Indigo Concentration Research Articles

A Novel, Dual-Initiator, Continuous-Suspension Grafting Strategy for the Preparation of PP-g-AA-MAH Fibers to Remove of Indigo from Wastewater.

The indigo dye found in wastewater from printing and dyeing processes is potentially carcinogenic, teratogenic, and mutagenic, making it a serious threat to the health of animals, plants, and humans. Motivated by the growing need to remove indigo from wastewater, this study prepared novel fiber absorbents using melt-blow polypropylene (PP) melt as a matrix, as well as acrylic acid (AA) and maleic anhydride (MAH) as functional monomers. The modification conditions were studied to optimize the double-initiation, continuous-suspension grafting process, and then functional fibers were prepared by melt-blown spinning the modified PP. The results showed that the optimum modification conditions were as follows: a 3.5 wt% interfacial agent, 8 mg/L of dispersant, 80% monomer content, a 0.8 mass ratio of AA to MAH, a 1000 r/min stir speed, 3.5 wt% initiator DBPH grafting at 130 °C for 3 h, and 1 wt% initiator BPO grafting at 90 °C for 2 h. The highest grafting rate of the PP-g-AA-MAH was 31.2%, and the infrared spectrum and nuclear magnetic resonance spectroscopic analysis showed that AA and MAH were successfully grafted onto PP fiber. This modification strategy also made the fibers more hydrophilic. The adsorption capacity of the PP-g-AA-MAH fibers was highly dependent on pH, and the highest indigo adsorption capacity was 110.43 mg/g at pH 7. The fiber adsorption capacity for indigo increased rapidly before plateauing with increasing time or indigo concentration, and the experimental data were well described in a pseudo-second-order kinetic model and a Langmuir isothermal adsorption model. Most impressively, the modified fiber adsorption capacity for indigo remained as high as 91.22 mg/g after eight regeneration and reuse cycles. In summary, the PP-g-AA-MAH fibers, with excellent adsorption-desorption characteristics, could be readily regenerated and reused, and they are a promising material for the removal of indigo from wastewater.

Physicochemical properties and antibacterial activity evaluation of new indigo extract from Baphicacanthus cusia (Nees) Bremek prepared by chemical conversion method

The effect of acidolysis time, hydrochloric acid concentration, ozonization time and pH on the yield of indigo were investigated by single factor experiment using dried leaves of Baphicacanthus cusia (Nees) Bremek (DLB) as raw material. On this basis, the technological condition for preparing new indigo extract (NIE) by directional chemical conversion method was optimized by orthogonal experiment. Then, the physiochemical properties of NIE were analyzed by combustion assay, nitric acid assay, thin layer chromatography identification assay, moisture detection and water-soluble pigment observation assay. Moreover, UPLC-Q-TOF-MS/MS technology was utilized to compare chemical composition difference between the NIE and traditional indigo naturalis (TIN). Finally, NIE emulsion was prepared by ultrasound assisted high pressure homogenization method and its stability, antibacterial activity as well as antibacterial mechanism were evaluated. The experimental results showed that optimum process for preparing NIE were hydrochloric acid concentration of 2 %, ozonization time of 3 min, pH of 7 and acidolysis time of 1 h; Under this condition, the content and yield of indigo in the NIE were significantly improved, which could reach up to 42.6 ± 0.28 % and 2.26 ± 0.04 %, separately. NIE possessed similar physiochemical properties with TIN described in Chinese pharmacopoeia 2020, and had more diverse active ingredients than TIN. The prepared NIE emulsion demonstrated excellent stability, whether at dark or bright place, and no matter at low temperature (4 ℃) or room temperature (25 ℃), the particle size, PDI, pH and indigo content of which displayed little variation. In addition, the NIE emulsion owned good inhibitory activity against S. aureus, and its MIC and MBC values were 40 and 80 μg/mL, respectively. Moreover, NIE emulsion exhibited antibacterial effect by influencing cell membrane integrity, Ca2+-Mg2+-ATPase activity on the cell membrane and intracellular Ca2+ levels of S. aureus. All of above results will lay the foundation for the green and sustainable utilization of Baphicacanthus cusia (Nees) Bremek.

