Removal Of Industrial Dyes Research Articles

Engineering aspects of biosorption processes applied to the removal of industrial dyes

Engineering aspects of biosorption processes applied to the removal of industrial dyes

Hierarchical heterostructures of Bi2MoO6 microflowers decorated with Ag2CO3 nanoparticles for efficient visible-light-driven photocatalytic removal of toxic pollutants.

Developing highly active and durable visible-light-driven photocatalysts for the degradation of toxic pollutants is of vital significance. Herein, Ag2CO3 nanoparticles were in situ formed on Bi2MoO6 microflowers to produce Ag2CO3/Bi2MoO6 heterostructures via a facile procedure. The morphologies, phases, chemical compositions, and optical properties of Ag2CO3/Bi2MoO6 were examined by multiple characterization techniques. The Ag2CO3/Bi2MoO6 heterostructures exhibited substantially improved performance in the removal of industrial dyes (rhodamine B (RhB), methyl orange (MO), and methyl blue (MB)), and the antibiotic tetracycline hydrochloride (TC), compared with bare Bi2MoO6 and Ag2CO3 under visible-light irradiation. The enhancement of activity was attributed to the high charge-separation capacity, which results from the matched band alignment of the two components. The cycling experiments showed a good durability of Ag2CO3/Bi2MoO6. Holes were found to be the dominant active species accounting for the pollutant degradation. This compound is a promising candidate for wastewater treatment.

Ag3VO4 Nanoparticles Decorated Bi2O2CO3 Micro-Flowers: An Efficient Visible-Light-Driven Photocatalyst for the Removal of Toxic Contaminants.

Semiconductor-based photocatalysis is of great potential for tackling the environmental pollution. Herein, a novel hierarchical heterostructure of Bi2O2CO3 micro-flowers in-situ decorated with Ag3VO4 nanoparticles was developed by a facile method. Various characterization techniques have been employed to study the physical and chemical property of the novel catalyst. The novel catalyst was utilized for the photocatalytic removal of industrial dyes (rhodamine B, methyl orange) and tetracycline antibiotic under visible-light irradiation. The results indicated that Ag3VO4/Bi2O2CO3 heterojunctions showed a remarkably enhanced activity, significantly higher than those of bare Ag3VO4, Bi2O2CO3, and the physical mixture of Ag3VO4 and Bi2O2CO3 samples. This could be ascribed to an enhanced visible-light harvesting capacity and effective separation of charge carriers by virtue of the construction of hierarchical Ag3VO4/Bi2O2CO3 heterojunction. Moreover, Ag3VO4/Bi2O2CO3 also possesses an excellent cycling stability. The outstanding performance of Ag3VO4/Bi2O2CO3 in removal of toxic pollutants indicates the potential of Ag3VO4/Bi2O2CO3 in real environmental remediation.Highlights Novel architectures of Ag3VO4 nanoparticles modified Bi2O2CO3 micro-flowers were constructed.Novel Ag3VO4/Bi2O2CO3 exhibited excellent photocatalytic activity and stability.Ag3VO4/Bi2O2CO3 heterojunctions significantly promote the charge separation.

Sustainable adsorbents formed from by-product of acid activation of vermiculite and leached-vermiculite-LDH hybrids for removal of industrial dyes and metal cations

Abstract Hydrotalcite-like layered double hydroxide (LDH) materials were synthesized from liquid waste by-product produced during acid activation of vermiculite (raw (W) and expanded (Ve)), and by combining the waste with the activated mineral, novel hybrid vermiculite-hydrotalcite-like materials were obtained in one-pot synthesis. Batch system adsorption experiments were performed on fresh and calcined (at 450 °C) materials using two anionic dyes (Congo Red - CR, and Reactive Red 184 - R), a cationic dye (Astrazon Red - AR), and Cu2+. Calcination significantly increased the materials' adsorption capacities for all the pollutants. The highest adsorption capacities of the LDH derived from W were 289 ± 2, 137 ± 2, 38.2 ± 0.6 and 64 ± 2 mg g−1, while for the ones derived from Ve were 214 ± 2, 119.5 ± 0.3, 35.9 ± 0.7 and 66 ± 3 mg g−1 for CR, R, AR and Cu2+, respectively. The hybrids obtained from W attained removal levels of 238 ± 3, 111 ± 2, 44 ± 1 and 70 ± 1 mg g−1 and their counterparts derived from Ve reached 84 ± 1, 34.1 ± 0.5, 43 ± 2 and 75 ± 1 mg g−1 for CR, R, AR and Cu2+, respectively. Strong synergic effect on adsorption was observed in the hybrid materials, especially in these derived from Ve. These adsorbents had higher (up to 400%) adsorption capacities than theoretical ones prepared by mixing ex-situ appropriate amounts of activated vermiculite and LDH. All the materials were characterized by XRD, SEM-EDS, and ATR techniques. The proposed procedure is a sustainable approach to clay minerals valorization and my open new possibilities in fields such as wastewater treatment or catalysis.

