Purification of arsenic-contaminated water using iron molybdate filters and monitoring of their genotoxic, mutagenic, and cytotoxic effects through bioassays.

Environmental contamination has been a cause of concern worldwide, being aggravated by anthropogenic activities carried out without the correct disposal of toxic products in the various habitats on our planet. In Brazil, mining companies are responsible for the contamination of large river basins with toxic elements from mining activities. Among these elements, arsenic draws attention because it is highly carcinogenic and found in waters in concentrations above those recommended by regulatory agencies. Here, Fe2(MoO4)3 nanoparticles are synthesized and used as a filter medium in water purification systems contaminated with arsenic. The adsorption kinetics of arsenic by Fe2(MoO4)3 nanoparticles is fast, showing pseudo-second-order rate constants of 0.0044, 0.0080, and 0.0106 g mg-1 min-1 for As3+, As5+, and MMA, respectively. The adsorption isotherms are better adjusted with the Langmuir and Redlich-Peterson models, indicating that the arsenic adsorption occurs in monolayers on the Fe2(MoO4)3 surface. The Fe2(MoO4)3 adsorption capacities determined for the As3+, As5+, and MMA species are 16.1, 23.1, and 23.5 mg g-1, respectively. The Fe2(MoO4)3 filter is efficient in purifying arsenic-contaminated water, reducing its initial concentration from 1000 μg L-1 to levels close to zero. Biological tests indicate that Fe2(MoO4)3 nanoparticles and filtered water have no cytotoxic, genotoxic, and mutagenic risks to human life. Those results suggest that the Fe2(MoO4)3 filter can be used as an efficient and safe technology for the purification of water contaminated by arsenic.