Dye Removal Efficiency Research Articles

Facile fabrication of a low-cost carboxymethyl cellulose–polyacrylamide composite for the highly efficient removal of cationic dye: optimization, kinetic and reusability

Facile fabrication of a low-cost carboxymethyl cellulose–polyacrylamide composite for the highly efficient removal of cationic dye: optimization, kinetic and reusability

Unripe Plantain Peel Biohydrogel for Methylene Blue Removal from Aqueous Solution

Dye contamination is a serious environmental issue, particularly affecting water bodies, driving efforts to synthesize adsorbent materials with high dye-removal capacities. In this context, eco-friendly and cost-effective materials derived from bioresidues are being explored to recycle and valorize waste. This study investigates the synthesis, characterization, and application of a biohydrogel made from unripe plantain peel (PP), modified with carboxymethyl groups and crosslinked using varying concentrations of citric acid (CA), an eco-friendly and economical organic acid. The materials were characterized by ATR-FTIR, TGA, and SEM, confirming the successful synthesis of hydrogels, which exhibited rough, irregular surfaces with micropores. Additionally, the materials were analyzed for their pH point of zero charge, swelling capacity, and methylene blue (MB) dye removal efficiency. The results indicate that the biohydrogel formed with 1% CA exhibited the most favorable characteristics for MB removal. Kinetic studies revealed that the adsorption mechanism is pH-dependent, with equilibrium being reached in 720 min. The Freundlich isotherm model provided the best fit for the adsorption data, suggesting a heterogeneous surface and a multilayer adsorption process, with a maximum retention capacity of 600.8 ± 2.1 mg/g at pH 4. These findings contribute to the development of cost-effective and efficient materials for dye removal, particularly from water bodies.

Adsorption of malachite green dyes from aqueous solution by metal organic framework-5 incorporated coal fly ash (MOF-5/CFA)

Dye contamination of water is a global issue with significant environmental and health risks. This research explores the use of metal organic framework-5 (MOF-5) adsorbents modified with coal fly ash to effectively remove malachite green (MG) dye from water, addressing global dye pollution. Preliminary batch adsorption experiments showed that the addition of CFA to MOF-5 significantly increased the removal efficiency of MG dye (77.90 ± 1.74%) compared to using pristine MOF-5 (30.00 ± 2.14%). Batch adsorption studies showed that MG adsorption efficiency increased with shaking rate and contact time but decreased with adsorbent dosage. Temperature study reveals exothermic behavior of adsorption process. MOF-5/CFA adsorbents can be regenerated for up to four cycles. The results demonstrated that the highest adsorption efficiency of 80.32 ± 0.90% was achieved under the following conditions: a stirring speed of 300 rpm, a dosage of 0.3 g of MOF-5/CFA adsorbent, a temperature of 27 °C, 2 h contact time, and an initial dye concentration of 100 mg/L. Analysis of adsorption isotherms and kinetics revealed that the Langmuir isotherm and pseudo-second-order kinetic models provided the most accurate fit to the experimental data. FTIR analysis revealed significant functional groups in the prepared adsorbent and only minor spectral changes in the spent adsorbents. SEM analysis showed a rough, porous MOF-5/CFA surface before dye adsorption, becoming smoother and less porous afterwards. This study demonstrates the promise of MOF-5/CFA as an alternative adsorbent for the removal of MG dyes from water, paving the way for advances in wastewater treatment and the sustainable use of industrial waste materials.

Honey-Derived Hydrochar Containing 2,2,6,6-tetramethylpiperidine-1-oxyl Free Radical for Degradation of Aqueous Organic Pollutants

The increasing demand for greener technologies in environmental remediation makes carbon materials from biomass and its derivatives some of the most attractive resources for a sustainable future. However, integrating these materials with stable free radicals remains challenging. This study presents a straightforward one-pot hydrothermal route using raw honey as the carbon source and 4-amino 2,2,6,6-tetramethylpiperidine-1-oxyl (4-amino-TEMPO) as the free radical. The addition of TEMPO derivative initiates Maillard reactions between its amino group and the carbonyl groups of the carbohydrates in honey, resulting in the formation of a functionalized hydrochar with a spherical morphology (~ 8 μm). The presence of free radicals within the carbonaceous matrix was confirmed by electron spin resonance spectroscopy, supported by infrared spectroscopy, elemental analysis, thermal analysis, scanning electron microscopy, and X-ray photoelectron spectroscopy. The free radical content was estimated at 0.4 mmol∙g-1. The material effectively removed methylene blue, fluorescein, and doxorubicin from water in the presence of green oxidants like hydrogen peroxide and sodium hypochlorite. After 24 h, removal efficiencies reached 92% for doxorubicin, 73% for methylene blue, and 23% for fluorescein. Moreover, the hydrochar demonstrated good regeneration capability, maintaining its dye removal efficiency over several cycles.

