DOI: https://doi.org/10.55373/mjchem.v28i4.89

Keywords: Adsorption, clinoptilolite, Congo Red, CTAB, modification

Abstract

The persistence of Congo Red (CR) dye in industrial effluents poses serious environmental and health risks, as it is a known carcinogen that can degrade into benzidine, a compound highly toxic to aquatic organisms. Clinoptilolite, a natural zeolite, is a low-cost and eco-friendly adsorbent with a strong inherent adsorption capacity. Surface modification with cetyltrimethylammonium bromide (CTAB) at concentrations of 0.05–5.0 mM has proven effective in enhancing its adsorption performance. This study comparatively evaluated the CR removal efficiency of CTAB-modified clinoptilolite in granular, powdered, and pelletized forms. The modified samples were characterized using FTIR, XRD, SEM and BET surface area analyses. FTIR and XRD confirmed successful surface modification without altering the zeolitic framework, while SEM revealed distinct morphological and porosity differences among the forms. BET analysis showed that pelletized CTAB-clinoptilolite had a surface area of 8.92 m²/g and an average pore diameter of 10.51 nm. The optimal CTAB concentration was 1.0 mM for the granule and powder forms, which achieved maximum adsorption capacities of 6.79 and 7.60 mg/g, respectively, whereas pellets performed optimally at 5.0 mM with a capacity of 5.35 mg/g. This study highlights the potential of tailored clinoptilolite for practical wastewater treatment by balancing adsorption performance and structural stability.