Waste-to-resource: utilizing soot as a performing adsorbent for rhodamine B. structural characterization and process optimization

Abstract

This study investigates the potential of soot, a low-cost byproduct of incomplete combustion, as an effective adsorbent for the removal of rhodamine B (RhB) from aqueous solutions. The adsorbent was prepared from poultry heating furnace soot and characterized using SEM-EDX, particle size distribution, pH point zero charge, BET surface area, FTIR and XRD analysis. Results revealed a mesoporous structure (BET surface area: 249.19 m2 g−1, average pore diameter: 3.89 nm), and functional groups favorable to RhB adsorption. A Central Composite Design (CCD) under Response Surface Methodology (RSM) was applied to optimize process parameters (contact time, pH, initial concentration of RhB, and soot dosage). The model achieved high predictive accuracy (R2 = 98.87%), with adsorbent dosage and dye concentration identified as the most influential factors. Under optimized conditions, complete RhB removal (100%) was achieved under both neutral (95 min, pH 7, 147 mg L−1, 2 g L−1 adsorbent) and acidic environments (95 min, pH 3, 5 mg L−1, 2 g L−1 adsorbent). Compared to conventional activated carbons and other modified adsorbents reported in the published studies, soot achieved a maximum adsorption capacity of 226.57 mg g−1, comparable to several higher-cost materials, without requiring chemical activation or synthesis, highlighting its potential as a low-cost alternative for sustainable wastewater treatment applications.