Efficient removal of cationic dyes by a bivanadyl capped, highly reduced Keggin polyoxometalate through flocculation

Flocculation is widely applied for dye wastewater treatment, due to its low cost, high efficiency and convenient operation. However, finding novel flocculant with high performance and low cost is still a challenge. Therefore, a fully characterized bivanadyl capped, highly reduced Keggin polyoxometalate (Et3NH)5[PMoV6MoVI6O40(VIVO)2] (PMoV2) was explored as flocculant for the treatment of simulated cationic dye wastewater. The effect of initial pH, PMoV2 dosage, and concentrations of dyes and inorganic salts on the flocculation rate of methylene blue (MB)/ crystal violet (CV)/rhodamine B (RhB) was investigated. Under the optimum conditions, the flocculation rates of MB, CV and RhB were 99.7%, 99.8% and 99.7% in 5min, respectively. In addition, PMoV2 and dyes could be easily recovered from flocs. PMoV2 exhibited high selectivity for CV in the binary systems of CV-MB and CV-MO. Even after five recycling tests, PMoV2 still kept high flocculation rate of MB/CV/RhB. The possible flocculation mechanisms for MB/CV/RhB single system, and MB-CV and MO-CV binary systems were charge neutralization, charge neutralization and π-π interaction, and charge neutralization and electrostatic interaction, respectively. PMoV2 was better than the reported flocculants in the respect of easy availability and operation conditions, reusability and high flocculation rate. The cost effectiveness, eco-friendly nature and excellent flocculation performance in individual and binary dye systems made PMoV2 competitive in the field of water environment remediation and material development. This is the first report about the flocculation activities of bivanadyl capped, highly reduced Keggin polyoxometalate.

The Ce-modified biochar for efficient removal of methylene blue dye: Kinetics, isotherms and reusability studies

Exploring modification methods for enhancing the adsorption performance of biochar-based adsorbents for effective removal of methylene blue (MB), biochar-loaded CeO2 nanoparticles (Ce/BC) were synthesized by pomelo peels through co-precipitation combined with the pyrolysis method. Ce/BC showed a higher specific surface area and disorder degree than that of BC. The 0.5Ce/BC (mass ratio of Ce(NO3)3·6H2O/BC=0.5/1) showed the best performance to adsorption of MB solution at different reaction conditions (MB concentration, Ce/BC composites dosage, and initial pH). Adsorption kinetics and equilibrium isotherms were well-described with a pseudo-first-order equation and Langmuir model, respectively. In addition, the maximum adsorption capacity of 0.5Ce/BC for MB was 105.68 mg·g−1 at 328 K. The strong adsorption was attributed to multi-interactions including pore filling, π-π interactions, electrostatic interaction, and hydrogen bonding between the composites and MB. This work demonstrated that the modified pomelo peels biochar, as a green promising material with cost-effectiveness, exhibited a great potential for broad application prospectively to dyeing-contaminated wastewater treatment.

Novel carboxymethyl cellulose-based hydrogel embedded with metal organic framework for efficient cationic dye removal from water

