Decolorization Of Textile Dyes Research Articles

Comparatively Investigation of Textile Dye Decolorization by a White Rot Fungus and Various Bacterial Strains

The aim of this study is to comparatively investigate the decolorization of Reactive Blue 171 (RB 171) by using three different bacterial strains as Bacillus megaterium A1 (A1), Gordonia sp. MC-D1 (D1) and Bacillus pumilus D3 (D3) and also a white rot fungus (Pleurotus ostreatus). All tested bacteria were incubated with RB 171 dye at 150 mg/L concentration for 24-72 h under static or agitated (150 rpm) conditions while the fungus was incubated with 150 mg/L of the dye under the same conditions for 3-24 h. The highest bacterial decolorization values were obtained after 72 h of incubation under static conditions and the maximum decolorization rates were detected as 84, 83 and 75% for A1, D1 and D3, respectively. However, the color of RB 171 dye was removed at 93% rate by Pleurotus ostreatus under static conditions after 24 h of incubation. Similar results were also obtained from the agitated studies of the tested fungal and bacterial strains except A1. The maximum decolorization values obtained with A1, D1 and D3 at 150 rpm, 72 h were 30, 88 and 89%, respectively. The highest decolorization activities of Pleurotus ostreatus were 93% for both static and agitated (150 rpm) conditions. In addition, zymogram analyzes of the fungal culture fluids obtained from SBM and SBM containing 150 mg/L RB 171 were also performed to detect the presence of laccase.

Laccase producing bacteria influenced the high decolorization of textile azo dyes with advanced study

Recent year, bacterial laccases are increasing interest in the field of industry and environmental applications especially decolorization of azo dyes. In industry, the dyes are present in stable nature including chemicals and lights. Due to these defects, the novel approaches are needed to removal of dyes before discharging into the environment. Among the various technologies, biological treatment methods and their strategies are very important, because of the decolorization and detoxification. Consecutively, biological mediated dyes removal are emerged with high potential especially microbes. Microbial laccases creates up new opportunities for their commercial applications. In this study, laccases were produced from Bacillus cereus (B. Cereus) and Pseudomonas parafulva (P. parafulva) by sub merged fermentation. For immobilization, the produced laccases were subjected to purify using 80% saturated ammonium sulphate and followed by dialysis. Then, crude laccases were immobilized through copper-alginate entrapment method. The maximum immobilized enzyme activity of the immobilized laccases were shown pH 8 at 50 °C and pH 7 at 40 °C for B. Cereus and P. parafulva respectively. In contrast, the normal enzyme activity was pH 10 at 40 °C and pH 8 at 40 °C were indicated for Bacillus cereus and P. parafulva respectively. Next, the free and immobilized laccases were performed the decolorization of three azo dyes T-blue, yellow GR and orange 3R, and exhibited that the 91.69 and 89.21% of Orange 3R were completely decolorized by both the B. Cereus and P. parafulva laccases when compared with free laccases enzymes. The confirmation of decolorization was monitored by UV–vis spectroscopy and FTIR spectroscopy, which clearly confirm the changes of peaks when compared with normal laccases. Finally, we have concluded that the B. Cereus and P. parafulva laccases are very important in azo dye decolorization and these used in future biological treatment of dyeing effluents.

Performance of Meyerozyma caribbica as a novel manganese peroxidase-producing yeast inhabiting wood-feeding termite gut symbionts for azo dye decolorization and detoxification

