Removal Of Toxic Dyes Research Articles

Removal of toxic dyes from aqueous solutions by adsorption onto a novel activated carbon prepared from chestnut shell

Removal of toxic dyes from aqueous solutions by adsorption onto a novel activated carbon prepared from chestnut shell

Removal of toxic dye (Rhodamine B) from aqueous solutions by natural smectite (SMC) and SMC-nanoTiO2

Removal of toxic dye (Rhodamine B) from aqueous solutions by natural smectite (SMC) and SMC-nanoTiO2

Selective removal of toxic organic dyes using Trӧger base-containing sulfone copolymers made from a metal-free thiol-yne click reaction followed by oxidation.

Three copolymers TCP1–3 bearing Trӧger's base (TB) units intercalated with various thioether groups were synthesized using a catalyst-free thiol-yne click reaction. TCP1–3 display excellent solubility in common organic solvents allowing for their structural, and photophysical characterization. The thioether groups in TCP1–3 were selectively oxidized into their respective sulfone derivatives under mild oxidation reaction conditions affording the postmodified copolymers TCP4–6. Investigation of organic dye uptake from water by TCP1–6 proved their efficiency as selective adsorbents removing up to 100% of the cationic dye methylene blue (MEB) when compared to anionic dyes, such as Congo red (CR), methyl orange (MO) and methyl blue (MB). The sulfone-containing copolymers TCP4–6 display superior and faster MEB removal efficiencies with respect to their corresponding synthons TCP1–3.

Synergistic Effects of Graphene Oxide Grafted Chitosan & Decorated Mno2 Nanorods Composite Materials Application in Efficient Removal of Toxic Industrial Dyes

Synergistic Effects of Graphene Oxide Grafted Chitosan & Decorated Mno2 Nanorods Composite Materials Application in Efficient Removal of Toxic Industrial Dyes

Sustainable fabrication, optical properties and rapid performance of bio-engineered copper nanoparticles in removal of toxic methylene blue dye in an aqueous medium

Copper nanoparticles have obtained due to the green process in a one-pot reaction at ambient temperature using Malva Sylvesteris leaves extract. The plant extract has used as a reducing and capping agent, providing stability and avoiding oxidation of synthesized copper nanoparticles for more than eight months. Many techniques have exploited for the investigation of optical and physicochemical properties of copper nanoparticles. UV-VIS spectroscopy showed two bands at different locations for the extract and nanoparticles at 340 and 390 ​nm, respectively. Fourier transform infrared spectroscopy confirmed the role of bioactive materials in the plant extract as a reducing and capping agent. X-ray diffraction tool affirmed the crystalline nature of fabricated copper nanoparticles at average (20 ​nm) and showed a centred cubic structure. Field emission scanning electron microscope (FESEM) chart illustrated the roughly spherical shape of distributed copper nanoparticles. The copper nanoparticles showed high-efficiency removal of methylene blue dye in water samples.

Superior adsorption removal of dye and high catalytic activity for transesterification reaction displayed by crystalline CaO nanocubes extracted from mollusc shells

Nano structuring and surface functionalization of industrially important Calcium Oxide (CaO) material has broad spectrum applications in daily civic life. In this context, cubical shape CaO nanoparticles are extracted via an eco-friendly green approach from dead mollusc shells collected from sea beaches. The surface structural morphology of as-prepared catalyst is thoroughly characterized by XRD, DLS particle size, SEM, TEM-EDS, TGA, TPD, BET surface area (80 m2g−1) analysis, adsorption and electro-kinetic (zeta potential/point of zero charge) properties etc. measurement. Practical applications of this cubic nano crystal (lattice constant 12.51 Å and size 60–80 nm) for adsorption removal of toxic neutral red dye and catalytic activity for transesterification are systematically studied relative to commercial CaO particles under similar experimental conditions. Influential factors responsible for optimum dye adsorption isotherms, kinetics/thermodynamics of catalytic activity, stability and reusability/leaching are properly investigated in correlation with its observed crystal structural and physicochemical properties.