The rGO/CMC/β-CD (RCβ) hydrogel was synthesized from reduced graphene oxide (rGO), β-cyclodextrin (β-CD) and sodium carboxymethyl cellulose (CMC) by radical polymerization. A novel hydrogel adsorbent was created by growing the metal-organic framework (Cu-BTC) in-situ on RCβ hydrogel, which has excellent adsorption capacities for cationic dyes in wastewater. The adsorption parameters such as the amount of adsorbent, pH of solution and adsorption time were optimized through batch adsorption experiments. Under the optimal conditions of pH 6.0, adsorbent dosage of 0.01 g and experimental temperature of 25 °C, Langmuir isothermal model was used to fit the maximum adsorption capacities of methylene blue (MB), crystal violet (CV) and malachite green (MG), which were 892.66, 842.75 and 633.77 mg g−1, respectively. The fitting results of adsorption kinetics revealed that the pseudo-second-order model can describe the adsorption process better. Based on proposed studies, the dye molecules were adsorbed onto RCβ@Cu-BTC hydrogel mainly through electrostatic interaction, hydrogen bonding and π–π interactions. After five cycles, the adsorption efficiency of the RCβ@Cu-BTC hydrogel for MB, CV and MG can still reach 80 %, 77 % and 72 %, which shows that the adsorbent has good adsorption performance. Various adsorption experiments shows that RCβ@Cu-BTC hydrogel has great potential in treating dye wastewater.

Amino acid functionalized carboxymethyl cellulose-based crosslinked aerogels for efficient removal of dye and metal ion from aqueous solution

In order to protect water resources and maintain sustainable development of society, it is crucial to design the adsorption materials with high adsorption capacity and environmental friendliness to effectively remove the pollutants in wastewater. In this study, amino acid functionalized carboxymethyl cellulose-based aerogels were successfully prepared by combining grafting, blending, freeze-drying and crosslinking technologies. The aerogels exhibited outstanding adsorption properties for methylene blue (MB) and lead ions (Pb (II)) with adsorption capacities of 461.68 and 304.60 mg/g, respectively. The adsorption experiment showed that the adsorption process of aerogels for MB conformed to Freundlich adsorption isotherm model and quasi-second-order kinetics model, and the adsorption process for Pb (II) conformed to Langmuir model and quasi-second-order kinetics model. Furthermore, the aerogels displayed excellent recyclability, with the removal efficiency of over 90.0 % for MB and only 14.0 % reduction for Pb (II) after 6 cycles. It is evident that the aerogels hold great potential for application in wastewater treatment, which has important practical significance for environmental protection and high-value utilization of natural polymers.

Enhanced cationic/anionic dyes removal in wastewater by green nanocomposites synthesized from acid-modified biomass and CuFe2O4 nanoparticles: Mechanism, Taguchi optimization and toxicity evaluation

This article addresses the nanoadsorption mechanisms of rhodamine B (RB), crystal violet (CV), and Congo red (CR) using acid-treated C.edulis (ATCE)/CuFe2O4 (ATCE@CuFe2O4) from an aqueous solution. The physical and chemical characterizations of nanobiomass were studied using different techniques. The specific surface areas of the ATCE and ATCE@CuFe2O4 composites were 15.88 and 337.81 m2/g, respectively, indicating a significant specific surface area of ​​the ATCE@CuFe2O4 nanocomposite. A number of functional groups were determined, which promote the binding of the dye to the adsorbent. The SEM also shows that the adsorbent has a homogeneous texture with deep voids and significant porosity, which likely explains the retention and binding of dye ions on the surface of the adsorbent. In fact, the Langmuir isotherm with a correlation coefficient of 99 % for CV, RB and CR, respectively, represents the most suitable model to explain the adsorption mechanism. The maximum adsorption amount is 666.6 mg/g for CV, 645.16 mg/g for RB and 434.71 mg/g for CR at 308 °K. The adsorption kinetic processes were predicted by the pseudo-second order kinetic model. The thermodynamic properties showed that the adsorption on ATCE@CuFe2O4 was possible and spontaneous. The ATCE@CuFe2O4 recycling and elimination CV, RB, and CR were 74.23 %, 72.75 %, and 67.84 %, respectively, after seven cycles. The design, modeling and optimization of the adsorption parameters were carried out using the Taguchi experimental design. The maximum removal efficiency of CV, RB and CR dyes in optimal operating conditions were 99.96, 98.29 and 97.76 %, respectively. Which at the optimal conditions of 1 g/L, 90 min, 20 mg/L, 298 °K, pH 10 for CV and RB dyes and 1 g/L, 90 min, 20 mg/L, 308 °K, pH 4 for CR. This research demonstrated the performance of ATCE@CuFe2O4 in bean seed germination test and its effectiveness in removing dyes from wastewater.