For hazardous toxic pollutants such as textile wastewater and azo dyes, microbial-based and peroxidase-assisted remediation represents a highly promising and environmentally friendly alternative. Under this scope, gut symbionts of the wood-feeding termites Coptotermes formosanus and Reticulitermes chinenesis were used for the screening of manganese peroxidase (MnP) producing yeasts intended for decolorization and detoxification of textile azo dyes, such as Acid Orange 7 (AO7). To this end, nine out of 38 yeast isolates exhibited high levels of extracellular MnP activity ranging from 23 to 27 U/mL. The isolate PPY-27, which had the highest MnP activity, was able to decolorize various azo dyes with an efficiency ranging from 87.2 to 98.8%. This isolate, which represents the molecularly identified species Meyerozyma caribbica, was successfully characterized in terms of morphological and physiological traits, as well as enzymatic activities. Almost complete decolorization was achieved by the MnP-producing M. caribbica strain SSA1654 after 6 h of incubation with 50 mg/L of the sulfonated azo dye AO7 at 28 °C with an agitation speed of 150 rpm. The maximum decolorization efficiency of AO7 reached 93.8% at 400 mg/L. The decolorization of AO7 was confirmed by Fourier transform infrared (FTIR) and UV–Vis spectral analysis. High performance liquid chromatography (HPLC) and gas chromatography–mass spectrometry (GC–MS) were used to identify AO7 decomposition intermediates. Based on UV–Vis spectra, FTIR, HPLC, and GC–MS analyses, a plausible AO7 biodegradation mechanism pathway was explored, showing azo bond (-N=N-) cleavage and toxic aromatic amines mineralization CO2 and H2O. Microtox® and phytotoxicity assays confirmed that the AO7 metabolites produced by the strain SSA1654 were almost non-toxic compared to the original sulfonated azo dye.

Laccases produced by Peniophora from marine and terrestrial origin: A comparative study

Although fungal laccases have been widely applied in environmental and industrial processes, little is known about laccases produced by marine fungi. In this study, the laccases from basidiomycetes of marine ( Peniophora sp. CBMAI 1063) and terrestrial ( Peniophora cinerea CCIBt 2541) origin were compared. Using crossflow filtration and anionic exchange chromatography, these laccases were partially purified and characterized. The marine fungus produced two laccase isoforms, whereas the terrestrial strain produced five. The enzymatic pool of the terrestrial Peniophora showed higher affinity (K M ) with the tested substrates. On the other hand, laccases from the marine fungus presented higher thermal resistance. The optimum temperature (55 °C) and pH values (4.0 with ABTS and 5.5 with SYG) were the same for both fungi. No significant difference was observed in the reactive blue dye decolorization rates (from 61.17 to 67.38%) after incubation with the laccases from both Peniophora strains and the pure commercial laccase from Trametes versicolor. The increase in toxicity only observed in the experiments using the laccases from the marine Peniophora strain indicates different decolorization mechanisms. This is the first report on reactive blue textile dye decolorization by laccases from the genus Peniophora , expanding their potential for biotechnological application. In this study, the adaptation of the Peniophora strains to the environments from where they were isolated was evidenced, and differences in their laccase isoforms and enzymatic characteristics were observed. The results highlight the advantage of the marine-derived fungus for laccase production under saline conditions and improve the knowledge on marine enzymes. • Laccases produced by marine and terrestrial Peniophora strains were compared. • The results revealed fungal adaptation to their original environment. • Different laccase isoforms were produced by these Peniophora strains. • Optimum T °C and pH were the same, while K M and thermal resistance were different. • Textile dye decolorization probably occurred by different enzymatic mechanisms.

Immobilization of a peroxidase from Moringa oleifera Lam. roots (MoPOX) on chitosan beads enhanced the decolorization of textile dyes

The textile industry is essential, but it is also responsible for causing environmental problems, particularly the discharge of dyes. In this context, this study aimed to immobilize a previously purified peroxidase, called MoPOX, on glutaraldehyde-activated chitosan beads in order to improve the potential for textile dye decolorization. The chitosan beads were activated with 8% glutaraldehyde for 1 h, and the immobilization was performed at 30 °C, pH 5.2 for 4 h. Scanning Electron Microscopy (SEM) analyses were used to observe the differences in the chitosan beads after immobilization. The optimum temperature dropped from 70 °C to 30 °C after immobilization, but immobilized MoPOX demonstrated excellent heat stability. The optimum pH remained 5.2, while the apparent kinetic constant value (Km) of immobilized MoPOX (14.67 mM) was lower in comparison to free MoPOX (46.8 mM). The immobilized enzyme showed improved activity after long storage times, and it could retain 40 % of its original activity even after 5 cycles. The potential for decolorization of different textile dyes was considerably enhanced after immobilization, reaching more than 80 %. Also, MoPOX showed no toxicity towards Artemia salina. Overall, the findings point to the promising potential of using immobilized MoPOX as a biocatalyst in a variety of biotechnological applications.

