Removal and recovery of hazardous congo red from aqueous environment by selective natural amino acids in simple processes

In simple processes, this study used natural amino acids to remove and recover toxic Congo red (CR) dye from different aqueous environments. Various biophysical methods have been used to confirm and estimate the removal of CR. CR was removed efficiently by selective amino acids, namely aspartic acid, glutamic acid, phenylalanine, and tryptophan. All these amino acids removed 95-97% of CR from an aqueous solution at room temperature. Irrespective of pH, CR could be removed easily and effectively (95-97%) by phenylalanine, tryp-tophan, and glutamic acid, while aspartic acid is effective at acidic pH, and efficiency was concentration dependent. Importantly, amino acids removed CR selectively from the dye solution mixture, and the effluent of leather processing (after the dying process) spiked with CR. The removal of the CR process was a simple two-step process without involving any equipment or hazardous chemicals and a tedious step. CR recovery from the amino acid-CR mixture was achieved (97%) by adding methanol, where CR got solubilized in methanol while amino acids remained solid. Since amino acids are biocompatible, biodegradable, and commercially viable, we firmly believe that amino acids could be a potential biomolecule for removing and recovering CR from colourant in-dustrial wastewater in adopting simple processes.

Automated summary

In this study, natural amino acids were used to efficiently remove and recover toxic Congo red dye from aqueous environments. Specific amino acids, such as aspartic acid, glutamic acid, phenylalanine, and tryptophan, were found to effectively remove 95-97% of the dye. The removal process was simple and did not require any equipment or hazardous chemicals.