Over dyeing of Lyocell fabric with natural indigo and rhubarb

In order to enrich the range of natural dye chromatography, this study used rhubarb to dye indigo dyed Lyocell fabric to obtain green Lyocell fabric. Firstly, the Lyocell fabric was dyed with indigo using a typical reduction method. The K/S and b* values of dyed fabrics were used as evaluation indicators to determine indigo concentration of 1.2 g/l before the over dyeing. The effects of rhubarb concentration, pH value, and dyeing temperature on the K/S value and color characteristic value of rhubarb dyed Lyocell fabric are discussed. The results showed that acidic solution, higher rhubarb concentration, and lower dyeing temperature were beneficial to obtain higher K/S and b* values for the rhubarb dyed Lyocell. Finally, these three factors were taken as independent variables in over dyeing, and the red-green value of dyed fabric was taken as response value for response surface analysis. The response surface analysis of three factors and three levels showed that the pH value of the dye solution had a significant impact on the a* value. The a* value of the dyed fabric decreased with the increase in rhubarb concentration and the decrease in the pH value and dyeing temperature. The optimization process suggested by the regression model statistical analysis was as follows: rhubarb concentration was 2.67 g/l, dye bath pH 3.5, and dyeing temperature 57°C. The verification result showed that a* value of the over dyed fabric was –10.75, which was close to the predicted value –10.98. The infrared results showed that the cellulose characteristic groups of the undyed and dyed Lyocell fabrics were almost same. The Lyocell fabric dyed with indigo and rhubarb showed a blue-green color, and 50+ ultraviolet protection factor. The washing color fastness of the over dyed Lyocell fabric was 2–3 and the rubbing fastness was above 3. This over dyeing method may enrich the chromatogram of Lyocell fabric dyed with natural dyes.

Single box dyeing of denim yarns under nitrogen protection with high indigo concentration

In the era of “double carbon,” green short process preparation of denim textiles will become more and more popular, and dyeing is an essential step in this process. In order to improve dye utilization and energy efficiency, a high-concentration indigo single box dyeing method based on nitrogen (N2) protection has been studied. The optimal dyeing conditions were obtained. The dyeing mechanism was revealed by evaluating the stability of the dyeing solution and dye distribution in the dyed yarns. Various dyeing properties, chemicals, energy consumption, and dyeing wastewater were measured and compared with conventional slasher dyeing. It has been shown that N2 protection effectively avoids the oxidation of soluble leuco-indigo and improves the stability of the leuco dyeing bath. In addition, the dyes diffused more deeply into the fiber in the dyeing box under a micro-positive pressure environment, enhancing the dyeing efficiency and depth. The proposed technique exhibited better dye utilization and excellent color fastness. Dyeing wastewater was more chemical and biodegradable, relieving wastewater treatment. Generally, cleaner dyeing not only reduces the consumption of energy, water, and chemicals, but also saves 46.8% of the economic cost compared with traditional slasher dyeing, indicating that the proposed technology is interesting for industrial application.

Utilization of Indigofera Leaves as Natural Dyes for Silk Fabrics

Indigo is a natural blue dye produced from the leaves of the Indigofera plant, which is environmentally friendly and non-carcinogenic. This study aimed to determine the reduction potential value of molasses and brown sugar as reducing agents, to examine the effect of the hydrochloric acid concentrations and aeration time on the amount of indigo, and to test the fastness of rubbing against solar heat, dry, wet and acid on silk fabrics that were dyed by indigo with various fixators. To extract the indigo dye, the Indian glycosides contained in Indigofera leaves were hydrolyzed to indoxyl and glucose using hydrochloric acid. Indoxyl was then oxidized to indigo using molasses as a polysaccharide compound. The results showed that the concentration of 0.01 M hydrochloric acid produced the highest indigo content of 26.83 ppm, and the best aeration time was 4 hours to produce indigo with a concentration of 22.32 ppm. The effect of the fixator types produced different colors. The fixator of ferrous sulfate produced a dark blue-green color, limestone produced a light blue color, while alum produced a bright blue color. The fastness test showed the same result as the gray sale value of 4-5 meaning that there was a slight fading.

