Novel Immobilization of Pseudomonas Aeruginosa on Graphene Oxide and Its Applications to Biodegradation of Phenol Existing in Industrial Wastewaters

A new biodegradtion method for removal of phenol and its derivatives has been considered. In this study the biochemical pathway involved in degradation of phenol through Pseudomonas aeruginosa bacterial cells which are immobilized on graphene oxide (GO) has been investigated. Since phenol is a toxic substance and eliminating it through a biological method is difficult, the phenol removal ability of the bacterial cells of P. aeruginosa has been considered in comparison with phenol adsorption on graphene oxide as a nanostructured adsorbent and P. aeruginosa supported on GO as a new biochemical adsorbent. For this purpose, graphene oxide was initially synthesized using the modified Hummer's method and the bacterial strain was supported on GO. Scanning electron microscopy was employed to identify their morphology and structure. Also surface functional groups were initially analyzed by FTIR. The variables involved in the phenol removal process including phenol initial concentration, adsorbent dosage, temperature. The best removal efficiency of the bacteria was carried out at optimum conditions of pH 7, biosorbent dose of 0.01 g and phenol initial concentration of 3 ppm after 45 min of contact time at 25 degrees C and up to 55% of phenol was removed. Using 0.01 g of GO and using 0.01 g of P. aeruginosa/GO attained to this removal efficiency at pH 7 after 60 and 45 min. of contact time, respectively, whereas the removal efficiency of the modified biochemical adsorbent of P. aeruginosa/GO was up to 92% at pH 3 after 45 min. of contact time. At the same condition phenol degradation using free cells of P. aeruginosa and using GO nanoparticles were 10.15 and 88.63%, respectively. Pseudo-second order kinetics described the biodegradation of phenol by P. aeruginosa supported on GO.