Dye Decolourization Research Articles

Soluble and supported hematin as a catalyst for decolourization of anthraquinone textile dyes: A kinetic modelling validation study

Hematin-catalysed decolourizations of alizarin red S solutions were carried out in order to validate a peroxidatic model in competition with pseudo-catalatic routes. Absorbance and dissolved oxygen were followed with time and hematin was used in solution or immobilized onto chitosan. Initial rates decreased with increasing dye concentration. Modelled dye concentration profiles properly reproduced experimental data. Optimized rate constants indicated that immobilization reduced hematin activity, emphasized dye inhibition and promoted the pseudo-catalatic pathway. The increase in H2O2 concentration increased oxygen evolution rates whereas the increase of dye concentration depleted them, which agree with the kinetic model proposal. These findings were also discussed considering some additional reactions which consume or evolve oxygen. UV–visible stack spectra of reacting systems allowed to propose some degradation products, whose molecular weights decreased with the increase of hydrogen peroxide to dye molar ratio. This is consistent with accumulation of inorganic radicalsproposed by the pseudo-catalatic mechanism.

Al-Fe LAYERED HYDROXIDE WITH BENTONITE CLAY AND APPLICATION FOR THE REMOVAL OF DYE FROM AQUEOUS SOLUTIONS

The research was aimed to investigate the effect of decolourisation of Alizarin yellow dye from aqueous solutions using Al-Fe layered Hydroxide clay.Batch adsorption technique was employed to determine the optimum values of some parameters i.e initial dye concentration (10 – 50 mg/l), contact time (10 – 50 minutes) and adsorbent dose (0.1 – 0.5 g). The results obtained indicate that the dye concentration decreases with increase in contact time and adsorbent dosage.The Adsorption isotherms observed showed that the Langmuir adsorption Isotherm was best fitted having the maximum decolourisation of 76.89 mg/g and R2 value of 0.986. The Al-Fe layered Hydroxide prepared was characterized by SEM, FT-IR and XRD before and after the adsorption process. The SEM results showed the porosity was roughly filled after the adsorption. The FT_IR spectra showed the presence of OH, C=O and N-CH at 3625 cm-1, 1633 cm-1 and 2806 cm-1. The XRD results indicate that the crystalline structure was not altered after the adsorption process. In this research, a low cost and effective adsorbent was used for the removal of Alizarin Yellow dye in an aqueous solution.

REDUCTION OF COD FROM REACTIVE DYE WASTE WATER

Due to the scarcity of water resources, it is crucial to safeguard public health and well-being. One way to achieve this is by enforcing stringent regulations on the discharge of wastewater effluents to minimize the introduction of harmful substances into water bodies. Furthermore, there is a growing trend to reduce total solids (TS) in wastewater and repurpose them for industrial applications. The treatment of wastewater to a high standard has expanded the potential uses while reducing negative impacts on freshwater ecosystems. Currently, the main environmental issue in wastewater treatment is related to dye effluents. This is because the textile industry consumes a substantial amount of water, resulting in wastewater that contains unused colours and their constituents. Dye-containing wastewater produced by the textile sector is extremely toxic and poses severe challenges for wastewater treatment facilities. Textile effluents contain high levels of colour, TDS, and hazardous metals, which have reduced the ability of contaminants to self-degrade in wastewater. Numerous techniques, such as chemical oxidation, coagulation and adsorption processes, as well as biological processes, are employed to remove dye using traditional methods, but none of these are sufficient on their own to remove dye from wastewater. For instance, biological processes are unsuitable for decolourization of dyes since the majority of the colours are inorganic and harmful to the process microorganisms. Activated carbon is effective for treating soluble colours, while coagulation is better suited for insoluble dyes but not for soluble ones. Due to the product of their degradation, most dyes in particular reactive dyes cause serious environmental problems. Due to the complicated structure and refractory nature of dyes, the degradation of colours from textile effluent is exceedingly hard. Wastewater produced in textile manufacturing plants may contain both natural and synthetic pollutants, the composition of which depends on the production techniques employed. Several parameters are commonly used to evaluate the characteristics of textile wastewater, such as Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), Suspended Solids (SS), Dissolved Solids (DS), pH, Chloride, Sodium, and others. The quality of textile wastewater is determined by these parameters, and it is important to take them into account when selecting appropriate treatment methods to ensure that the environment is not adversely impacted.