Enhanced synthesis of silver nanoparticles by combination of plants extract and starch for the removal of cationic dye from simulated waste water using response surface methodology

In the present study, starched silver nanoparticles (St-AgNPs) were synthesized by using polyphenolic compounds from aqueous extracts of Malus domestica-Green Delicious (MD-GD) and Lagenaria siceraria (LS) with starch. This combination not only gears up the synthesizing parameters but also the removal efficiency of dyes making it facile to be used on industrial scale. The surface morphology of pure, crystalline and non-agglomerated, spherical NPs was determined by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) techniques. The reduction of Ag+1 to Ag0 by polyphenolic compounds from green reducing agents and their stabilization by starch was confirmed by Fourier Transform Infrared spectroscopy (FTIR) studies. St-AgNPs were then employed for the removal of industrial dye, Malachite Green (MG) by adsorption method. Response surface methodology (RSM) was employed to optimize the operating parameters (OP) including sorbent dosage, contact time, dye concentration and temperature. % Removal Efficiency (%RE) at optimized OP was found to be 85.01% and 95.90% for St-AgNPs-MD-GD and St-AgNPs-LS, respectively. It was observed that the Langmuir isotherm was best fitted for the St-AgNPs-MD-GD system while for other systems Dubinin–Radushkevich (D-R) was established more feasible at higher temperatures. The thermodynamic study was also conducted and ΔG°, ΔS°, and ΔH° were estimated. The kinetics of dye removal depicted the pseudo second order rate constant for St-AgNPs-MD-GD system, whereas pseudo first order was observed for the St-AgNPs-LS system. Desorption of dye from adsorbent and pHpzc were also investigated. The cost evaluation of adsorbent per cubic meter was also found. It was about 126.5US$ for St-AgNPs-MD-GD and 58.10US$ for St-AgNPs-LS. The results obtained from the present study represent that this improved process can be employed on the industrial scale in economical way.

Removal of Colored Organic Pollutants from Wastewaters by Magnetite/Carbon Nanocomposites: Single and Binary Systems

This work develops a methodology for selective removal of industrial dyes from wastewaters using adsorption technology based on magnetic adsorbents. The magnetic nanoparticles embedded within a matrix of activated carbon were tested as adsorbents for removal of industrial dyes from aqueous solutions. The effects of four independent variables, solution pH, initial concentration of pollutant, adsorbent dose, contact time, and their interactions on the adsorption capacity of the nanocomposite were investigated in order to optimize the process. The removal efficiency of pollutants depends on solution pH and increases with increasing the carbon content, with initial concentration of the pollutants, the temperature, and the dose of magnetite/carbon nanocomposites. Pseudo-second-order kinetic model was fitted to the kinetic data, and adsorption isotherm analysis and thermodynamics were used to elucidate the adsorption mechanism. The maximum adsorption capacities were 223.82 mg g−1 for Nylosan Blue, 114.68 mg g−1 for Chromazurol S, and 286.91 mg g−1 for Basic Red 2. The regeneration and reuse of the sorbent were evaluated in seven adsorption/desorption cycles. The optimum conditions obtained for individual adsorption were selected as starting conditions for simultaneous adsorption of dyes. In binary systems, in normal conditions, selectivity decreases in the order: Red Basic 2 > Nylosan Blue > Chromazurol S.

Regeneration performance of clay-based adsorbents for the removal of industrial dyes: a review.