Quantification of indigo on denim textiles as basis for jeans recycling

Concepts for circularity of post-consumer textile wastes have to consider the presence of dyes in the respective feedstock. Denim textiles form an important group of products which almost exclusively have been dyed with indigo, thus fibre-to-fibre recycling will allow reuse of the dye. Such an approach will require an appropriate analytical method to quantify the indigo content on a textile material. The alkaline Fe(II)-complex with triethanolamine as ligand allows rapid and time stable reduction of the indigo dye into its soluble leuco-form. After desorption of the indigo leuco-dianion quantification of the dye concentration can be achieved by photometry at 410 nm. The measurement of the dye concentration in solution makes the method independent of the uneven dye distribution in denim, which consists of ring-dyed warp and white weft yarn. This uneven dye distribution in denim textiles makes common methods of colour measurement unsuitable for indigo quantification in denim wastes. The presented technique thus will be an essential tool for any approach to recycle denim textiles including valuable indigo dye therein.

Electrocatalytic hydrogenation of indigo by NiMoS: energy saving and conversion improving.

An NiMo alloy bonded with sulfur (NiMoS) exhibits enhanced surface affinity toward water and organic molecules, thereby enhancing electrocatalytic hydrogenation (ECH) reactions through synergistic effects. In industrial processes, indigo, an ancient dye employed in the denim industry, is typically chemically reduced using sodium dithionite. However, this process generates an excess of toxic sulfide, which heavily contaminates the environment. ECH is a sustainable alternative for indigo reduction due to its reduced reliance on chemicals and energy consumption. In this study, carbon-felt (CF)-supported NiMoS was synthesized in a two-step process. First, the NiMo alloy was electrodeposited onto the CF surface, followed by sulfidation in an oven at 600 °C. NiMoS exhibits a larger electrochemically active surface area and a smaller charge transfer resistance compared to pure Ni and NiMo. Furthermore, NiMoS demonstrates excellent thermodynamic and kinetic properties for water splitting in strong alkaline solutions (1.0 M KOH). Additionally, optimal reaction conditions for the ECH of indigo were explored. Under the conditions of a 1.0 M KOH hydroxide medium with 10% methanol (v/v), an indigo concentration of 5 g L-1, a reaction temperature of 70 °C, and a current density of 10 mA cm-2, NiMoS/CF achieved remarkable improvements in both conversion (99.2%) and Faraday efficiency (38.1%). The results of this experimental work offer valuable insights into the design and application of novel catalytic materials for the ECH of vat dyes, opening up new possibilities for sustainable and environmentally friendly processes in the dye industry.

Genetic variability studies in Indigo (Indigofera tinctoria L.)

An experiment to estimate the extent of variability, heritability and genetic advance as percent of mean on twenty accessions of Indigofera tinctoria collected from diverse geographical locations and raised in the Orchard unit of the Department of Horticulture, Faculty of Agriculture, Annamalai University.  The experiment was laid out in a randomized block design with three replications. The biometric observations of plant height, plant spread, the number of branches, the number of leaves, leaf area, biomass, fresh weight of shoots, fresh weight of leaves, glucoside content, indigo content dye yield and dye recovery were recorded at 160 days after sowing. High GCV estimates were recorded for dye yield, leaf area, dye recovery, glucoside content, the number of branches, the number of leaves, indigo content, plant height, fresh weight of leaves and fresh weight of shoot. The high heritability estimate for the glucoside content (82.02 %) revealed the possibility of increasing the glucoside content. The character dye yield was positively and significantly correlated with plant height, plant spread, the number of branches, the number of leaves, leaf area, fresh weight of leaves, fresh weight of shoot, biomass, glucoside content, dye recovery and indigo content both at genotypic as well as phenotypic levels. Keywords: Indigo, Variability, PCV, GCV, Genetic advance