Decolorisation of Reactive Congo Red Dye Solution by Electro Coagulation Process

The decolourisation of the reactive Congo red dye from synthetic wastewater was studied using ElectroCoagulation (EC) technique. In an effort to increase removal efficiency, the effects of operating parameters including flow, inter electrode distance, conductivity, voltage, and Hydraulic Detention Time (HDT) were investigated. An electrochemical cell was initially created with an aluminum cathode and anode. Following that, each variable's impact was examined independently using synthetic wastewater. The colour removal efficiency was 93% when the initial dye concentration was 4 mg/L, the conductivity was 300 ppm, the temperature was 24 oC, the interelectrode spacing was 1 cm, and the HDT of the electrolysis was 120 min.

Preparation and Characterization of Yeast-Immobilized Cotton-Based Materials and Their Usage for Textile Dye Decolourization

Preparation and Characterization of Yeast-Immobilized Cotton-Based Materials and Their Usage for Textile Dye Decolourization

Microbial Decolorization of Crystal Violet Dye by a Native Multi-Metal Tolerant <i>Aeromonas caviae</i> MT-1 Isolate from Dye-Contaminated Soil: Optimization and Phytotoxicity Study

In the recent past, one of the main environmental issues is the contamination of textile dye wastes. The toxicity of dyes poses adverse effects on the flora and fauna of the ecosystem. The present study aimed to isolate bacteria that decolourize crystal violet dye, optimization of various environmental factors for effective decolourization, and phytotoxicity analysis. Out of 13 isolated bacteria, a single isolate was able to grow at 250 mg/L crystal violet dye concentration in a synthetic medium and identified as Aeromonas caviae MT-1 strain (accession number; LC720408) using morphological, biochemical and molecular analyses. Presumably, this is the first report of crystal violet dye decolourization by a native Aeromonas caviae isolate. In this study, after a 72-hour incubation period, a maximum of 98.0% dye decolourization was observed at neutral pH and 35°C with 5% v/v bacterial culture under static culture conditions. Dye decolourization was inhibited to a significant degree by the rising of its concentration. UV-Vis spectra analysis of samples before and after decolourization showed the possible degradation of crystal violet dye by A. caviae. The strain MT-1 was also tolerant to toxic heavy metals like arsenic, lead, and chromium. Phytotoxicity tests revealed that decolourized dye products inhibited Vigna radiata growth less than the un-decolourized dye solution. The findings revealed that a native multi-metal tolerant A. caviae MT-1 isolate could decolourize crystal violet dye rapidly, and possibly have the ability for extensive treatment of dyecontaminated waste.

Bacterial enzymes for azo dye degradation: an insight

Azo dye has a massive marketplace in various industries, biological laboratories and clinics. A significant drawback is the excessive flush-off of azo dyes and their intermediate products are that they pollute the environment. Several environmental bacteria degrade azo dye under certain specific ecological conditions. Decolourisation by different bacteria occurs under aerobic, anoxic and anaerobic conditions. Bacterial genera such as Pseudomonas, Bacillus and Rhodococcus are used for the rapid decolourisation of azo dyes. Bacterial enzymes play an essential role in the degradation of azo dyes by cleavage of azo bonds (-N=N-). It is degraded by both oxidative and reductive enzymes including azo reductase, laccase, lignin peroxidase, NADH-DCIP reductase, malachite green reductase, polyphenol oxidase (tyrosinase), veratrol alcohol oxidase. This review describes the role and mechanism of these enzymes in the degradation of azo dyes.

Decolourization and Detoxification of Carcinogenic Azo Dyes by Isolated bacterial strains

Different bacterial cultures were isolated from different sources and screened for their ability to decolourize and detoxify azo dyes contained in the textile effluent. Three strains, identified as Fictibacillus gelatini, Bacillus subtilis subsp. inaquosorum and Bacillus subtilis subsp. subtilis showed tremendous potential in decolourizing azo dyes. Enzyme profiling revealed that they are producing Laccase and Azoreductase efficiently. The parametric optimization of different variables, namely carbon and nitrogen sources, pH, temperature, inoculum size and dye concentrations showed significant effect on azo dye decolourization percentage. Significant results of decolourization were obtained when microbial consortia were used. These isolates not only degraded or removed the dyes from these effluents but also caused reduction in the cost of effluent treatment processes along with tremendously decrease the COD, TDS and TSS levels.