Stable silver nanoparticle doped mesoporous biochar-based nanocomposite for efficient removal of toxic dyes

In this present study, biochar-based silver nanocomposite (Ag-nBC) has been synthesized by combining (i) AgNPs, synthesized biochemically using Shorea robusta leaf extract, and (ii) S. robusta leaf biochar, produced via mild thermal pyrolysis (300 °C) and tested for toxic dye removal efficiency. The Ag-nBC was characterized by FESEM-EDX, BET, XRD, XPS, TGA, and FTIR, found to be irregular, heterogeneous, and mesoporous, containing a significant amount of surface functional groups. The Ag-nBC showed > 90% removal for Congo red (CR) and Rhodamine B (RhB), where the dye removal experiments were found to be spontaneous exothermic, followed Freundlich isotherm and pseudo-second order reaction kinetic model. The adsorption mechanism of CR involved surface complexation through specific electrostatic attraction and H-bonding, while RhB exhibited only surface complexation. Notably, this heterogeneous Ag-nBC system showed excellent stability at wide ranges of pH and promising reusability, suggesting great potential for waste biomass minimization and dye effluent treatment.

Modified Electrospun Polymeric Nanofibers and Their Nanocomposites as Nanoadsorbents for Toxic Dye Removal from Contaminated Waters: A Review.

Electrospun polymer nanofibers (EPNFs) as one-dimensional nanostructures are characterized by a high surface area-to-volume ratio, high porosity, large number of adsorption sites and high adsorption capacity. These properties nominate them to be used as an effective adsorbent for the removal of water pollutants such as heavy metals, dyes and other pollutants. Organic dyes are considered one of the most hazardous water pollutants due to their toxic effects even at very low concentrations. To overcome this problem, the adsorption technique has proven its high effectiveness towards the removal of such pollutants from aqueous systems. The use of the adsorption technique depends mainly on the properties, efficacy, cost and reusability of the adsorbent. So, the use of EPNFs as adsorbents for dye removal has received increasing attention due to their unique properties, adsorption efficiency and reusability. Moreover, the adsorption efficiency and stability of EPNFs in aqueous media can be improved via their surface modification. This review provides a relevant literature survey over the last two decades on the fabrication and surface modification of EPNFs by an electrospinning technique and their use of adsorbents for the removal of various toxic dyes from contaminated water. Factors affecting the adsorption capacity of EPNFs, the best adsorption conditions and adsorption mechanism of dyes onto the surface of various types of modified EPNFs are also discussed. Finally, the adsorption capacity, isotherm and kinetic models for describing the adsorption of dyes using modified and composite EPNFs are discussed.

Pharmaceutical and Biotechnological Importance of Actinobacterial Products

Abstract: Many compounds produced by marine microbes possess significant pharmaceutical applications. Actinobacteria are one among the microbes producing a variety of antibiotics. Apart from antibiotics, it also produces many novel enzymes and important pharmaceutical products. Actinobacteria serves as a reservoir of antibiotics and novel chemical compounds and it contributes 80% of antibiotics available in the market. It was continuously been explored for novel bioactive compounds and new chemical entities. Many of them are more promising against microbial pathogens and even drug resistant pathogens. Apart from antibiotics, many enzymes are also produced by actinobacteria. The usage of enzymes in diverse pharmaceutical and biotechnological industries is gaining momentum and moreover, there is a growing demand for the discovery of novel metabolites and enzymes to fulfill the requirement of pharmaceutical industry. Apart from all these products actinobacteria also produces biosurfactants. Members of actinobactaerial genera have been extensively used in the removal of toxic dyes and other toxic pollutants. In this review, the up to date information available on the pharmaceutical and biotechnological uses of actinobacterial products and the scope for screening of actinobacterial genome for production of novel compounds for pharmaceutical applications have been discussed. Key words: Actinobacteria, Metabolites, Antibiotics, Enzymes, Biosurfactants, Dye degradation.

