Dye Removal Potential Research Articles

Cu and Fe doped NiCo2O4/g-C3N4 nanocomposite ferroelectric, magnetic, dielectric and optical properties: Visible light-driven photocatalytic degradation of RhB and CR dyes

A novel Cu and Fe doped NiCo2O4/g-C3N4 nanocomposites were prepared with varying dopant concentrations via a precipitation and ultrasonication route. The resulting Ni1-xCuxCo2-yFeyO4/g-C3N4 nanocomposites were characterized by advanced techniques and effect of doping was investigated based on ferroelectric, dielectric, magnetic, electrical, optical and photocatalytic properties. The results confirmed the FCC spinel geometry of NiCo2O4 nanoparticles with a spherical shape (ranging from 18 to 32 nm). The absorption range in the visible region and the suppression of electron-hole recombination were investigated through UV–Vis diffused reflectance spectra and PL analysis. The Cu and Fe doping significantly influenced the dielectric properties and the AC conductivity of Ni1-xCuxCo2-yFeyO4/g-C3N4 nanocomposites was also increased with Cu and Fe substitution. The photocatalytic activity of doped Ni0.75Cu0.25Co1.5Fe0.25O4/g-C3N4 (NCCF3/g-CN) were evaluated for the removal of rhodamine B (RhB) and Congo red dyes under visible light irradiation. The NCCF3/gCN nanocomposite exhibited the dye removal of 89 % versus undoped nanocomposite (50 %). The rate constants for CR dye degradation were found to be 0.04366 and 0.1009 (min−1) for the NCCF3/gCN nanocomposite and undoped nanocomposite NiCo2O4/gC3N4 (NCO/gCN), respectively. The efficient separation of charge carriers was facilitated by the migration of photo-induced electrons from the g-C3N4 surface to the NiCo2O4. The influence of pH and catalyst dose on the kinetics of photocatalytic activity revealed a significant effect on the dye degradation rate. The results indicate that the NiCo2O4/g-C3N4 shows a promising potential for photocatalytic removal of dyes under visible light illumination, which could be employed for the removal of dyes from the effluents.

Zero-valent iron supported by dendritic mesoporous silica nanoparticles to purify dye wastewater

The presence of different types of organic dyes in water stream will clearly give rise to unexceptional side effects on living organisms. Emerging physical or chemical methods have been developed for the treatment of dye-involving water, but the exploration for adequate design strategy and technique available is still ongoing. Here, zero-valent iron (ZVI) was prepared by a liquid phase sodium borohydride reduction approach and then integrated with dendritic mesoporous silica nanoparticle (DMSN) to construct Janus magnetic adsorbent (denoted as ZVI-DMSN), which could be employed to purify dye wastewater. The structure, magnetic properties and dye adsorption results of ZVI-DMSN were systematically investigated. The ZVI component can enable efficient solid-liquid separation through magnetic separation route, and, more importantly, provided additional binding sites for adsorption process to increase the adsorption capacity. The thermodynamic analysis of adsorption indicated that the adsorption of typical organic dyes was an irreversible, spontaneous and endothermic process. Moreover, ZVI-DMSN adsorbent was recyclable, showing a regeneration efficiency of more than 80% after 5 cycles. We believe that ZVI-DMSN, as an inexpensive adsorbent material with excellent adsorption properties, e.g., short time, high efficiency and large capacity, will host vast potential for removal of dyes in water bodies.