Decolourisation of Metal-Azo Dyes in Wastewaters by Sodium Peroxodisulphate: A Template for Experimental Investigations

Background It has long been recognized that the presence of azo metal complex dyes and their non-complexed counterparts in wastewaters, which arise from their manufacturing and their use in the textile industries, renders natural waterways intensely coloured, and is therefore aesthetically unacceptable. Azo dye moieties are also known to be precursors of human carcinogenicity. Objective This work aimed at the decolourisation of metal-azo dyes present in wastewaters so that pollution of natural bodies of water can be prevented. Decolourisation is indicative of the destruction of the metal-ligand complex, allowing the retrieval of transition metal ions, which are also water contaminants. Fracturing of the azo bond itself minimizes the potential for carcinogenicity of these dyes. Methods Decolourisation is achieved by the oxidative action of free radicals furnished by Na2S2O8, the sodium salt of peroxodisulphuric acid (Marshall’s acid). Raman spectroscopy characterizes the dye (ligand) known as “Eriochrome Black T (EBT)” by a peak at 1425 cm-1. Dismantling of its molecular structure by peroxodisulphate will lead to decolourisation accompanied by the collapse of the peak. Concomitantly, as EBT ligands fracture and cease to chelate, metallic ions are released, oxidized to a higher oxidation state, and precipitated as insoluble compounds in alkaline media. Results The concentration of metallic ions in the aqueous phase has been found to be substantially reduced. The successfully treated dye solutions are mostly clear and colourless; their Beer-Lambert absorbances are in the range of 0.02 ≤ absorbance ≤ 0.05. The treatment of Ni(II), Co(II) and Fe(II)-EBT solutions is straightforward; the Cu(II) and Cr(III)-EBT solutions require additional treatment to be included in the above absorbance range. The Cr(III)-EBT is the least responsive to treatment. Fracturing of the azo bond is evinced by Raman Spectroscopy. Conclusion A template to investigate the feasibility of decolourisation of metal-complex dye solutions is pioneered and recommended.

A sustainable approach for synthesis of zinc oxide nanoparticle by Aloe barbadensisand its application in photocatalytic decolouration of commercial dyes.

A sustainable approach for synthesis of zinc oxide nanoparticle by Aloe barbadensisand its application in photocatalytic decolouration of commercial dyes.

Biotreatment of azo dye containing textile industry effluent by a developed bacterial consortium immobilised on brick pieces in an indigenously designed packed bed biofilm reactor.

This study highlights the development of a lab-scale, indigenously designed; Packed-Bed Biofilm Reactor (PBBR) packed with brick pieces. The developed biofilm in the reactor was used for the decolourisation and biodegradation of the textile industry effluent. The PBBR was continuously operated for 264 days, during which 301 cycles of batch and continuous treatment were operated. In batch mode under optimised conditions, more than 99% dye decolourisation and ≥ 92% COD reduction were achieved in 6h of contact time upon supplementation of effluent with 0.25g L-1 glucose, 0.25g L-1 urea, and 0.1g L-1 phosphates. A decolourisation rate of 133.94 ADMI units h-1 was achieved in the process. PBBR, when operated in continuous mode, showed ≥ 95% and ≥ 92% reduction in ADMI and COD values. Subsequent aeration and passage through the charcoal reactor assisted in achieving a ≥ 96% reduction in COD and ADMI values. An overall increase of 81% in dye-laden effluent decolourisation rate, from 62to 262mg L-1h-1, was observed upon increasing the flow rate from 18 to 210 mL h-1. Dye biodegradation was determined by UV-Vis and FTIR spectroscopy and toxicity study. SEM analysis showed the morphology of the attached-growth biofilm.

Evaluation of Dye Decolourization ability of Laccase Produced Curvularia lunata SS17

The increasing discharge of dyes into the environment and their consequential ecological effects has necessitated the need for the ecofriendly decolourization methods. Laccases became enzymes of research interest due to their broad substrates specificities. The aim of the study was to purify, characterize and determine the decolourization ability of Curvularia lunata SS17 produced laccase. Laccase was produced using maize cob as substrate under optimized culture conditions and purified using Gel Filtration Chromatography. Biuret method was then used to estimate the protein contents of the crude and partially purified laccase. Specific activities, purification fold and yield (%) of the crude and purified laccase enzyme were also estimated. Decolourization potentials of the crude and partially purified enzyme were evaluated using four dyes namely: Congo red, Methylene blue, Bromocresol green and direct yellow. Elution profile of partially purified laccase revealed that fraction 5 had the highest laccase activity (3.654 U/mL). Optimum conditions for enzyme activity were estimated to be 35oC and pH 6. Enzyme activity of the partially purified laccase (3.654 U/mL) was observed to be higher than that of the crude laccase (1.635 U/mL). Also, the partially purified laccase had higher specific activity (1.87 U/mg) compared to that of the crude laccase (0.41 U/mg). Higher percentage dye decolourization potential was observed using the partially purified laccase compared to the crude laccase. Increase in percentage decolourization of the dyes by the partially purified laccase as well as crude laccase was observed as incubation time proceeds.