Synthesis of Fe3O4@chitosan@ZIF-8 towards removal of malachite green from aqueous solution: Theoretical and experimental studies

Discharges of dyes-containing wastewater from industries have created global concern. Removal of these substances from aqueous solution is very important and essential. Magnetic chitosan coated with ZIF-8 was prepared successfully and used to eliminate cationic dye malachite green in various conditions. To find the effectiveness of ZIF-8 towards malachite green removal, their surface interaction was investigated using density functional theory (DFT) calculations for the first time which the results show physisorption of malachite green on ZIF-8. The characteristics of adsorbent synthesized were evaluated using XRD, FTIR, FE-SEM, TEM and TGA analysis. In addition, the influence of different parameters on malachite green removal was investigated. The results showed that pH = 7, 40 mg of adsorbent dosage, 10 mg/L initial concentration, 40 min contact time and temperature of 25 °C were obtained as an optimum values for Fe3O4@chitosan@ZIF-8. The equilibrium data were in good agreement with the Langmuir model having maximum capacity (qm) value of 3.282 mg/g. The experimental data revealed that the adsorption process obeyed to pseudo-second order kinetic model. It was concluded that Fe3O4@chitosan@ZIF-8 can be utilized as an efficient and effective adsorbent for removal of toxic malachite green dye from aqueous solution.

Enhanced adsorptive removal of toxic anionic dye by novel magnetic polymeric nanocomposite: optimization of process parameters

The novel magnetic manganese ferrite/polyaniline nanocomposite (MnFe2O4-PANI-NC) was prepared for eradication of toxic anionic methyl orange (MO) dye from wastewater at almost neutral pH condition by impregnating polyaniline onto manganese ferrite. The characterization properties of MnFe2O4-PANI-NC was found by XRD, FEGSEM, TEM, FTIR, VSM, and BET analysis to analyze the adsorption process. The MO dye removal efficiency by sono-assisted adsorption was found to be 90.03% at solution pH 6.0 and sonication time 15 min, whereas the batch stirring and shaking gives the MO dye removal of ∼65% to ∼74% at same experimental condition. The adsorption kinetics followed pseudo-second order kinetics model with additional effect of intra-particle diffusion. The linear fitting of isotherm model followed Langmuir isotherm with equilibrium adsorption capacity of 175.44 mg/g at room temperature. The MO dye adsorption mechanism onto MnFe2O4-PANI-NC can be described by the synergistic effect of electrostatic interaction and π–π dispersive bonding between anionic MO dye molecules and positively charged MnFe2O4-PANI-NC surface. The central composite design (CCD) predicts the maximum MO dye removal of 99.01% at optimum condition of sonication time 14 min, MnFe2O4-PANI-NC dose 0.5 g/L and initial methyl orange (MO) dye concentration 10.0 mg/L. The MnFe2O4-PANI-NC is found to be stable even after 5th consecutive cycle of adsorption-desorption without compromising its adsorptive potential. Thus the fabricated MnFe2O4-PANI-NC can be a potential adsorbent material for sono-assisted removal of MO dye for large scale application due to less dependency on solution pH, facile fabrication technique, and rapid as well as decent dye uptake capacity.

Aquatic plant, Ipomoea aquatica, as a potential low-cost adsorbent for the effective removal of toxic methyl violet 2B dye

