Bioremediation of malachite green dye using <i>Sargassum wightii</i> seaweed and its biological and physicochemical characterization
Kumaravel Kaliaperumal, Janeeba Aboobacker, Vigneshpriya Dhanapal, Abinaya Gayathri, Kumaran Subramanian, Arumugam Suresh, Elumalai Sanniyasi, Shobana Sampath, Sandhanasamy Devanesan, Mohamad S. AlSalhi, Perumal Asaithambi
Abstract
Abstract Textile dye effluents and their contamination in aquatic environments is a serious risk pose of aquatic pollution. Degradation of such dyes using a biological treatment like microbe and plant-based remediation is an eco-friendly approach and more feasible than the physical and chemical treatment processes. In the present study, the biosorption of malachite green (MG) dye from aqueous solution using Sargassum wightii seaweed was evaluated. Using batch mode, several factors, including biosorbent concentration (1–6 g/L), pH (3–10), and temperature (25–60°C), that affected biosorption over a range of time intervals were determined. The absorption capacity was lowered as the temperature increased over 40°C. Similarly, at pH 3.0, the least adsorption of 23 mg/g was recorded. With a large elevation in pH, a gradual increment in adsorption was seen. At pH 7, a maximum uptake capacity of 78 mg/g was observed. The concentrations of dissolved oxygen demand and biological oxygen demand were much reduced in the treated dye-contaminated water. The BOD value decreased from 0.5 to 5,440 mg/L, and the COD value decreased from 20 to 2,080 mg/L as the biosorption time increased. S. wightii- mediated dye degradation resulted in reduced water toxicity level, which is ensured by seed germination when the dye-treated water was used using S. wightii . The dye-treated water exhibited no antimicrobial properties in terms of antifungal and antibacterial when compared to non-treated water. The biosorbent and adsorbent interactions were characterized using FTIR and SEM. FTIR interpretation revealed that the treated water reduces the dye concentration in water, which is evident through reduction of functional groups when compared with FTIR results of untreated water. Dye-treated water and its safe physicochemical and biological parameters were assessed using a green gram germination test and microbial toxicity assay using the treated water.