A co-operative endeavor by nitrifying bacteria Nitrosomonas and Zirconium based metal organic framework to remove hexavalent chromium

The problems associated with heavy metal pollution require effective methods for their decontamination. Biosorption is an eco-friendly option to alleviate this problem. In this work, we propose the utility of Nitrosomonas modified Zirconium metal organic framework as a novel biosorbent for the remediation of toxic hexavalent chromium. Detailed analytical characterization of the synthesized biosorbent was performed using various techniques such as Powder X-ray Diffraction (PXRD), Fourier Transform Infrared (FTIR), X-ray Photoelectron Spectroscopy (XPS), Thermo Gravimetric analysis (TGA), Optical microscopy, Field Emission Scanning Electron Microscopy (FESEM), High Resolution Transmission Electron Microscopy (HRTEM), surface area and porosity measurements. The developed biosorbent has a surface area of 921 m2 g−1. Important batch adsorption parameters such as pH variation, adsorbent dosage, kinetics, isotherms and temperature variation were studied. A multilayer Freundlich adsorption and pseudo second order kinetics drive the exothermic biosorption process. The electrostatic interactions between the biosorbent surface and metal ions aid towards understanding the adsorption mechanism. Laboratory scale column studies were conducted and the regeneration of the biosorbent was done using sodium hydroxide. The validity of the method was tested in a certified reference material BCR-032 (Moroccan rock phosphate) for the removal of total chromium.