What environmental and health concerns are associated with dye contaminants in wastewater, and why is methylene blue a particular focus in remediation efforts?

Industries are discharging significant quantities of dyes into ecosystems, leading to contamination of soil, groundwater, and surface water, and the textile industry's rapid growth exacerbates this issue with residual dyes in wastewater contributing to environmental degradation. Dye contaminants in textile wastewater are a major concern due to their complicated molecular structure and non-biodegradability. Methylene blue (MB) is a frequently investigated dye because of its widespread use in textiles, paper, printing, and leather processing, which results in its presence in industrial effluent. MB molecules have a positively charged cationic group, attracting them to negatively charged surfaces, which facilitates their adsorption. The release of methylene blue-rich effluent negatively impacts aquatic life and ecosystems, as it can harm fish, algae, and invertebrates by interfering with their respiratory and metabolic functions. Furthermore, MB's persistence and potential for bioaccumulation present long-term hazards. In humans, methylene blue can cause skin and eye irritation, with prolonged or high-level exposure potentially leading to methemoglobinemia, a condition that reduces the blood's oxygen-carrying capacity.

Intervention strategies are critical for managing methylene blue-containing wastewater to reduce potential harm to environmental and human health. Adsorption has emerged as a practical and effective method for removing methylene blue from wastewater by binding MB molecules to solid surfaces called adsorbents. Various materials, including activated carbons, metal-organic frameworks, charcoal, and agriculture waste-derived compounds, have been explored as methylene blue adsorbents. This study specifically focuses on the use of both treated and untreated adsorbents derived from discarded fruit seeds. Biowaste fruit seeds offer a low-cost alternative to commercial activated carbon for effective, large-scale removal of various pollutants from aquatic environments.