Assessing South American Guadua chacoensis bamboo biochar and Fe3O4 nanoparticle dispersed analogues for aqueous arsenic(V) remediation

ALCHOURON, JACINTA; NAVARATHNA, C.; CHLUDIL, H. D.; DEWAGE, N. B.; PEREZ, F.; HASSAN, E. B.; PITTMAN JR., C. U.; ANDREA S. VEGA; MLSNA, T. E.

THE SCIENCE OF TOTAL ENVIRONMENT

ELSEVIER

Año: 2020 vol. 706

0048-9697

Discarded bamboo culms of Guadua chacoensis were used for biochar remediation of aqueous As(V).Raw biochar (BC), activated biochar (BCA), raw Fe3O4 nanoparticle-covered biochar (BC-Fe), and activated biochar covered with Fe3O4 nanoparticles (BCA-Fe) were prepared, characterized and tested for As(V) aqueous adsorption. The goalistodevelopaneconomic,viable,andsustainableadsorbenttoprovidesafearsenic-freewater.Adsorbents were characterized using scanning electron microscopy (SEM) and energy dispersive analysis by X-ray (SEMEDX),transmissionelectronmicroscopy(TEM)andenergydispersiveX-rayspectroscopy(TEM-EDS),X-rayphotoelectronspectroscopy(XPS),X-raypowderdiffraction (XRD),Brunauer-Emmett-Tellersurface areameasurements(SBET),pointofzerochargedeterminations(PZC),andelementalanalysis.ActivationwithKOHincreased the O/C ratio and the surface area of BC from 6.7 m2/g to 1239.7 m2/g (BCA). As(V) sorption equilibrium was achieved within b2 h for all four adsorbents and kinetics followed the pseudo-second-order model. At a 10mg/LinitialAs(V)concentration,BC-Feachieveda100%removal(5mg/g)overapH5to9window.Sorption was endothermic on all four adsorbents and the capacities rose with the increasing temperature. Langmuir capacities at 40 °C for BC, BCA, BC-Fe, and BCA-Fe were 256, 217, 457, and 868 mg/g, respectively, and capacities were compared with other sorbents. Breakthrough fixed-bed column sorption was carried out for BC and BCFeproducing6.6mg/gand13.9mg/g bed capacities,respectively.Potassium phosphate was a better As stripping agent than sodium bicarbonate.Performance oftheadsorbentsinanAs(V)-spiked natural water and a naturally As(V)-contaminated domestic water were assessed. Robust arsenate sequestration occurred generating As-safe water (As b0.01 mg/L), despite the presence of competing ions. Stoichiometric precipitation of iron-arsenate complexes triggered by iron dissolution was also established.