Structural, compositional study, and thermal behavior of TiO2/Cr2O3/GO nanocomposite for methylene blue degradation

This study emphasizes the methylene blue (MB) dye degradation potential of mixed systems of TiO2, Cr2O3, and graphene oxide (GO) based nanocomposites (NCs). Structural and thermal studies for TiO2, Cr2O3, TiO2/GO, Cr2O3/GO, TiO2/Cr2O3, and TiO2/Cr2O3/GO compositions are executed. XRD, FTIR, and EDX confirm the lack of impurities within compositions. Additionally, the EDX, and FTIR results are agreeing with each other in highly oxygenated NC formation. Regarding the morphological study, TEM micro-graphing supports TNC formation owing to aggregation-growing inhibition that causes surface area widening and enhances dye removal potential. On the other hand, FESEM is agreeing with TEM that TNC shows a lowering in grains size and aggregations that TiO2, and Cr2O3 record 60, and 75 nm, respectively. This agreement with TEM, and FESEM in widening surface area and adding crystallinity defects raising which recommended the occurrence of chemical decontamination operation. The thermodynamic study reports almost equal values of enthalpy (ΔH) and activation energy (i.e. according to the CR model: 155.6, 147.7 KJ mole−1, respectively), this is explained by the presence of TNC in the condensed phase through the temperature scope (545–750 °C), besides its significant stability. Moreover, the EDX, and FTIR results are agreeing TiO2/Cr2O3NC shows intermediate thermal behavior between its pure ingredient, leaving 97.3 % as a residual. TNC total weight loss hits 9.2 %. This percentage is contributed to four stages, 1.3 % (30–300 °C/dehydration), 2.3 % (300–545 °C/structure rearrangement), 3.5 % (545–750 °C/GO reduction process & structure rearrangement), and 2.1 % (750–100 °C/GO reduction). The inorganic compositions show acceptable thermal stability for environmental usage. The stated NCs able to be recycled that TiO2/Cr2O3/GO shows a minor decline in MB degradation potential that decreases from 98.8 to 87.5 % after five cycles.

Equilibrium and DFT modeling studies for the biosorption of Safranin O dye from water samples using Bacillus subtilis biosorbent

Current study deals with the biosorption of Safranin O dye from water by using high potential Bacillus subtilis biosorbent material. The presence of functional groups and surface morphology of biosorbent was analyzed by using sophisticated analytical techniques such as FT-IR (Fouirer Transform Infrared Spectrophotometer), SEM (Scanning Electron Microscopy), EDX (Energy Dispersive X-Ray Analysis), and TGA (Thermogravimetric Analysis). To check the dye removal potential of Bacillus subtilis sorbent, batch adsorption experiments were performed under the optimized conditions. The biosorption experiments showed that the Bacillus subtilis sorbents remove 80% of safranin O dye from water. The biosorption mechanism is depends upon the solution pH thus the maximum biosorption was observed at (5.5–6.5). Moreover, the biosorbent dose has been optimized and it has observed that the maximum concentration of safranin O dye has been removed using the 50 mg.L−1 of Bacillus subtilis. The biosorption equilibrium data were well fitted by the Langmuir adsorption isotherm due to good regression coefficient value (R2=0.98) and better Langmuir capacity (0.383 mmol.g−1), while the kinetic studies indicated that the biosorption followed the pseudo-second-order model. The thermodynamic parameters values showed that the biosorption is process is endothermic and spontaneous nature. In addition, molecular docking was also performed to examine the interaction between the safranin O dye molecule and the Bacillus subtilis bacterial cell line.

Antibacterial and Dye Removal Potential of Modified Kaolinite for the Treatment of Drinking Water

Antibacterial and Dye Removal Potential of Modified Kaolinite for the Treatment of Drinking Water

Fe3O4 embedded κ-carrageenan/sodium alginate hydrogels for the removal of basic dyes

