Enhancing Organic Dye Removal with Biopolymeric Ferric Sulfate-Modified Diatomite: Characterization, Adsorption Performance, and Mechanism Insights

Abstract

Diatomite (DE) is a widely used adsorption material in wastewater treatment due to its cost-effectiveness, high porosity, and stability. To improve its adsorption properties, we synthesized biopolymeric ferric sulfate (BPFS) through biocatalytic oxidation, known for its efficient removal of organic compounds. In this study, we prepared a novel adsorbent, biopolymeric ferric sulfate-modified diatomite (BPFS-DE), by modifying DE with BPFS. We characterized DE and BPFS-DE using various techniques, including scanning electron microscopy (SEM), N2 adsorption–desorption, and X-ray diffraction (XRD), to assess their physical and chemical properties before and after modification. We investigated the adsorption performance of BPFS-DE for acid chrome blue K (ACBK) and analyzed the adsorption mechanisms. Our results revealed that modification with BPFS increased the porosity and specific surface area of DE. BPFS-DE exhibited remarkable adsorption capabilities (98.6%) for ACBK under pH 6.0, 30 °C, and a 30-minute adsorption time. Langmuir adsorption isotherm models demonstrated excellent agreement (R = 0.9896) with the adsorption data, highlighting the effectiveness of the BPFS-DE adsorbent. Furthermore, the pseudo-second-order reaction kinetics model provided a better fit (R = 0.9075) than the pseudo-first-order model, accurately reflecting the adsorption process. The adsorption process was found to be spontaneous and exothermic. Notably, BPFS-DE outperformed DE in terms of adsorption efficiency. The synthesized BPFS-DE emerges as a promising adsorbent for treating industrial wastewater contaminated with dyes.