The Removal of Binary Mixture of Dyes by Heterogeneous Fenton Oxidation: Kinetics, Product Identification and Toxicity Assessment.

The removal of mixture of two azo dyes, Acid blue 29 and Ponceau xylidine, was studied by heterogeneous Fenton and Fenton-type processes using hydrogen peroxide and sodium persulphate as oxidants in the presence of and nano and micro- particles as catalysts. The synthesised nano- particles were characterised using analytical techniques viz. FT-IR, TEM, EDX, powder XRD and VSM. We have examined the effects of particle size on the COD removal efficiency and the reusability of the catalyst after optimising pH, and concentrations of catalyst and oxidant. Combination of nano-  and hydrogen peroxide possessed higher COD removal efficiency, which was accelerated in acidic pH and inhibited at pH > 6. Total consumption of hydrogen peroxide confirmed the efficiency of the optimised parameters. The mechanism of the formation of intermediate ions and products are proposed. COD removal and consumption of hydrogen peroxide follow pseudo-first-order kinetics. The toxicity of the solutions was assessed using Aliivibrio fischeri light loss and Escherichia coli growth inhibition assays. Both the assays showed different toxicity levels for the same solution.

Boosted sono-oxidative catalytic degradation of Brilliant green dye by magnetic MgFe2O4 catalyst: Degradation mechanism, assessment of bio-toxicity and cost analysis.

The magnetic MgFe2O4 nanoparticles (NPs) were fabricated via a facile co-precipitation technique and was comprehensively characterized by XRD, FTIR, SEM, EDX and VSM. The prepared NPs were used as catalyst in presence of ultrasound (US) irradiation to activate persulfate (PS) for generation of sulfate radicals (SO4·-) for boosted degradation of toxic Brilliant Green (BG) dye. Preliminary experiments revealed that highest BG dye degradation efficiency of 91.63% was achieved at MgFe2O4 catalyst dose of 1.0 g/L, PS dose of 300 mg/L, and initial dye concentration of 70 ppm within 15 min of US irradiation. However, only US, US in presence of PS oxidation and US in presence of MgFe2O4 catalyst have shown 20.2%, 83.6% and 45.0% of BG dye removal, respectively. Furthermore, response surface methodology (RSM) based central composite design (CCD) was executed to investigate the effect of interaction between independent variables such as MgFe2O4 catalyst dose (0.5-1.5 g/L), PS dose (150-350 mg/L), initial BG dye concentration (50-150 ppm) and US irradiation time (4-12 min). The RSM based quadratic model was used to predict the experimental data, and the prediction accuracy was confirmed by analysis of variance (R2 = 0.98). The established RSM model has predicted the optimum experimental conditions as MgFe2O4 catalyst dose of 0.75 g/L, PS dose of 300 mg/L, initial dye concentration of 75 ppm and sonication time of 10 min. Subsequently, the treatment cost analysis was performed for all thirty experimental runs of CCD, and the RSM predicted response was found to be evidently optimum as this has delivered best economic condition (140 $/kg of BG removed) with respect to relative dye removal (%). COD removal and residual sulfate analysis have demonstrated satisfactory reduction of COD (90.31%) as well as sulfate ions (42.87 ppm) in the dye solution after treatment. Results of degradation pathway analysis portrayed the transformation of BG molecule (M/Z ratio 385) into simpler fractions with M/Z ratio of 193, 161, 73, and 61. Moreover, the toxicity analysis revealed that sono-catalytically activated PS system has efficiently reduced the toxicity level of BG dye from 93.9% to 5.13%.

Synthesis, characterization, and assessment of cationic and anionic dye adsorption performance of functionalized silica immobilized chitosan bio-polymer.

