Effective Removal of Different Heavy Metals Ion (Cu, Pb, and Cd) from Aqueous Solutions by Various Molecular Weight and Salt Types of Poly--Glutamic Acid

In light of industrial developments, water pollution by heavy metals as hazardous chemicals has garnered attention. Addressing the urgent need for efficient heavy metal removal from aqueous environments, this study delves into using poly-gamma-glutamic acid (gamma-PGA) for the bioflocculation of heavy metals. Utilizing gamma-PGA variants from Bacillus subtilis with different molecular weights and salt forms (Na-bonded and Ca-bonded), the research evaluates their adsorption capacities for copper (Cu), lead (Pb), and cadmium (Cd) ions. It was found that Na-bonded gamma-PGA with a high molecular weight showed the highest heavy metal adsorption (92.2-98.3%), particularly at a 0.5% concentration which exhibited the highest adsorption efficiency. Additionally, the study investigated the interaction of gamma-PGA in mixed heavy metal environments, and it was discovered that Na-gamma-PGA-HM at a 0.5% concentration showed a superior adsorption efficiency for Pb ions (85.4%), highlighting its selectivity as a potential effective biosorbent for wastewater treatment. This research not only enlightens the understanding of gamma-PGA's role in heavy metal remediation but also underscores its potential as a biodegradable and non-toxic alternative for environmental cleanup. The findings pave the way for further exploration into the mechanisms and kinetics of gamma-PGA's adsorption properties.