Phytotoxicity and genotoxicity study of reactive red 141 dye on mung bean (Vigna radiata (L.) Wilczek) seedlings.

BACKGROUND: Reactive Red (RR) 141 dye is widely used in various industrial applications, but its environmental impact remains a growing concern. In this study, the phytotoxic and genotoxic effects of RR 141 dye on mung bean seedlings (Vigna radiata (L.) Wilczek) were investigated, serving as a model for potential harm to plant systems. METHODS AND RESULTS: Short-term (14 days) and long-term (60 days) experiments in paddy soil pot culture exposed mung bean seedlings to RR 141 dye. The dye delayed germination and hindered growth, significantly reducing germination percentage and seedling vigor index (SVI) at concentrations of 50 and 100 ml/L. In short-term exposure, plumule and radical lengths dose-dependently decreased, while long-term exposure affected plant length and grain weight, leaving pod-related parameters unaffected. To evaluate genotoxicity, high annealing temperature-random amplified polymorphic DNA (HAT-RAPD) analysis was employed with five RAPD primers having 58-75% GC content. It detected polymorphic band patterns, generating 116 bands (433 to 2857 bp) in plant leaves exposed to the dye. Polymorphisms indicated the appearance/disappearance of DNA bands in both concentrations, with decreased genomic template stability (GTS) values suggesting DNA damage and mutation. CONCLUSION: These findings demonstrate that RR 141 dye has a significant impact on genomic template stability (GTS) and exhibits phytotoxic and genotoxic responses in mung bean seedlings. This research underscores the potential of RR 141 dye to act as a harmful agent within plant model systems, highlighting the need for further assessment of its environmental implications.

Biotransformation of Reactive Red 141 by Paenibacillus terrigena KKW2-005 and Examination of Product Toxicity.

A total of 37 bacterial isolates were obtained from dye-contaminated soil samples at a textile processing factory in Nakhon Ratchasima Province, Thailand, and the potential of the isolates to decolorize and biotransform azo dye Reactive Red 141 (RR141) was investigated. The most potent bacterium was identified as Paenibacillus terrigena KKW2-005, which showed the ability to decolorize 96.45% of RR141 (50 mg/l) within 20 h under static conditions at pH 8.0 and a broad temperature range of 30-40°C. The biotransformation products were analyzed by using UV-Vis spectrophotometry and Fourier-transform infrared spectroscopy. Gas chromatography-mass spectroscopy analysis revealed four metabolites generated from the reductive biodegradation, namely sodium 3-diazenylnaphthalene-1,5-disulfonate (I), sodium naphthalene-2-sufonate (II), 4-chloro-1,3,5-triazin-2-amine (III) and N1-(1,3,5-triazin-2-yl) benzene-1,4-diamine (IV). Decolorization intermediates reduced phytotoxicity as compared with the untreated dye. However, they had phytotoxicity when compared with control, probably due to naphthalene and triazine derivatives. Moreover, genotoxicity testing by high annealing temperature-random amplified polymorphic DNA technique exhibited different DNA polymorphism bands in seedlings exposed to the metabolites. They compared to the bands found in seedlings subjected to the untreated dye or distilled water. The data from this study provide evidence that the biodegradation of Reactive Red 141 by P. terrigena KKW2-005 was genotoxic to the DNA seedlings.

Adsorption of Reactive Red 141 from wastewater onto modified chitin.

This research involved the adsorption of synthetic reactive dye wastewater (SRDW) by chitin modified by sodium hypochlorite and original chitin in batch experiments. The comparison of maximum adsorption capacity used the Langmuir model to describe SRDW adsorption onto chitin and modified chitin under a system pH of 11.0. Maximum dye adsorption by chitin increased from 133mgg(-1) to 167mgg(-1) at temperatures of 30-60 degrees C, respectively. For modified chitin, the capacity decreased from 124mgg(-1) to 59mgg(-1) when the temperature increased from 30 degrees C to 60 degrees C, respectively. Both Na(2)SO(4) and Na(2)CO(3) increased in dye adsorption. The spectra of attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectrometry confirmed the hydroxyl groups as functional groups of modified chitin, which affected the modification and the SRDW adsorption. The adsorbed dyes were eluted by distilled water and 1M NaOH to confirm the dye adsorption mechanism. Total elution of modified chitin and chitin were 92.76% and 55.29%, respectively. Although modified chitin had a maximum adsorption capacity less than chitin, elution of the dye from modified chitin was easier than chitin. Therefore, modified chitin could be suitable in a column system for dye pre-concentration as well as wastewater minimisation. In addition, the column study showed that modified chitin could be used for more than four cycles of adsorption and elution by distilled water.

Adsorption mechanism of synthetic reactive dye wastewater by chitosan.

Chitosan was able to remove the color from synthetic reactive dye wastewater (SRDW) under acidic and caustic conditions. The effect of the initial pH on SRDW indicated that electrostatic interaction occurred between the effective functional groups (amino groups) and the dye under acidic conditions. Moreover, SRDW adsorption under caustic conditions was also affected by the covalent bonding of dye and hydroxyl groups of chitosan. In addition, elution tests confirmed that chemical adsorption occurred under acidic conditions, while both physical and chemical adsorption appeared under caustic conditions. The spectra of attenuated total reflectance Fourier transform infrared spectrometry confirmed the functional groups of chitosan that affected the SRDW adsorption. However, the maximum adsorption capacities of chitosan increased when the temperature increased. The maximum adsorption capacity of chitosan obtained from the Langmuir model was 68, 110, and 156 mg g(-1) under a system pH of 11.0 at 20, 40, and 60 degrees C, respectively. The negative values of enthalpy change (DeltaH), free energy change (DeltaG), and entropy change (DeltaS) indicated an exothermic, spontaneous process and decreasing disorder of the system, respectively. Therefore, the mechanism of SRDW adsorption by chitosan was probably by chemical adsorption for a wide range of pH's and at high temperatures.