The presence of harmful contaminants in the waste stream is an important concern worldwide. The convergence of biotechnology and nanoscience offers a sustainable alternative in treating contaminated waters. Hexavalent chromium, being carcinogenic deserves effective and sustainable methods for sequestration. Here in, we report the immobilization of a prokaryote (Rhizobium) and eukaryote (Saccharomyces cerevisiae) in multiwalled carbon nanotubes (MWCNTs) for the effective adsorption of hexavalent chromium. The carboxylic groups were introduced into the MWCNTs during oxidation using potassium permanganate and were subjected to EDC-HOBT coupling to bind with microbial cell surface. FTIR, TGA, BET, FESEM-EDAX, HRTEM, XPS and confocal microscopy were the investigative techniques used to characterize the developed biosorbents. Experimental variables such as pH, adsorbent dosage, kinetics, isotherms and thermodynamics were investigated and it was observed that the system follows pseudo second order kinetics with a best fit for Langmuir isotherm. Electrostatic interactions between the functional groups in the microbial cell wall and hydrochromate anion at pH 2.0 propel the adsorption mechanism. The lab scale column studies were performed with higher volumes of the Cr(VI) contaminated water. Sodium hydroxide was used as the desorbing agent for reuse of the biosorbents. The sustainable biosorbents show prospects to treat chromium contaminated water.

Multidisciplinary approach involving biotechnology and chemistry opens up avenues to develop adsorbent materials that can be very useful to alleviate heavy metal toxicity. Towards this direction, we have explored the potential of endomycorrizhal fungal spores in conjunction with a clay mineral as a novel approach for chromium (VI) adsorption. The immobilization of AMF (Arbuscular Mycorrhizal fungus) spores in montmorillonite (in its Na+ form) provides a good platform to adsorb hexavalent chromium. The adsorption was observed at pH 2.0‐3.0 involving the electrostatic interaction between the functional groups present in the fungi‐clay biosorbent surface and tetraoxohydrochromate (VI) anion. Diverse characterization techniques such as Fourier Transform‐Infrared spectroscopy (FTIR), X‐ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), confocal microscopy and X‐ray fluorescence (XRF) were used to observe the interaction of chromium with the biosorbent. Batch adsorption studies involving the experimental variables such as pH variation, kinetics, isotherms and thermodynamics were performed. Pseudo second order kinetics coupled with a Langmuir adsorption capacity of 11.185 mg g−1was realized for this biosorption process. The biosorbent was stable and regenerated for three adsorption‐desorption cycles using sodium hydroxide.