Evaluation of growth and yield of indigo ecotypes in different sowing dates and genetic diversity analysis using AFLP markers

AbstractIndigo (Indigoferatinctoria L.), as a forgotten crop, has immense industrial and medicinal value. In this research, the effect of sowing date on the leaf, seed, and dye yield of indigo was examined at Jiroft, Iran, during the 2013 and 2014 growing seasons. The experiment was arranged as a split‐plot based on a randomized complete block design with three replications. Planting dates (5 May, 20 May, and 5 June) and indigo ecotypes as landraces of Jiroft, Roudbar, Rigan, and Ghale‐ganj were considered as main and subplots, respectively, aiming to evaluate their effects on pod number/plant, 1,000‐seed weight, seed number/pod, leaf dry weight, seed yield, as well as indigo dye percentage and yield. The results indicated that the indigo content was greater at the second sowing date (0.68%) than the first (0.66%) and third (0.65%) dates. Further, the indigo percentage was greater in Jiroft and Roudbar ecotypes compared with Rigan and Ghale‐ganj. Seed yield at the second and third sowing dates significantly increased (560.3 kg ha–1) and reduced (188.4 kg ha–1), respectively, compared with the first sowing date (261.4 kg ha–1). Furthermore, the highest value of leaf dry weight, indigo yield, and seed yield were obtained from the Jiroft ecotype at the second sowing date; in contrast, the lowest of these parameters were recorded in the Ghale‐ganj ecotype at the latest sowing date. Moreover, the genetic diversity of ecotypes was studied using the amplified fragment length polymorphism (AFLP) marker. Based on the dendrogram, the four ecotypes of indigo were divided into three groups; thus, Jiroft and Rudbar, geographically close to each other and almost the same, were in one group, and Reagan and Ghale‐Ganj were in separate groups. Overall, based on this research results, Jiroft and 20 May could be suggested as the best ecotype and sowing date of indigo for the examined region. Obtained results can also be useful for expanding and facilitating the cultivation of neglected plants.

Effect of Physicochemical Process Variables on Natural Indigo Dye Production from <i>Strobilanthes cusia</i> Leaves by Response Surface Methodology

The recovery process of indigoid compounds involves enzymatic hydrolysis of indigo precursors continued by oxidation reaction to synthesize indigo pigment. The purpose of this research was to evaluate the effect of physicochemical process variables, i.e., temperature, time, and pH aeration, on indigo yield from Strobilanthes cusia leaves. Small leaf pieces were immersed in distilled water and heated at temperatures (40, 50, and 60 °C) and duration (1, 2, and 3 h). The extract was aerated at different pHs (8, 10, and 12) to form the indigo product. The indigo concentration was quantified through a visible spectrophotometer and high-performance liquid chromatography (HPLC). The optimized condition for indigo production was studied using response surface methodology (RSM). Temperature, time, and interaction between temperature and time significantly affected the indigo yield. The optimized conditions for extraction of indigo dyes were determined to be at 60 °C for 1 h and pH 8 for maximizing the indigo yield. On that condition, the indigo concentration quantified by HPLC was 1.15% (w/v) which was lower than that by the spectrophotometry. By spectrophotometric analysis, the actual indigo content of 1.68% (w/v) on that optimum condition was close to the predicted indigo content of 1.77% (w/v) using RSM.

Application of Fluorescence Spectroscopy in Indigo Reduction Process : Identification of Reduction Stages and Reduced Indigo Concentration

Application of Fluorescence Spectroscopy in Indigo Reduction Process : Identification of Reduction Stages and Reduced Indigo Concentration

Effect of light intensity on growth, yield and indigo content of Indigofera tinctoria L.

