Highly Efficient Sorption of Methyl Orange by a Metal–Organic Resin–Alginic Acid Composite

The composite anion‐exchange material MOR‐1–HA (metal–organic resin‐1–alginic acid) was investigated as sorbent for the capture of the methyl orange anion (MO − ) from aqueous solutions. MOR‐1–HA shows a remarkably high sorption capacity (up to 859 mg g −1 ) and rapid sorption kinetics, the fastest among the reported metal–organic sorbents. It is capable of absorbing MO − over a wide pH range (1–8) and, in addition, it exhibits significant MO − sorption affinity even in the presence of large excesses of competing anions (e.g., Cl − , NO 3 − , SO 4 2− ). The exceptional MO − ‐sorption properties of MOR‐1–HA arise not only from its highly porous structure and easily exchangeable Cl − anions, but also from a multitude of interaction effects, such as electrostatic interactions between MO − and the NH 3 + groups of the material, hydration/dehydration, hydrophobicity/hydrophilicity, size and capacity of generating lateral interactions, and intercalation as revealed by theoretical studies. An ion‐exchange column with a stationary phase containing MOR‐1–HA and silica sand showed high efficiency for the removal of MO − from various types of aqueous samples. The column can be readily regenerated and reused for many runs with minimal loss (2.3–9.3 %) of its exchange capacity. The simplicity of the MOR‐1–HA /sand column and its high regeneration capability and reusability make it particularly attractive for application in the remediation of MO − ‐contaminated industrial wastewater.