Electrochemical determination of harmful catechol and rapid decolorization of textile dyes using ceria and tin doped ZnO nanoparticles

Electrochemical sensing of toxic pollutants as well as the degradation of toxic dyes using cost effective nanoparticles-based photocatalyst are one of the most effective ways to reduce environmental contaminants. Herein, ZnO and different percentage (1, 3, 5 & 10%) of Ce and Sn doped ZnO nanoparticles were synthesized by a facile chemical method. The synthesized nanoparticles were used as modified electrode towards electrochemical detection of catechol (CA). It was found that the limit of detection and the sensitivity of the Ce/ZnO (5%) to be 0.21 μM and 0.494 μM μA−1, respectively. The doped ZnO exhibited lower band gap compared to pure ZnO, which facilitates to rapid photocatalytic degradation (~93%) of textile dyes (Crystal Violet & Rhodamine B) and catechol under visible light radiation. The environmental pollutants such as catechol, crystal violet and rhodamine B dye were effectively determined and degraded very successfully using couple of techniques such as cyclic voltametric and photodegradation.

Adsorption-biodegradation coupled remediation process for the efficient removal of a textile dye through chemically functionalized sugarcane bagasse.

Textile dye effluents have many deleterious effects; therefore, it is essential to remove before releasing into waterbodies. This study developed a two-step process for decolorization of textile dye using sugarcane bagasse (SCB). The first step of the process involved functionalization of SCB with alginic acid and applying as packing material in column and assessing its performance for adsorptive removal of Drimarene red. The designed column showed 90% removal of the dye in dye-aqueous solution whereas 80% removal in dye-house wastewater. Adsorption capacity was increased at first 10min and then gradually decreased with time. Breakthrough point was not achieved during the 60min of experiment. Three non-equilibrium models were applied to understand the column bed properties. In the second step, the adsorbed dye molecules in SCB were degraded using an edible fungus Pleurotus sp. to obtain a dye-free nitrogen-rich bagasse. The fungus-treated SCB showed no residual toxicity and a considerable improvement in nitrogen content (from 0.14% to 0.62%) was noticed after the study of elemental profile. New design of the column bed, the processes of the chemical functionalization of the SCB, and bioremediation of dye treated bagasse through Pleurotus sp. offer a novel solution for efficient and safe disposal of textile dyes. PRACTITIONER POINTS: Two-step process for remediation of a textile dye using an agrowaste and Pleurotus sp. Chemical functionalization of an agrowaste for enhanced dye removal. New process of adsorption-fungal degradation for safe disposal of the dyes. Novel technology for a sustainable use of the agrowaste for environmental safety.

Molecular characterization of marine bacterial isolates of Visakhapatnam coast—efficacy in dye decolorization and bioremediation of cadmium

BackgroundMicrobial community is one of the diversified communities of the marine environment. Studies have shown that microorganisms isolated from the marine environment are metabolically active and have adapted to life in the ocean. The marine microorganisms use various survival strategies to combat heavy metal stress and decolorization of various textile dyes, thus playing an important role in the bioremediation of cadmium and degradation of textile dyes. The present study deals with the isolation and 16S rRNA molecular characterization of M3 and M8 bacterial strains isolated from marine water samples collected from Visakhapatnam harbor. M3 and M8 isolates were also checked for their efficacy in the removal of cadmium and decolorization of various textile dyes from the environment. ResultsThe water sample was subjected to tube dilution method to isolate bacterial strains, and ten different isolates were screened. The biochemical tests were performed for the isolates to prove their validity and 16S rRNA molecular sequencing and phylogenetic analysis for species identification. Out of interest, two bacterial strains, namely, M3 and M8 were subjected to 16S rRNA molecular sequencing and phylogenetic analysis and were identified as Bacillus subtilis and Pseudomonas resinovorans. The two bacterial strains showed promising dye degradation property when checked with nine different textile dyes of wavelength ranging from 400 to 600 nm and removal of cadmium from the growth medium. ConclusionThe present study demonstrates the isolates M3 and M8 to be potential strains having dye decolorization and bioremediation of cadmium applications.

