Optimized removal of Orange G dye using cetyltrimethylammonium bromide-modified natural waste material

Abstract The adsorption efficiency of modified pine cone powder using cetyltrimethylammonium bromide (PC-CTAB) biosorbent to remove Orange G (OG) dye from synthetic medium was investigated through batch adsorption experiments. The adsorbent was characterized by scanning electron microscopy (SEM), Fourier transform infrared, and X-ray diffraction spectroscopy. Optimum operating conditions for the adsorption process were determined by varying the solution pH, biosorbent dosage, contact time, initial concentration of OG dye, and temperature. The highest OG removal was achieved when 2 g L−1 of biosorbent was used to eliminate 30 mg L−1 of dye for an acidic medium of pH around 3.5 at an ambient temperature about 25 °C. The Dubinin-Radushkevich and sips isotherm models best described the adsorption of OG onto PC-CTAB, yielding the highest R 2 values (R 2 ≥ 0.98) associated with the lowest error values (χ 2, RMSE, SSE, and Δq). The calculated Dubinin-Radushkevich mean energy (E) was less than 8 kJ/mol, confirming the physical nature of adsorption onto PC-CTAB sorbent. The higher correlation coefficient for pseudo-second-order kinetics (R 2 > 0.9) compared to pseudo-first-order ones suggests that the pseudo-second-order kinetic model best describes the OG dye adsorption kinetics by PC-CTAB biosorbent. In conclusion, PC-CTAB is a promising efficient, low-cost, and eco-friendly adsorbent for dye wastewater removal.