Sustainable Dye Removal for Wastewater Treatment in the Textile Industry

Poor waste management of organic dyes by the textile industry frequently leads to severe contamination of nearby water bodies, posing significant threats to both the environment and public health. These organic dyes, which include a wide range of synthetic chemicals, are particularly harmful to aquatic ecosystems due to their ability to block light penetration in water, inhibiting photosynthesis in aquatic plants and disrupting the balance of the ecosystem. Additionally, many dyes contain carcinogenic aromatic structures and azo groups, which have been linked to various health risks, including cancer. The issue of dye pollution is most pronounced in countries with large textile manufacturing sectors, such as India, where the economic disparity exacerbates the problem. In these regions, inadequate waste management infrastructure, combined with the high demand for textiles, often leads to untreated or poorly treated dye effluents being released directly into rivers and lakes, affecting vulnerable communities.Addressing this environmental challenge requires practical and affordable remediation methods [1-14]. The most widely accepted approach for the removal of organic dyes from wastewater is adsorption, a process in which pollutants adhere to the surface of adsorbent materials. Activated carbon and zeolite are among the most commonly used adsorbents due to their high surface area and efficiency in capturing dye molecules. However, the cost and availability of these materials can be prohibitive, particularly in low-income regions with significant textile industries. This has led to a growing interest in the development of more sustainable and cost-effective alternatives.One promising solution is biochar, a carbon-rich material produced through the pyrolysis of organic waste. Biochar has gained attention for its potential use in water treatment due to its porous structure and surface functional groups, which enhance its ability to adsorb pollutants. Research has explored the production of biochar from various organic materials, including agricultural waste like banana peels. However, recent studies suggest that biochar made from Camellia sinensis leaves (chai tea), particularly Camellia sinensis, could be an even more effective adsorbent for dye removal. Tea leaves are abundant and possess a highly porous structure, making them ideal candidates for biochar production.In this study, the effectiveness of chai tea biochar as an adsorbent for methylene blue, a common organic dye, was assessed. The results showed that the chai tea biochar followed a Freundlich isotherm model with an R2 value of 0.99, indicating a strong correlation between the adsorption capacity and the concentration of methylene blue in the solution. The Freundlich constant (Kf) was determined to be 0.968 mg/g, and the n value was 0.629, suggesting a high affinity for methylene blue. These findings highlight the potential of chai tea biochar as a low-cost, environmentally friendly solution for dye removal in wastewater treatment, particularly in regions where traditional adsorbents may be economically or logistically inaccessible. References A Elmekawy, Q Quach, TM Abdel-Fattah, Nanomaterials 14 (13), 1143 (2024)SELME Mahmoud, TM Abdel-Fattah, ME Mahmoud, E Díaz, Environmental Nanotechnology, Monitoring & Management 22, 100977 (2024)SELME Mahmoud, D Ursueguia, ME Mahmoud, TM Abdel-Fattah, E Díaz, Biomass Conversion and Biorefinery, 1-1 (2023)A Elmekawy, Q Quach, TM Abdel-Fattah, Scientific Reports 13 (1), 12845 (2023)Omar H. Elsayed-Ali, Hani E. Elsayed-Ali and Tarek M. Abdel-Fattah, Journal of Hazardous Materials, 185 (2-3), 1550-1557 (2011)Alya Elsayed-Ali, Tarek Abdel-Fattah, Hani Elsayled-Ali, Hani, Journal of Chemical Education, 88(8), 1126-1129 (2011).TM Abdel-Fattah, ME Mahmoud, Chemical engineering journal 172 (1), 177-183 (2011)TM Abdel-Fattah, ME Mahmoud, MM Osmam, SB Ahmed, Journal of Environmental Science and health, part A 49 (9), 1064-1076 (2014)ME Mahmoud, TM Abdel-Fattah, MM Osman, SB Ahmed, Journal of Environmental Science and Health, Part A 47 (1), 130-141 (2012)TM Abdel-Fattah, B Bishop, Journal of Environmental Science and Health, Part A 39 (11-12), 2855-2866 (2004)ME Mahmoud, MM Osman, SB Ahmed, TM Abdel-Fattah, The Scientific World Journal 2012 (2012)ME Mahmoud, SS Haggag, TM Abdel-Fattah, Polyhedron 26 (14), 3956-3962 (2007)ME Mahmoud, AA Yakout, MT Abed El Aziz, MM Osman, TM Abdel-Fattah, Journal of Environmental Science and Health, Part A 50 (10), 1072-1081 (2015)H Namkoong, E Biehler, G Namkoong, TM Abdel-Fattah, ACS omega 7 (44), 39931-39937 (2022)