Bio-sorption of metformin from aqueous solution using algae-based as effective biosorbents: Process optimization, kinetic, and isotherm studies

Abstract

The use of algae-based biosorbents to remove pollutants is one of the effective methods for the purification of contaminated water which has received great attention. Here, we used a blue-green algae Spirulina platensis (SP) in three different forms pure SP, KCl-modified SP, and H₃PO₄-modified SP as biosorbents for the removal of metformin from aqueous environments. The removal experiments of metformin using prepared biosorbents were monitored by various parameters such as pH of the media, contact time, sorbent dosage, and initial concentration of metformin. Adsorption kinetics and isotherms of metformin molecules onto all three biosorbents followed the pseudo-second-order and Langmuir models. Based on the Langmuir model, the maximum adsorption capacity of metformin onto SP, SP/KCl, and SP/H₃PO₄ was determined as 43.12, 44.64, and 48.54 mg/g, respectively. Green and environmentally friendly nature, cost-effective, easy preparation, good adsorption capacity, high fidelity, and recyclability are some of the prominent characteristics of the introduced biosorbents, which can act as a universal device for water and sewage treatment. A notable benefit of the bio compound of SP/H₃PO₄ is its optimal use as phosphorus fertilizer before the adsorption of metformin or after the desorption of adsorbed metformin.