Here, we introduce κ-carrageenan and sodium alginate based hydrogel (CAG-NaAlg-cl-polyAA) and hydrogel nanocomposite (CAG-NaAlg-cl-polyAA/Fe3O4) through a free radical crosslinking method using acrylic acid/ N,N′- methylenebisacrylamide as a monomer/crosslinker system. The hydrogel is stimuli-responsive and its water absorption efficiency is enhanced through the optimization of synthesis parameters. The synthesized superabsorbents have been sequentially characterized through HR-TEM, powder XRD, FTIR, SEM-EDS, and XPS analysis. The average particle size of Fe3O4 nanoparticles stabilized through the CAG-NaAlg-cl-polyAA hydrogel matrix is 10.7 ± 2.5 nm. The CAG-NaAlg-cl-polyAA hydrogel exhibited > 95 % dye removal efficiency for the removal of basic dyes (auramine O, crystal violet and malachite green), whereas the % dye removal potential of CAG-NaAlg-cl-polyAA/Fe3O4 is enhanced upto 99 % after the incorporation of Fe3O4 nanoparticles. Langmuir adsorption is the most favorable adsorption isotherm with R2 = 0.992 (auramine O, AU), 0.989 (malachite green, MG), and 0.974 (crystal violet, CV). Kinetic studies indicate that the adsorption of AU, CV, and MG follows pseudo 2nd order kinetics. Moreover, the reusability of the fabricated samples upto five consecutive cycles further explores its potential for the separation of basic textile dyes from industrial wastewater.

Environmentally benign approach for the efficient sequestration of methylene blue and coomassie brilliant blue using graphene oxide emended gelatin/κ-carrageenan hydrogels

Herein, we report the synthesis and characterization of gelatin/κ-carrageenan crosslinked polyacrylic acid hydrogel (GT-CAG-cl-polyAA) and graphene oxide incorporated hydrogel nanocomposite (GOHNC) through a free radical crosslinking pathway. Under optimized reaction conditions, GT-CAG-cl-polyAA displayed 486 % maximum swelling percentage. TEM image depicted wrinkled silk veil wave-type surface morphology of graphene oxide (GO), whereas, the SEM analysis indicated the porous nature of the GT-CAG-cl-polyAA and GOHNC capable of accumulating a large number of water/dye molecules. GT-CAG-cl-polyAA exhibited 96.11 % and 82.16 % dye removal potential for the adsorption of methylene blue (MB) and coomassie brilliant blue (CB), respectively under optimized conditions. GOHNC enhanced the % dye removal efficiency (98.39 % for MB and 94.50 % for CB). The maximum adsorption capacity of GOHNC for the removal of CB and MB was 312.7 mg/g and 94.9 mg/g, respectively. The adsorption of CB and MB exhibited best fitting with Flory-Huggins adsorption isotherms data. The negative values of ΔG° and positive values of ΔS° which were obtained from the adsorption isotherm plot suggested the thermodynamic feasibility of the adsorption. Also, the samples were reusable for up to five consecutive cycles without any degradation and hence suggested a considerable pathway for the separation of textile dyes.

Antarctic yeasts: potential use in a biologic treatment of textile azo dyes

We investigated the dye-removal potential of a collection of 61 cold-adapted yeasts from the King George Island, Antarctica, on agar plates supplemented with 100 mg L–1 of several textile dyes; among which isolates 81% decolorized Reactive Black 5 (RB-5), with 56% decolorizing Reactive Orange 16, but only 26% doing so with Reactive Blue 19 and Acid Blue 74. Furthermore, we evaluated the ligninolytic potential using 2,2ʹ-azino-bis(3-ethylbenzothiazoline-6-sulfonic-acid) diammonium salt-, 3,5-dimethoxy-4-hydroxybenzaldehydazine-, or manganese-supplemented plates but detected no activity, possibly due to a dye-removal mechanism involving reductases. The removal kinetics were studied in liquid medium supplemented with 100 mg L–1 of RB-5 in a selection of 9 yeasts. The highest volumetric-removal rates (η) were found for Candida sake 41E (4.14 mg L–1 h–1), Leucosporidium muscorum F20A (3.90 mg L–1 h–1), and Cystofilobasidium infirmominiatum F13E (3.90 mg L–1 h–1). Different UV–Vis spectra were obtained if the dye removal occurred by biodegradation or biosorption/bioaccumulation. L. muscorum F20A was selected to study the dye-removal mechanism of RB-5 and the effect of different chemical and environmental parameters on the process. Optimum dye-removal conditions were obtained with 10 g L–1 of glucose within an initial medium pH range of 5.0 to 6.0. Up to 700 mg L–1 of dye could be removed in 45 h. High-performance liquid chromatography profiles obtained were consistent with a biodegradation of the dye. Phytotoxicity was estimated by calculating the 50%-inhibition concentration (IC50) with Lactuca sativa L. seeds. These findings propose psychrophilic yeasts as a novel environmentally suitable alternative for the treatment of dye-industry wastewaters.