The functionalization of polymers is still an efficient scheme to provide materials with new properties. In this paper, 4-methyl-2-(naphthalen-2-yl)-N-propylpentanamide-functionalized ethoxy-silica was successfully immobilized onto chitosan bio-polymer spherical beads to improve their adsorption characteristics. The interaction between the polymer and the functionalized silica was analyzed using FT-IR spectroscopy and SEM analysis. FT-IR investigation suggested that the interaction between chitosan and functionalized silica occurred through hydrogen bonding. The morphology of the prepared composite gel beads exhibited a spherical shape surface covered by silica particles. The unfunctionalized and functionalized beads were studied for the adsorption of methylene blue (MB) and Acid blue 25 (AB25) from water. The influence of pH, time, dye concentration, and temperature on the adsorption characteristics was investigated. The results showed that the highest adsorption amount of dyes was reached using the functionalized chitosan beads under the following conditions; pH = 5 for AB25 and pH = 6 for MB, time = 120 min, and T = 20 °C. The adsorbed yield of MB using the composite beads increased three times more than the capacity of chitosan beads and it was improved 1.4 times in the case of AB25. The mean free energy values (74.53-223.61 kJ mol-1), computed from the Dubinin-Radushkevich model suggested the chemi-sorption nature of the adsorption phenomenon.

Prospective Study of Microbial Colorants under the Focus of Patent Documents.

BACKGROUND: Colorant-producing microorganisms are quite common in nature. These biomolecules present many biological activities such as antitumoral, antimicrobial and antioxidant, in addition to the various nuances of color, making them of special technological importance to the industrial sectors. OBJECTIVE: This study aims to conduct a technological mapping in the patent, at European patent Office (EPO), in order to evaluate the global panorama of the use of microbial colorants. METHODS: The experimental design was acquired by the keyword-driven approach through the advanced search in the Espacenet database European Patent Office (EPO). The keywords selected were bacteria or fungi* or yeast or algae or microorganism* but not plant* and pigment* or color* or colorant* or dye* and the International Patent Classification code, C09B61, for prospecting of interest. RESULTS: There has been a linear increase in patents developed in the last 20 years, with Japan as the largest depositor in the area. The companies Dainippon Ink and Chemicals and Ajinomoto, both being Japanese, are the largest depositors with 20% of all patents. Among the microorganisms, the filamentous fungi appeared in the first place with 32% of documents and the fungi of the genus Monascus were the most frequently used. CONCLUSION: The use of microbial colorants has been growing among industries, mainly in food sectors, due to the growing demand for products of natural origin. Thus, the increase in research and technological development in the area of microbial colorants can become an economically viable and promising strategy for the various industrial sectors.

Ultrasound as a Rapid and Low-Cost Extraction Procedure to Obtain Anthocyanin-Based Colorants from Prunus spinosa L. Fruit Epicarp: Comparative Study with Conventional Heat-Based Extraction.

An ultrasound rapid and low-cost procedure for anthocyanin-based colorants from Prunus spinosa L. fruit epicarp was developed, and the advantages were compared with conventional heat-based extraction. To obtain the conditions that maximize anthocyanins' extraction, a response surface methodology was applied using the variables of time, temperature, and ethanol content, in the case of heat extraction, whereas for ultrasound assisted extraction, temperature was replaced by ultrasound power. Two anthocyanin compounds were identified by HPLC-DAD-ESI/MS-namely, cyanidin 3-rutinoside and peonidin 3-rutinoside. The responses used were the extraction yield and the content of the identified anthocyanins. Ultrasound extraction was the most effective method at 5.00 ± 0.15 min, 400.00 ± 32.00 W, and 47.98% ± 2.88% of ethanol obtaining 68.60% ± 2.06% of extracted residue, with an anthocyanin content of 18.17 mg/g (extract-basis) and 11.76 mg/g (epicarp-basis). Overall, a viable green process was achieved that could be used to support pilot-scale studies for industrial production of anthocyanin-based colorants from P. spinosa fruit epicarp.

Urtica dioica leaves-calcium alginate as a natural, low cost and very effective bioadsorbent beads in elimination of dyes from aqueous medium: Equilibrium isotherms and thermodynamic studies.