Ipomoea aquatica (IA) was investigated for its potential as a low-cost adsorbent to remove toxic methyl violet 2B (MV2B) dye in aqueous solutions. Optimising parameters such as the effects of contact time, medium pH and ionic strength (using NaCl, NaNO3, KCl and KNO3) were investigated. The results indicated that 150 min were sufficient for the adsorption to reach an equilibrium state and no adjustment of pH medium was necessary. Batch adsorption experiments such as adsorption isotherm, thermodynamics and kinetics were investigated and the experimental isotherm data were fitted to six isotherm models, namely Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Redlich-Peterson and Sips, with the latter being the best-fit isotherm model showing maximum adsorption capacity (qmax) of 267.9 mg g−1. Thermodynamics studies indicated adsorption of MV2B to be exothermic in nature, occurring spontaneously. The kinetics was best described by the pseudo-second-order model. Regeneration of IA pointed to its reusability, maintaining high adsorption capacity even up until Cycle 5 when treated with acid (HCl) and base (NaOH). Functional groups such as hydroxyl and amine groups which could be involved in the adsorption of MV2B were determined using FTIR spectroscopy, and the point of zero charge of IA was found to be at pH 6.81.

Flower- and Grass-like Self-Assemblies of an Oleanane-Type Triterpenoid Erythrodiol: Application in the Removal of Toxic Dye from Water.

Erythrodiol (3β-olean-12-ene-3, 28-diol) (C30H50O2) 1 is a nanosized oleanane-type fused 6-6-6-6-6 pentacyclic triterpeneoid extractable from the dried leaves of olive (Olea europia). One step reduction of oleanolic acid extracted from Lantana camara also yields the same compound. The triterpenoid has one secondary −OH group attached at C3 of the “A” ring and one primary −OH group at C28 present at the junction of the “D” and “E” rings. Here, we report the spontaneous self-assembly of erythrodiol in different neat organic liquids and aqueous-organic liquid mixtures. The nanosized dihydroxy triterpenoid having an oleanane-type lipophilic rigid skeleton self-assembled in liquids, yielding nanosized fibrils, microsized flowers, and grass-like architectures via formation of densely assembled fibrils and petals or 2D sheets. The microstructures of the self-assemblies have been characterized by different techniques like optical microscopy, electron microscopy, atomic force microscopy, FTIR, and wide angle X-ray diffraction studies. The porous self-assemblies having a large surface area obtained from 1 were capable of adsorbing toxic fluorophores like rhodamine-B, rhodamine-6G, methylene blue, and crystal violet (CV). Moreover, removal of the aforementioned toxic pigments has also been demonstrated from their aqueous solutions by using UV–visible spectrophotometry and epifluorescence microscopy.

Evaluation of a Dynamic Bioremediation System for the Removal of Metal Ions and Toxic Dyes Using Sargassum Spp.

This work presents the results obtained in the design and manufacture of a simple, economic and ecological filter based on Sargassum spp. (Sspp), consisting of the species S. natans and S. fluitans, for the elimination of organic and inorganic toxic substances. The main objective is to make use of Sspp, as the massive amounts of this alga arriving at the Mexican Caribbean coast have caused serious problems over recent years. The toxic substances treated were organic dyes (methyl blue, methyl orange and methyl red) and the metal ion, lead (II). To obtain optimal removal conditions, grinding of the Sspp used, its mass and humidity were evaluated. In the design of the filter the area, flow rate and the number of layers were evaluated. Removal rates of almost 100%, 65% and 25% were obtained for methylene blue, methyl red and methyl orange respectively, and in the case of lead (II), values up to 95% were obtained. After the tests, the Sspp was characterized, using Fourier Transform Infrared (FTIR) spectroscopy and scanning electron microscopy, showing the presence of the dyes and the ionic species. These results demonstrate the efficiency of the dynamic Sspp-based filtration system proposed, which can be industrially scaled for the treatment of water contaminated with these kinds of substances.

Adsorptive removal of cationic methylene blue and anionic Congo red dyes using wet-torrefied microalgal biochar: Equilibrium, kinetic and mechanism modeling.