The present review covers the regeneration capacity and adsorption efficiency of different adsorbents for the treatment of industrial dyes to control water pollution. Various techniques and materials have been employed to remove organic pollutants from water; however, adsorption techniques using cost-effective, ecofriendly, clay-supported adsorbents are widely used owing to their simplicity and good efficiency. Among all the natural adsorbents, activated carbon has been found to be the most effective for dye adsorption; however, its use is restricted due to its high regeneration cost. Clays and modified clay-based adsorbents are the most efficient clarifying agents for organic pollutants as compared to activated carbon, organic/inorganic, and composite materials. Regeneration is an important aspect to stimulate the adsorption efficiency of the exhausted/spent adsorbent for water treatment. A number of techniques, including chemical treatment, supercritical extraction, thermal, and photocatalytic and biological degradation, have been developed to regenerate spent or dye-adsorbed clays. This review discusses how these techniques enhance the adsorption and retention potential of spent low-cost adsorbents and reflects on the future perspectives for their use in wastewater treatment.

Synthesis of amphiphilic hyperbranched polyglycerol through “thiol-ene” chemistry and its application on the removal of industrial dyes

ABSTRACTAn amphiphilic dodecyl-modified hyperbranched polyglycerol (DSHPG) with the core–shell structure and good solubility in n-hexane is prepared through “thiol-ene” reaction. The concentration of dye or DSHPG, temperature, contacting time, and molecular weight of DSHPG were taken into consideration to evaluate the transfer capability. It is shown that the extraction effect of this polymer on cationic dyes is better than that on anionic dyes. With malachite green as the experimental dye, the value of removal ratio can be as high as 98.6% in the period of 120 min. This “molecular nanocapsules” can extract dyes with high extraction rate and good efficiency, and the extraction process can be well described with the pseudo-first-order model. The reusability investigation confirms that the DSHPG can obtain appropriate applications in the extraction of dyes from wastewater due to the high adsorption efficiency and environmental-friendly economy.

Removal of industrial dyes and heavy metals by Beauveria bassiana: FTIR, SEM, TEM and AFM investigations with Pb(II).

Presence of industrial dyes and heavy metal as a contaminant in environment poses a great risk to human health. In order to develop a potential technology for remediation of dyes (Reactive remazol red, Yellow 3RS, Indanthrene blue and Vat novatic grey) and heavy metal [Cu(II), Ni(II), Cd(II), Zn(II), Cr(VI) and Pb(II)] contamination, present study was performed with entomopathogenic fungi, Beauveria bassiana (MTCC no. 4580). High dye removal (88-97%) was observed during the growth of B. bassiana while removal percentage for heavy metals ranged from 58 to 75%. Further, detailed investigations were performed with Pb(II) in terms of growth kinetics, effect of process parameters and mechanism of removal. Growth rate decreased from 0.118h-1 (control) to 0.031h-1, showing 28% reduction in biomass at 30mgL-1 Pb(II) with 58.4% metal removal. Maximum Pb(II) removal was observed at 30°C, neutral pH and 30mgL-1 initial metal concentration. FTIR analysis indicated the changes induced by Pb(II) in functional groups on biomass surface. Further, microscopic analysis (SEM and atomic force microscopy (AFM)) was performed to understand the changes in cell surface morphology of the fungal cell. SEM micrograph showed a clear deformation of fungal hyphae, whereas AFM studies proved the increase in surface roughness (RSM) in comparison to control cell. Homogenous bioaccumulation of Pb(II) inside the fungal cell was clearly depicted by TEM-high-angle annular dark field coupled with EDX. Present study provides an insight into the mechanism of Pb(II) bioremediation and strengthens the significance of using entomopathogenic fungus such as B. bassiana for metal and dye removal.

Biodegradation of methylene blue from aqueous solution by bacteria isolated from contaminated soil

The use of biodegradation methods by microorganisms in the removal of industrial dyes are widely considered owing to their high efficiency and compatibility to the environment. Therefore, this study aims to evaluate the biodegradation of methylene blue (MB) from aqueous solution by bacteria isolated from contaminated soil. This study was performed in laboratory scale on bacteria isolated and purified from contaminated soil with methylene blue. Initially, the bacteria was isolated from contaminated soil. Thereafter, medium containing 50, 100, 200, 400, 800 and 1000 mg/l of methylene blue, 50 ml of salt medium with glucose and 2.5 ml of Brain-heart infusion (BHI) medium containing bacteria were prepared. The results of dye removal were analyzed using UV/Vis spectrophotometer at 665 nm. The results of purification and identification of the bacterial species which degrade methylene blue indicated that Pseudomonas aeruginosa was the dominant bacteria. In this study, the removal efficiency of bacteria was attained from 82.25 to 97.82% with an increase in initial MB concentration from 50 to 200 mg/l. Nevertheless, with increase in MB oncentration from 200 to 1000 mg/l, removal efficiency was reduced to 43.08%. The optimum concentration of MB removal was 200 mg/l. It is evident from the results that the bacteria had used methylene blue as an auxiliary source of carbon apart from glucose. Finally, it can be concluded that P. aeruginosa is an appropriate candidate for the removal of methylene blue from the environment. Keywords Biodegradation; Methylene blue; Bacteria; environmental pollution