Synthetic dyes can increase the amount of pollutants that become a serious problem in the environment. The use of synthetic dyes can be replaced with dyes from natural ingredients, namely Indigofera tinctoria. These plants are a source of blue natural dyes because it contains indigo. The content of indigo is very responsive to light. The impact of climate change is a serious threat to the supply of natural dyes. So, judge the suitability of the environment and indigo content under climate change are essential for the sustainable production of natural dyes Indigofera tinctoria. The research aimed to examine the role of light on the growth, yield, and indigo content in Indigofera tinctoria. The study was conducted using a randomized complete design with one factor, namely light intensity with 3 levels namely light intensity 100%, 50%, and 25%, with 9 replications. Light intensity affected the number of leaves, nodes, fresh weight, and indigo content. The highest number of leaves, nodes, and fresh weight were at 100% light intensity, while the highest indigo content was at 25% light intensity. The fresh weight with indigo paste is positively correlated. The higher the fresh weight of the plant, the more paste will be produced. However, the content of indigo was negatively correlated with indigo paste.

Study on dyeing of vegetable tanned leather with indigo

In order to improve the dyeing fastness of indigo plant dyes for leather, save the cost of dyeing and reduce the environmental pollution in the dyeing process, the appearance quality is improved by improving the traditional indigo dyeing method. In this study, we try to use indigo acid environment to dye vegetable tanned leather to avoid the damage of basic environment to leather in the process of indigo vat dyeing. The single factor and orthogonal experiments of indigo natural dye dyeing vegetable tanned leather were carried out with the amount of iron medium, indigo dye, dyeing temperature and pre mordant dyeing time as experimental parameters, and the dyeing effect was evaluated with the K/S levels and color fastness as measurement indexes. The results showed that the concentration of iron powder was 10g / L, the pre mordant dyeing time was 25 minutes, the concentration of indigo was 16 g / L, and the dyeing temperature was 35 °C; the vegetable tanned leather after dyeing had better K/S levels, dry wet friction and tensile strength, but the light fastness needs to be further improved.

Induction of Cytochrome P4501 Genes by Various Inducers in Rainbow Trout (Oncorhynchus mykiss)

Gao, K.; Tian, J.; Wu, Y.; Mei, P.; Zhang, Z.; Jonsson, M., and Brandt, I., 2021. Induction of cytochrome P4501 genes by various inducers in rainbow trout (Oncorhynchus mykiss). Journal of Coastal Research, 37(1), 143–148. Coconut Creek (Florida), ISSN 0749-0208.Juvenile rainbow trout is widely found in various aquatic systems, such as freshwater, coastal, and marine habitats all over the world. Expression patterns of the cytochrome P4501 (CYP1) genes exposed to various stressors in such fish could be informative and useful in biomonitoring. In the present study, the induction of CYP1 in rainbow trout by indigo, humic acid (HA), and benzo(a)pyrene (BaP) was studied through a 12-hour exposure experiment by using rainbow trout as an experimental object. First, 7-ethoxyresorufin O-deethylase (EROD) activity and CYP1 expression levels in fish exposed to different concentrations of indigo were analyzed. The EROD activities in fish gills were greatly affected by the concentration of indigo (1, 18, 50, and 80 nM). The expression level of CYP1A1 and CYP1A3 in gills was higher compared with CYP1B1 and CYP1Cs. Second, the gill EROD activity and CYP1 mRNA expressions levels were compared when induced by indigo, HA, and BaP at the same concentration (1 nM). Results indicated that rainbow trout were sensitive to all three inducers. Among them, the HA affected CYP1A1 and CYP1A3 most obviously. CYP1A, as an important biomarker, was more sensitive than CYP1B and CYP1C to those inducers. The observed effects of the different CYP1 inducers could provide a useful tool for monitoring of AhR-active pollutants in the aquatic environment.

