Fabrication of Fe-Ti heteroatom-based metal-organic framework with vantage defects for high-efficient arsenic removal from water

Abstract

<p>Arsenic (As) contamination in water remains a formidable concern due to its high toxicity and detrimental impacts on human health and the environment. Selective adsorption utilizing solid adsorbents has emerged as a promising method for the removal of arsenate (As(V)) from drinking water. However, current adsorbents encounter limitations in effectively reducing relatively low-concentration As(V) from water. Here, we designed a Fe-Ti heteroatom-based metal–organic framework (MOF) MIL-125(Ti,Fe) with vantage defects for efficient As(V) removal. In the batch adsorption experiments, MIL-125(Ti,Fe) exhibited an exceptional removal efficiency of 99.3 % from the 10 ppm As(V)-containing water, which clearly overperformed counterpart MOF adsorbents of MIL-125(Ti) and MIL-101(Fe). Kinetic analysis indicated that the adsorption behavior of all three adsorbents followed pseudo-second-order kinetics. Importantly, dynamic breakthrough experiments demonstrated that MIL-125(Ti,Fe) could effectively reduce the As(V) concentration from 1 ppm to 3 ppb, well below the safety limit of 10 ppb set by WHO. Mechanistic analysis revealed that the arsenic adsorption mechanism of MIL-125(Ti,Fe) involved chemical adsorption between As(V) and the incorporated Fe as well as formed oxygen vacancies in MIL-125(Ti,Fe), which acted as essential adsorption sites and interacted with As(V) through the formation of Fe-O-As groups. The novel MIL-125(Ti,Fe) adsorbent demonstrated its great potential for arsenic removal, particularly in treating relatively low-concentration As-contaminated water.</p>