Development of efficient and sustainable adsorbents with perovskite and pyrochlore structures for removing pollutants

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The development of adsorbents for removing contaminants from wastewater, which have not only high efficiency, but also the capacity for regeneration and reuse is extremely necessary. In this study, sustainable and efficient adsorbents with perovskite (LaFeO3) and pyrochlore (La2Zr2O7 and La2Fe0.3Zr1.7O7) structures were developed for removing organic pollutants (such as the turquoise blue (TB)) from the aqueous media. They were synthesized by a previously reported synthesis method, and have a specific surface area between 12 and 29 m2 g−1, pH at a point of zero charge from 3.5 to 6.9, and a surface charge density negative value. The adsorbents presented high efficiency for the removal of TB contaminant, with values of up to 98% ( q ≅ 294), and they maintained the adsorption capacities and efficiency high ( E% > 95%; q > 115) in all three studied regeneration-reuse of adsorbents cycles using the methodology 2 and in five cycles ( E% = 70 to 98, q = 27 to 165) using methodology 1. They also proved to be efficient in removing a pollutant compound from real effluent collected from a small local industry, as well as showing capacity for regeneration and reuse in three cycles studied. The perovskite and pyrochlore structures are maintained after adsorption test and regeneration and the TB compound adsorbed is degraded during thermal treatment. The removal mechanism may involve acid–base interactions, hydrogen bonds, electrostatic interactions, and cation–π interactions.