Optimization and efficacy studies of Laccase immobilized on Zein-Polyvinyl pyrrolidone nano fibrous membrane in decolorization of Acid Red 1

Abstract Azo dyes are widely used in textile industries. A significant portion of these recalcitrant dyes are being discharged to the natural waters. Due to their low biodegradability they pose serious pollution problems if untreated. In this work, decolourization studies of Acid Red 1 (AR1) by laccase enzyme immobilized onto zein–polyvinyl pyrrolidone (PVP) composite nanofiber is done. The nanofibers were characterized by scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) analysis. pH and temperature profiles of immobilized enzyme were found to be broader than its free counterpart. The Km value was found to be 0.243 mM for free laccase and 0.958 mM for immobilized laccase. Similarly, Vmax for the free enzyme was 3.572 U/mg compared to 2.48 U/mg of immobilized laccase. The relative activity of immobilized laccase was 64.91% after storage for 30 days at room temperature while it was 28.64% for free laccase. The temperature and pH for AR 1 decolorization were optimized and was found to be 60 °C and 5, respectively. Also, decolorization percentage was found to be 91.67% for immobilized laccase and 72.03% of free laccase in the presence of natural mediators like vanillin. From phytotoxicity studies it was found that the germination rate, shoot and root length was increased compared to untreated dye. Therefore, zein–PVP nanofiber immobilized laccase could be an ideal candidate for the textile dye decolorization.

Facile one step green synthesis of iron nanoparticles using grape leaves extract: textile dye decolorization and wastewater treatment.

The existing knowledge on the reactivity of green iron particles on textile dye and wastewater decolorization is very limited. In this study, the potential of green iron particles synthesized using grape leaves extract on reactive dye (reactive red 195, reactive yellow 145, reactive blue 4 and reactive black 5) decolorization were investigated. 95-98% of decolorization was achieved for all reactive dyes at 1.4-2.0 g/L of green iron. Maximum decolorization was attained at lower dye concentration and showed very little impact on decolorization when pH was increased from 3 to 11. The pseudo-first-order fit confirms the reaction between iron particles and dye molecules with rate constant 0.317-0.422 and it is followed by adsorption, data fit with pseudo-second-order model. Hence, not only adsorption but also the reduction process is involved in the reactive dye decolorization. Benzene, phenyl sodium, 2-chloro-1,3,5-triazine, naphthalene, sodium benzene sulfonate, benzene 1,2 di amine, anthracene-9,10 dione, aniline, phenol, benzene sulfonic acid were the major intermediates detected in dye decolorization and the respective reaction pathway is proposed. Green iron from grape leaves extract demonstrated better performance and it is recognized as the promising cost-effective material for textile wastewater treatment.

Investigations on inhibitory effects of nickel and cobalt salts on the decolorization of textile dyes by the white rot fungus Phanerochaete velutina

Organic aromatic compounds used for dyeing and coloring in the textile industry are persistent and hazardous pollutants that must be treated before they are discharged into rivers and surface waters. Therefore, we investigated the potential of the white rot fungus Phanerochaete velutina to decolorize commonly used reactive dyes. The fungus decolorized in average 55% of Reactive Orange 16 (RO-16) after 14 days at a maximum rate of 0.09 d−1 and a half-life of 8 days. Furthermore, we determined the inhibitory effects of co-present inorganic contaminants Nickel (Ni) and Cobalt (Co) salts on the decolorization potential and determined IC50 values of 5.55 mg l−1 for Co and a weaker inhibition by Ni starting from a concentration of 20 mg l−1. In the decolorization assay for Remazol Brilliant Blue R (RBBR) we observed the interference of a metabolite of P. velutina, which did not allow us to investigate the kinetics of the reaction. The formation of the metabolite, however, could be used to obtain IC50 values of 3.37 mg l−1 for Co and 7.58 mg l−1 for Ni. Our results show that living white rot fungi, such as P. velutina, can be used for remediation of dye polluted wastewater, alternatively to enzyme mixtures, even in the co-presence of heavy metals.