A very effective and low cost bioadsorbents derived from Urtica dioica leaf powder (UDL) and composite beads UDL encapsulated with calcium alginate (UDL/A) were used in removal of cationic dye crystal violet (CV) from aqueous medium. The new adsorbents were characterized by Fourier transform infrared spectroscopy (FTIR) and isoelectric points (pHpzc). Adsorption was studied in batch system according to initial CV concentration (30-150 mg/L), contact time, pH (2-11), temperature (10 to 40 °C) and adsorbent mass (10 to 200 mg). UDL and UDL/A beads showed maximum CV adsorption of 137.8 and 121.8 mg/g for 150 mg/L initial CV dye concentration, pH 6.5, 1 g/L adsorbent dose, temperature of 23 ±â€¯1 °C and contact time of 6 h. Analysis of kinetics data shows that adsorption of CV onto adsorbents was well described by pseudo-second order model. The equilibrium adsorption data fitted the Langmuir isotherm well with a maximum adsorption capacity of 1790 and 1107 mg/g respectively for UDL and UDL/A beads. Results of thermodynamic studies showed negative values of ΔG°; positive values of ΔH° 10.30 and 6.54 kJ/mol for CV onto UDL and UDL/A beads respectively. Adsorption processes are spontaneous, physical and endothermic in nature.

Cationic and anionic dyes removal by low-cost hybrid alginate/natural bentonite composite beads: Adsorption and reusability studies.

Using the extrusion method, novel hybrid beads were prepared from natural bentonite and alginate. Alginate to clay ratios was varied (1/1; 1/2 and 1/3) and used to eliminate two dyes (methylene blue and Congo red).Adsorbents were characterized by Fourier transformed infrared spectroscopy, X-ray diffraction, Brunauer-Emmett-Teller method (BET) from N2 adsorption-desorption isotherm at 77 K, and the point of zero charge (pHPZC). The adsorption of methylene blue and Congo red was studied according to different parameters. The results showed that isotherms were well described by the Langmuir model justifying monolayer and homogeneous adsorption. Kinetics were well followed the pseudo-second-order model. Adsorption capacities of MB onto A-B 1/1 and CR onto A-B 1/3 were 1171 and 95.55 mg/g respectively. MB adsorption on A-B 1/1 and CR adsorption on A-B 1/3 were endothermic and exothermic respectively. Regeneration study showed that dyes were successfully desorbed from A-B 1/1 and A-B 1/3 with removal percentages of 99.65% and 86.2% respectively in the first cycle. Hybrid alginate-bentonite composites are low-cost, effective and regenerable for a wide variety of dyes.

Assessment on the decolourization of textile dye (Reactive Yellow) using Pseudomonas sp. immobilized on fly ash: Response surface methodology optimization and toxicity evaluation.

This study focuses on the investigation of removal of textile dye (Reactive Yellow) by a combined approach of sorption integrated with biodegradation using low cost adsorbent fly ash immobilized with Pseudomonas sp. To ensure immobilization of bacterial species on treated fly ash, fly ash with immobilized bacterial cells was characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and fluorescence microscopy. Comparative batch studies were carried out using Pseudomonas sp, fly ash and immobilized Pseudomonas sp on flyash and were observed that immobilized Pseudomonas sp on flyash acted as better decolourizing agent. The optimized pH, temperature, and immobilized adsorbent dosage for highest percentage of dye removal were observed to be pH 6, 303 K, 1.2 g/L in all the cases. At optimum condition, the highest percentage of dye removal was found to be 88.51%, 92.62% and 98.72% for sorption (flyash), biodegradation (Pseudomonas sp) and integral approach (Pseudomonas sp on flyash) respectively. Optimization of operating parameters of textile dye decolourization was done by response surface methodology (RSM) using Design Expert 7 software. Phytotoxicity evaluation with Cicer arietinum revealed that seeds exposed to untreated dye effluents showed considerably lower growth, inhibited biochemical, and enzyme parameters with compared to those exposed to treated textile effluents. Thus this immobilized inexpensive technique could be used for removal of synthetic dyes present in textile wastewater.