This study aims to investigate the adsorption behavior of cationic and anionic dyes of methylene blue (MB) and Congo red (CR) onto wet-torrefied Chlorella sp. microalgal biochar respectively, as an approach to generate a waste-derived and low-cost adsorbent. The wet-torrefied microalgal biochar possessed microporous properties with pore diameter less than 2nm. The optimum adsorbent dosage of wet-torrefied microalgal biochar for MB and CR dyes removal were determined at 1g/L and 2g/L, respectively, with their natural pHs as the optimum adsorption pHs. The determined equilibrium contact times for MB and CR were 120h and 4h, respectively. Based on the equilibrium modeling, the results revealed that Langmuir isotherm showed the best model fit, based on the highest R2 coefficient, for both the adsorption processes of MB and CR using the wet-torrefied microalgal biochar, indicating that the monolayer adsorption was the dominant process. From the modeling, the maximum adsorption capacities for MB and CR were 113.00mg/g and 164.35mg/g, respectively. The kinetic modeling indicated the adsorption rate and mechanism of the dyes adsorption processes, which could be crucial for future modeling and application of wet-torrefied microalgal biochar. From the results, it suggests that the valorization of microalgae by utilizing wet-torrefied microalgal biochar as the effective adsorbent for the removal of toxic dyes with an approach of microalgal biorefinery and value-added application to the environment is feasible.

Removal of toxic malachite green dye from aqueous environment using reduced magnetic graphene oxide as an efficient and reusable adsorbent

ABSTRACT In the present study, reduced magnetic graphene oxide (rmGO) was synthesized and explored as an adsorbent for the removal of MG from the aqueous environment in a batch system. The successful synthesis of rmGO was confirmed from XRD, FT-IR and EDX spectral analyses. SEM images of rmGO show the irregular-sheet like morphological structure with anchored magnetic nanoparticles with enhanced thermal stability and 4.25 as point of zero charge (PZC). During the adsorption study, the best experimental conditions for various operating parameters such as pH (6.5), contact time (120 min), adsorbent dose (30 mg), temperature (358 K), and MG concentration (20 µgmL–1) were achieved. The data follows the pseudo-second-order kinetic and Langmuir-Freundlich adsorption models with maximum adsorption capacity of 158.95 mgg−1. Moreover, the adsorption process was spontaneous/nonspontaneous and endothermic (13837.8 kJmol−1) in nature with the increased randomness at the solid-solution boundary. The rmGO was used for five consecutive adsorption cycles, maintain good adsorption capacity (reaching 115.4 ± 1.98 mgg−1 at the 5th cycle) and selectively in a binary mixture (selectivity coefficient values for congo red, methylene blue and sunset yellow as 10.27, 10.16, and 9.30 respectively) on the adsorption toward MG dye. The efficient, recyclable, chemical and thermally stable nature of the synthesized rmGO declare it as a promising candidates for the treatment of colored water and wastewater.

Peptide-Based Gel in Environmental Remediation: Removal of Toxic Organic Dyes and Hazardous Pb2+ and Cd2+ Ions from Wastewater and Oil Spill Recovery.

A dipeptide-based synthetic amphiphile bearing a myristyl chain has been found to form hydrogels in the pH range 6.9-8.5 and organogels in various organic solvents including petroleum ether, diesel, kerosene, and petrol. These organogels and hydrogels have been thoroughly studied and characterized by different techniques including high-resolution transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, and rheology. It has been found that the xerogel obtained from the peptide gelator can trap various toxic organic dyes from wastewater efficiently. Moreover, the hydrogel has been used to remove toxic heavy metal ions Pb2+ and Cd2+ from wastewater. Dye adsorption kinetics has been studied, and it has been fitted by using the Freundlich isotherm equation. Interestingly, the gelator amphiphilic peptide gels fuel oil, kerosene, diesel, and petrol in a biphasic mixture of salt water and oil within a few seconds. This indicates that these gels not only may find application in oil spill recovery but also can be used to remove toxic organic dyes and hazardous toxic metal ions from wastewater. Moreover, the gelator can be recycled several times without significant loss of activity, suggesting the sustainability of this new gelator. This holds future promise for environmental remediation by using peptide-based gelators.

