Amorphous Fe-Mn binary oxides nanoparticles decorating waste bamboo biomass-based monolith for efficient arsenic removal with column adsorption

The removal of naturally occurring arsenic from aqueous media remains a challenging endeavor for the protection of public health and ecosystems. Herein, we devised a workable fresh-biomass-based monolith adsorbent by in situ generation of amorphous Fe-Mn binary oxides nanoparticles (Fe-Mn-O) on a waste bamboo biomass (MB) via a simple procedure of pre-oxidation plus co-precipitation. In the pre-oxidation process of MB, the surface underwent roughening and the manganese ions permeated deeply inside the biomass, both of which facilitated the loading of Fe-Mn-O (25.06 wt%). As a result, the Fe-Mn-O/MB had outstanding adsorption capacities of 33.41 and 36.88 mg g(-1) for As(III) and As(V), respectively. XRD and FTIR analyses show that the amorphous structure of Fe-Mn-O with low-coordinated active centers provides numerous hydroxyl functional groups that enhance arsenic adsorption, moreover, oxidation of As(III) was realized. In different water matrix, the Fe-Mn-O/MB composite exhibited a retention of 87.33 % and 89.53 % of its original adsorption capacity for As(III) and As(V) after five cycles of reuse as well as enabled continuous operation in a fixed-bed system with a bed volume of around 1150. Therefore, this work provides a promising approach for efficient abatement of inorganic arsenic-caused water pollution.