Efficient removal of basic yellow 28 dye from water using facilely synthesized ZnO and Mg3B2O6 nanostructures

Basic yellow 28 dye, used extensively in the textile and leather industries, poses significant environmental and health risks, including allergic reactions, skin irritation, and respiratory problems. This study reports the Pechini sol-gel synthesis of novel ZnO/Mg3B2O6 nanostructures for the decontamination of basic yellow 28 dye from aqueous solutions. The nanostructures were synthesized by calcining at 650 and 850 °C for 5 h, producing ZM650 and ZM850, respectively. The average crystallite sizes were 39.28 nm for ZM650 and 51.03 nm for ZM850. BET surface areas were 70.71 m2/g for ZM650 and 48.13 m2/g for ZM850. FE-SEM and HR-TEM analyses revealed distinct morphological structures, with ZM650 exhibiting a dense aggregation of rod-like particles and ZM850 showing larger clusters. The maximum adsorption capacities were 381.68 mg/g for ZM650 and 303.03 mg/g for ZM850. The optimum adsorption was observed at a pH of 10, a contact time of 70 min, and a temperature of 298 K. Regeneration using a 6 M HCl solution demonstrated efficient reusability over five cycles. The adsorption process followed pseudo-second-order kinetics and the Langmuir isotherm, indicating monolayer adsorption. Also, the adsorption process was found to be physical and exothermic.

Ag@AgCl/carbon nitride/graphene oxide three-dimensional nanocomposite constructed for efficient removal of organic dyes by synergistic adsorption-photocatalysis

The efficient removal of dye pollutants from wastewater is a significant and hotspot research. In this manuscript, Ag@AgCl nanoparticles were anchored on three-dimensional carbon nitride/graphene oxide (CN/GO) using an in-situ photoreduction strategy, and thus a novel (Ag@AgCl/CN/GO) was achieved. The results showed that the Ag@AgCl/CN/GO was a highly efficient adsorption and photocatalytic material for the removal of dye pollutants. The maximum adsorption capacity of malachite green (MG), methylene blue (MB), rhodamine B (RhB) and crystal violet (CV) can be reached as 324, 216, 148 and 112 mg g−1, and the photocatalytic degradation rate were 95 %, 83 %, 76 % and 93 % under irradiation for 60 min, which were greatly higher than some comparisons reported. The improved visible light, enhanced absorption and electron transfer in the Ag@AgCl/CN/GO three-dimensional structure were responsible to the highly efficient removal of dyes. Furthermore, the Ag@AgCl/CN/GO showed a good reusability in the cycling test. The constructed nanocomposite will be attractive for removing pollutants in wastewater.

Synthesis of magnetically tuneable molybdic acid-functionalized Fe3O4 nanoparticles for efficient dye removal in aqueous media

Synthesis of magnetically tuneable molybdic acid-functionalized Fe3O4 nanoparticles for efficient dye removal in aqueous media

Adsorptive Removal of Dyes: A Comparison of Graphene Oxide to Granular Activated Carbon and Zeolite NaY

Synthetic carbon-based compounds are a prevalent wastewater contaminant that can adversely impact water resources due to their potential carcinogenic and toxic effects on aquatic biota and human health. This research investigates the versatility of graphene oxide (GO) as an alternative to commonly used adsorbents (zeolite NaY (NaY) and granular activated carbon (GAC)) for removal of synthetic cationic dyes. Rhodamine B (RhB) and methylene blue (MB), were selected as the target contaminants to represent cationic synthetic dyes with differing molecular sizes and structural compositions. Batch experiments using GO, NaY, and GAC as adsorbents were used to assess both physicochemical interactions between adsorbent surfaces and contaminants, and removal efficiency. GO demonstrated the highest removal efficiency for both target contaminants—at 99% and 86%, respectively—while the lowest removal efficiency was observed for NaY. Langmuir, Freundlich, Temkin, and BET isotherm models were used to describe the adsorption isotherms. Overall, GO demonstrated a more robust and higher removal efficiency of cationic dyes compared with GAC and NaY, indicating the potential of graphene oxide for the removal of complex structured organic contaminants in wastewater treatment.

