Simultaneous scavenging of As(V) and safranin O dye by Mg/Al LDH-zeolite heterocoagulated materials: The effect of adsorbent synthesis approach on its efficiency in static and dynamic system

Abstract

Increasing demand for simultaneous removal of organic and inorganic pollutants from wastewaters causes a growing popularity of hybrid materials with dual adsorption properties. This study investigated the effect of heterocoagulated materials synthesis conditions on their adsorption efficiency both in static and dynamic conditions. The heterostructures containing layered double hydroxides (LDHs) and zeolite were synthesized via two approaches: facile, one-pot hydrothermal synthesis and co-precipitation of LDH on the hydrothermally obtained zeolite. The low-cost and abundant kaolin group minerals have been used as precursors for the zeolite synthesis. The results emphasized the advantage of hydrothermal materials in removal of As(V) and cationic dye safranin O (SO) in both single and dual-component systems. The high specific surface area of hydrothermal materials (139.5 m2/g) influenced the superior SO removal properties. All of the obtained heterostructures were also highly effective in As(V) adsorption due to their significant anion exchange capacity of 56.5–120.4 meq/100 g. The best material was transformed into hydrogel beads by encapsulation with the use of sodium alginate polymer. It was tested in a custom-made flow-through column. In addition to the efficient adsorbates removal, the dynamic experiments highlighted the importance of the physical behavior of the adsorbent granules in the adsorption column.