Decolorization property of living Lichen Evernia prunastri on textile Acid Red P-2BX dye

The removal of textile dye using the biosorption technique is important for improving water quality and avoiding the harmful effects of the traditional approach for removing wastewater on human health. Lichens are symbiotic organisms that have great potential for decolorization and degradation of textile dye. The present study evaluates Acid Red P-2BX dye decolorization by living lichen Evernia prunastri at the pH range of 2–10. Dye decolorization rates at pH 2 were 84.62%, 87.5% and 88.54% at 25, 50 and 100 mg/L of initial dye concentrations, respectively. The pigment analysis and mean intensity of chlorophyll autofluorescence results indicated that pH could be the main factor affecting lichen physiology and thalli decolorization capacity. Fourier transform infrared spectroscopy was used as a high-throughput method for understanding biomolecular changes in thalli. The lipid/amide I and carbohydrate/amide I ratio increased at pH 2. The present study also indicated, for the first time, that decolorization rate is related to altering lichen carbohydrate and especially lipid metabolism in the E. prunastri thalli. Thus, we demonstrated that the lichen E. prunastri could be a good candidate for use as a biosorbent.

Decolorization of textile azo dye Novacron Red using bacterial monoculture and consortium: Response surface methodology optimization.

The present study was intended toward the optimization of a textile dye Novacron Red decolorization by single and mixed culture of Bacillus strains namely, B.firmus, B.filamentosus and B.subterraneus. Optimization of dye decolorization using Bacillus monocultures was conducted using central composite design. The maximum dye decolorization achieved under optimized conditions for B.firmus, B.filamentosus and B.subterraneus was 89.24%, 88.28% and 88.45%, respectively. The effect of various consortia of selected Bacillus strains on dye removal was evaluated by applying a mixture design. The best dye (100mg/L) decolorization yield (84%) was achieved using the consortium of B.filamentosus and B.subetrraneus.The Fourier Transform Infrared Spectroscopy analyses confirmed biodegradation potential of the two Bacillus strains. The results highlighted the potential of mono- and co-cultures of Bacillus strains for application in textile wastewater treatment. PRACTITIONER POINTS: Novel dye-decolorizing Bacillus strains were isolated from marine sediment. Optimization of decolorization was conducted using response surface methodology. Efficient decolorization of textile dye by Bacillus strains on mono- and co-cultures. The efficiency of the consortium B.filamentosus and B.subetrraneus on dye removal.

Dopamine-modified pectin for a Streptomyces cyaneus laccase induced microbeads formation, immobilization, and textile dyes decolorization

Abstract Pectins are a group of heterologous polysaccharides capable of forming hydrogels and applicable in many industrial processes. A new type of modified pectin was synthesized by periodate oxidation and reductive amination with dopamine and sodium cyanoborohydride. The success of modification was confirmed by UV–Vis,FTIR, and 1H NMR spectroscopy. The obtained dopamine-pectin could form hydrogels by ionic crosslinking of carboxyl groups with calcium or by crosslinking phenol groups with laccase. For enzymatic crosslinking with laccase from Streptomyces cyaneus expressed in E. coli, isolation and purification of the enzyme was done. Using emulsion-based enzymatic crosslinking polymerization, dopamine-pectin microbeads with immobilized laccase were made. The immobilized laccase showed improved thermal and pH stability in comparison to the free enzyme. The immobilized biocatalyst effectively decolorized various dyes: Amido Black 10B, Reactive Black 5, and Evans Blue. After ten cycles of repeated use, the microbead immobilized laccase could still decolorize 60% and 36% of Amido Black 10B and Reactive Black 5, respectively.

