Synthesis of S-doped activated carbons and evaluation in azo dye adsorption

The increasing environmental challenges and the urgent need for sustainable solutions have driven the exploration of advanced materials for various applications. Activated carbon has emerged as a versatile and promising option due to its exceptional adsorption capabilities. In this study, the production of activated carbon from Distillers Dried Grains with Solubles (DDGS) biomass samples was investigated through chemical activation and K2SO4 modification. For chemical activation, different impregnation ratios (1:1 and 2:1) of NaOH were employed, and the carbonization process was carried out at activation temperatures ranging from 650 to 750 °C. The obtained activated carbon samples were characterized using BET, FTIR, and SEM methods, and subsequently applied for the removal of Acid Red 111 dye from aqueous solutions. According to the results obtained from the study, the activated carbon sample with the highest surface area (994.9 m2/g) was achieved with a 2:1 impregnation ratio and a carbonization temperature of 750 °C. In the second phase of the study, the activated carbon obtained through the subsequent impregnation process with K2SO4 at 750 °C exhibited a maximum dye removal efficiency of 97.12%, and the maximum adsorption value (qmax) obtained using the Langmuir model was 158.73 mg/g. The characteristics of the obtained activated carbon were observed to be significantly influenced by the process conditions and production methods during the preparation of activated carbon. This study concludes that activated carbon derived from DDGS can be effectively used for the removal of dyes from aqueous solutions.