Effect of drought stress on indigo and seed yield of Indigofera tinctoria ecotypes

The objective of the the current study was to elucidate the effect of drought stress on indigo yield and to derive certain morphological traits of indigo ecotypes. This experiment was laid out in a split-plot arranged at a randomized complete block design, with three replications in the Jiroft Agricultural and Natural Resources Research and Education Center, Kerman, Iran, during 2013-14 growing seasons. The main plot and the subplot included drought stress (100, 75, and 50% of crop water requirement) and indigo ecotypes (Jiroft, Roudbar, Rigan, and Ghale Ganj), respectively. The obtained results showed that morphological and indigo content attributes revealed significant differences between the control and the drought-stress plants. Increasing water stress (up to 50% of crop water requirement) resulted in a severe loss of leaf dry mass, plant height, and seed yield of 25, 25 and 58%, respectively, in comparison to the control condition; the highest indigo yield and content obtained from the mid-stress level. Moreover, interaction effects of drought and ecotypes on leaf dry mass, seed, and indigo yield were significant; thus, the LDM and seed yield was the greatest in the Jiroft ecotype in the control, the indigo yield was the greatest under mid-level stress, and it was the lowest in the Ghale Ganj ecotype under severe water-stress level. Therefore, the results of this research suggest that the Jiroft ecotype will perform well with respect to drought tolerance and will be useful for cultivation in the semi-arid regions of Jiroft.

Photocatalysed decolouration of indigo in solution via in situ generation of an organic hydroperoxide.

Indigo, an emblematic violet dye used for thousands of years to colour fabric, is resistant to fading on exposure to sunlight. Prior work has indicated that indigo is reactive towards both hydroperoxyl radicals and superoxide anions in solution. In order to promote photobleaching of indigo, we have utilised a BOPHY-based (BOPHY = aryl fused symmetrical pyrrole-BF2 complex) chromophore known to form both superoxide ions and a stable alkyl hydroperoxide under illumination in aerated solution. Selective irradiation of the photocatalyst causes relatively fast fading of indigo, with the rate increasing gently with increasing concentration of indigo. Molecular oxygen and light are essential for effective bleaching. One molecule of photocatalyst can bleach more than 40 molecules of indigo. An active component of the photocatalyst is a butylated hydroxytoluene (BHT) residue which itself quenches the triplet excited state of indigo. This provides an ancillary mechanism for effecting photofading of indigo but, because the triplet is formed in very low yield, this route is less practical.

Comparative transcriptome analyses revealed differential strategies of roots and leaves from methyl jasmonate treatment Baphicacanthus cusia (Nees) Bremek and differentially expressed genes involved in tryptophan biosynthesis.

Baphicacanthus cusia (Nees) Bremek (B. cusia) is an effective herb for the treatment of acute promyelocytic leukemia and psoriasis in traditional Chinese medicine. Methyl jasmonate (MeJA) is a well-known signaling phytohormone that triggers gene expression in secondary metabolism. Currently, MeJA-mediated biosynthesis of indigo and indirubin in B. cusia is not well understood. In this study, we analyzed the content of indigo and indirubin in leaf and root tissues of B. cusia with high-performance liquid chromatography and measured photosynthetic characteristics of leaves treated by MeJA using FluorCam6 Fluorometer and chlorophyll fluorescence using the portable photosynthesis system CIRAS-2. We performed de novo RNA-seq of B. cusia leaf and root transcriptional profiles to investigate differentially expressed genes (DEGs) in response to exogenous MeJA application. The amount of indigo in MeJA-treated leaves were higher than that in controled leaves (p = 0.004), and the amounts of indigo in treated roots was higher than that in controlled roots (p = 0.048); Chlorophyll fluorescence of leaves treated with MeJA were significantly decreased. Leaves treated with MeJA showed lower photosynthetic rate compared to the control in the absence of MeJA. Functional annotation of DEGs showed the DEGs related to growth and development processes were down-regulated in the treated leaves, while most of the unigenes involved in the defense response were up-regulated in treated roots. This coincided with the effects of MeJA on photosynthetic characteristics and chlorophyll fluorescence. The qRT-PCR results showed that MeJA appears to down-regulate the gene expression of tryptophan synthase β-subunits (trpA-β) in leaves but increased the gene expression of anthranilate synthase (trp 3) in roots responsible for increased indigo content. The results showed that MeJA suppressed leaf photosynthesis for B. cusia and this growth-defense trade-off may contribute to the improved adaptability of B. cusia in changing environments.