Decolourization of malachite green dye by endolichenic fungi from the lichen Usnea sp.: A novel study on their dye removal potential

ObjectiveThis novel study explored the potential of two endolichenic fungi, Pseudopestalotiopsis theae (PT, accession number MG881833) and Astrocystis bambusae (AB, accession number MH370741) in decolorizing Malachite Green (MG). MethodsTheir efficacy in dye decolorization was compared to non-endolichenic fungus Trichoderma asperellum (TA, accession number KP792512). Decolorization test was performed using MG (100 ppm) for 14 days (absorbance at 617 nm) to determine decolorization efficiency (DE, %). The pellet was collected for FTIR analysis (4000 to 700 cm−1, 50-scan speed) while the supernatant was analysed with UV-spectral analysis (300–800 nm) to detect for biodegradation. ResultsP. theae demonstrated the highest decolorization efficiency (DE%) at 89.22%, followed by T. asperellum (76.19%) and A. bambusae (67.69%). Common functional groups (i.e., OH, COOH, NH, CH, CO, CH) were detected in all isolates and their roles in biosorption were evident by the shifts in peaks and peak intensity. Biodegradation of MG was concluded based on UV-spectra peaks at 617 nm, which were significantly reduced (or absent). ConclusionThis study is the first to reveal that endolichenic fungi P. theae and A. bambusae are capable of decolorizing the toxic dye malachite green.

Development of biogenic bimetallic Pd/Fe nanoparticle–impregnated aerobic microbial granules with potential for dye removal

The objective of this study was to develop bimetallic core–shell Pd/Fe nanoparticles on the surface of aerobic microbial granules (Bio-Pd/Fe) and to evaluate their dye removal potential using a representative dye, methyl orange (MO). The aerobic microbial granules (1.5 ± 0.32 mm) were grown for 70 days in a 3-L glass sequencing batch reactor (SBR) with a 12-h cycle time. The Bio-Pd/Fe formation was catalyzed by the Bio-H2 gas produced by the granules. The developed Bio-Pd/Fe was further used for MO removal from aqueous solutions, and the reaction parameters were optimized by response surface methodology (RSM). The XRD, SEM, EDAX, elemental mapping, and XPS studies confirmed the formation of Bio-Pd/Fe. Under the optimized removal conditions, 99.33% MO could be removed by Bio-Pd/Fe, whereas removal by Bio-Pd, Bio-Fe, aerobic microbial granules, and heat-killed granules were found to be quite low (68.91 ± 0.2%, 76.8 ± 0.3%, 19.8 ± 0.6%, and 6.59 ± 0.2%, respectively). The mechanism of removal was investigated by UV–visible spectroscopy, redox potential analysis, HR-LCMS analyses of the solution phase, and XRD and XPS analyses of the solid sorbent. The degradation products of MO exhibited m/z values corresponding to 292, 212, and 160 m/z. The remnant toxicity of the intermediate degradation products was analysed using freshwater algae, Scenedesmus sp. And Allium cepa, as indicator organisms. These assays suggested that after the treatment with Bio-Pd/Fe, MO was transformed to a lesser toxic form.

Enhanced Photocatalytic Activity of Spherical Nd3+ Substituted ZnFe2O4 Nanoparticles.

