Abstract
Remazol brilliant blue (RBB) is an anthraquinone anionic dye that has several commercial uses, especially in the textile industries and is well-known for its detrimental impacts on marine life and the surrounding ecosystem. Mercury (Hg2+) is also one of the most severe hazardous environmental contaminants due to its bioaccumulation through the food chain and high toxicity to the human embryo and fetus. The biosorption potential of Gelidium corneum biomass for bioremoval of Hg2+ and RBB dye simultaneously from binary mixture was assessed. The effects of initial pH, contact time, Hg2+, RBB, and biomass concentrations on the biosorption process were investigated in 50 batch experiments using a Face-centered central composite design. The maximum removal percentage of Hg2+ (98.25%) was achieved in the run no. 14, under optimum experimental conditions: 200 mg/L Hg2+, 75 mg/L RBB, pH 5. At 30 °C, 4 g/L algal biomass was used, with a contact time of 180 min. Whereas, the maximum removal percentage of RBB (89.18%) was obtained in the run no. 49 using 200 mg/L Hg2+, 100 mg/L RBB, pH 5, 4 g/L algal biomass and 180 min of contact time. FTIR analysis of Gelidium corneum biomass surface demonstrated the presence of many functional groups that are important binding sites responsible for Hg2+ and RBB biosorption. SEM analysis showed apparent morphological alterations including surface shrinkage and the appearance of new shiny adsorbate ion particles on the Gelidium corneum biomass surface after the biosorption process. The EDX study reveals an additional optical absorption peak for Hg2+, confirming the role of Gelidium corneum biomass in Hg2+ biosorption. In conclusion, Gelidium corneum biomass has been shown to be an eco-friendly, sustainable, promising, cost-effective and biodegradable biosorbent to simultaneously biosorb Hg2+ and RBB dye from aquatic ecosystems.
Highlights
Heavy metal cations are amongst the most frequent inorganic pollutants in industrial effluents
The red alga Gelidium corneum biomass was used as a sustainable feedstock for the biosorption process of Hg2+ and Remazol brilliant blue dye from binary solution
The simultaneous biosorption process of dyes and heavy metals by algae could be affected by many operating process variables such as contact time, initial pH level, algal biomass dosage, initial metal and dye concentrations[25,26]
Summary
Heavy metal cations are amongst the most frequent inorganic pollutants in industrial effluents. Several traditional methods were used to remove the water pollutants, including chemical oxidation or reduction, chemical precipitation, evaporation and adsorption, filtration, reverse osmosis, electrochemical treatment and ion exchange[15] These approaches are often limited in terms of technological feasibility due to a high cost, ineffectiveness in achieving legal discharge levels (especially in low concentrations effluents), the use of a lot of reagents or energy, as well as the production of a lot of toxic wastes. Several studies have shown that removal of the contaminants from wastewater by microorganisms has many advantages over conventional treatment methods These include high efficacy in diluted effluents, environmental friendliness, high metal binding ability, utilizing different cost-effective biosorbents, minimization of chemical and/or biological sludge, and the ability to regenerate biosorbents with the possibility of recovering the m etal[20]
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