Efficacy of hazardous congo red removal from aqueous solutions via adsorption with carbon black: Batch and column study insights

Abstract

This study investigates the potential of commercial carbon black, sourced from a local waste tyre recycling plant, as an adsorbent in both batch and continuous column adsorption processes for the removal of Congo red (CR). The carbon black has been characterized using Fourier transform infrared spectroscopy and scanning electron microscopy to assess its surface properties. Additionally, the study aims to analyze the physicochemical interactions between carbon black and CR. Key experimental variables, including adsorbent dosage, pH, and contact time, are optimized through batch adsorption experiments to determine their impact on the removal efficiency of CR dye. Batch adsorption experiments confirmed that carbon black (adsorbent) attains maximum adsorption capacities of 76.92 mg/g for CR dye. Among the tested kinetic models, the pseudo-second-order model (R2 = 0.998) best described CR adsorption onto carbon black, outperforming the pseudo-first-order model (R2 = 0.986). A continuous adsorption study has been done to determine the effect of the flow rate of water, adsorbent bed diameter and bed height on the breakthrough time. About 90% removal of CR occurs when the bed height is larger than 5 cm and the bed diameter is larger than 2.7 cm.