Bonney's blue paint BP 1980

Pollution of water resources with hazardous substances of anthropogenic origin (e.g., synthetic dyes, heavy metal ions) is currently one of the most important environmental issues, and the development of not only effective and economical but also eco-friendly methods of removing these substances from aqueous solutions is one of the greatest challenges. Among the various separation methods, techniques based on the utilization of different types of polymer membranes have gained increasing interest due to their usually high efficiency, the materials' stability and reusability, and the possibility of using "green" components for their formation. Recent research efforts have been concentrated, inter alia, on the application of natural polysaccharide polymers (e.g., cellulose, alginates, starch, cyclodextrins) and their derivatives to produce well-performing membranes. Appropriately composed polysaccharide-based membranes under optimal process conditions enable effective separation of dyes, salts, and metal ions (e.g., often with a rejection rates of >95% for dyes and metal ions and <7% for salts). This review concerns the latest developments in the formation and utilization of novel polysaccharide-based membranes for the separation of synthetic dyes and metal ions from aqueous solutions and suspensions, with emphasis on their most important advantages, limitations, and potential impact on the environment and sustainability.

Abstract licence: CC BY

The worldwide textile industry extensively uses azo dyes, which pose serious health and environmental risks. Effective cleanup is necessary but challenging. Developing bioremediation methods for textile effluents will improve color removal efficiency. The recent attention to effectively utilizing microbes to convert toxic industrial azo dyes into non-hazardous compounds has garnered significant attention. In the present study, four fungal strains-Aspergillus flavus, Aspergillus terreus, Aspergillus niger, and Fusarium oxysporium-were employed to screen for the degradation and detoxification of azo dyes including congo red, crystal violet, bromophenol blue, and malachite green. After eight days, A. flavus had degraded azo dyes at the maximum proportion. The maximum decolorization (%) was achieved at 50 mg/L of dye concentration, 8 days of incubation, pH 6, 30 °C temperature, sucrose as a carbon source, NaNO3 as a nitrogen source, Ca+2 as minerals, and using static culture. The efficient production of laccases, lignin peroxidase, and manganese peroxidase enzymes by A. flavus proved that the enzyme played a crucial role in decolorizing the harmful azo dyes. The Fourier Transform Infrared spectrometer (FT-IR) data validated the decolorization and degradation process brought on by absorption and biodegradation. Compared to control plants, the results of the phytotoxicity assay showed that the degraded product was less harmful to maize and common bean plant's growth and germination rates. As a result, the findings indicate that A. flavus is a viable option for remediating azo dyes. This aids in the biodegradation of azo dyes found in wastewater.

Abstract licence: CC BY

A viability test for in vitro cultures, based on the intake of the textile dye alphazurine A by dead cells and its exclusion by viable cells, is described. This test uses the affinity of alphazurine A for proteins, so that the dye is retained in dead cells even after rinsing, while its anionic character prevents it from entering live cells. This feature makes this dye exclusion test amenable to a reading in a plate format. The alphazurine viability test provides an indicator of the absolute number of dead cells present in the culture well. To reach a cell viability index, a "dead cells" control (e.g. cells killed with ethanol) must be added. We also describe a double viability test, which first uses the alphazurine assay to provide the number of dead cells then a crystal violet assay to provide an index of the number of cells present in the plate. This double test provides a complete appraisal of the situation in the cell culture wells, and has been compared to other viability tests such as propidium iodide exclusion or tetrazolium reduction. Its performances to study the toxicity of substances such as pigments are also established, and allowed us to publish the first public toxicological data on the recently described Pigment Blue 86.

Abstract licence: CC BY-NC