Nanoscale ferrihydrite incorporated biopolymeric composites prepared for arsenic removal from water. Composite shows excellent adsorption capacities for both arsenite and arsenate (overall >100 mg/g). Low dosage of the composite shows very fast kinetics over a wide pH range of water sample. The green synthesis yields a thermally stable composite with very high mechanical strength. This robust nanocomposite is industrially viable and offers an affordable and sustainable solution to arsenic contamination. © Springer Nature Switzerland AG 2020.