Efficient adsorption of Sudan dyes from food and plants by activated carbon derived from Nelumbinis stamen

This study uses phosphoric acid activation and carbonization processes to create Nelumbinis stamen activated carbon (NSAC) from food waste precursors in a single step. The resultant NSAC was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, N-2 adsorption/desorption methods, X-ray diffraction, and Raman spectroscopy for surface morphology, structural features, and surface chemistry. The operating conditions, including the carbonization temperature, amount of adsorbent, adsorption temperature, and aqueous solution pH, were optimized to maximize the removal efficiency of Sudan dyes. Therefore, the values of the optimized conditions were selected as 500celcius for the carbonization temperature, 0.4 g L-1 for the adsorbent dose, 50celcius for the adsorption temperature, and a pH of 3.0 for the aqueous solution. In addition, the pseudosecond-order kinetic model and Langmuir isotherm model fit the experimental data best. Moreover, the maximum adsorption capacities of the four dyes on NSAC calculated according to the Langmuir adsorption model were in the range of 34.60-38.97 mg g(-1). Furthermore, thermodynamic results revealed that the adsorption process was spontaneous, feasible, and endothermic. Finally, the activated carbon was used for the adsorption of Sudan dye solution from chrysanthemum tea and cooked egg samples, and the results showed that the adsorbent could be successfully used for the adsorption and removal of the dyestuff solution.

Automated summary

This study developed Nelumbinis stamen activated carbon (NSAC) through phosphoric acid activation and carbonization processes. The NSAC was characterized for its surface morphology, structural features, and surface chemistry. The optimal operating conditions were determined to maximize the removal efficiency of Sudan dyes. The NSAC exhibited high adsorption capacity for the dyes and the adsorption process was found to be spontaneous, feasible, and endothermic.