Identification of three species commonly known as “daqingye” by internal leaf anatomy and high-performance liquid chromatography analyses

The macroscopic and microscopic morphologies and indigo and indirubin concentration of the traditional Chinese medicine herbs <em>Isatis indigotica</em> Fort., <em>Polygonum tinctorium</em> Ait., and <em>Baphicacanthus cusia</em> (Nees) Bremek, all commonly known as “daqingye”, were determined and compared. The morphological analyses indicated that <em>I. indigotica</em> has leaves with winged petioles and no glandular hairs or crystals, <em>P. tinctorium</em> has leaves with membranous ocrea and clusters of calcium oxalate, and <em>B. cusia</em> has palisade cells in the mesophyll running over the main vein and single cells containing calcium carbonate crystals. Indigo and indirubin are chemical constituents that have been previously isolated from daqingye and were selected in this study as identification markers for high-performance liquid chromatography analysis due to their pharmacological activities. The chromatographic results showed that indigo and indirubin concentration varied significantly among the three species: high concentration of both indigo and indirubin were observed in <em>I. indigotica</em>, the highest concentration among the three daqingye plants was found in <em>P. tinctorium</em> but with low levels of indirubin, and the concentration of indigo and indirubin was quite low in <em>B. cusia</em>. In summary, three different species commonly known as daqingye were accurately distinguished by morphological observation, internal leaf anatomy analysis, and chromatographic analysis.

Applications Indigo (Indigofera Tinctoria L.) as Natural Dyeing in Milkfish [Chanos Chanos (Forsskal, 1775)] Skin Tanning Process

Dyeing is one of the stages in tanning process to apply base color on leather to avoid broken finishing coat. One of natural substance used in leather tanning is true indigo (Indigofera tinctoria L.). This substance has blue color and contains tannin to increase the quality of tanned Milkfish skin. The research was aimed to determine the effect of using different concentrations of true indigo application as natural substance to the quality of tanned milkfish skin. This research used completely randomized design (CRD) using three repetitions, the treatment were using the concentration of indigo 20%, 25% and 30%. The result shows that different concentrations of true indigo has significant effect (p < 0.05) to rub resistance on wet and dry coating, fastness to perspiration, tensile strength, elongation, hedonic, and micrograph photos of skin tissue. Tanned milkfish skin using 25% concentration of true indigo has the best quality based on the criteria: rub resistance on wet coating test (3.83%) and dry coating test (4.42%), fastness to perspiration (4.75%), tensile strength (1 843.53N · cm–2), elongation (47.61%), and skin tissue micrograph photos showing better display of collagen fibers.

Industrial textile effluent decolourization in stirred and static batch cultures of a new fungal strain Chaetomium globosum IMA1 KJ472923

The treatment of an industrial textile effluent (ITE) was investigated by using a mono-culture of a novel fungal strain Chaetomium globosum IMA1. This filamentous fungus was selected based on its capacity for dye removal via the biodegradation mechanism. The respirometric analysis showed that C. globosum IMA1 was resistant to an indigo concentration up to 700 mg equivalent COD/L. The decolourization of the ITE by C. globosum was performed in static and stirred batch systems. The better lignin peroxidase (LiP), laccase and the manganese peroxidase (MnP) productions were 829.9 U/L, 83 U/L and 247.8 U/L, respectively since 3–5 days under a stirred condition. Therefore, the chemical oxygen demand (COD) and colors (OD620) removal yields reached 88.4% and 99.8%, respectively. Fourier transforms infrared spectroscopy (FTIR) analysis of the treated effluent showed that the decolourization was due to the degradation and the transformation of dye molecules. However, spectrophotometric examination showed that the complete dye removal was through fungal adsorption (8%), followed by degradation (92%).