Corncob as an effective, eco-friendly, and economic biosorbent for removing the azo dye Direct Yellow 27 from aqueous solutions.

The corncob is an agricultural waste generated in huge quantities during corn processing. In this paper, we tested the capacity of corncob particles for water purification by removing the azo dye Direct Yellow 27 (DY27) via biosorption. The biosorption process was investigated in terms of the kinetics, equilibria, and thermodynamics. Batch biosorption studies showed that the biosorption performance has strong inverse correlations to the solution pH and the corncob particle size, and it increases quickly with increasing contact time and initial dye concentration. The pseudo-second-order kinetic model provides the best fit to the experimental data, whereas the Redlich-Peterson isotherm model is most suitable for describing the observed equilibrium biosorption. The biosorption process is exothermic, spontaneous, and physisorption in character. Fourier transform infrared (FTIR) spectroscopy and confocal scanning laser microscopy (CSLM) studies suggest that lignocellulose and proteins play key roles in the biosorption of DY27 from aqueous solutions by corncob. Furthermore, after biosorption onto the corncob, the dye can be effectively desorbed using 0.1 M NaOH solution. Therefore, the corncob can be used as a promising biosorbent to remediate DY27-contaminated water and wastewater.

Facile synthesis of low-cost magnetic biosorbent from peach gum polysaccharide for selective and efficient removal of cationic dyes.

Magnetic biosorbents derived from renewable resource are emerging as a new class of adsorbing material for environmental cleanup because of their eco-friendly characteristic, easy availability and low cost. Herein, a novel magnetic peach gum bead (MPGB) biosorbent was successfully fabricated by a simple one-step reaction based on the simultaneous formation of magnetic nanoparticles and cross-linking of natural peach gum polysaccharide. Benefiting from the combined merits of peach gum and magnetic nanoparticles, the MPGB not only showed excellent adsorption performance for cationic dyes but also exhibited convenient magnetic separation capability. The influences of pH, ionic strength, initial dye concentration, contact time and temperature on the adsorption property of MPGB biosorbent were investigated by choosing methylene blue (MB) as a representative cationic dye. The Langmuir isotherm fitted the adsorption isotherm well with maximum adsorption capacity of 231.5mgg-1. Kinetic data showed good correlation with pseudo-second-order model. Thermodynamic investigation revealed that the adsorption process was spontaneous and endothermic. Moreover, the MPGB exhibits nice reusability. Considering the facile fabrication process and excellent adsorption performance, the MPGBs hold great promise for using as biosorbent for environmental cleanup.

Optimisation of the recovery of carotenoids from tomato processing wastes: application on textile dyeing and assessment of its antioxidant activity.

The present study has been focused on the extraction of natural pigments from tomato industry waste. At first, different solvents and solvents mixture were compared to determine which one is the best for extracting carotenoids compounds from tomato by-products. A mixture of hexane and acetone gave the highest carotenoids extraction yield among the others examined. The extraction conditions were optimised using a five-level-five-factor central composite design. Under optimal conditions, solvent solid ratio 90, hexane percentage in the solvent mixture 60, extraction duration 50, number of extractions 4 and extraction temperature 35 °C, the yield of carotenoids was 80.7 µg/g. The coloured extract of tomato by-products was applied on textile fabrics to investigate the dyeing characteristics and antioxidant activities. The results indicate that extract can be applied on textile fabrics (wool, silk and polyamide) to produce coloured clothing with acceptable antioxidant properties.

An efficient removal of crystal violet dye from waste water by adsorption onto TLAC/Chitosan composite: A novel low cost adsorbent.