Pyrazine substituted chitosan: an adsorbent material for the efficient removal of anionic dyes from aqueous solutions

Pyrazine substituted chitosan: an adsorbent material for the efficient removal of anionic dyes from aqueous solutions

Peroxymonosulfate activation over (Cu+ decorated g-C3N4)/Bi2WO6 composites with S-scheme heterojunction for RhB degradation

Catalytic activation of peroxymonosulfate (PMS) is one of the important research areas in the development of advanced oxidation technology for wastewater treatment. At present, the development of high-performance catalysts for PMS activation has become a research hotspot. Herein, (Cu+ decorated g-C3N4)/Bi2WO6 ((Cu+/g-C3N4)/Bi2WO6) composite was prepared successively by calcination and solvothermal method, which was used in visible light-assisted PMS activation for the degradation of rhodamine B (RhB). The construction of S-scheme heterojunctions between Cu+ decorated g-C3N4 and Bi2WO6 facilitated the activation of PMS, leading to a RhB degradation ratio of 98.46 % within 50 min. The corresponding reaction kinetic was significantly improved by a factor of 2.32 and 7.94 compared with that of CCN and BWO, respectively. The enhanced performance of the (Cu+/g-C3N4)/Bi2WO6 can be attributed to the successful construction of S-scheme heterojunction, which facilitates the separation of photogenerated carriers and accelerates the PMS activation to produce abundant active species. Furthermore, the (Cu+/g-C3N4)/Bi2WO6 composites exhibit strong stability and reusability following three cycles. In addition, the intermediates produced during the RhB degradation process were investigated by liquid chromatograph mass spectrometer (LC-MS). This study provides a new insight into the preparation of S-scheme photocatalysts for the photocatalytic-PMS activation system that will achieve efficient removal of dyes from wastewater.

Cu-TiO2/Zeolite/PMMA Tablets for Efficient Dye Removal: A Study of Photocatalytic Water Purification

In this study, Cu-doped TiO2 combined with natural zeolite (ZT) was synthesized and applied as a fixed powder layer on poly(methyl methacrylate) (PMMA) tablets. The material’s morphology, structural, and chemical properties were characterized using high-resolution scanning electron microscopy, Raman spectroscopy, and Brunauer–Emmett–Teller analysis. The antioxidant capacity was evaluated by assessing the neutralization of hydroxyl radicals and iron (III) ions. For the first time, tablets with Cu-TiO2 and ZT deposited on PMMA as the carrier were investigated for removing two dyes, methyl orange (MO) and methylene blue (MB), from water under simulated solar (SS) and UVC irradiation. Under SS irradiation, the Cu-TiO2/PMMA and Cu-TiO2/ZT/PMMA tablets achieved about 21% degradation of MB after 240 min. This result is particularly noteworthy because SS radiation provides lower energy compared with UVC, making the process more economically efficient. Furthermore, the photocatalysts are immobilized on a stable carrier, which enhances the method’s cost-effectiveness by reducing material loss and simplifying recovery. In the presence of ZT/PMMA tablets, 69% of MB was removed by adsorption after 240 min. Additionally, we explored the mechanism of degradation, revealing that the enhanced generation of hydroxyl radicals plays a pivotal role in the effective degradation of MB. At the same time, photogenerated holes contribute to the removal of MO. The overall results suggest that the tablets obtained are a promising solution for water purification due to their effectiveness, simplicity, and low processing cost.

Biobased amphoteric aerogel with core-shell structure for the hierarchically efficient adsorption of anionic and cationic dyes

Efficient and simultaneous removal of anionic and cationic dyes from wastewater using low-cost and environmentally-friendly adsorbent is highly required. Herein, the carboxylated cellulose (carboxyl content: 2.97 mmol/g) derived from pomelo peel was extracted by a one-step H2O2/H2SO4-mediated oxidation method. Subsequently, a novel pomelo-peel cellulose/chitosan/sodium alginate (PCS) amphoteric aerogel with a specific core-shell structure was synthesized by multiple physical cross-linking strategies. The shell layer and core layer of the optimized P3CS0.75 aerogel can selectively adsorb cationic dyes and anionic dyes, in which, the theoretical maximum adsorption capacities were 888.27 mg/g and 1816.87 mg/g towards methylene blue (MB) and Congo red (CR), respectively. Especially, the aerogel’s core/shell layer exhibited hierarchical adsorption behavior without overlapping sites even in the binary dye systems. The adsorption performance of obtained amphoteric aerogel remained effective in a wide pH range and under different practical water systems. Moreover, the removal efficiencies for MB and CR were slightly reduced from 90.76 % and 99.66 % to 88.08 % and 91.39 %, respectively, after 5 adsorption-desorption cycles, and the aerogel’s structural integrity was also maintained due to its good compressive strength (487.16 KPa). In addition, the adsorption mechanism of PCS aerogel was investigated using adsorption kinetics, isotherm, thermodynamics, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. It was proved that the adsorption process was endothermic spontaneous-monolayer adsorption driven by electrostatic attraction and hydrogen bonding. Therefore, the prepared biobased aerogel was expected to be a prospective material for removing mixed dyes from wastewater.