In this study, nanocrystalline ZnNdxFe2−xO4 ferrites with x = 0.0, 0.01, 0.03 and 0.05 were fabricated and used as a catalyst for dye removal potential. The effect of Nd3+ ions substitution on the structural, optical and photo-Fenton activity of ZnNdxFe2−xO4 has been investigated. The addition of Nd3+ ions caused a decrease in the grain size of ferrites, the reduction of the optical bandgap energies and thus could be well exploited for the catalytic study. The photocatalytic activity of the ferrite samples was evaluated by the degradation of Rhodamine B (RhB) in the presence of H2O2 under visible light radiation. The results indicated that the ZnNdxFe2−xO4 samples exhibited higher removal efficiencies than the pure ZnFe2O4 ferrites. The highest degradation efficiency was 98.00%, attained after 210 min using the ZnNd0.03Fe1.97O4 sample. The enhanced photocatalytic activity of the ZnFe2O4 doped with Nd3+ is explained due to the efficient separation mechanism of photoinduced electron and holes. The effect of various factors (H2O2 oxidant concentration and catalyst loading) on the degradation of RhB dye was clarified.

Green synthesis of Fe nanoparticles by using Mangifera indica extract and its application in photo-catalytic degradation of dyes.

An exceedingly facile green approach that produces a reliable adsorbent based on a transition metal such as Iron (Fe) using Mangifera indica leaf extract at room temperature is described. A single pot method was used for synthesis with no capping agents, surfactants or other templates. The main intention of this study is to synthesize iron nanoparticles from leaf extract (Mangifera indica) and examine its degradation potential for photo-catalytic removal of dyes (Congo red and brilliant green) from wastewater. Characterization of synthesized nanoparticles was executed by pHpzc, scanning electron microscopy and Fourier transform infrared spectroscopy studies and results confirm the presence of iron nano-sheets with biomolecules. All photo-catalytic experimental results were assessed by sum of squared estimate of errors and simple linear regression R2 with dye concentration, pH, contact time and dose rate as dependent and independent variables. Adsorption experimental data was verified by kinetics and isothermal models. Results showed that Langmuir and pseudo second order models give best fitness towards the photo-catalytic adsorption procedure. Thermodynamics revealed that adsorption mechanism is endothermic, described by the values of changes in Gibbs free energy, enthalpy and entropy, and is chemisorption in nature, with spontaneous processes. Overall photo-catalytic adsorption execution with synthesized iron nanoparticles and simple biomass of Mangifera indica gives satisfactory results for treating dye wastewater.

Bifunctional gelatin/dextrin hybrid backbone based fluorescent chemo-sensor for the detection of tannic acid and removal of eosin yellow dye

In this work, we developed a green strategy for the fabrication of bio-based gelatin/dextrin semi-interpenetrating network (Gel-dex-cl-polyAAm) and carbon quantum dots (CQDs) nanocomposite (CQDs/Gel-dex-cl-polyAAm) for the detection of tannic acid and removal of eosin yellow dye present in water sample. The synthesis of semi-interpenetrating network (semi-IPN) was done under hot air reaction conditions using acrylamide and N,N′-methylenbisacrylamide monomer-crosslinker system. The maximum swelling response of the synthesized semi-IPN was found to be 597% after optimizing all the process parameters. The nanocomposite was derived through in-situ incursion of carbon quantum dots inside the crosslinked matrix of semi-IPN and it was capable of detecting the presence of tannic acid, selectively in wastewater through fluorescence quenching analysis. Maximum quenching efficiency was observed to be 98%. The synthesized devices were also found to be an effective absorbent for the removal of eosin yellow dye from contaminated water. Maximum dye removal potential in case of nanocomposite was found to be 92%. Adsorption isotherm and kinetics studies indicated the applicability of flory huggin's adsorption isotherm along with 2nd order kinetics. The industrial applicability of the samples was depicted from regeneration and reusability experimental essay.

