Biosorption of Cadmium by Living and Non‐living Cells of Pseudomonas aeruginosa DR7

ABSTRACT The global concern over health issues related to heavy metal pollution has driven the adoption of various treatment technologies. The investigation into optimal conditions for cadmium biosorption and bioaccumulation was conducted using a resilient bacterial strain, Pseudomonas aeruginosa DR7, which was isolated from ponds. The equilibrium time of the adsorption process of living cells was much longer than that of non‐living cells, which was about 240 min, which indicates that living cells have intracellular accumulation and delay the adsorption process. Living cells favored a pH of 6.0, while non‐living cells showed higher efficiency at pH 7.0, demonstrating the pH‐dependent nature of metal biosorption. In this context, the maximum biosorption capacities for cadmium using non‐living cells and living cells were 103.8 mg/g and 70.94 mg/g, under cell mass of 1.0 g/L, pH 7.0, initial metal concentration of 200 mg/L, and contact time of 240 min, respectively. Cadmium biosorption by living cells was more accurately described by the Freundlich isothermal model, whereas the Langmuir model was used for non‐living cells. Living cells tend to show pseudo‐second‐order kinetic adsorption behavior, while non‐living cells tend to show pseudo‐first‐order kinetic adsorption behavior. Fourier‐transform infrared spectroscopy (FTIR) analysis suggested that the hydroxyl, amino, and carboxyl groups all play a role in biosorption. Scanning electron microscopy (SEM)–energy dispersive x‐ray spectroscopy (EDS) showed that the high‐temperature treatment destroys the integrity of the cell wall, which enhances the permeability of the cell wall, thus increasing the biosorption of Cd (II) by the non‐living cells. The study found that P. aeruginosa DR7 with high temperature inactivation has a higher Cd(II) adsorption capacity than living cells, making it a green and environmentally friendly biological adsorbent for wastewater treatment with heavy metals.