LACCASE ISOLATION FROM SPENT MUSHROOM WASTE (AGARICUS BISPORUS): PARTIAL PURIFICATION, CHARACTERIZATION, IMMOBILIZATION AND BIOTECHNOLOGICAL APPLICATION

Laccase was partially purified from mushroom compost with cheap and simple purification methods. Partially purified laccase was immobilized onto Amberlite XAD-7 resin. Immobilization conditions and textile dye (Direct Green B) decolorization of immobilized enzyme were examined. Laccase was partially purified from mushroom compost with 3.22 purification fold. Immobilization time for laccase was 30 minutes with 97% efficiency. The immobilization yield based on the activity was calculated by about 90%. The immobilization yield was calculated as nearly 95% based on the measurement of protein amount at each stage. Immobilized enzyme preserved its initial activity with an 84% rate even after its tenth use. The free enzyme lost its activity immediately when it was incubated with the dye solution under its optimal conditions (pH 3.0 and 65°C). On the contrary, the immobilized enzyme maintained its initial activity with a 53% rate when incubated with dye solution under its optimal conditions (pH 3.5 and 65°C).

Lanthanum: A novel inducer for enhancement of fungal laccase production by Shiraia bambusicola

Fungal laccases are industrially important inducible enzymes extensively used in the delignification of lignocellulosics, detoxification of environmental wastes and decolorization of textile dyes. The discovery of new inducers is crucial for laccase productivity by filamentous fungi. In this study, a novel laccase-producing strain S8 from a bambusicolous fungus Shiraia bambusicola was identified by using 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) as laccase secretion indicator and native polyacrylamide gel electrophoresis. The corresponding full-length cDNA of laccase was cloned and characterized. The effect of lanthanum (LaCl3) on extracellular laccase activity was tested at the concentration from 0.2 to 2.0 g/L and at different addition time (day 1–4) in the mycelium culture. In the presence of 1.0 g/L La3+ at the beginning of the mycelium cultures, the highest laccase activity (2.7 × 104 U/L) is reached after 10 days of cultivation, about tenfold higher compared with non-induced cultures. La3+ is shown to be a very strong inducer for fungal laccase activity with no inhibitory effect on fungal growth at the optimized concentration. In vivo, La3+ added to the mycelium culture not only promotes a continuous and high expression of laccase gene (lcc1), but also induces a rapid generation of signaling molecules including reactive oxygen species (ROS) and nitric oxygen (NO). Both the NO donor sodium nitroprusside (SNP) and exogenous hydrogen peroxide (H2O2) potentiate La3+-induced laccase activity and increase membrane permeability of hyphal cells. Moreover, the scavengers such as 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) for NO and vitamin C for ROS suppress the induction. These results suggest that these signals can mediate La3+-induced laccase biosynthesis and its secretion. Our study provides a basis for understanding the induction mechanism of La3+ on laccase and a practical strategy for enhanced fungal laccase production.

Marine associated microbial consortium applied to RBBR textile dye detoxification and decolorization: Combined approach and metatranscriptomic analysis

The combination of different microorganisms and their metabolisms makes the use of microbial consortia in bioremediation processes a useful approach. In this sense, this study aimed at structuring and selecting a marine microbial consortium for Remazol Brilliant Blue R (RBBR) detoxification and decolorization. Experimental design was applied to improve the culture conditions, and metatranscriptomic analysis to understand the enzymatic pathways. A promising consortium composed of Mucor racemosus CBMAI 847, Marasmiellus sp. CBMAI 1062, Bacillus subtilis CBMAI 707, and Dietzia maris CBMAI 705 was selected. This consortium showed 52% of detoxification and 86% of decolorization in the validation assays after seven days of incubation in the presence of 500 ppm of RBBR. Reduction in RBBR color and toxicity were achieved by biosorption and microbial metabolisms. Metatranscriptomic data indicate that the consortium was able to decolorize and breakdown the RBBR molecule using a coordinated action of oxidases, oxygenases, and hydrolases. Epoxide hydrolases and glyoxalases expression could be associated with the decrease in toxicity. The efficiency of this marine microbial consortium suggests their use in bioremediation processes of textile effluents.