Application of macroalgal biomass derived biochar and bioelectrochemical system with Shewanella for the adsorptive removal and biodegradation of toxic azo dye

The present study aimed towards adsorptive removal of the toxic azo dye onto biochar derived from Eucheuma spinosum biomass. Characterization of the produced biochar was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET). Eucheuma spinosum biochar (ES-BC) produced at 600 °C revealed a maximum adsorption capacity of 331.97 mg/g towards reactive red 120 dye. The adsorption data fitted best to the pseudo-second order kinetics (R2 > 0.99) and Langmuir isotherm (R2 > 0.98) models. These adsorption models signified the chemisorption mechanism with monolayer coverage of the adsorbent surface with dye molecules. Furthermore, the adsorption process was mainly governed by electrostatic interaction, ion exchange, metal complexation, and hydrogen bonding as supported by the solution pH, FTIR, XPS, and XRD investigation. Nevertheless, alone adsorption technology could not offer a complete solution for eliminating the noxious dyes. Therefore, the bioelectrochemical system (BES) equipped with previously isolated marine Shewanella marisflavi BBL25 was intended for the complete remediation of azo dye. The BES II demonstrated highest dye decolorization (97.06%) within 48 h at biocathode where the reductive cleavage of the azo bond occurred. Cyclic voltammetry (CV) studies of the BES revealed perfect redox reactions taking place where the redox mediators shuttled the electrons to the dye molecule to accelerate the dye decolorization. Besides, the GC-MS analysis revealed biotransformation of the dye into less toxic metabolites as tested using a phyto and cytogenotoxicity.

An efficient and comparative adsorption of Congo red and Trypan blue dyes on MgO nanoparticles: Kinetics, thermodynamics and isotherm studies

Cubic phase of MgO nanoparticles were prepared by microwave-assisted combustion synthesis and investigated for the removal of toxic dyes like Congo Red (CR) and Trypan blue (TB). The crystallite size of the MgO nanoparticle was calculated to be 18 nm from XRD pattern. The sample was further characterized by FTIR, TGA and FESEM techniques. The dyes were subjected to prototypical batch adsorption process, including investigation of different parameters like MgO dosage, dye concentration, solution pH, agitation speed and temperature. It was found that, 0.2 g of MgO NPs showed maximum removal efficiency for both the dyes (more than 98%), having 25 ppm of dye concentration at an acidic pH (3–4). The maximum loading capacity of MgO NPs was obtained to be 136 mg/g and 132 mg/g for CR and TB, respectively. Different thermodynamic parameters like ΔG0, ΔH0 and ΔS0 were measured. The negative ΔH0 and the positive ΔS0 values for both the dyes correspond to an exothermic process and an increase in randomness of the adsorbent and dye. The isotherm analysis exhibited that the Freundlich model fits better to the experimental equilibrium data, suggesting heterogeneous surface of the nanoparticles. Whereas, the kinetic data revealed a pseudo 2nd order rate for adsorption process.

Biodegradable natural carbohydrate polymeric sustainable adsorbents for efficient toxic dye removal from wastewater

The toxic anionic dye of methyl orange encapsulation was studied using biodegradable natural carbohydrate polymeric adsorbents of rice flour (RF) and graham flour (GF). The adsorbents were characterized by several instrumentations to understand the functionality and potential use. The dye adsorption parameter was measured based on the solution acidity, contact time, initial concentration effect, competing anions affinity, bonding mechanism, maximum adsorption capacity and reuses with biodegradability. The solution acidity was exhibited the key factor, and the suitable pH 7.0 and 5.50 were selected for RF and GF adsorbent, respectively based on the efficiency. The competing ions were not adversely affected in the dye adsorption as defined by the stable bonding mechanism. The adsorption data were highly fitted with the Langmuir adsorption model with monolayer coverage. The determined maximum adsorption was 173.24 and 151.27 mg/g for RF and GF, respectively, which was comparable with the other forms of materials. The desorption data was promising as the RF and GF adsorbents were used several cycles and therefore, the biodegradable adsorbents are promising to use in the real sample treatment to clean up the contaminated water.