Eco-friendly approach for biosorption of Pb²⁺ and carcinogenic Congo red dye from binary solution onto sustainable...

Dyes constitute an important group of organic contaminants and are recognized for its harmful effects on the aquatic environments and humans. Heavy metals are also the largest group of inorganic pollutants due to their accumulation in the environment, contaminate food chains and cause adverse effects on the living organisms. Biosorption capacity of Ulva lactuca biomass was assessed in batch experiments for simultaneous removal of Pb²⁺ and Congo red dye from binary solution. The process variables effects on Congo red dye and Pb²⁺ removal percentages were explored by performing 50 experiments using Face-centered central composite design. The highest removal percentages of Congo red dye (97.89%) and Pb²⁺ (98.78%) were achieved in the run no. 24, using 100 mg/L Congo red dye, 200 mg/L Pb²⁺, 3 g/L algal biomass, initial pH 6 and contact time was 120 min at 30 °C. FTIR analysis of the algal biomass showed the existence of many functional groups responsible for the biosorption process. After the biosorption process, SEM analysis revealed obvious morphological changes including surface shrinkage and the presence of new glossy Pb²⁺ particles, and the EDS spectra reveals presence of additional Pb²⁺ peak confirming the capacity of Ulva lactuca biomass to remove Pb²⁺ from binary solution.