Efficient removal of para arsanilic acid with Ca-Al-Fe composite: Performances and mechanisms

Para arsanilic acid (p-ASA) as the one of the sources of highly toxic and carcinogenic inorganic arsenic is frequently excreted into the aqueous systems, raising serious environmental hazards and human health risks. Thus, it is compelling to develop techniques that can realize high efficiency of p-ASA removal while being cost effective. Here, a ternary composite material Ca-Al-Fe was designed via facile mechanochemistry and lowtemperature calcination on the mixture of inexpensive and readily available Ca(OH)(2), C6H9AlO6 and FeC2O4. The results showed that the resulting Ca-Al-Fe composite was capable of achieving a preferable p-ASA adsorption from water with high adsorption capacity (41.23 mg/g), fast kinetic (30 min), long-term stability and reusability on account of the interfacial synergetic effect between ternary composite components. Furthermore, the mechanism investigation demonstrated that, in the preparation stage, CO2 was liberated by the decomposition of FeC2O4, leading to a favorable porous structure and the formation of CaCO3. In the adsorption stage, the hydrolysis of generated CaCO3 enabled the continuous release of OH-, which induced in situ formation of high reactive Fe and Al hydroxides by Al3+ and Fe3+ to adsorb p-ASA by hydrogen bond and coordination interactions. The current work provides a new insight and direction for the development of high-performance metal composite materials.