Enhanced decolourisation and degradation of azo dyes using wild versus mutagenic improved bacterial strain: a review

Enhanced decolourisation and degradation of azo dyes using wild versus mutagenic improved bacterial strain: a review

Laccase from Truncatella angustata showing Pb2+ induced burst of activity and dye decolourization without mediator and carbon footprint in cold climate

A cold-active laccase is required for multiple applications in cold climate, and reducing carbon footprint. Thus laccase from the psychrophilic fungus T. angustata BPF5 originally isolated from Baramullah (India) soil was characterized. The enzyme showed apparent molecular masses of 36 kDa and 49 kDa, maximal activity at 15 °C, >98 % activity between pH 3.0 and 5.0, and burst of activity in presence of Pb2+. The enzyme was stable at 15 °C and acidic pH (3.0–5.0) for 24 h losing only 30 % activity in 48 h. It was tolerant to Na1+ and other tested metals and organic solvents. The enzyme could decolourize dyes belonging to azo and triphenyl amine at cold temperatures, and without any mediator to spectrophotometric zero level. Pb+2 though amplified laccase activity had no impact on the dyes decolourization rate. The enzyme is potentially applicable in cold climate and unraveling the novel mechanism of Pb2+ induced burst of activity.

Laccase production from Bacillus aestuarii KSK using Borassus flabellifer empty fruit bunch waste as a substrate and assessing their malachite green dye degradation.

The lignocellulosic waste, Borassus flabellifer empty fruit bunch waste (BFEFBW), was employed to produce laccase using Bacillus aestuarii KSK under solid-state fermentation (SSF) conditions and to assess the efficiency of malachite green (MG) dye decolourization. Abiotic factors such as pH (5.0-9.0), temperature (25-45°C) and incubation time (24-96 h) were optimized using Response surface methodology-Box-Behenan Design (RSM-BBD) to exploit the laccase production. The anticipated model revealed that the highest laccase activity of 437 U/ml shows after 60 h of incubation at 35°C at pH7.0. The bacterial laccase was used to remove 89% of the MG dye in less time. The laccase from B. aestuarii KSK decolorizes the MG and thereby making it a suitable choice for wastewater treatment from industrial effluents. This study is the first report on the production of laccase from B. flabellifer empty fruit bunch waste as a substrate. Bacillus aestuarii KSK was isolated from the soil sample and used to produce laccase under SSF conditions. The bacterial laccase has the potential for industrial application in textile waste dye treatment.

Generation of Synechocystis sp. PCC 6803 mutant with enhanced laccase-like activity

Cyanobacteria offer a good alternative to fungi for laccase production at industrial scales. Random mutagenesis approaches with ethyl methanesulfonate were used in combination with enzymatic assays screenings to select a mutant of Synechocystis sp. PCC 6803, A2, with enhanced extracellular laccase-like activity. Anthraquinone dye decolourisation assays revealed 7 % enhanced decolourisation in A2 relative to the wild type after 24 h. The comparison of microbiome structure and diversity of the wild type and A2 strains confirmed that the improved traits were due to the mutation(s) and not the associated bacteria. The newly isolated Synechocystis mutant is the first example of successful random mutagenesis of cyanobacteria for laccase production. Attempts to characterise the biochemical reaction and putative laccase in A2 strain were unsuccessful but will be the subject of further research. This study suggests that random mutagenesis as a powerful approach for generating cyanobacterial strains with enhanced laccase-like activity for prospective commercial applications.

Biosorption of Synthetic Dye by Macrofungi

This research project aimed to provide an environmentally friendly method for the decolorization and biosorption of synthetic dye by utilizing fungi as biosorbents. The study was carried out by first growing the fungi in solid medium and then using the fungi as biosorbent to absorb dye in aqueous solution. In the first stage, screening experiments were carried out among 5 different types of fungi, and Pleurotus ostreatus was determined to have the highest growth rate. The Pleurotus ostreatus was recultivated with Remazol Brilliant Blue R dye to determine its dye removal ability. Pleurotus ostreatus sp. exhibited vigorous dye decolorization in agar medium within 2 days. By carrying out batch analysis, 4 parameters were examined, which were the effect of pH, surfactant concentration (Tween 80), salinity concentration and dosage of biosorbent. The results showed that the maximum dye decolourization by Pleurotus ostreatus can be achieved through establishing an acidic condition of pH 2, addition of 0.1mL of Tween 80, 0mg/l of sodium chloride concentration, and dosage of 8 plugs. Lastly, the experimental data was found to fit the Jovanovic Isotherm the most. In conclusion, Pleurotus ostreatus is capable of decolourizing and adsorbing dye particles in the dye aqueous solution.