A composite of Typha latifolia activated carbon (TLAC) (a novel, low cost absorbent) and chitosan (TLAC/Chitosan composite) was prepared. The composite was characterised using IR spectra, XRD, FESEM and Pore size studies. Its effectivity was tested for the removal of crystal violet dye from aqueous solutions. The effect of pH, dose rate and initial dye concentration was evaluated. The adsorption isotherm, kinetics and thermodynamic parameters were studied. Langmuir and Freundlich isotherm models were found fit effectively for the dye adsorption data in the present study. The adsorption followed pseudo-second order kinetics. The evaluated thermodynamic parameters show a spontaneous and exothermic reaction. Overall, this study indicates TLAC/Chitosan composite as an effective adsorbent for the removal of crystal violet dye from aqueous solutions.

Assessment of the banana pseudostem as a low-cost biosorbent for the removal of reactive blue 5G dye.

In this work, the removal of reactive blue 5G (RB5G) dye using the drying biomass of banana pseudostem (BPS) was investigated. The characterization of BPS particles was performed. Improvement in the RB5G dye removal performance at the following sorption conditions was evidenced: pH 1, 30°C sorption temperature and 40 rpm shaking, regardless of the particle size range. Kinetic RB5G dye sorption data obtained at better conditions fit well in an Elovich model. A combined Langmuir-BET isotherm model provides a good representation of the RB5G dye equilibrium sorption data, which shows the evidence of a physical sorption process on the BPS surface. Based on the results, the removal of RB5G dye molecules by BPS is based on a physical sorption process.

Biobleaching of industrial important dyes with peroxidase partially purified from garlic.

An acidic peroxidase was extracted from garlic (Allium sativum) and was partially purified threefold by ammonium sulphate precipitation, dialysis, and gel filtration chromatography using sephadex G-200. The specific activity of the enzyme increased from 4.89 U/mg after ammonium sulphate precipitation to 25.26 U/mg after gel filtration chromatography. The optimum temperature and pH of the enzyme were 50°C and 5.0, respectively. The Km and V max for H2O2 and o-dianisidine were 0.026 mM and 0.8 U/min, and 25 mM and 0.75 U/min, respectively. Peroxidase from garlic was effective in decolourizing Vat Yellow 2, Vat Orange 11, and Vat Black 27 better than Vat Green 9 dye. For all the parameters monitored, the decolourization was more effective at a pH range, temperature, H2O2 concentration, and enzyme concentration of 4.5-5.0, 50°C, 0.6 mM, and 0.20 U/mL, respectively. The observed properties of the enzyme together with its low cost of extraction (from local sources) show the potential of this enzyme for practical application in industrial wastewater treatment especially with hydrogen peroxide. These Vat dyes also exhibited potentials of acting as peroxidase inhibitors at alkaline pH range.

Extraction of anthocyanins from black bean canning wastewater with macroporous resins.

This study investigated purification of anthocyanins from black bean canning wastewater by column chromatography with 5 types of macroporous resins (Diaion Hp20, Sepabeads Sp70, Sepabeads Sp207, Sepabeads Sp700, and Sepabeads Sp710). By-product of canned black beans was partially purified by filtration, in anticipation of higher performance during column chromatography. Equilibrium adsorption isotherms were measured and analyzed using Langmuir and Freundlich isotherm models. Both Langmuir (all R² ≥ 0.98) and Freundlich (all R² ≥ 0.97) models can describe the adsorption process of anthocyanins from black bean canning wastewater using the tested resins. The adsorption and desorption behaviors of anthocyanins were studied using a dynamic method on the 5 types of resins, and Sp700 presented the highest adsorption capacity (39 ± 4 mg/g; P < 0.05) as well as desorption capacity (19 ± 2%; P < 0.05), indicating that of the resins examined, Sp700 is a better candidate for purification of anthocyanins from black bean canning wastewater.

Adsorption properties of low-cost biomaterial derived from Prunus amygdalus L. for dye removal from water.

The capability of Prunus amygdalus L. (almond) shell for dye removal from aqueous solutions was investigated and methyl orange was used as a model compound. The effects of operational parameters including pH, ionic strength, adsorbent concentration and mesh size, dye concentration, contact time, and temperature on the removal of dye were evaluated. The adsorption kinetics conformed to the pseudo-second-order kinetic model. The equilibrium data pointed out excellent fit to the Langmuir isotherm model with maximum monolayer adsorption capacity of 41.34 mg g(-1) at 293 K. Thermodynamic analysis proved a spontaneous, favorable, and exothermic process. It can be concluded that almond shell might be a potential low-cost adsorbent for methyl orange removal from aqueous media.