Studies of the kinetics and mechanism of the removal process of proflavine dye through adsorption by graphene oxide

Abstract Proflavine, a nitrogen-containing dye is used for DNA staining and as an efficient marker, however, it is harmful to body cells, and its efficient removal is essential. In this work, graphene oxide (GO) has been used as an adsorbent for the removal of the dye through the process of adsorption. Though GO is now being used as an adsorbent for the removal of industrial dyes, very few experiments have been done on biologically useful dyes. GO is synthesized from graphite powder by the modified Hummer's method and is characterized by X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), Raman and ultra-violet spectroscopies, etc. These characterization techniques indicate the presence of oxygen containing functional groups, e.g., carbonyl, carboxyl and hydroxyl groups on the graphene sheets. These sheets are held well apart by these groups. Parameters like concentration of the adsorbent, pH and temperature have been varied to find the optimum conditions for the most efficient removal of the dye molecules from the solution. Then, for the optimum external conditions, the time dependence of the adsorption was analyzed using pseudo-first and pseudo-second orders kinetics. The adsorption isotherms were also obtaining throws light on the mechanism of the adsorption process which we investigated further by using FTIR characterization.

Green synthesis of highly stable carbon nanodots and their photocatalytic performance.

The present study reports a novel, facile, biosynthesis route for the synthesis of carbon nanodots (CDs) with an approximate quantum yield of 38.5%, using Musk melon extract as a naturally derived-precursor material. The synthesis of CDs was established by using ultraviolet-visible (UV-vis) spectroscopy, Dynamic light scattering, photoluminescence spectroscopy, X-ray diffraction, transmission electron microscopy and Fourier transform infrared (FTIR) spectroscopy. The as-prepared CDs possess an eminent fluorescence under UV-light (λex = 365 nm). The size range of CDs was found to be in the range of 5-10 nm. The authors further explored the use of such biosynthesised CDs as a photocatalyst material for removal of industrial dye. Degradation of methylene blue dye was performed in a photocatalytic reactor and monitored using UV-vis spectroscopy. The CDs show excellent dye degradation capability of 37.08% in 60 min and reaction rate of 0.0032 min-1. This study shows that synthesised CDs are highly stable in nature, and possess potential application in wastewater treatment.

Pentaazatetraethylene supported polyacrylamide (PAA-N5) as a novel adsorbent for the efficient removal of industrial dyes from aqueous solutions: adsorption isotherms and kinetics

Modified cross-linked polyacrylamide (PAA) with pentaazatetraethylene group (N5) was used as a chelating agent for the removal of Congo red (CR) and Calmagite (CG) as industrial dyes from aqueous solutions. The proposed adsorbent, PAA-N5, was prepared by transamidation reaction in aqueous and non-aqueous media by Hofmann reaction. All experimental conditions including adsorbent dosage, contact time, pH value, and initial dye concentration were optimized to get efficient removal of dyes. The removal of CR and CG is pH dependent and the optimum pH values for the maximum removal efficiencies were found to be 7.0. The experimental isotherm data were analyzed using Langmuir, Freundlich, and Temkin isotherm models. The results showed that the adsorption behavior of CR and CG on PAA-N5 was well fitted with the Langmuir model at 25 °C and the maximum adsorption capacities were obtained for CR and CG to be 396.07 and 1980.1 mg/g, respectively. The kinetic adsorption rates were modeled using the pseudo-first order, pseudo-second order, and intra-particle models. It was found that the intra-particle and pseudo-second order model were well fitted for CR and CG adsorption with highest correlation coefficients, respectively.