A Recent and Systemic Approach Towards Microbial Biodegradation of Dyes from Textile Industries

The textile industry generated a series of synthetic dyestuffs that threatened environmental protection. Azo dyes, widely utilized in textile, paper, fruit, leathers, cosmeceuticals and pharmaceutical fields, account for most of the dyestuffs made. Since they have colour fastness properties, stability, and susceptibility to oxidation, existing effluent treatment methods cannot entirely strip different dyes from effluents. Under certain environmental factors, bacteria decolourize and degrade dyes. The treatment process is cheap, environmentally safe, and can be used on various dyes. However, textile plant wastewater can produce many polluting chemicals and dyes. Environmental legislation is increasingly being enacted to regulate mainly azo-based dyes in the environment. The potential of the microbes for the decolourization of dyes and metabolizing them is long-known knowledge. The toxic components of dyes challenge a potential threat to all the living forms of life. Though both natural and synthetic dyes are used for the colourization of textiles, only synthetic ones are challenging to decolourize. Microbial-based bioremediation of dyes has been studied and reviewed primarily to accelerate dye degradation. The various piece of the literature revealed that the majority of these dye removal microbes belong to mainly white-rot fungi, a consortium of anaerobic bacteria. In addition to this, there are several (genetically engineered microorganisms) GEMs that remediate dyes efficiently. Here in the current review, the authors have tried to bridge the existing gap in the bioremediation of dyestuff. Moreover, the authors have also tried to provide the latest trend in this field. This study will surely benefit the industries and researchers related to dyestuffs by maintaining eco-friendly approaches.

Solar expedited photodegradation of orange-g using H2O2

Decolourisation and degradation of azo dye Orange G was carried out by using the solarassisted photodegradation process using H2O2 and the effect of various parameters on decolourisation and degradation were analysed. Dye solutions of concentration 100 mg/L treated with 30% H2O2 were taken in 250 ml conical flasks and they were exposed to sunlight in the lux intensity range of 60,000 to 90,000 lux to study its decolourisation and degradation. Effect of various parameters on decolourisation and degradation of dye like the effect of initial pH, the effect of initial H2O2concentration, the effect of initial dye concentration, the effect of additives like chloride and dihydrogen phosphate of concentration 1 M, the effect of solar light intensity, the effect of temperature were studied as kinetic studies. Optimum pH was found to be 11 and optimum H2O2 concentration was found to be 250 mM to achieve 100 % decolourisation of the dye within the shortest time duration of 1.5 hours. Kinetic studies done on the effect of pH and the effect of H2O2 concentration also provided evidence for that. Effect of chloride ion has lead to enhancement in the rate of decolourisation whereas addition of dihydrogen phosphate ion inhibits the rate of decolourisation. An increase in solar light intensity has lead to increase in the rate of decolourisation. An increase in temperature has lead to increase in the rate of decolourisation. UV spectrum was taken for the dye and degraded dye to study the extent of degradation of the dye. COD and TOC removal were also studied to know about the mineralisation of the dye.

Experimental Design and Optimization of Decolourization of Reactive Black-5 Dye Using Cloud Point Extraction

A two-phase separation method called cloud point extraction (CPE) does not use hazardous or flammable organic solvents. The efficient removal of the dye Reactive Black-5 (RB-5) from an aqueous solution using Triton X-114, a nonionic surfactant, is described in this study. Three-level factorial design and response-surface methods were used to quantify the impact of process variables on the CPE process, such as operating temperature and surfactant concentration. Investigations were conducted into how these process variables affected the ratio between the phase volumes, the concentration of dye in the surfactant-rich phase, and the residual amounts of dye in the diluted phase. As a result, ANOVA was used to create and validate mathematical models. The findings demonstrated that the correlation coefficients (R2) exceeded 0.98. The acquired findings showed that the suggested extraction process is efficient, and the proposed CPE approach removes 98% of the RB-5 dye under optimal conditions.