Development, characterization and evaluation of iron-coated honeycomb briquette cinders for the removal of As(V) from aqueous solutions

The adsorptive removal of As(V) from aqueous solutions using iron-coated honeycomb briquette cinder (Fe-HBC) is presented. Low cost mechanical granulation process was integrated with surface amendment technology to prepare iron-oxide modified granular adsorbent for clean water production. Detailed characterizations were performed using FTIR, XRD, EDS and SEM techniques. Operating parameters including initial As(V) concentration, pH, contact time, adsorbent dose, iron leaching and the effects of competing ions on As(V) removal were evaluated. Results demonstrated that high amount of arsenate (961.5 μg g−1) was adsorbed at pH 7.5 in 14 h contact time. Langmuir, Freundlich and Temkin isotherm models were used to analyze the adsorption data, whereas Langmuir model was found to best represent the data with a correlation co-efficient (R2 = 0.999). Thus, As(V) sorption on Fe-HBC surface suggested monolayer adsorption and indicated surface homogeneity. Moreover, the dimensionless parameter (RL) value calculated to be about 0.118 that reiterated the process is favorable and spontaneous. The influences of competing ions on As(V) removal decreased in the following order: PO43−>HCO3−>F−>Cl−. The profound inhibition effects of PO43− revealed a high affinity toward iron(oxy) hydroxide. Life-cycle assessment confirmed that spent HBC is non-hazardous and can be used as a promising sorbent for arsenic removal.