Equilibrium and DFT modeling studies for the biosorption of Safranin O dye from water samples using Bacillus subtilis biosorbent

Current study deals with the biosorption of Safranin O dye from water by using high potential Bacil- lus subtilis biosorbent material. The presence of functional groups and surface morphology of biosor- bent was analyzed by using sophisticated analytical techniques such as FT-IR (Fouirer Transform Infrared Spectrophotometer), SEM (Scanning Electron Microscopy), EDX (Energy Dispersive X-Ray Analysis), and TGA (Thermogravimetric Analysis). To check the dye removal potential of Bacillus subtilis sorbent, batch adsorption experiments were performed under the optimized conditions. The biosorption experiments showed that the Bacillus subtilis sorbents remove 80% of safranin O dye from water. The biosorption mechanism is depends upon the solution pH thus the maximum biosorption was observed at (5.5–6.5). Moreover, the biosorbent dose has been optimized and it has observed that the maximum concentra- tion of safranin O dye has been removed using the 50 mg.L −1 of Bacillus subtilis . The biosorption equi- librium data were well fitted by the Langmuir adsorption isotherm due to good regression coefficient value ( R 2 = 0.98) and better Langmuir capacity (0.383 mmol.g −1 ), while the kinetic studies indicated that the biosorption followed the pseudo-second-order model. The thermodynamic parameters values showed that the biosorption is process is endothermic and spontaneous nature. In addition, molecular docking was also performed to examine the interaction between the safranin O dye molecule and the Bacillus subtilis bacterial cell line.