Graphene oxide/zinc oxide nanocomposite: A superior adsorbent for removal of methylene blue - statistical analysis by response surface methodology (RSM)

Graphene oxide (GO) was synthesized from natural graphite using the Hummers method. Graphene oxide/zinc oxide nano composite were synthesized by mixing of GO and ZnO solutions and then freeze drying. The adsorptive performance of the nano composite was investigated in the removal of methylene blue. The statistical study of the adsorption process was carried out by response surface methodology (RSM). Experimental variables such as sample pH, adsorption time, dye concentration and adsorbent dosage were considered for the optimization process. The process was optimized by response surface methodology (RSM) through Box-Benhken method. The optimum conditions, predicted by the RSM were obtained at pH, contact time, initial dye concentration and adsorbent dosage of 6, 8.5 min, 5 ppm, 0.02 g, respectively. The removal of methylene blue under optimum conditions was predicted to be 98.17%and resulted in 97% in practice. The Pareto analysis suggested that order of relative importance of the factors were as follows: adsorbent dosage > dye concentration > adsorption time > pH. Under optimized conditions, GO/ZnO nano composite showed a higher capacity than GO, carbon nanotube (CNT), ZnO and ZnO/CNT for adsorption of methylene blue. The study revealed that GO/ZnO could be a promising adsorbent for removal of industrial dyes from wastewaters.

Assessment of drying temperature of sugarcane bagasse on sorption of reactive blue 5G dye

We studied the effect of drying temperature of sugarcane bagasse (SB) on sorption of reactive blue 5G (RB5G) dye to test whether SB is a suitable biosorbent for industrial dye removal. First we assessed a set of SB characteristics that could influence the sorption capacity of dried biomass. Kinetic drying of the SB biomass was measured at different drying temperatures, ranging from 30 °C to 80 °C. We used a static gravimetric method to perform equilibrium moisture sorption experiments at drying temperatures of 35–65 °C. In addition, we measured activation energy and net isosteric heat of sorption. SB biomass was characterized as a heterogeneous low-porous and hygroscopic material, with a series of functional groups on its surface. A Lewis thin-layer model best represented the kinetic drying data. In addition, moisture diffusion into the SB biomass was characterized by a rate-controlling step in the drying process. Equilibrium moisture sorption data showed the expected effects of temperature controlling the sorption capacity and a multilayer sorption process. A sigmoidal sorption isotherm data was best represented by a BET model. A high energy demand is required for moisture removal from biomass as suggested by the measured isosteric heat of moisture sorption. Drying temperature did not influence the RB5G adsorption capacity of bagasse, therefore any drying temperature in the range of 30 °C to 80 °C could be used to make this material feasible as an industrial adsorbent.

Bioremoval of an azo textile dye, Reactive Red 198, by Rhizopus oryzae

Among all environmental contaminants, industrial dye is one of the major pollutants of soil, water, and air. There are different chemical, physical, and biological methods for removal of all types of synthetic media from the environment. One common method is to utilize microorganisms like yeast, fungi, or bacteria. In this study, we identified a soil-derived microorganism and evaluated its efficacy for removal of industrial dye from wastewater. First, a strain of fungus isolated from various samples of soil was defined via colonial identification and DNA sequencing. Second, the bioremoval activity of the defined fungus (Rhizopus oryzae) in treating the water-soluble monoazo dye, Reactive Red 198, in synthetic media was evaluated using high-performance liquid chromatography. The effects of varying factors in processing, including dye concentration, fungal volume, time, and pH were determined. Under optimal conditions, a dye removal rate of 96% was obtained.

Bioadsorbtion of industrial dyes from aqueous solution onto water hyacinth (Eichornia crassipes): equilibrium, kinetic, and sorption mechanism study

In the present investigation, bioadsorbtion of different industrial dyes, such as, methylene blue, Congo red, crystal violet, and malachite green from aqueous solution have been performed by water hyacinth using lab-scale batch bioreactor. Maximum removal of different dyes, such as, methylene blue, Congo red, crystal violet, and malachite green were found at pH 7.0, 6.0, 8.0, and 8.0, respectively. Optimum doses of adsorbent were found to be 6.5, 7.5, 6.0, and 7.0g L−1 for methylene blue, Congo red, crystal violet, and malachite green, respectively. Optimum initial dyes concentration were found to be 65, 75, 70, and 75 mg L−1 for methylene blue, Congo red, crystal violet, and malachite green, respectively. Optimum contact time for adsorbtion was found to be 5 days for all the dyes. The maximum percentages of removals were found to be 90, 88, 92, and 90% for methylene blue, Congo red, crystal violet, and malachite green, respectively. The adsorption kinetic data are adequately fitted to the pseudo-second-order adsorption kinetic model. The Langmuir isotherm model well described the equilibrium dyes uptake. High value of intra particle diffusion parameter (Ki), and diffusion coefficient (Di) suggest that water hyacinth is an effective adsorbent for the removal of industrial dyes from wastewater.