One-pot synthesis of A novel metal organic framework-modified TiO2@Cr-PTC-HIna as adsorbent for Pb2+ removal in aqueous system

Metal Organic Framework (MOF) has great potential to be applied as an adsorbent in the removal of heavy metal ions Pb²⁺ in wastewater because it has a large specific surface area with abundant pores, as well as good chemical stability in aqueous systems. To improve its adsorption ability, MOF is incorporated with other materials to form a composite such as TiO₂. This study aims to synthesize a new MOF-based composite containing chromium metal and isonicotinic acid-modulated perylene organic linker (Cr-PTC-HIna) with TiO₂ loading using one-pot solvothermal for enhanced Pb²⁺ removal in aqueous systems. Then, the adsorbent materials were characterized by fourier transform infrared (FT-IR), X-ray diffraction (XRD), surface area analyzer (SAA), scanning electron microscopy-energy dispersive X-ray (SEM-EDX). TiO₂ loading created composites with larger surface area and greater adsorption capacity than Cr-PTC-HIna MOFs without TiO₂. The batch experiment exhibited The Cr-PTC-HIna composite with Cr and Ti mole ratio of 1:2 mmol showed an adsorption capacity of 135.14 mgg⁻¹ at 200 ppm Pb²⁺, pH 4, time 90 min and 298 K. The isotherm studies explained that Pb²⁺ was adsorbed through both physical and chemical interactions, followed the pseudo second-order model, and occurred exothermically, non-spontaneous. FT-IR and XRD investigations before and after use showed that the composites have good stability in aqueous solutions especially under acidic conditions, which implies that the developed composites provide enormous potential in the development of adsorbent materials for the removal of heavy metal ions in industrial wastewater which generally has a low pH value.