Magnetic alginate beads with high basic dye removal potential and excellent regeneration ability

The adsorption of crystal violet (CV) dye onto magnetic alginate (MAlg) composite from aqueous solutions was studied. Experiments were carried out as function of contact time, dosage, temperature, pH, and CV concentration in the solutions. Optimum CV uptake was observed at equilibrium pH 7 and most of the CV was sorbed within 30 min. The equilibrium adsorption data were analyzed using two common adsorption models: Langmuir and Freundlich. The results revealed that Langmuir isotherm fit the experimental results well. The maximum adsorption capacity obtained from Langmuir isotherm equation was 0.113 mmol g−1at 298 ± 1 K. The kinetics adsorption of CV onto MAlg composite was investigated using the pseudo first-order and pseudo second-order kinetic models. The results showed that the adsorption of CV onto MAlg composite followed pseudo second-order kinetic model. Thermodynamic data indicated that the adsorption process is an endothermic and spontaneous reaction. Due to its outstanding adsorption capacities, MAlg composite is an excellent adsorbent for the removal of CV. The composite regeneration was greater than 98.6% with 0.01 mol/L HCl, and MAlg composite could be repeatedly utilized for CV removal with negligible loss in sorption capacity.

Structural study, photoluminescence and photocatalytic properties of La2O3 ⋅ Fe3O4 ⋅ ZnO,AgO ⋅ NiO ⋅ ZnO and La2O3 ⋅ AgO ⋅ ZnO nanocomposites

Nanocomposites La2O3⋅Fe3O4⋅ZnO,AgO⋅NiO⋅ZnO and La2O3⋅AgO⋅ZnO were synthesized by a co-precipitation method and characterized by FTIR, XRD and PL spectroscopic analysis. Surface morphology of La2O3⋅Fe3O4⋅ZnO,AgO⋅NiO⋅ZnO and La2O3⋅AgO⋅ZnO was studied by AFM. It was observed that the PL behavior of the catalysts depend on excitation wavelength. Dye removal potential of the La2O3⋅Fe3O4⋅ZnO,AgO⋅NiO⋅ZnO and La2O3⋅AgO⋅ZnO composite materials was examined by the photocatalytic process. Suitable pH for the degradation of MV 6B was found to be 9 for all three catalysts. The experimental studies exposed that AgO⋅NiO⋅ZnO and La2O3AgO⋅ZnO can be used as efficient photocatalysts because of their dye removal ability and reusability. Nanocomposite AgO⋅NiO⋅ZnO was found to be an outstanding anti-bacterial agent.

Biosorption of Food Green 3 by a novel green generation composite biosorbent from aqueous environment

ABSTRACTA green type composite biosorbent composed of pine, oak, hornbeam, and fir sawdust biomasses modified with cetyltrimethylammonium bromide (CTAB) was first used for biosorption of an unsafe synthetic food dye, Food Green 3 from liquid medium in this study. Batch studies were carried by observing the effects of pH, dye concentration, biosorbent amount, and contact time. The equilibrium data were analyzed using Freundlich, Langmuir, and Dubinin–Radushkevich equations. Freundlich model gave a better conformity than other equations. The maximum dye removal potential of biosorbent was found to be 36.6 mg/g based on Langmuir isotherm. The pseudo-first-order, pseudo-second-order, Elovich, and intra-particle diffusion models were applied to clarify the process kinetics of biosorption. The mechanism studies suggested the biosorption process obeying Elovich kinetics and involving pore diffusion. The estimated values of biosorption free energy from Dubinin–Radushkevich isotherm (E value <8 kJ/mol) and thermodynamic studies (0 < ΔG° < −20 kJ/mol) implied a spontaneous, feasible, and physical process. Hence, this investigation suggested that the CTAB modified mix sawdust biomass could be a promising biosorbent for biosorption of such problematic dyes from impacted media.

Utilization of two agrowastes for adsorption and removal of methylene blue: kinetics and isotherm studies.

Fresh water streams contaminated with synthetic dye-containing effluents pose a threat to aquatic and human life either by preventing aquatic photosynthesis or by entering into the food chain. Adsorptive removal of such dyes with potent biosorbents is an important technique to reduce bioaccumulation and biomagnifications of the dyes in human life. We report use of betel nut (BN) husk and banana peel (BP), two most abundant ligno-cellulosic wastes, as efficient adsorbents for the removal of the basic dye methylene blue (MB). The adsorption by BN and BP was consistently high over wide ranges of pH and temperature, suggesting their dye removal potential in diverse conditions. Physico-chemical studies, e.g. scanning electron microscopy and Fourier transform-infrared spectroscopy studies, revealed changes in surface topology and functional moieties of BN and BP post adsorption, implying dye interaction with the biomass surface. The dye adsorption in both cases followed pseudo-second-order kinetics. While adsorption of MB by BN was better fitted with the Temkin isotherm model, adsorption with BP followed both Langmuir and Freundlich isotherm models. Our studies concluded that both adsorbents efficiently remove MB from its aqueous solution with BP proved to be marginally superior to BN.