Biodegradation and decolorization of textile dyes by bacterial strains: a biological approach for wastewater treatment

Abstract Textile industry releases large quantities of toxic dyes, which is a threat to public health and needs proper management before their release into environment. Out of the different approaches used these days, biodegradation and bio-decolorization is considered an eco-friendly and effective technique as this involves the use of microbes. This technique has the potential to be used effectively for a wide variety of dyes. In biological methods, mainly bacteria, fungi, and some algae are usually employed to remove or decolorize dyes present in textiles effluents and wastewaters. A number of researchers have used bacterial strains and relevant isolated enzymes successfully to decolorize a number of dyes. In this review article, various biological methods that have been used for the biodegradation and decolorization of textile dyes have been described. The review will also revive the significance of biological methods over other physical and chemical treatment methods that would be helpful in ensuring clean environment if used on large scale. Out of these methods, biodegradation through bacterial strains is considered as the best alternative to control water pollution as the growth rate of bacteria is considerably high as compared to other microorganisms. Thus if used the required biomass needed for biodegradation can be obtained in comparatively short interval of time.

Biological mediated synthesis of RGO-ZnO composites with enhanced photocatalytic and antibacterial activity

In this study, we reported the biological approach to synthesis of ZnO nanorod (NR) on the reduced graphene oxide (RGO) for photocatalytic, antibacterial activity and hydrogen production under sunlight. Bacillus subtilis played a vital role in the production of biogenic ammonia from synthetic urine and utilized for the synthesis of ZnONR on the RGO sheet. The morphological study revealed that RGO sheets displayed a tremendous role in anchoring ZnONR. XRD patterns showed the ZnO crystal phase on the RGO sheets. XPS and Raman spectra confirmed that the bio-hydrothermal method as suitable for GO converted into RGO. The transient photocurrent and I/V measurement are exhibited as an increment on the RGO-ZnONR compared to ZnONR. The RGO-ZnONR composites showed excellent performance with decolorization of MB and textile dyes and efficient control of the E. coli and S. aureus. RGO-ZnONR exhibited remarkable noted as a higher photocatalytic hydrogen evolution rate (940 μmol/h/gcat) than the ZnONR (369.5 μmol/h/g cat). As a result of photocatalytic performance to correlate with sunlight intensity was extensively studied. RGO plays an essential role in interface electron transfer from sunlight to ZnONR for enhancing •OH radical formation to cleavage of dye color substance and eradicated bacterial cells.

Decolorization of Textile Dye by Brevibacillus laterosporus (TS5) and Influencing Factors Optimization through Response Surface Methodology

The dye removal bacteria Brevibacillus laterosporus (TS5) was isolated from dye contaminated soil, and it’s identified by 16S rDNA sequencing method. The prospective bacterial strain exhibited a highest decolorization (97.8%) in Luria-Bertani broth medium. Among the operational factors, Plackett-Burman design, experimental results indicated that pH, incubation period, and yeast extract significantly contributed for the dye decolorization. Also, dye concentration, starch, temperature, and inoculum size noted as insignificant factors on dye decolorization. Central composite design applied for optimization of important factors to enhance the dye decolorization by Brevibacillus laterosporus (TS5). The optimal values of significant factors were determined by the Response surface methodology (RSM) as follows: 0.60% (w/v) yeast extract, 7.23 pH and 61.45 hrs incubation period, which assisted for Brevibacillus laterosporus (TS5) to attain 90.66% dye removal. Brevibacillus laterosporus (TS5) showed 90.08% decolorization in validation experiments by the support of optimal factors, and implies that explored strain could be a suitable candidate for bioremediation of dye containing effluents.