Assessment of Organobentonite’s Adsorption Kinetics for Efficient Removal of Methylene Blue Dye from Aqueous Solutions

Assessment of Organobentonite’s Adsorption Kinetics for Efficient Removal of Methylene Blue Dye from Aqueous Solutions

A novel multifunctional photocatalytic membrane based on β-FeOOH for oily wastewater purification

In order to deal with the environmental pollution caused by complex oily wastewater, it is necessary to develop filtration membrane materials. However, significant challenges such as poor effect of emulsion separation, limited functionality, and susceptibility to membrane fouling require urgent resolution. Here, we successfully prepared a β-hydroxyl iron oxide/polydopamine-polyethylenimine/polyacrylonitrile (β-FeOOH/PDA-PEI/PAN) nanofiber membrane for treatment of complex wastewater by growing PDA-PEI on a blow-spinning PAN nanofiber membrane and decorating the membrane with β-FeOOH. The porous structure and the large number of hydrophilic groups greatly increase the hydrophilicity of the membrane and give the membrane high permeation fluxes (11531.26 L m−2 h−1) for surfactant-free kerosene-in-water emulsion. The loaded β-FeOOH nanorods increase the roughness of the membrane surface, which enhances the underwater superoleophobic ability of the membrane, and promotes the demulsification of the emulsion and makes it have high separation efficiency of 99.48 % for surfactant-stabilized kerosene-in-water emulsion. In addition, the β-FeOOH/PDA-PEI/PAN also exhibited high organic dye removal efficiency (99.38 %) due to the presence of β-FeOOH. The synergistic effect of low oil adhesion and photocatalysis enhances the antifouling and self-cleaning performances of the material. Significantly, the multifunctional membrane also shows exceptional oil/water separation ability and good stability. The presented synergistic strategy of β-FeOOH/PDA-PEI/PAN membrane materials represents a prospective candidate for the treatment of complex wastewater.

Decolorization of Acid Red 337 dye with hydroxyl and sulfate radical based advanced oxidation processes using different iron Catalyst: An experimental and statistical Investigation

The removal efficiencies of Acid Red 337 dye were investigated by combining advanced oxidation processes based on OH and SO4− radicals. The photocatalytic oxidation processes were carried out at the natural pH (5.4) and acidic pH (3.0) values of the dye solution. In the experiments, iron (II) sulfate (Fe2+) and potassium ferrioxalate (FeOx) were used as catalysts, hydrogen peroxide (H2O2) and peroxymonosulfate (PMS) were used as oxidants to compare dye removal efficiency and to determine the optimum doses. This comparison provided the opportunity to identify suitable catalysts and oxidants for dye removal. Furthermore, time-based comparisons were conducted from 2 to 10 min using the optimum catalyst doses. It was obtained that PMS was more effective as an oxidant in the presence of both iron catalysts for colour removal. The colour removal efficiency of 98.2 % was achieved in the PMS/Fe2+/UV process with doses of 1 mM PMS and 0.1 mM Fe2+ at pH 5.4 and an irradiation time of 10 min. In experiments using light-sensitive ferrioxalate (FeOx), colour removal was achieved in the PMS/FeOx/UV process with an efficiency of 97.8 %. Additionally, an artificial neural networks (ANNs) model effectively optimized the oxidation parameters, with predicted values closely matching the experimental data. The ANNs model yielded excellent statistical performance, with a root mean square error (RMSE) of 0.0317, 0.0223 and coefficient of determination (R2) of 0.9690 and 0.9854 for UV/Fe2+/H2O2-UV/FeOx/H2O2 and UV/Fe2+/PMS-UV/FeOx/PMS oxidation systems respectively.