Pseudo first ordered adsorption of noxious textile dyes by low-temperature synthesized amorphous carbon nanotubes

Amorphous carbon nanotubes (a-CNTs) were synthesized by solid state reaction. The as prepared a-CNTs were characterized by X-ray diffraction, field emission scanning and high resolution transmission electron microscope and Raman spectroscopy. As-synthesized a-CNTs were used for, the first time, for removing different organic dyes from water. The dyes mainly include Rhodamine B and Methyl Orange and systematic batch mode studies of a-CNTs assisted adsorption have been executed in detail. The removing efficiency of a-CNTs has also been investigated for various sorption parameters like contact time, dosage, pH, initial dye concentration, contact time etc.It is seen that a-CNTs can be material of potential for removal of dyes. In case of Rhodamine B, the maximum time for removal was 45min whereas for Methyl orange rapid removal was plausible in about 30min even in ambient condition. The experimental data have been well correlated with classical Langmuir-Freundlich and Temkin adsorption models.

Biosorption of malachite green dye from aqueous solution by calcium alginate nanoparticles: Equilibrium study

Alginates, in the form of beads and hydrogels have been widely investigated for their effectiveness in pollutant removal from aqueous solution. Nanoparticles with the advantage of greater surface area and ease of mixing with contaminated water are more effective in water purification and are not much investigated. Here the dye removal potential of calcium cross-linked alginate nanoparticles, prepared by green method, is investigated in batch adsorption technique. Effect of system variables such as pH, initial dye concentration, contact time, temperature and adsorbent dose on sorption process was studied. The synthesized nanoparticles exhibited a maximum dye removal efficiency of 98.5% at 60°C and at pH10 in 5min contact time. The experimental data fitted well with Langmuir model indicating monolayer adsorption mechanism and the sorption process obeyed pseudo second order kinetics. The rate-limiting mechanism in the biosorption of the dye involves a combination of intraparticle diffusion and surface adsorption. The investigation of thermodynamic parameters such as ∆G0, ∆H0 and ∆S0 confirmed the spontaneity, randomness and endothermic nature of the biosorption process. This study demonstrates that calcium alginate nanoparticles are promising biosorbent for the removal of dyes from aqueous solution as exemplified by malachite green.

Ultrasound-assisted treatment of chitin: evaluation of physicochemical characteristics and dye removal potential

AbstractChitin was ultrasonically treated to improve its dye adsorption characteristics. The effects of ultrasound cycle and amplitude on the chitin Sauter diameter (DSauter), deacetylation degree (DD), crystallinity index (CI) and specific surface area (SBET) were evaluated. The untreated and treated chitin samples were applied to remove Methylene Blue (MB) and Ponceau 4R (P4R) dyes from aqueous solutions. Chitin DSauter decreased from 625 to 250 μm after the ultrasonic treatment. Chitin DD was not influenced by the ultrasound treatment, remaining in the range of 42.3–45.8%. For all ultrasonic conditions, the chitin CI values decreased from 86.3% (untreated chitin) to 70.0%. The specific surface area (SBET) increased from 2.2 to 38.5 m2 g-1. After ultrasonic treatment, the dye removal percentage increased from 53.2 to 74.3% for MB and from 3.3 to 20.2% for P4R, at initial dye concentration of 50 mg l-1. Treated chitin can be used seven times maintaining the same performance. The ultrasound-assisted treatment is an alternative to improve the chitin dye adsorption characteristics.