Packed multi-channels for parallel chromatographic separations in microchips.

Here we report on a simple method to fabricate microfluidic chip incorporating multi-channel systems packed by conventional chromatographic particles without the use of frits. The retaining effectivities of different bottlenecks created in the channels were studied. For the parallel multi-channel chromatographic separations several channel patterns were designed. The obtained multipackings were applied for parallel separations of dyes. The implementation of several chromatographic separation units in microscopic size makes possible faster and high throughput separations.

Techno-economical optimization of Reactive Blue 19 removal by combined electrocoagulation/coagulation process through MOPSO using RSM and ANFIS models.

In this research, Response Surface Methodology (RSM) and Adaptive Neuro Fuzzy Inference System (ANFIS) models were applied for optimization of Reactive Blue 19 removal using combined electrocoagulation/coagulation process through Multi-Objective Particle Swarm Optimization (MOPSO). By applying RSM, the effects of five independent parameters including applied current, reaction time, initial dye concentration, initial pH and dosage of Poly Aluminum Chloride were studied. According to the RSM results, all the independent parameters are equally important in dye removal efficiency. In addition, ANFIS was applied for dye removal efficiency and operating costs modeling. High R(2) values (≥85%) indicate that the predictions of RSM and ANFIS models are acceptable for both responses. ANFIS was also used in MOPSO for finding the best techno-economical Reactive Blue 19 elimination conditions according to RSM design. Through MOPSO and the selected ANFIS model, Minimum and maximum values of 58.27% and 99.67% dye removal efficiencies were obtained, respectively.

Adsorption of dyestuff from aqueous solutions through oxalic acid-modified swede rape straw: adsorption process and disposal methodology of depleted bioadsorbents.

Swede rape straw (Brassica napus L.) was modified by oxalic acid under mild conditions producing an efficient dye adsorbent (SRSOA). This low-cost and environmental friendly bioadsorbent was characterized by various techniques and then applied to purify dye-contaminated aqueous solutions. Equilibrium study showed that the Langmuir model demonstrated the best fit to the equilibrium data and the methylene blue (MB) adsorption capacity calculated by this model was 432mgg(-1). The adsorption process and mechanism is also discussed. To properly deal with the dye-loaded bioadsorbents, the disposal methodology is discussed and a biochar based on depleted bioadsorbents was for the first time produced and examined. This method both solved the disposal problem of contaminant-loaded bioadsorbents and produced an useful adsorbent thereafter. The study indicates that SRSOA is a promising substitute for ACs in purifying dye-contaminated wastewater and that producing biochars from contaminant-loaded bioadsorbents maybe a feasible disposal method.

Low-cost adsorbents from bio-waste for the removal of dyes from aqueous solution.

Activated carbons (ACs) were developed from bio-waste materials like rice husk and peanut shell (PS) by various physicochemical activation methods. PS char digested in nitric acid followed by treatment at 673 K resulted in high surface area up to ∼585 m(2)/g. The novelty of the present study is the identification of oxygen functional groups formed on the surface of activated carbons by infrared and X-ray photoelectron spectroscopy and quantification by using temperature programmed decomposition (TPD). Typical TPD data indicated that each activation method may lead to varying amounts of acidic and basic functional groups on the surface of the adsorbent, which may be a crucial factor in determining the adsorption capacity. It was shown that ACs developed during the present study are good adsorbents, especially for the removal of a model textile dye methylene blue (MB) from aqueous solution. As MB is a basic dye, H(2)O(2)-treated rice husk showed the best adsorption capacity, which is in agreement with the acidic groups present on the surface. Removal of the dye followed Langmuir isotherm model, whereas MB adsorption on ACs followed pseudo-second-order kinetics.